inital commit

go.mod

@@ -0,0 +1,20 @@
+module erp_system
+
+go 1.25.6
+
+require (
+	github.com/dustin/go-humanize v1.0.1 // indirect
+	github.com/google/uuid v1.6.0 // indirect
+	github.com/gorilla/securecookie v1.1.2 // indirect
+	github.com/gorilla/sessions v1.4.0 // indirect
+	github.com/mattn/go-isatty v0.0.20 // indirect
+	github.com/ncruces/go-strftime v1.0.0 // indirect
+	github.com/remyoudompheng/bigfft v0.0.0-20230129092748-24d4a6f8daec // indirect
+	golang.org/x/crypto v0.47.0 // indirect
+	golang.org/x/exp v0.0.0-20251023183803-a4bb9ffd2546 // indirect
+	golang.org/x/sys v0.40.0 // indirect
+	modernc.org/libc v1.67.6 // indirect
+	modernc.org/mathutil v1.7.1 // indirect
+	modernc.org/memory v1.11.0 // indirect
+	modernc.org/sqlite v1.44.3 // indirect
+)

go.sum

@@ -0,0 +1,29 @@
+github.com/dustin/go-humanize v1.0.1 h1:GzkhY7T5VNhEkwH0PVJgjz+fX1rhBrR7pRT3mDkpeCY=
+github.com/dustin/go-humanize v1.0.1/go.mod h1:Mu1zIs6XwVuF/gI1OepvI0qD18qycQx+mFykh5fBlto=
+github.com/google/uuid v1.6.0 h1:NIvaJDMOsjHA8n1jAhLSgzrAzy1Hgr+hNrb57e+94F0=
+github.com/google/uuid v1.6.0/go.mod h1:TIyPZe4MgqvfeYDBFedMoGGpEw/LqOeaOT+nhxU+yHo=
+github.com/gorilla/securecookie v1.1.2 h1:YCIWL56dvtr73r6715mJs5ZvhtnY73hBvEF8kXD8ePA=
+github.com/gorilla/securecookie v1.1.2/go.mod h1:NfCASbcHqRSY+3a8tlWJwsQap2VX5pwzwo4h3eOamfo=
+github.com/gorilla/sessions v1.4.0 h1:kpIYOp/oi6MG/p5PgxApU8srsSw9tuFbt46Lt7auzqQ=
+github.com/gorilla/sessions v1.4.0/go.mod h1:FLWm50oby91+hl7p/wRxDth9bWSuk0qVL2emc7lT5ik=
+github.com/mattn/go-isatty v0.0.20 h1:xfD0iDuEKnDkl03q4limB+vH+GxLEtL/jb4xVJSWWEY=
+github.com/mattn/go-isatty v0.0.20/go.mod h1:W+V8PltTTMOvKvAeJH7IuucS94S2C6jfK/D7dTCTo3Y=
+github.com/ncruces/go-strftime v1.0.0 h1:HMFp8mLCTPp341M/ZnA4qaf7ZlsbTc+miZjCLOFAw7w=
+github.com/ncruces/go-strftime v1.0.0/go.mod h1:Fwc5htZGVVkseilnfgOVb9mKy6w1naJmn9CehxcKcls=
+github.com/remyoudompheng/bigfft v0.0.0-20230129092748-24d4a6f8daec h1:W09IVJc94icq4NjY3clb7Lk8O1qJ8BdBEF8z0ibU0rE=
+github.com/remyoudompheng/bigfft v0.0.0-20230129092748-24d4a6f8daec/go.mod h1:qqbHyh8v60DhA7CoWK5oRCqLrMHRGoxYCSS9EjAz6Eo=
+golang.org/x/crypto v0.47.0 h1:V6e3FRj+n4dbpw86FJ8Fv7XVOql7TEwpHapKoMJ/GO8=
+golang.org/x/crypto v0.47.0/go.mod h1:ff3Y9VzzKbwSSEzWqJsJVBnWmRwRSHt/6Op5n9bQc4A=
+golang.org/x/exp v0.0.0-20251023183803-a4bb9ffd2546 h1:mgKeJMpvi0yx/sU5GsxQ7p6s2wtOnGAHZWCHUM4KGzY=
+golang.org/x/exp v0.0.0-20251023183803-a4bb9ffd2546/go.mod h1:j/pmGrbnkbPtQfxEe5D0VQhZC6qKbfKifgD0oM7sR70=
+golang.org/x/sys v0.6.0/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
+golang.org/x/sys v0.40.0 h1:DBZZqJ2Rkml6QMQsZywtnjnnGvHza6BTfYFWY9kjEWQ=
+golang.org/x/sys v0.40.0/go.mod h1:OgkHotnGiDImocRcuBABYBEXf8A9a87e/uXjp9XT3ks=
+modernc.org/libc v1.67.6 h1:eVOQvpModVLKOdT+LvBPjdQqfrZq+pC39BygcT+E7OI=
+modernc.org/libc v1.67.6/go.mod h1:JAhxUVlolfYDErnwiqaLvUqc8nfb2r6S6slAgZOnaiE=
+modernc.org/mathutil v1.7.1 h1:GCZVGXdaN8gTqB1Mf/usp1Y/hSqgI2vAGGP4jZMCxOU=
+modernc.org/mathutil v1.7.1/go.mod h1:4p5IwJITfppl0G4sUEDtCr4DthTaT47/N3aT6MhfgJg=
+modernc.org/memory v1.11.0 h1:o4QC8aMQzmcwCK3t3Ux/ZHmwFPzE6hf2Y5LbkRs+hbI=
+modernc.org/memory v1.11.0/go.mod h1:/JP4VbVC+K5sU2wZi9bHoq2MAkCnrt2r98UGeSK7Mjw=
+modernc.org/sqlite v1.44.3 h1:+39JvV/HWMcYslAwRxHb8067w+2zowvFOUrOWIy9PjY=
+modernc.org/sqlite v1.44.3/go.mod h1:CzbrU2lSB1DKUusvwGz7rqEKIq+NUd8GWuBBZDs9/nA=

internal/database/database.go

@@ -0,0 +1,33 @@
+package database
+
+import (
+	"database/sql"
+	"fmt"
+	"log"
+
+	_ "modernc.org/sqlite"
+)
+
+func Initialize(dbPath string) (*sql.DB, error) {
+	db, err := sql.Open("sqlite", dbPath+"?_pragma=journal_mode(WAL)&_pragma=foreign_keys(1)")
+	if err != nil {
+		return nil, fmt.Errorf("opening database: %w", err)
+	}
+
+	if err := db.Ping(); err != nil {
+		return nil, fmt.Errorf("pinging database: %w", err)
+	}
+
+	db.SetMaxOpenConns(1) // SQLite handles one writer at a time
+
+	if err := runMigrations(db); err != nil {
+		return nil, fmt.Errorf("running migrations: %w", err)
+	}
+
+	if err := seedData(db); err != nil {
+		return nil, fmt.Errorf("seeding data: %w", err)
+	}
+
+	log.Println("Database initialized successfully")
+	return db, nil
+}

internal/database/migrations.go

@@ -0,0 +1,164 @@
+package database
+
+import (
+	"database/sql"
+	"fmt"
+	"log"
+
+	"golang.org/x/crypto/bcrypt"
+)
+
+func runMigrations(db *sql.DB) error {
+	migrations := []string{
+		// Users table
+		`CREATE TABLE IF NOT EXISTS users (
+			id INTEGER PRIMARY KEY AUTOINCREMENT,
+			username TEXT NOT NULL UNIQUE,
+			password_hash TEXT NOT NULL,
+			created_at DATETIME DEFAULT CURRENT_TIMESTAMP
+		)`,
+
+		// Customers table
+		`CREATE TABLE IF NOT EXISTS customers (
+			id INTEGER PRIMARY KEY AUTOINCREMENT,
+			name TEXT NOT NULL,
+			email TEXT NOT NULL DEFAULT '',
+			phone TEXT NOT NULL DEFAULT '',
+			address TEXT NOT NULL DEFAULT '',
+			created_at DATETIME DEFAULT CURRENT_TIMESTAMP,
+			updated_at DATETIME DEFAULT CURRENT_TIMESTAMP
+		)`,
+
+		// Orders table
+		`CREATE TABLE IF NOT EXISTS orders (
+			id INTEGER PRIMARY KEY AUTOINCREMENT,
+			customer_id INTEGER NOT NULL,
+			status TEXT NOT NULL DEFAULT 'draft',
+			order_date DATE NOT NULL DEFAULT (date('now')),
+			total_amount REAL NOT NULL DEFAULT 0,
+			notes TEXT NOT NULL DEFAULT '',
+			created_at DATETIME DEFAULT CURRENT_TIMESTAMP,
+			updated_at DATETIME DEFAULT CURRENT_TIMESTAMP,
+			FOREIGN KEY (customer_id) REFERENCES customers(id)
+		)`,
+
+		// Order lines table
+		`CREATE TABLE IF NOT EXISTS order_lines (
+			id INTEGER PRIMARY KEY AUTOINCREMENT,
+			order_id INTEGER NOT NULL,
+			description TEXT NOT NULL,
+			quantity REAL NOT NULL DEFAULT 1,
+			unit_price REAL NOT NULL DEFAULT 0,
+			line_total REAL NOT NULL DEFAULT 0,
+			FOREIGN KEY (order_id) REFERENCES orders(id) ON DELETE CASCADE
+		)`,
+
+		// Invoices table
+		`CREATE TABLE IF NOT EXISTS invoices (
+			id INTEGER PRIMARY KEY AUTOINCREMENT,
+			order_id INTEGER,
+			customer_id INTEGER NOT NULL,
+			invoice_number TEXT NOT NULL UNIQUE,
+			status TEXT NOT NULL DEFAULT 'pending',
+			amount REAL NOT NULL DEFAULT 0,
+			due_date DATE NOT NULL,
+			paid_date DATE,
+			created_at DATETIME DEFAULT CURRENT_TIMESTAMP,
+			FOREIGN KEY (order_id) REFERENCES orders(id),
+			FOREIGN KEY (customer_id) REFERENCES customers(id)
+		)`,
+
+		// GL Accounts table (Chart of Accounts)
+		`CREATE TABLE IF NOT EXISTS gl_accounts (
+			id INTEGER PRIMARY KEY AUTOINCREMENT,
+			code TEXT NOT NULL UNIQUE,
+			name TEXT NOT NULL,
+			type TEXT NOT NULL,
+			balance REAL NOT NULL DEFAULT 0,
+			created_at DATETIME DEFAULT CURRENT_TIMESTAMP
+		)`,
+
+		// Journal Entries table
+		`CREATE TABLE IF NOT EXISTS journal_entries (
+			id INTEGER PRIMARY KEY AUTOINCREMENT,
+			entry_date DATE NOT NULL DEFAULT (date('now')),
+			description TEXT NOT NULL,
+			reference TEXT NOT NULL DEFAULT '',
+			created_at DATETIME DEFAULT CURRENT_TIMESTAMP
+		)`,
+
+		// Journal Lines table
+		`CREATE TABLE IF NOT EXISTS journal_lines (
+			id INTEGER PRIMARY KEY AUTOINCREMENT,
+			journal_entry_id INTEGER NOT NULL,
+			account_id INTEGER NOT NULL,
+			debit REAL NOT NULL DEFAULT 0,
+			credit REAL NOT NULL DEFAULT 0,
+			FOREIGN KEY (journal_entry_id) REFERENCES journal_entries(id) ON DELETE CASCADE,
+			FOREIGN KEY (account_id) REFERENCES gl_accounts(id)
+		)`,
+	}
+
+	for i, m := range migrations {
+		if _, err := db.Exec(m); err != nil {
+			return fmt.Errorf("migration %d failed: %w", i, err)
+		}
+	}
+
+	log.Println("Migrations completed")
+	return nil
+}
+
+func seedData(db *sql.DB) error {
+	// Seed admin user if not exists
+	var count int
+	db.QueryRow("SELECT COUNT(*) FROM users").Scan(&count)
+	if count == 0 {
+		hash, err := bcrypt.GenerateFromPassword([]byte("admin123"), bcrypt.DefaultCost)
+		if err != nil {
+			return fmt.Errorf("hashing password: %w", err)
+		}
+		_, err = db.Exec("INSERT INTO users (username, password_hash) VALUES (?, ?)", "admin", string(hash))
+		if err != nil {
+			return fmt.Errorf("inserting admin user: %w", err)
+		}
+		log.Println("Seeded admin user (admin / admin123)")
+	}
+
+	// Seed Chart of Accounts if not exists
+	db.QueryRow("SELECT COUNT(*) FROM gl_accounts").Scan(&count)
+	if count == 0 {
+		accounts := []struct {
+			Code, Name, Type string
+		}{
+			// Assets
+			{"1000", "Cash", "asset"},
+			{"1100", "Accounts Receivable", "asset"},
+			{"1200", "Inventory", "asset"},
+			// Liabilities
+			{"2000", "Accounts Payable", "liability"},
+			{"2100", "Sales Tax Payable", "liability"},
+			// Equity
+			{"3000", "Owner's Equity", "equity"},
+			{"3100", "Retained Earnings", "equity"},
+			// Revenue
+			{"4000", "Sales Revenue", "revenue"},
+			{"4100", "Service Revenue", "revenue"},
+			// Expenses
+			{"5000", "Cost of Goods Sold", "expense"},
+			{"5100", "Salaries Expense", "expense"},
+			{"5200", "Rent Expense", "expense"},
+			{"5300", "Utilities Expense", "expense"},
+		}
+
+		for _, a := range accounts {
+			_, err := db.Exec("INSERT INTO gl_accounts (code, name, type) VALUES (?, ?, ?)", a.Code, a.Name, a.Type)
+			if err != nil {
+				return fmt.Errorf("inserting account %s: %w", a.Code, err)
+			}
+		}
+		log.Println("Seeded chart of accounts")
+	}
+
+	return nil
+}

internal/handlers/auth.go

@@ -0,0 +1,63 @@
+package handlers
+
+import (
+	"html/template"
+	"net/http"
+	"path/filepath"
+
+	"erp_system/internal/models"
+)
+
+func (h *Handler) LoginPage(w http.ResponseWriter, r *http.Request) {
+	// If already logged in, redirect to dashboard
+	session, _ := h.Store.Get(r, "erp-session")
+	if session.Values["user_id"] != nil {
+		http.Redirect(w, r, "/", http.StatusSeeOther)
+		return
+	}
+
+	tmpl, err := template.ParseFiles(filepath.Join("templates", "login.html"))
+	if err != nil {
+		http.Error(w, err.Error(), http.StatusInternalServerError)
+		return
+	}
+	tmpl.Execute(w, map[string]interface{}{"Error": ""})
+}
+
+func (h *Handler) LoginSubmit(w http.ResponseWriter, r *http.Request) {
+	username := r.FormValue("username")
+	password := r.FormValue("password")
+
+	user, err := models.Authenticate(h.DB, username, password)
+	if err != nil {
+		tmpl, _ := template.ParseFiles(filepath.Join("templates", "login.html"))
+		tmpl.Execute(w, map[string]interface{}{"Error": "Invalid username or password"})
+		return
+	}
+
+	session, _ := h.Store.Get(r, "erp-session")
+	session.Values["user_id"] = user.ID
+	session.Values["username"] = user.Username
+	session.Save(r, w)
+
+	// HTMX redirect
+	if r.Header.Get("HX-Request") == "true" {
+		w.Header().Set("HX-Redirect", "/")
+		return
+	}
+	http.Redirect(w, r, "/", http.StatusSeeOther)
+}
+
+func (h *Handler) Logout(w http.ResponseWriter, r *http.Request) {
+	session, _ := h.Store.Get(r, "erp-session")
+	session.Values["user_id"] = nil
+	session.Values["username"] = nil
+	session.Options.MaxAge = -1
+	session.Save(r, w)
+
+	if r.Header.Get("HX-Request") == "true" {
+		w.Header().Set("HX-Redirect", "/login")
+		return
+	}
+	http.Redirect(w, r, "/login", http.StatusSeeOther)
+}

internal/handlers/customers.go

@@ -0,0 +1,175 @@
+package handlers
+
+import (
+	"net/http"
+	"strconv"
+
+	"erp_system/internal/models"
+)
+
+func (h *Handler) CustomerList(w http.ResponseWriter, r *http.Request) {
+	search := r.URL.Query().Get("search")
+	customers, err := models.CustomerGetAll(h.DB, search)
+	if err != nil {
+		http.Error(w, err.Error(), http.StatusInternalServerError)
+		return
+	}
+
+	data := map[string]interface{}{
+		"Title":      "Customers",
+		"Username":   h.getUsername(r),
+		"ActivePage": "customers",
+		"Customers":  customers,
+		"Search":     search,
+	}
+
+	// HTMX partial for search
+	if r.Header.Get("HX-Request") == "true" && r.URL.Query().Get("partial") == "true" {
+		h.renderPartial(w, "customers/list.html", "customer-table", data)
+		return
+	}
+
+	h.render(w, []string{"layout.html", "customers/list.html"}, data)
+}
+
+func (h *Handler) CustomerNew(w http.ResponseWriter, r *http.Request) {
+	data := map[string]interface{}{
+		"Title":      "New Customer",
+		"Username":   h.getUsername(r),
+		"ActivePage": "customers",
+		"Customer":   &models.Customer{},
+		"IsNew":      true,
+	}
+	h.render(w, []string{"layout.html", "customers/form.html"}, data)
+}
+
+func (h *Handler) CustomerCreate(w http.ResponseWriter, r *http.Request) {
+	c := &models.Customer{
+		Name:    r.FormValue("name"),
+		Email:   r.FormValue("email"),
+		Phone:   r.FormValue("phone"),
+		Address: r.FormValue("address"),
+	}
+
+	if c.Name == "" {
+		data := map[string]interface{}{
+			"Title":      "New Customer",
+			"Username":   h.getUsername(r),
+			"ActivePage": "customers",
+			"Customer":   c,
+			"IsNew":      true,
+			"Error":      "Name is required",
+		}
+		h.render(w, []string{"layout.html", "customers/form.html"}, data)
+		return
+	}
+
+	if err := models.CustomerInsert(h.DB, c); err != nil {
+		http.Error(w, err.Error(), http.StatusInternalServerError)
+		return
+	}
+
+	if r.Header.Get("HX-Request") == "true" {
+		w.Header().Set("HX-Redirect", "/customers/"+strconv.Itoa(c.ID))
+		return
+	}
+	http.Redirect(w, r, "/customers/"+strconv.Itoa(c.ID), http.StatusSeeOther)
+}
+
+func (h *Handler) CustomerDetail(w http.ResponseWriter, r *http.Request) {
+	id, _ := strconv.Atoi(r.PathValue("id"))
+	customer, err := models.CustomerGetByID(h.DB, id)
+	if err != nil {
+		http.Error(w, "Customer not found", http.StatusNotFound)
+		return
+	}
+
+	// Get customer's orders
+	orders, _ := models.OrderGetAll(h.DB, "")
+	var customerOrders []models.Order
+	for _, o := range orders {
+		if o.CustomerID == id {
+			customerOrders = append(customerOrders, o)
+		}
+	}
+
+	// Get customer's invoices
+	invoices, _ := models.InvoiceGetByCustomerID(h.DB, id)
+
+	data := map[string]interface{}{
+		"Title":      customer.Name,
+		"Username":   h.getUsername(r),
+		"ActivePage": "customers",
+		"Customer":   customer,
+		"Orders":     customerOrders,
+		"Invoices":   invoices,
+	}
+	h.render(w, []string{"layout.html", "customers/detail.html"}, data)
+}
+
+func (h *Handler) CustomerEdit(w http.ResponseWriter, r *http.Request) {
+	id, _ := strconv.Atoi(r.PathValue("id"))
+	customer, err := models.CustomerGetByID(h.DB, id)
+	if err != nil {
+		http.Error(w, "Customer not found", http.StatusNotFound)
+		return
+	}
+
+	data := map[string]interface{}{
+		"Title":      "Edit " + customer.Name,
+		"Username":   h.getUsername(r),
+		"ActivePage": "customers",
+		"Customer":   customer,
+		"IsNew":      false,
+	}
+	h.render(w, []string{"layout.html", "customers/form.html"}, data)
+}
+
+func (h *Handler) CustomerUpdate(w http.ResponseWriter, r *http.Request) {
+	id, _ := strconv.Atoi(r.PathValue("id"))
+	c := &models.Customer{
+		ID:      id,
+		Name:    r.FormValue("name"),
+		Email:   r.FormValue("email"),
+		Phone:   r.FormValue("phone"),
+		Address: r.FormValue("address"),
+	}
+
+	if c.Name == "" {
+		data := map[string]interface{}{
+			"Title":      "Edit Customer",
+			"Username":   h.getUsername(r),
+			"ActivePage": "customers",
+			"Customer":   c,
+			"IsNew":      false,
+			"Error":      "Name is required",
+		}
+		h.render(w, []string{"layout.html", "customers/form.html"}, data)
+		return
+	}
+
+	if err := models.CustomerUpdate(h.DB, c); err != nil {
+		http.Error(w, err.Error(), http.StatusInternalServerError)
+		return
+	}
+
+	if r.Header.Get("HX-Request") == "true" {
+		w.Header().Set("HX-Redirect", "/customers/"+strconv.Itoa(id))
+		return
+	}
+	http.Redirect(w, r, "/customers/"+strconv.Itoa(id), http.StatusSeeOther)
+}
+
+func (h *Handler) CustomerDelete(w http.ResponseWriter, r *http.Request) {
+	id, _ := strconv.Atoi(r.PathValue("id"))
+	if err := models.CustomerDelete(h.DB, id); err != nil {
+		http.Error(w, err.Error(), http.StatusInternalServerError)
+		return
+	}
+
+	if r.Header.Get("HX-Request") == "true" {
+		w.Header().Set("HX-Redirect", "/customers")
+		return
+	}
+	http.Redirect(w, r, "/customers", http.StatusSeeOther)
+}

internal/handlers/dashboard.go

@@ -0,0 +1,23 @@
+package handlers
+
+import (
+	"net/http"
+
+	"erp_system/internal/models"
+)
+
+func (h *Handler) Dashboard(w http.ResponseWriter, r *http.Request) {
+	data := map[string]interface{}{
+		"Title":             "Dashboard",
+		"Username":          h.getUsername(r),
+		"ActivePage":        "dashboard",
+		"CustomerCount":     models.CustomerCount(h.DB),
+		"OpenOrderCount":    models.OrderCountByStatus(h.DB, "draft") + models.OrderCountByStatus(h.DB, "confirmed"),
+		"PendingInvoices":   models.InvoiceCountByStatus(h.DB, "pending"),
+		"OutstandingAmount": models.InvoiceTotalOutstanding(h.DB),
+		"RevenueThisMonth":  models.RevenueThisMonth(h.DB),
+		"FulfilledOrders":   models.OrderCountByStatus(h.DB, "fulfilled"),
+	}
+
+	h.render(w, []string{"layout.html", "dashboard.html"}, data)
+}

internal/handlers/handler.go

@@ -0,0 +1,108 @@
+package handlers
+
+import (
+	"database/sql"
+	"fmt"
+	"html/template"
+	"net/http"
+	"path/filepath"
+	"time"
+
+	"github.com/gorilla/sessions"
+)
+
+type Handler struct {
+	DB    *sql.DB
+	Store *sessions.CookieStore
+}
+
+// Template helper functions
+var funcMap = template.FuncMap{
+	"formatMoney": func(amount float64) string {
+		return fmt.Sprintf("$%.2f", amount)
+	},
+	"formatDate": func(date string) string {
+		t, err := time.Parse("2006-01-02", date)
+		if err != nil {
+			return date
+		}
+		return t.Format("Jan 02, 2006")
+	},
+	"statusBadge": func(status string) template.HTML {
+		colors := map[string]string{
+			"draft":     "bg-gray-100 text-gray-800",
+			"confirmed": "bg-blue-100 text-blue-800",
+			"fulfilled": "bg-green-100 text-green-800",
+			"cancelled": "bg-red-100 text-red-800",
+			"pending":   "bg-yellow-100 text-yellow-800",
+			"paid":      "bg-green-100 text-green-800",
+			"overdue":   "bg-red-100 text-red-800",
+		}
+		color, ok := colors[status]
+		if !ok {
+			color = "bg-gray-100 text-gray-800"
+		}
+		return template.HTML(fmt.Sprintf(`<span class="inline-flex items-center px-2.5 py-0.5 rounded-full text-xs font-medium %s">%s</span>`, color, status))
+	},
+	"capitalize": func(s string) string {
+		if len(s) == 0 {
+			return s
+		}
+		return string(s[0]-32) + s[1:]
+	},
+	"accountTypeBadge": func(t string) template.HTML {
+		colors := map[string]string{
+			"asset":     "bg-blue-100 text-blue-800",
+			"liability": "bg-red-100 text-red-800",
+			"equity":    "bg-purple-100 text-purple-800",
+			"revenue":   "bg-green-100 text-green-800",
+			"expense":   "bg-orange-100 text-orange-800",
+		}
+		color, ok := colors[t]
+		if !ok {
+			color = "bg-gray-100 text-gray-800"
+		}
+		return template.HTML(fmt.Sprintf(`<span class="inline-flex items-center px-2.5 py-0.5 rounded-full text-xs font-medium %s">%s</span>`, color, t))
+	},
+	"sub": func(a, b float64) float64 {
+		return a - b
+	},
+}
+
+func (h *Handler) render(w http.ResponseWriter, templates []string, data interface{}) {
+	paths := make([]string, len(templates))
+	for i, t := range templates {
+		paths[i] = filepath.Join("templates", t)
+	}
+
+	tmpl, err := template.New("").Funcs(funcMap).ParseFiles(paths...)
+	if err != nil {
+		http.Error(w, fmt.Sprintf("Template error: %v", err), http.StatusInternalServerError)
+		return
+	}
+
+	if err := tmpl.ExecuteTemplate(w, "layout", data); err != nil {
+		http.Error(w, fmt.Sprintf("Render error: %v", err), http.StatusInternalServerError)
+	}
+}
+
+func (h *Handler) renderPartial(w http.ResponseWriter, templateFile string, templateName string, data interface{}) {
+	path := filepath.Join("templates", templateFile)
+	tmpl, err := template.New("").Funcs(funcMap).ParseFiles(path)
+	if err != nil {
+		http.Error(w, fmt.Sprintf("Template error: %v", err), http.StatusInternalServerError)
+		return
+	}
+
+	if err := tmpl.ExecuteTemplate(w, templateName, data); err != nil {
+		http.Error(w, fmt.Sprintf("Render error: %v", err), http.StatusInternalServerError)
+	}
+}
+
+func (h *Handler) getUsername(r *http.Request) string {
+	session, _ := h.Store.Get(r, "erp-session")
+	if username, ok := session.Values["username"].(string); ok {
+		return username
+	}
+	return ""
+}

internal/handlers/invoices.go

@@ -0,0 +1,64 @@
+package handlers
+
+import (
+	"fmt"
+	"net/http"
+	"strconv"
+
+	"erp_system/internal/models"
+)
+
+func (h *Handler) InvoiceList(w http.ResponseWriter, r *http.Request) {
+	status := r.URL.Query().Get("status")
+	invoices, err := models.InvoiceGetAll(h.DB, status)
+	if err != nil {
+		http.Error(w, err.Error(), http.StatusInternalServerError)
+		return
+	}
+
+	data := map[string]interface{}{
+		"Title":        "Invoices",
+		"Username":     h.getUsername(r),
+		"ActivePage":   "invoices",
+		"Invoices":     invoices,
+		"FilterStatus": status,
+	}
+
+	if r.Header.Get("HX-Request") == "true" && r.URL.Query().Get("partial") == "true" {
+		h.renderPartial(w, "invoices/list.html", "invoice-table", data)
+		return
+	}
+
+	h.render(w, []string{"layout.html", "invoices/list.html"}, data)
+}
+
+func (h *Handler) InvoiceDetail(w http.ResponseWriter, r *http.Request) {
+	id, _ := strconv.Atoi(r.PathValue("id"))
+	invoice, err := models.InvoiceGetByID(h.DB, id)
+	if err != nil {
+		http.Error(w, "Invoice not found", http.StatusNotFound)
+		return
+	}
+
+	data := map[string]interface{}{
+		"Title":      invoice.InvoiceNumber,
+		"Username":   h.getUsername(r),
+		"ActivePage": "invoices",
+		"Invoice":    invoice,
+	}
+	h.render(w, []string{"layout.html", "invoices/detail.html"}, data)
+}
+
+func (h *Handler) InvoicePay(w http.ResponseWriter, r *http.Request) {
+	id, _ := strconv.Atoi(r.PathValue("id"))
+	if err := models.InvoiceMarkPaid(h.DB, id); err != nil {
+		http.Error(w, err.Error(), http.StatusInternalServerError)
+		return
+	}
+
+	if r.Header.Get("HX-Request") == "true" {
+		w.Header().Set("HX-Redirect", fmt.Sprintf("/invoices/%d", id))
+		return
+	}
+	http.Redirect(w, r, fmt.Sprintf("/invoices/%d", id), http.StatusSeeOther)
+}

internal/handlers/ledger.go

@@ -0,0 +1,160 @@
+package handlers
+
+import (
+	"net/http"
+	"strconv"
+	"time"
+
+	"erp_system/internal/models"
+)
+
+func (h *Handler) ChartOfAccounts(w http.ResponseWriter, r *http.Request) {
+	accounts, err := models.GLAccountGetAll(h.DB)
+	if err != nil {
+		http.Error(w, err.Error(), http.StatusInternalServerError)
+		return
+	}
+
+	data := map[string]interface{}{
+		"Title":      "Chart of Accounts",
+		"Username":   h.getUsername(r),
+		"ActivePage": "ledger",
+		"Accounts":   accounts,
+	}
+	h.render(w, []string{"layout.html", "ledger/chart_of_accounts.html"}, data)
+}
+
+func (h *Handler) JournalEntries(w http.ResponseWriter, r *http.Request) {
+	entries, err := models.JournalEntryGetAll(h.DB)
+	if err != nil {
+		http.Error(w, err.Error(), http.StatusInternalServerError)
+		return
+	}
+
+	data := map[string]interface{}{
+		"Title":      "Journal Entries",
+		"Username":   h.getUsername(r),
+		"ActivePage": "ledger",
+		"Entries":    entries,
+	}
+	h.render(w, []string{"layout.html", "ledger/journal_entries.html"}, data)
+}
+
+func (h *Handler) JournalEntryNew(w http.ResponseWriter, r *http.Request) {
+	accounts, _ := models.GLAccountGetAll(h.DB)
+
+	data := map[string]interface{}{
+		"Title":      "New Journal Entry",
+		"Username":   h.getUsername(r),
+		"ActivePage": "ledger",
+		"Accounts":   accounts,
+		"Today":      time.Now().Format("2006-01-02"),
+	}
+	h.render(w, []string{"layout.html", "ledger/journal_entry_form.html"}, data)
+}
+
+func (h *Handler) JournalEntryCreate(w http.ResponseWriter, r *http.Request) {
+	r.ParseForm()
+
+	je := &models.JournalEntry{
+		EntryDate:   r.FormValue("entry_date"),
+		Description: r.FormValue("description"),
+		Reference:   r.FormValue("reference"),
+	}
+
+	// Parse lines from form
+	accountIDs := r.Form["account_id"]
+	debits := r.Form["debit"]
+	credits := r.Form["credit"]
+
+	for i := range accountIDs {
+		accID, _ := strconv.Atoi(accountIDs[i])
+		debit, _ := strconv.ParseFloat(debits[i], 64)
+		credit, _ := strconv.ParseFloat(credits[i], 64)
+
+		if accID == 0 || (debit == 0 && credit == 0) {
+			continue
+		}
+
+		je.Lines = append(je.Lines, models.JournalLine{
+			AccountID: accID,
+			Debit:     debit,
+			Credit:    credit,
+		})
+	}
+
+	if len(je.Lines) < 2 {
+		accounts, _ := models.GLAccountGetAll(h.DB)
+		data := map[string]interface{}{
+			"Title":      "New Journal Entry",
+			"Username":   h.getUsername(r),
+			"ActivePage": "ledger",
+			"Accounts":   accounts,
+			"Today":      time.Now().Format("2006-01-02"),
+			"Error":      "At least two lines are required",
+		}
+		h.render(w, []string{"layout.html", "ledger/journal_entry_form.html"}, data)
+		return
+	}
+
+	if err := models.JournalEntryInsert(h.DB, je); err != nil {
+		accounts, _ := models.GLAccountGetAll(h.DB)
+		data := map[string]interface{}{
+			"Title":      "New Journal Entry",
+			"Username":   h.getUsername(r),
+			"ActivePage": "ledger",
+			"Accounts":   accounts,
+			"Today":      time.Now().Format("2006-01-02"),
+			"Error":      err.Error(),
+		}
+		h.render(w, []string{"layout.html", "ledger/journal_entry_form.html"}, data)
+		return
+	}
+
+	if r.Header.Get("HX-Request") == "true" {
+		w.Header().Set("HX-Redirect", "/ledger/journal")
+		return
+	}
+	http.Redirect(w, r, "/ledger/journal", http.StatusSeeOther)
+}
+
+func (h *Handler) JournalEntryDetail(w http.ResponseWriter, r *http.Request) {
+	id, _ := strconv.Atoi(r.PathValue("id"))
+	entry, err := models.JournalEntryGetByID(h.DB, id)
+	if err != nil {
+		http.Error(w, "Journal entry not found", http.StatusNotFound)
+		return
+	}
+
+	data := map[string]interface{}{
+		"Title":      "Journal Entry #" + strconv.Itoa(id),
+		"Username":   h.getUsername(r),
+		"ActivePage": "ledger",
+		"Entry":      entry,
+	}
+	h.render(w, []string{"layout.html", "ledger/journal_entry_detail.html"}, data)
+}
+
+func (h *Handler) TrialBalance(w http.ResponseWriter, r *http.Request) {
+	rows, err := models.GetTrialBalance(h.DB)
+	if err != nil {
+		http.Error(w, err.Error(), http.StatusInternalServerError)
+		return
+	}
+
+	var totalDebit, totalCredit float64
+	for _, row := range rows {
+		totalDebit += row.Debit
+		totalCredit += row.Credit
+	}
+
+	data := map[string]interface{}{
+		"Title":       "Trial Balance",
+		"Username":    h.getUsername(r),
+		"ActivePage":  "ledger",
+		"Rows":        rows,
+		"TotalDebit":  totalDebit,
+		"TotalCredit": totalCredit,
+	}
+	h.render(w, []string{"layout.html", "ledger/trial_balance.html"}, data)
+}

internal/handlers/orders.go

@@ -0,0 +1,271 @@
+package handlers
+
+import (
+	"fmt"
+	"net/http"
+	"strconv"
+	"time"
+
+	"erp_system/internal/models"
+)
+
+func (h *Handler) OrderList(w http.ResponseWriter, r *http.Request) {
+	status := r.URL.Query().Get("status")
+	orders, err := models.OrderGetAll(h.DB, status)
+	if err != nil {
+		http.Error(w, err.Error(), http.StatusInternalServerError)
+		return
+	}
+
+	data := map[string]interface{}{
+		"Title":        "Orders",
+		"Username":     h.getUsername(r),
+		"ActivePage":   "orders",
+		"Orders":       orders,
+		"FilterStatus": status,
+	}
+
+	if r.Header.Get("HX-Request") == "true" && r.URL.Query().Get("partial") == "true" {
+		h.renderPartial(w, "orders/list.html", "order-table", data)
+		return
+	}
+
+	h.render(w, []string{"layout.html", "orders/list.html"}, data)
+}
+
+func (h *Handler) OrderNew(w http.ResponseWriter, r *http.Request) {
+	customers, _ := models.CustomerGetAll(h.DB, "")
+
+	data := map[string]interface{}{
+		"Title":      "New Order",
+		"Username":   h.getUsername(r),
+		"ActivePage": "orders",
+		"Order":      &models.Order{OrderDate: time.Now().Format("2006-01-02"), Status: "draft"},
+		"Customers":  customers,
+		"IsNew":      true,
+	}
+	h.render(w, []string{"layout.html", "orders/form.html"}, data)
+}
+
+func (h *Handler) OrderCreate(w http.ResponseWriter, r *http.Request) {
+	customerID, _ := strconv.Atoi(r.FormValue("customer_id"))
+	o := &models.Order{
+		CustomerID: customerID,
+		Status:     "draft",
+		OrderDate:  r.FormValue("order_date"),
+		Notes:      r.FormValue("notes"),
+	}
+
+	if o.CustomerID == 0 {
+		customers, _ := models.CustomerGetAll(h.DB, "")
+		data := map[string]interface{}{
+			"Title":      "New Order",
+			"Username":   h.getUsername(r),
+			"ActivePage": "orders",
+			"Order":      o,
+			"Customers":  customers,
+			"IsNew":      true,
+			"Error":      "Customer is required",
+		}
+		h.render(w, []string{"layout.html", "orders/form.html"}, data)
+		return
+	}
+
+	if o.OrderDate == "" {
+		o.OrderDate = time.Now().Format("2006-01-02")
+	}
+
+	if err := models.OrderInsert(h.DB, o); err != nil {
+		http.Error(w, err.Error(), http.StatusInternalServerError)
+		return
+	}
+
+	if r.Header.Get("HX-Request") == "true" {
+		w.Header().Set("HX-Redirect", fmt.Sprintf("/orders/%d", o.ID))
+		return
+	}
+	http.Redirect(w, r, fmt.Sprintf("/orders/%d", o.ID), http.StatusSeeOther)
+}
+
+func (h *Handler) OrderDetail(w http.ResponseWriter, r *http.Request) {
+	id, _ := strconv.Atoi(r.PathValue("id"))
+	order, err := models.OrderGetByID(h.DB, id)
+	if err != nil {
+		http.Error(w, "Order not found", http.StatusNotFound)
+		return
+	}
+
+	data := map[string]interface{}{
+		"Title":      fmt.Sprintf("Order #%d", order.ID),
+		"Username":   h.getUsername(r),
+		"ActivePage": "orders",
+		"Order":      order,
+	}
+	h.render(w, []string{"layout.html", "orders/detail.html"}, data)
+}
+
+func (h *Handler) OrderEdit(w http.ResponseWriter, r *http.Request) {
+	id, _ := strconv.Atoi(r.PathValue("id"))
+	order, err := models.OrderGetByID(h.DB, id)
+	if err != nil {
+		http.Error(w, "Order not found", http.StatusNotFound)
+		return
+	}
+
+	if order.Status != "draft" {
+		http.Error(w, "Only draft orders can be edited", http.StatusBadRequest)
+		return
+	}
+
+	customers, _ := models.CustomerGetAll(h.DB, "")
+
+	data := map[string]interface{}{
+		"Title":      fmt.Sprintf("Edit Order #%d", order.ID),
+		"Username":   h.getUsername(r),
+		"ActivePage": "orders",
+		"Order":      order,
+		"Customers":  customers,
+		"IsNew":      false,
+	}
+	h.render(w, []string{"layout.html", "orders/form.html"}, data)
+}
+
+func (h *Handler) OrderUpdate(w http.ResponseWriter, r *http.Request) {
+	id, _ := strconv.Atoi(r.PathValue("id"))
+	customerID, _ := strconv.Atoi(r.FormValue("customer_id"))
+
+	o := &models.Order{
+		ID:         id,
+		CustomerID: customerID,
+		OrderDate:  r.FormValue("order_date"),
+		Notes:      r.FormValue("notes"),
+	}
+
+	if err := models.OrderUpdate(h.DB, o); err != nil {
+		http.Error(w, err.Error(), http.StatusInternalServerError)
+		return
+	}
+
+	if r.Header.Get("HX-Request") == "true" {
+		w.Header().Set("HX-Redirect", fmt.Sprintf("/orders/%d", id))
+		return
+	}
+	http.Redirect(w, r, fmt.Sprintf("/orders/%d", id), http.StatusSeeOther)
+}
+
+func (h *Handler) OrderConfirm(w http.ResponseWriter, r *http.Request) {
+	id, _ := strconv.Atoi(r.PathValue("id"))
+	if err := models.OrderUpdateStatus(h.DB, id, "confirmed"); err != nil {
+		http.Error(w, err.Error(), http.StatusInternalServerError)
+		return
+	}
+
+	if r.Header.Get("HX-Request") == "true" {
+		w.Header().Set("HX-Redirect", fmt.Sprintf("/orders/%d", id))
+		return
+	}
+	http.Redirect(w, r, fmt.Sprintf("/orders/%d", id), http.StatusSeeOther)
+}
+
+func (h *Handler) OrderFulfill(w http.ResponseWriter, r *http.Request) {
+	id, _ := strconv.Atoi(r.PathValue("id"))
+
+	// Update status
+	if err := models.OrderUpdateStatus(h.DB, id, "fulfilled"); err != nil {
+		http.Error(w, err.Error(), http.StatusInternalServerError)
+		return
+	}
+
+	// Generate invoice and GL entries
+	if err := models.GenerateInvoiceFromOrder(h.DB, id); err != nil {
+		http.Error(w, fmt.Sprintf("Order fulfilled but invoice generation failed: %v", err), http.StatusInternalServerError)
+		return
+	}
+
+	if r.Header.Get("HX-Request") == "true" {
+		w.Header().Set("HX-Redirect", fmt.Sprintf("/orders/%d", id))
+		return
+	}
+	http.Redirect(w, r, fmt.Sprintf("/orders/%d", id), http.StatusSeeOther)
+}
+
+func (h *Handler) OrderCancel(w http.ResponseWriter, r *http.Request) {
+	id, _ := strconv.Atoi(r.PathValue("id"))
+	if err := models.OrderUpdateStatus(h.DB, id, "cancelled"); err != nil {
+		http.Error(w, err.Error(), http.StatusInternalServerError)
+		return
+	}
+
+	if r.Header.Get("HX-Request") == "true" {
+		w.Header().Set("HX-Redirect", fmt.Sprintf("/orders/%d", id))
+		return
+	}
+	http.Redirect(w, r, fmt.Sprintf("/orders/%d", id), http.StatusSeeOther)
+}
+
+func (h *Handler) OrderDelete(w http.ResponseWriter, r *http.Request) {
+	id, _ := strconv.Atoi(r.PathValue("id"))
+	if err := models.OrderDelete(h.DB, id); err != nil {
+		http.Error(w, err.Error(), http.StatusInternalServerError)
+		return
+	}
+
+	if r.Header.Get("HX-Request") == "true" {
+		w.Header().Set("HX-Redirect", "/orders")
+		return
+	}
+	http.Redirect(w, r, "/orders", http.StatusSeeOther)
+}
+
+// Order line handlers (HTMX partials)
+
+func (h *Handler) OrderLineAdd(w http.ResponseWriter, r *http.Request) {
+	orderID, _ := strconv.Atoi(r.PathValue("id"))
+	qty, _ := strconv.ParseFloat(r.FormValue("quantity"), 64)
+	price, _ := strconv.ParseFloat(r.FormValue("unit_price"), 64)
+
+	line := &models.OrderLine{
+		OrderID:     orderID,
+		Description: r.FormValue("description"),
+		Quantity:    qty,
+		UnitPrice:   price,
+	}
+
+	if line.Description == "" || line.Quantity <= 0 {
+		http.Error(w, "Description and quantity are required", http.StatusBadRequest)
+		return
+	}
+
+	if err := models.OrderLineInsert(h.DB, line); err != nil {
+		http.Error(w, err.Error(), http.StatusInternalServerError)
+		return
+	}
+
+	// Return updated order detail
+	order, err := models.OrderGetByID(h.DB, orderID)
+	if err != nil {
+		http.Error(w, err.Error(), http.StatusInternalServerError)
+		return
+	}
+
+	h.renderPartial(w, "orders/detail.html", "order-lines", order)
+}
+
+func (h *Handler) OrderLineDelete(w http.ResponseWriter, r *http.Request) {
+	orderID, _ := strconv.Atoi(r.PathValue("id"))
+	lineID, _ := strconv.Atoi(r.PathValue("lineID"))
+
+	if err := models.OrderLineDelete(h.DB, lineID, orderID); err != nil {
+		http.Error(w, err.Error(), http.StatusInternalServerError)
+		return
+	}
+
+	// Return updated order detail
+	order, err := models.OrderGetByID(h.DB, orderID)
+	if err != nil {
+		http.Error(w, err.Error(), http.StatusInternalServerError)
+		return
+	}
+
+	h.renderPartial(w, "orders/detail.html", "order-lines", order)
+}

internal/middleware/auth.go

@@ -0,0 +1,27 @@
+package middleware
+
+import (
+	"net/http"
+
+	"github.com/gorilla/sessions"
+)
+
+func RequireAuth(store *sessions.CookieStore) func(http.Handler) http.Handler {
+	return func(next http.Handler) http.Handler {
+		return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+			session, _ := store.Get(r, "erp-session")
+			userID, ok := session.Values["user_id"]
+			if !ok || userID == nil {
+				// Check if this is an HTMX request
+				if r.Header.Get("HX-Request") == "true" {
+					w.Header().Set("HX-Redirect", "/login")
+					w.WriteHeader(http.StatusUnauthorized)
+					return
+				}
+				http.Redirect(w, r, "/login", http.StatusSeeOther)
+				return
+			}
+			next.ServeHTTP(w, r)
+		})
+	}
+}

internal/models/customer.go

@@ -0,0 +1,86 @@
+package models
+
+import (
+	"database/sql"
+	"time"
+)
+
+type Customer struct {
+	ID        int
+	Name      string
+	Email     string
+	Phone     string
+	Address   string
+	CreatedAt time.Time
+	UpdatedAt time.Time
+}
+
+func CustomerGetAll(db *sql.DB, search string) ([]Customer, error) {
+	query := "SELECT id, name, email, phone, address, created_at, updated_at FROM customers"
+	args := []interface{}{}
+	if search != "" {
+		query += " WHERE name LIKE ? OR email LIKE ?"
+		s := "%" + search + "%"
+		args = append(args, s, s)
+	}
+	query += " ORDER BY name"
+
+	rows, err := db.Query(query, args...)
+	if err != nil {
+		return nil, err
+	}
+	defer rows.Close()
+
+	var customers []Customer
+	for rows.Next() {
+		var c Customer
+		if err := rows.Scan(&c.ID, &c.Name, &c.Email, &c.Phone, &c.Address, &c.CreatedAt, &c.UpdatedAt); err != nil {
+			return nil, err
+		}
+		customers = append(customers, c)
+	}
+	return customers, nil
+}
+
+func CustomerGetByID(db *sql.DB, id int) (*Customer, error) {
+	c := &Customer{}
+	err := db.QueryRow(
+		"SELECT id, name, email, phone, address, created_at, updated_at FROM customers WHERE id = ?", id,
+	).Scan(&c.ID, &c.Name, &c.Email, &c.Phone, &c.Address, &c.CreatedAt, &c.UpdatedAt)
+	if err != nil {
+		return nil, err
+	}
+	return c, nil
+}
+
+func CustomerInsert(db *sql.DB, c *Customer) error {
+	result, err := db.Exec(
+		"INSERT INTO customers (name, email, phone, address) VALUES (?, ?, ?, ?)",
+		c.Name, c.Email, c.Phone, c.Address,
+	)
+	if err != nil {
+		return err
+	}
+	id, _ := result.LastInsertId()
+	c.ID = int(id)
+	return nil
+}
+
+func CustomerUpdate(db *sql.DB, c *Customer) error {
+	_, err := db.Exec(
+		"UPDATE customers SET name = ?, email = ?, phone = ?, address = ?, updated_at = CURRENT_TIMESTAMP WHERE id = ?",
+		c.Name, c.Email, c.Phone, c.Address, c.ID,
+	)
+	return err
+}
+
+func CustomerDelete(db *sql.DB, id int) error {
+	_, err := db.Exec("DELETE FROM customers WHERE id = ?", id)
+	return err
+}
+
+func CustomerCount(db *sql.DB) int {
+	var count int
+	db.QueryRow("SELECT COUNT(*) FROM customers").Scan(&count)
+	return count
+}

internal/models/invoice.go

@@ -0,0 +1,132 @@
+package models
+
+import (
+	"database/sql"
+	"fmt"
+	"time"
+)
+
+type Invoice struct {
+	ID            int
+	OrderID       sql.NullInt64
+	CustomerID    int
+	CustomerName  string
+	InvoiceNumber string
+	Status        string
+	Amount        float64
+	DueDate       string
+	PaidDate      sql.NullString
+	CreatedAt     time.Time
+}
+
+func InvoiceGetAll(db *sql.DB, status string) ([]Invoice, error) {
+	query := `SELECT i.id, i.order_id, i.customer_id, c.name, i.invoice_number, i.status, i.amount, i.due_date, i.paid_date, i.created_at
+		FROM invoices i JOIN customers c ON i.customer_id = c.id`
+	args := []interface{}{}
+	if status != "" {
+		query += " WHERE i.status = ?"
+		args = append(args, status)
+	}
+	query += " ORDER BY i.created_at DESC"
+
+	rows, err := db.Query(query, args...)
+	if err != nil {
+		return nil, err
+	}
+	defer rows.Close()
+
+	var invoices []Invoice
+	for rows.Next() {
+		var inv Invoice
+		if err := rows.Scan(&inv.ID, &inv.OrderID, &inv.CustomerID, &inv.CustomerName, &inv.InvoiceNumber, &inv.Status, &inv.Amount, &inv.DueDate, &inv.PaidDate, &inv.CreatedAt); err != nil {
+			return nil, err
+		}
+		invoices = append(invoices, inv)
+	}
+	return invoices, nil
+}
+
+func InvoiceGetByID(db *sql.DB, id int) (*Invoice, error) {
+	inv := &Invoice{}
+	err := db.QueryRow(
+		`SELECT i.id, i.order_id, i.customer_id, c.name, i.invoice_number, i.status, i.amount, i.due_date, i.paid_date, i.created_at
+		FROM invoices i JOIN customers c ON i.customer_id = c.id WHERE i.id = ?`, id,
+	).Scan(&inv.ID, &inv.OrderID, &inv.CustomerID, &inv.CustomerName, &inv.InvoiceNumber, &inv.Status, &inv.Amount, &inv.DueDate, &inv.PaidDate, &inv.CreatedAt)
+	if err != nil {
+		return nil, err
+	}
+	return inv, nil
+}
+
+func InvoiceMarkPaid(db *sql.DB, id int) error {
+	inv, err := InvoiceGetByID(db, id)
+	if err != nil {
+		return err
+	}
+
+	// Update invoice status
+	_, err = db.Exec("UPDATE invoices SET status = 'paid', paid_date = date('now') WHERE id = ?", id)
+	if err != nil {
+		return err
+	}
+
+	// Create GL journal entry: Debit Cash, Credit AR
+	result, err := db.Exec(
+		"INSERT INTO journal_entries (entry_date, description, reference) VALUES (date('now'), ?, ?)",
+		fmt.Sprintf("Payment received for %s", inv.InvoiceNumber),
+		inv.InvoiceNumber,
+	)
+	if err != nil {
+		return err
+	}
+	jeID, _ := result.LastInsertId()
+
+	// Debit Cash (1000)
+	var cashID int
+	db.QueryRow("SELECT id FROM gl_accounts WHERE code = '1000'").Scan(&cashID)
+	db.Exec("INSERT INTO journal_lines (journal_entry_id, account_id, debit, credit) VALUES (?, ?, ?, 0)", jeID, cashID, inv.Amount)
+
+	// Credit AR (1100)
+	var arID int
+	db.QueryRow("SELECT id FROM gl_accounts WHERE code = '1100'").Scan(&arID)
+	db.Exec("INSERT INTO journal_lines (journal_entry_id, account_id, debit, credit) VALUES (?, ?, 0, ?)", jeID, arID, inv.Amount)
+
+	// Update account balances
+	db.Exec("UPDATE gl_accounts SET balance = balance + ? WHERE code = '1000'", inv.Amount) // Cash increases
+	db.Exec("UPDATE gl_accounts SET balance = balance - ? WHERE code = '1100'", inv.Amount) // AR decreases
+
+	return nil
+}
+
+func InvoiceCountByStatus(db *sql.DB, status string) int {
+	var count int
+	db.QueryRow("SELECT COUNT(*) FROM invoices WHERE status = ?", status).Scan(&count)
+	return count
+}
+
+func InvoiceTotalOutstanding(db *sql.DB) float64 {
+	var total float64
+	db.QueryRow("SELECT COALESCE(SUM(amount), 0) FROM invoices WHERE status = 'pending'").Scan(&total)
+	return total
+}
+
+func InvoiceGetByCustomerID(db *sql.DB, customerID int) ([]Invoice, error) {
+	rows, err := db.Query(
+		`SELECT i.id, i.order_id, i.customer_id, c.name, i.invoice_number, i.status, i.amount, i.due_date, i.paid_date, i.created_at
+		FROM invoices i JOIN customers c ON i.customer_id = c.id WHERE i.customer_id = ? ORDER BY i.created_at DESC`, customerID,
+	)
+	if err != nil {
+		return nil, err
+	}
+	defer rows.Close()
+
+	var invoices []Invoice
+	for rows.Next() {
+		var inv Invoice
+		if err := rows.Scan(&inv.ID, &inv.OrderID, &inv.CustomerID, &inv.CustomerName, &inv.InvoiceNumber, &inv.Status, &inv.Amount, &inv.DueDate, &inv.PaidDate, &inv.CreatedAt); err != nil {
+			return nil, err
+		}
+		invoices = append(invoices, inv)
+	}
+	return invoices, nil
+}

internal/models/ledger.go

@@ -0,0 +1,219 @@
+package models
+
+import (
+	"database/sql"
+	"fmt"
+	"time"
+)
+
+type GLAccount struct {
+	ID        int
+	Code      string
+	Name      string
+	Type      string
+	Balance   float64
+	CreatedAt time.Time
+}
+
+type JournalEntry struct {
+	ID          int
+	EntryDate   string
+	Description string
+	Reference   string
+	CreatedAt   time.Time
+	Lines       []JournalLine
+	TotalDebit  float64
+	TotalCredit float64
+}
+
+type JournalLine struct {
+	ID             int
+	JournalEntryID int
+	AccountID      int
+	AccountCode    string // joined
+	AccountName    string // joined
+	Debit          float64
+	Credit         float64
+}
+
+type TrialBalanceRow struct {
+	Code   string
+	Name   string
+	Type   string
+	Debit  float64
+	Credit float64
+}
+
+func GLAccountGetAll(db *sql.DB) ([]GLAccount, error) {
+	rows, err := db.Query("SELECT id, code, name, type, balance, created_at FROM gl_accounts ORDER BY code")
+	if err != nil {
+		return nil, err
+	}
+	defer rows.Close()
+
+	var accounts []GLAccount
+	for rows.Next() {
+		var a GLAccount
+		if err := rows.Scan(&a.ID, &a.Code, &a.Name, &a.Type, &a.Balance, &a.CreatedAt); err != nil {
+			return nil, err
+		}
+		accounts = append(accounts, a)
+	}
+	return accounts, nil
+}
+
+func GLAccountGetByID(db *sql.DB, id int) (*GLAccount, error) {
+	a := &GLAccount{}
+	err := db.QueryRow("SELECT id, code, name, type, balance, created_at FROM gl_accounts WHERE id = ?", id).
+		Scan(&a.ID, &a.Code, &a.Name, &a.Type, &a.Balance, &a.CreatedAt)
+	if err != nil {
+		return nil, err
+	}
+	return a, nil
+}
+
+func JournalEntryGetAll(db *sql.DB) ([]JournalEntry, error) {
+	rows, err := db.Query("SELECT id, entry_date, description, reference, created_at FROM journal_entries ORDER BY created_at DESC")
+	if err != nil {
+		return nil, err
+	}
+	defer rows.Close()
+
+	var entries []JournalEntry
+	for rows.Next() {
+		var je JournalEntry
+		if err := rows.Scan(&je.ID, &je.EntryDate, &je.Description, &je.Reference, &je.CreatedAt); err != nil {
+			return nil, err
+		}
+
+		// Get totals
+		db.QueryRow("SELECT COALESCE(SUM(debit), 0), COALESCE(SUM(credit), 0) FROM journal_lines WHERE journal_entry_id = ?", je.ID).
+			Scan(&je.TotalDebit, &je.TotalCredit)
+
+		entries = append(entries, je)
+	}
+	return entries, nil
+}
+
+func JournalEntryGetByID(db *sql.DB, id int) (*JournalEntry, error) {
+	je := &JournalEntry{}
+	err := db.QueryRow("SELECT id, entry_date, description, reference, created_at FROM journal_entries WHERE id = ?", id).
+		Scan(&je.ID, &je.EntryDate, &je.Description, &je.Reference, &je.CreatedAt)
+	if err != nil {
+		return nil, err
+	}
+
+	// Load lines
+	rows, err := db.Query(
+		`SELECT jl.id, jl.journal_entry_id, jl.account_id, a.code, a.name, jl.debit, jl.credit
+		FROM journal_lines jl JOIN gl_accounts a ON jl.account_id = a.id
+		WHERE jl.journal_entry_id = ? ORDER BY jl.id`, id,
+	)
+	if err != nil {
+		return nil, err
+	}
+	defer rows.Close()
+
+	for rows.Next() {
+		var l JournalLine
+		if err := rows.Scan(&l.ID, &l.JournalEntryID, &l.AccountID, &l.AccountCode, &l.AccountName, &l.Debit, &l.Credit); err != nil {
+			return nil, err
+		}
+		je.TotalDebit += l.Debit
+		je.TotalCredit += l.Credit
+		je.Lines = append(je.Lines, l)
+	}
+
+	return je, nil
+}
+
+// JournalEntryInsert creates a journal entry with its lines. Validates debits == credits.
+func JournalEntryInsert(db *sql.DB, je *JournalEntry) error {
+	var totalDebit, totalCredit float64
+	for _, l := range je.Lines {
+		totalDebit += l.Debit
+		totalCredit += l.Credit
+	}
+
+	// Allow small floating point differences
+	diff := totalDebit - totalCredit
+	if diff > 0.01 || diff < -0.01 {
+		return fmt.Errorf("debits (%.2f) must equal credits (%.2f)", totalDebit, totalCredit)
+	}
+
+	tx, err := db.Begin()
+	if err != nil {
+		return err
+	}
+	defer tx.Rollback()
+
+	result, err := tx.Exec(
+		"INSERT INTO journal_entries (entry_date, description, reference) VALUES (?, ?, ?)",
+		je.EntryDate, je.Description, je.Reference,
+	)
+	if err != nil {
+		return err
+	}
+	jeID, _ := result.LastInsertId()
+	je.ID = int(jeID)
+
+	for _, l := range je.Lines {
+		_, err := tx.Exec(
+			"INSERT INTO journal_lines (journal_entry_id, account_id, debit, credit) VALUES (?, ?, ?, ?)",
+			jeID, l.AccountID, l.Debit, l.Credit,
+		)
+		if err != nil {
+			return err
+		}
+
+		// Update account balance
+		// For assets/expenses: balance increases with debit, decreases with credit
+		// For liabilities/equity/revenue: balance increases with credit, decreases with debit
+		netEffect := l.Debit - l.Credit
+		_, err = tx.Exec("UPDATE gl_accounts SET balance = balance + ? WHERE id = ?", netEffect, l.AccountID)
+		if err != nil {
+			return err
+		}
+	}
+
+	return tx.Commit()
+}
+
+func GetTrialBalance(db *sql.DB) ([]TrialBalanceRow, error) {
+	rows, err := db.Query(`
+		SELECT a.code, a.name, a.type,
+			COALESCE(SUM(jl.debit), 0) as total_debit,
+			COALESCE(SUM(jl.credit), 0) as total_credit
+		FROM gl_accounts a
+		LEFT JOIN journal_lines jl ON a.id = jl.account_id
+		GROUP BY a.id, a.code, a.name, a.type
+		ORDER BY a.code
+	`)
+	if err != nil {
+		return nil, err
+	}
+	defer rows.Close()
+
+	var result []TrialBalanceRow
+	for rows.Next() {
+		var r TrialBalanceRow
+		if err := rows.Scan(&r.Code, &r.Name, &r.Type, &r.Debit, &r.Credit); err != nil {
+			return nil, err
+		}
+		result = append(result, r)
+	}
+	return result, nil
+}
+
+func RevenueThisMonth(db *sql.DB) float64 {
+	var total float64
+	db.QueryRow(`
+		SELECT COALESCE(SUM(jl.credit), 0)
+		FROM journal_lines jl
+		JOIN gl_accounts a ON jl.account_id = a.id
+		JOIN journal_entries je ON jl.journal_entry_id = je.id
+		WHERE a.type = 'revenue'
+		AND je.entry_date >= date('now', 'start of month')
+	`).Scan(&total)
+	return total
+}

internal/models/order.go

@@ -0,0 +1,224 @@
+package models
+
+import (
+	"database/sql"
+	"fmt"
+	"time"
+)
+
+type Order struct {
+	ID           int
+	CustomerID   int
+	CustomerName string // joined field
+	Status       string
+	OrderDate    string
+	TotalAmount  float64
+	Notes        string
+	CreatedAt    time.Time
+	UpdatedAt    time.Time
+	Lines        []OrderLine
+}
+
+type OrderLine struct {
+	ID          int
+	OrderID     int
+	Description string
+	Quantity    float64
+	UnitPrice   float64
+	LineTotal   float64
+}
+
+func OrderGetAll(db *sql.DB, status string) ([]Order, error) {
+	query := `SELECT o.id, o.customer_id, c.name, o.status, o.order_date, o.total_amount, o.notes, o.created_at, o.updated_at
+		FROM orders o JOIN customers c ON o.customer_id = c.id`
+	args := []interface{}{}
+	if status != "" {
+		query += " WHERE o.status = ?"
+		args = append(args, status)
+	}
+	query += " ORDER BY o.created_at DESC"
+
+	rows, err := db.Query(query, args...)
+	if err != nil {
+		return nil, err
+	}
+	defer rows.Close()
+
+	var orders []Order
+	for rows.Next() {
+		var o Order
+		if err := rows.Scan(&o.ID, &o.CustomerID, &o.CustomerName, &o.Status, &o.OrderDate, &o.TotalAmount, &o.Notes, &o.CreatedAt, &o.UpdatedAt); err != nil {
+			return nil, err
+		}
+		orders = append(orders, o)
+	}
+	return orders, nil
+}
+
+func OrderGetByID(db *sql.DB, id int) (*Order, error) {
+	o := &Order{}
+	err := db.QueryRow(
+		`SELECT o.id, o.customer_id, c.name, o.status, o.order_date, o.total_amount, o.notes, o.created_at, o.updated_at
+		FROM orders o JOIN customers c ON o.customer_id = c.id WHERE o.id = ?`, id,
+	).Scan(&o.ID, &o.CustomerID, &o.CustomerName, &o.Status, &o.OrderDate, &o.TotalAmount, &o.Notes, &o.CreatedAt, &o.UpdatedAt)
+	if err != nil {
+		return nil, err
+	}
+
+	// Load lines
+	lines, err := OrderLinesGetByOrderID(db, id)
+	if err != nil {
+		return nil, err
+	}
+	o.Lines = lines
+	return o, nil
+}
+
+func OrderInsert(db *sql.DB, o *Order) error {
+	result, err := db.Exec(
+		"INSERT INTO orders (customer_id, status, order_date, total_amount, notes) VALUES (?, ?, ?, ?, ?)",
+		o.CustomerID, o.Status, o.OrderDate, o.TotalAmount, o.Notes,
+	)
+	if err != nil {
+		return err
+	}
+	id, _ := result.LastInsertId()
+	o.ID = int(id)
+	return nil
+}
+
+func OrderUpdate(db *sql.DB, o *Order) error {
+	_, err := db.Exec(
+		"UPDATE orders SET customer_id = ?, order_date = ?, notes = ?, updated_at = CURRENT_TIMESTAMP WHERE id = ?",
+		o.CustomerID, o.OrderDate, o.Notes, o.ID,
+	)
+	return err
+}
+
+func OrderUpdateStatus(db *sql.DB, id int, status string) error {
+	_, err := db.Exec("UPDATE orders SET status = ?, updated_at = CURRENT_TIMESTAMP WHERE id = ?", status, id)
+	return err
+}
+
+func OrderRecalcTotal(db *sql.DB, orderID int) error {
+	_, err := db.Exec(
+		"UPDATE orders SET total_amount = (SELECT COALESCE(SUM(line_total), 0) FROM order_lines WHERE order_id = ?), updated_at = CURRENT_TIMESTAMP WHERE id = ?",
+		orderID, orderID,
+	)
+	return err
+}
+
+func OrderDelete(db *sql.DB, id int) error {
+	_, err := db.Exec("DELETE FROM orders WHERE id = ?", id)
+	return err
+}
+
+func OrderCount(db *sql.DB) int {
+	var count int
+	db.QueryRow("SELECT COUNT(*) FROM orders WHERE status NOT IN ('cancelled')").Scan(&count)
+	return count
+}
+
+func OrderCountByStatus(db *sql.DB, status string) int {
+	var count int
+	db.QueryRow("SELECT COUNT(*) FROM orders WHERE status = ?", status).Scan(&count)
+	return count
+}
+
+// Order Lines
+
+func OrderLinesGetByOrderID(db *sql.DB, orderID int) ([]OrderLine, error) {
+	rows, err := db.Query("SELECT id, order_id, description, quantity, unit_price, line_total FROM order_lines WHERE order_id = ? ORDER BY id", orderID)
+	if err != nil {
+		return nil, err
+	}
+	defer rows.Close()
+
+	var lines []OrderLine
+	for rows.Next() {
+		var l OrderLine
+		if err := rows.Scan(&l.ID, &l.OrderID, &l.Description, &l.Quantity, &l.UnitPrice, &l.LineTotal); err != nil {
+			return nil, err
+		}
+		lines = append(lines, l)
+	}
+	return lines, nil
+}
+
+func OrderLineInsert(db *sql.DB, l *OrderLine) error {
+	l.LineTotal = l.Quantity * l.UnitPrice
+	result, err := db.Exec(
+		"INSERT INTO order_lines (order_id, description, quantity, unit_price, line_total) VALUES (?, ?, ?, ?, ?)",
+		l.OrderID, l.Description, l.Quantity, l.UnitPrice, l.LineTotal,
+	)
+	if err != nil {
+		return err
+	}
+	id, _ := result.LastInsertId()
+	l.ID = int(id)
+	return OrderRecalcTotal(db, l.OrderID)
+}
+
+func OrderLineDelete(db *sql.DB, lineID, orderID int) error {
+	_, err := db.Exec("DELETE FROM order_lines WHERE id = ?", lineID)
+	if err != nil {
+		return err
+	}
+	return OrderRecalcTotal(db, orderID)
+}
+
+// GenerateInvoiceFromOrder creates an invoice and GL entries when an order is fulfilled
+func GenerateInvoiceFromOrder(db *sql.DB, orderID int) error {
+	order, err := OrderGetByID(db, orderID)
+	if err != nil {
+		return err
+	}
+
+	// Generate invoice number
+	var maxID int
+	db.QueryRow("SELECT COALESCE(MAX(id), 0) FROM invoices").Scan(&maxID)
+	invoiceNumber := fmt.Sprintf("INV-%05d", maxID+1)
+
+	// Create invoice (due in 30 days)
+	_, err = db.Exec(
+		`INSERT INTO invoices (order_id, customer_id, invoice_number, status, amount, due_date)
+		VALUES (?, ?, ?, 'pending', ?, date('now', '+30 days'))`,
+		order.ID, order.CustomerID, invoiceNumber, order.TotalAmount,
+	)
+	if err != nil {
+		return fmt.Errorf("creating invoice: %w", err)
+	}
+
+	// Create GL journal entry: Debit AR, Credit Revenue
+	result, err := db.Exec(
+		"INSERT INTO journal_entries (entry_date, description, reference) VALUES (date('now'), ?, ?)",
+		fmt.Sprintf("Invoice %s - Order #%d fulfilled", invoiceNumber, orderID),
+		invoiceNumber,
+	)
+	if err != nil {
+		return fmt.Errorf("creating journal entry: %w", err)
+	}
+	jeID, _ := result.LastInsertId()
+
+	// Debit Accounts Receivable (1100)
+	var arID int
+	db.QueryRow("SELECT id FROM gl_accounts WHERE code = '1100'").Scan(&arID)
+	_, err = db.Exec("INSERT INTO journal_lines (journal_entry_id, account_id, debit, credit) VALUES (?, ?, ?, 0)", jeID, arID, order.TotalAmount)
+	if err != nil {
+		return fmt.Errorf("creating AR debit line: %w", err)
+	}
+
+	// Credit Sales Revenue (4000)
+	var revID int
+	db.QueryRow("SELECT id FROM gl_accounts WHERE code = '4000'").Scan(&revID)
+	_, err = db.Exec("INSERT INTO journal_lines (journal_entry_id, account_id, debit, credit) VALUES (?, ?, 0, ?)", jeID, revID, order.TotalAmount)
+	if err != nil {
+		return fmt.Errorf("creating revenue credit line: %w", err)
+	}
+
+	// Update account balances
+	db.Exec("UPDATE gl_accounts SET balance = balance + ? WHERE code = '1100'", order.TotalAmount) // AR increases (debit)
+	db.Exec("UPDATE gl_accounts SET balance = balance + ? WHERE code = '4000'", order.TotalAmount) // Revenue increases (credit)
+
+	return nil
+}

internal/models/user.go

@@ -0,0 +1,33 @@
+package models
+
+import (
+	"database/sql"
+	"fmt"
+	"time"
+
+	"golang.org/x/crypto/bcrypt"
+)
+
+type User struct {
+	ID           int
+	Username     string
+	PasswordHash string
+	CreatedAt    time.Time
+}
+
+func Authenticate(db *sql.DB, username, password string) (*User, error) {
+	u := &User{}
+	err := db.QueryRow(
+		"SELECT id, username, password_hash, created_at FROM users WHERE username = ?",
+		username,
+	).Scan(&u.ID, &u.Username, &u.PasswordHash, &u.CreatedAt)
+	if err != nil {
+		return nil, fmt.Errorf("user not found")
+	}
+
+	if err := bcrypt.CompareHashAndPassword([]byte(u.PasswordHash), []byte(password)); err != nil {
+		return nil, fmt.Errorf("invalid password")
+	}
+
+	return u, nil
+}

main.go

@@ -0,0 +1,103 @@
+package main
+
+import (
+	"log"
+	"net/http"
+	"os"
+
+	"erp_system/internal/database"
+	"erp_system/internal/handlers"
+	"erp_system/internal/middleware"
+
+	"github.com/gorilla/sessions"
+)
+
+func main() {
+	// Initialize database
+	db, err := database.Initialize("erp.db")
+	if err != nil {
+		log.Fatalf("Failed to initialize database: %v", err)
+	}
+	defer db.Close()
+
+	// Session store
+	sessionKey := os.Getenv("SESSION_KEY")
+	if sessionKey == "" {
+		sessionKey = "erp-system-dev-secret-key-change-in-prod"
+	}
+	store := sessions.NewCookieStore([]byte(sessionKey))
+	store.Options = &sessions.Options{
+		Path:     "/",
+		MaxAge:   86400, // 24 hours
+		HttpOnly: true,
+	}
+
+	// Create handler context
+	h := &handlers.Handler{
+		DB:    db,
+		Store: store,
+	}
+
+	// Auth middleware
+	authMw := middleware.RequireAuth(store)
+
+	// Router
+	mux := http.NewServeMux()
+
+	// Static/public routes
+	mux.HandleFunc("GET /login", h.LoginPage)
+	mux.HandleFunc("POST /login", h.LoginSubmit)
+	mux.HandleFunc("POST /logout", h.Logout)
+
+	// Protected routes
+	mux.Handle("GET /{$}", authMw(http.HandlerFunc(h.Dashboard)))
+
+	// Customers
+	mux.Handle("GET /customers", authMw(http.HandlerFunc(h.CustomerList)))
+	mux.Handle("GET /customers/new", authMw(http.HandlerFunc(h.CustomerNew)))
+	mux.Handle("POST /customers", authMw(http.HandlerFunc(h.CustomerCreate)))
+	mux.Handle("GET /customers/{id}", authMw(http.HandlerFunc(h.CustomerDetail)))
+	mux.Handle("GET /customers/{id}/edit", authMw(http.HandlerFunc(h.CustomerEdit)))
+	mux.Handle("PUT /customers/{id}", authMw(http.HandlerFunc(h.CustomerUpdate)))
+	mux.Handle("DELETE /customers/{id}", authMw(http.HandlerFunc(h.CustomerDelete)))
+
+	// Orders
+	mux.Handle("GET /orders", authMw(http.HandlerFunc(h.OrderList)))
+	mux.Handle("GET /orders/new", authMw(http.HandlerFunc(h.OrderNew)))
+	mux.Handle("POST /orders", authMw(http.HandlerFunc(h.OrderCreate)))
+	mux.Handle("GET /orders/{id}", authMw(http.HandlerFunc(h.OrderDetail)))
+	mux.Handle("GET /orders/{id}/edit", authMw(http.HandlerFunc(h.OrderEdit)))
+	mux.Handle("PUT /orders/{id}", authMw(http.HandlerFunc(h.OrderUpdate)))
+	mux.Handle("POST /orders/{id}/confirm", authMw(http.HandlerFunc(h.OrderConfirm)))
+	mux.Handle("POST /orders/{id}/fulfill", authMw(http.HandlerFunc(h.OrderFulfill)))
+	mux.Handle("POST /orders/{id}/cancel", authMw(http.HandlerFunc(h.OrderCancel)))
+	mux.Handle("DELETE /orders/{id}", authMw(http.HandlerFunc(h.OrderDelete)))
+
+	// Order lines (HTMX partials)
+	mux.Handle("POST /orders/{id}/lines", authMw(http.HandlerFunc(h.OrderLineAdd)))
+	mux.Handle("DELETE /orders/{id}/lines/{lineID}", authMw(http.HandlerFunc(h.OrderLineDelete)))
+
+	// Invoices
+	mux.Handle("GET /invoices", authMw(http.HandlerFunc(h.InvoiceList)))
+	mux.Handle("GET /invoices/{id}", authMw(http.HandlerFunc(h.InvoiceDetail)))
+	mux.Handle("POST /invoices/{id}/pay", authMw(http.HandlerFunc(h.InvoicePay)))
+
+	// General Ledger
+	mux.Handle("GET /ledger/accounts", authMw(http.HandlerFunc(h.ChartOfAccounts)))
+	mux.Handle("GET /ledger/journal", authMw(http.HandlerFunc(h.JournalEntries)))
+	mux.Handle("GET /ledger/journal/new", authMw(http.HandlerFunc(h.JournalEntryNew)))
+	mux.Handle("POST /ledger/journal", authMw(http.HandlerFunc(h.JournalEntryCreate)))
+	mux.Handle("GET /ledger/journal/{id}", authMw(http.HandlerFunc(h.JournalEntryDetail)))
+	mux.Handle("GET /ledger/trial-balance", authMw(http.HandlerFunc(h.TrialBalance)))
+
+	port := os.Getenv("PORT")
+	if port == "" {
+		port = "8080"
+	}
+
+	log.Printf("ERP System starting on http://localhost:%s", port)
+	log.Printf("Default login: admin / admin123")
+	if err := http.ListenAndServe(":"+port, mux); err != nil {
+		log.Fatalf("Server failed: %v", err)
+	}
+}

templates/customers/detail.html

@@ -0,0 +1,104 @@
+{{define "content"}}
+<div class="space-y-6">
+    <div class="sm:flex sm:items-center sm:justify-between">
+        <h1 class="text-2xl font-bold text-gray-900">{{.Customer.Name}}</h1>
+        <div class="flex space-x-3">
+            <a href="/customers" class="text-sm text-gray-500 hover:text-gray-700">&larr; All Customers</a>
+            <a href="/customers/{{.Customer.ID}}/edit"
+                class="rounded-md bg-white px-3 py-2 text-sm font-semibold text-gray-900 shadow-sm ring-1 ring-inset ring-gray-300 hover:bg-gray-50">Edit</a>
+            <button class="rounded-md bg-red-600 px-3 py-2 text-sm font-semibold text-white shadow-sm hover:bg-red-500"
+                hx-delete="/customers/{{.Customer.ID}}"
+                hx-confirm="Are you sure you want to delete this customer?">Delete</button>
+        </div>
+    </div>
+
+    <!-- Customer Info -->
+    <div class="bg-white shadow sm:rounded-lg">
+        <div class="px-4 py-5 sm:p-6">
+            <dl class="grid grid-cols-1 gap-x-4 gap-y-6 sm:grid-cols-2">
+                <div>
+                    <dt class="text-sm font-medium text-gray-500">Email</dt>
+                    <dd class="mt-1 text-sm text-gray-900">{{if .Customer.Email}}{{.Customer.Email}}{{else}}-{{end}}</dd>
+                </div>
+                <div>
+                    <dt class="text-sm font-medium text-gray-500">Phone</dt>
+                    <dd class="mt-1 text-sm text-gray-900">{{if .Customer.Phone}}{{.Customer.Phone}}{{else}}-{{end}}</dd>
+                </div>
+                <div class="sm:col-span-2">
+                    <dt class="text-sm font-medium text-gray-500">Address</dt>
+                    <dd class="mt-1 text-sm text-gray-900">{{if .Customer.Address}}{{.Customer.Address}}{{else}}-{{end}}</dd>
+                </div>
+                <div>
+                    <dt class="text-sm font-medium text-gray-500">Created</dt>
+                    <dd class="mt-1 text-sm text-gray-900">{{.Customer.CreatedAt.Format "Jan 02, 2006"}}</dd>
+                </div>
+            </dl>
+        </div>
+    </div>
+
+    <!-- Customer Orders -->
+    <div class="bg-white shadow sm:rounded-lg">
+        <div class="px-4 py-5 sm:p-6">
+            <div class="sm:flex sm:items-center sm:justify-between mb-4">
+                <h2 class="text-lg font-medium text-gray-900">Orders</h2>
+                <a href="/orders/new" class="text-sm text-indigo-600 hover:text-indigo-500">+ New Order</a>
+            </div>
+            {{if .Orders}}
+            <table class="min-w-full divide-y divide-gray-300">
+                <thead>
+                    <tr>
+                        <th class="py-2 pr-3 text-left text-sm font-semibold text-gray-900">Order #</th>
+                        <th class="px-3 py-2 text-left text-sm font-semibold text-gray-900">Date</th>
+                        <th class="px-3 py-2 text-left text-sm font-semibold text-gray-900">Status</th>
+                        <th class="px-3 py-2 text-right text-sm font-semibold text-gray-900">Amount</th>
+                    </tr>
+                </thead>
+                <tbody class="divide-y divide-gray-200">
+                    {{range .Orders}}
+                    <tr>
+                        <td class="py-2 pr-3 text-sm"><a href="/orders/{{.ID}}" class="text-indigo-600 hover:text-indigo-900">#{{.ID}}</a></td>
+                        <td class="px-3 py-2 text-sm text-gray-500">{{formatDate .OrderDate}}</td>
+                        <td class="px-3 py-2 text-sm">{{statusBadge .Status}}</td>
+                        <td class="px-3 py-2 text-sm text-gray-900 text-right">{{formatMoney .TotalAmount}}</td>
+                    </tr>
+                    {{end}}
+                </tbody>
+            </table>
+            {{else}}
+            <p class="text-sm text-gray-500">No orders yet.</p>
+            {{end}}
+        </div>
+    </div>
+
+    <!-- Customer Invoices -->
+    <div class="bg-white shadow sm:rounded-lg">
+        <div class="px-4 py-5 sm:p-6">
+            <h2 class="text-lg font-medium text-gray-900 mb-4">Invoices</h2>
+            {{if .Invoices}}
+            <table class="min-w-full divide-y divide-gray-300">
+                <thead>
+                    <tr>
+                        <th class="py-2 pr-3 text-left text-sm font-semibold text-gray-900">Invoice #</th>
+                        <th class="px-3 py-2 text-left text-sm font-semibold text-gray-900">Status</th>
+                        <th class="px-3 py-2 text-left text-sm font-semibold text-gray-900">Due Date</th>
+                        <th class="px-3 py-2 text-right text-sm font-semibold text-gray-900">Amount</th>
+                    </tr>
+                </thead>
+                <tbody class="divide-y divide-gray-200">
+                    {{range .Invoices}}
+                    <tr>
+                        <td class="py-2 pr-3 text-sm"><a href="/invoices/{{.ID}}" class="text-indigo-600 hover:text-indigo-900">{{.InvoiceNumber}}</a></td>
+                        <td class="px-3 py-2 text-sm">{{statusBadge .Status}}</td>
+                        <td class="px-3 py-2 text-sm text-gray-500">{{formatDate .DueDate}}</td>
+                        <td class="px-3 py-2 text-sm text-gray-900 text-right">{{formatMoney .Amount}}</td>
+                    </tr>
+                    {{end}}
+                </tbody>
+            </table>
+            {{else}}
+            <p class="text-sm text-gray-500">No invoices yet.</p>
+            {{end}}
+        </div>
+    </div>
+</div>
+{{end}}

templates/customers/form.html

@@ -0,0 +1,59 @@
+{{define "content"}}
+<div class="space-y-6">
+    <div class="sm:flex sm:items-center sm:justify-between">
+        <h1 class="text-2xl font-bold text-gray-900">{{if .IsNew}}New Customer{{else}}Edit Customer{{end}}</h1>
+        <a href="{{if .IsNew}}/customers{{else}}/customers/{{.Customer.ID}}{{end}}" class="text-sm text-gray-500 hover:text-gray-700">&larr; Back</a>
+    </div>
+
+    {{if .Error}}
+    <div class="rounded-md bg-red-50 p-4">
+        <div class="text-sm text-red-700">{{.Error}}</div>
+    </div>
+    {{end}}
+
+    <div class="bg-white shadow sm:rounded-lg">
+        <form class="space-y-6 p-6"
+            {{if .IsNew}}
+                method="POST" action="/customers" hx-post="/customers"
+            {{else}}
+                method="POST" action="/customers/{{.Customer.ID}}" hx-put="/customers/{{.Customer.ID}}"
+            {{end}}>
+
+            <div class="grid grid-cols-1 gap-6 sm:grid-cols-2">
+                <div>
+                    <label for="name" class="block text-sm font-medium text-gray-700">Name *</label>
+                    <input type="text" name="name" id="name" required value="{{.Customer.Name}}"
+                        class="mt-1 block w-full rounded-md border border-gray-300 px-3 py-2 shadow-sm focus:border-indigo-500 focus:outline-none focus:ring-indigo-500 sm:text-sm">
+                </div>
+
+                <div>
+                    <label for="email" class="block text-sm font-medium text-gray-700">Email</label>
+                    <input type="email" name="email" id="email" value="{{.Customer.Email}}"
+                        class="mt-1 block w-full rounded-md border border-gray-300 px-3 py-2 shadow-sm focus:border-indigo-500 focus:outline-none focus:ring-indigo-500 sm:text-sm">
+                </div>
+
+                <div>
+                    <label for="phone" class="block text-sm font-medium text-gray-700">Phone</label>
+                    <input type="tel" name="phone" id="phone" value="{{.Customer.Phone}}"
+                        class="mt-1 block w-full rounded-md border border-gray-300 px-3 py-2 shadow-sm focus:border-indigo-500 focus:outline-none focus:ring-indigo-500 sm:text-sm">
+                </div>
+            </div>
+
+            <div>
+                <label for="address" class="block text-sm font-medium text-gray-700">Address</label>
+                <textarea name="address" id="address" rows="3"
+                    class="mt-1 block w-full rounded-md border border-gray-300 px-3 py-2 shadow-sm focus:border-indigo-500 focus:outline-none focus:ring-indigo-500 sm:text-sm">{{.Customer.Address}}</textarea>
+            </div>
+
+            <div class="flex justify-end space-x-3">
+                <a href="{{if .IsNew}}/customers{{else}}/customers/{{.Customer.ID}}{{end}}"
+                    class="rounded-md bg-white px-3 py-2 text-sm font-semibold text-gray-900 shadow-sm ring-1 ring-inset ring-gray-300 hover:bg-gray-50">Cancel</a>
+                <button type="submit"
+                    class="rounded-md bg-indigo-600 px-3 py-2 text-sm font-semibold text-white shadow-sm hover:bg-indigo-500">
+                    {{if .IsNew}}Create Customer{{else}}Update Customer{{end}}
+                </button>
+            </div>
+        </form>
+    </div>
+</div>
+{{end}}

templates/customers/list.html

@@ -0,0 +1,63 @@
+{{define "content"}}
+<div class="space-y-6">
+    <div class="sm:flex sm:items-center sm:justify-between">
+        <h1 class="text-2xl font-bold text-gray-900">Customers</h1>
+        <a href="/customers/new" class="inline-flex items-center rounded-md bg-indigo-600 px-3 py-2 text-sm font-semibold text-white shadow-sm hover:bg-indigo-500">
+            + New Customer
+        </a>
+    </div>
+
+    <!-- Search -->
+    <div class="max-w-md">
+        <input type="search" name="search" placeholder="Search customers..."
+            value="{{.Search}}"
+            class="block w-full rounded-md border border-gray-300 px-3 py-2 shadow-sm focus:border-indigo-500 focus:outline-none focus:ring-indigo-500 sm:text-sm"
+            hx-get="/customers?partial=true"
+            hx-trigger="input changed delay:300ms, search"
+            hx-target="#customer-table"
+            hx-include="this">
+    </div>
+
+    <div id="customer-table">
+        {{template "customer-table" .}}
+    </div>
+</div>
+{{end}}
+
+{{define "customer-table"}}
+<div class="overflow-hidden bg-white shadow ring-1 ring-black ring-opacity-5 sm:rounded-lg">
+    <table class="min-w-full divide-y divide-gray-300">
+        <thead class="bg-gray-50">
+            <tr>
+                <th class="py-3.5 pl-4 pr-3 text-left text-sm font-semibold text-gray-900">Name</th>
+                <th class="px-3 py-3.5 text-left text-sm font-semibold text-gray-900">Email</th>
+                <th class="px-3 py-3.5 text-left text-sm font-semibold text-gray-900">Phone</th>
+                <th class="px-3 py-3.5 text-left text-sm font-semibold text-gray-900">Actions</th>
+            </tr>
+        </thead>
+        <tbody class="divide-y divide-gray-200 bg-white">
+            {{if .Customers}}
+                {{range .Customers}}
+                <tr class="hover:bg-gray-50">
+                    <td class="whitespace-nowrap py-4 pl-4 pr-3 text-sm font-medium text-indigo-600">
+                        <a href="/customers/{{.ID}}">{{.Name}}</a>
+                    </td>
+                    <td class="whitespace-nowrap px-3 py-4 text-sm text-gray-500">{{.Email}}</td>
+                    <td class="whitespace-nowrap px-3 py-4 text-sm text-gray-500">{{.Phone}}</td>
+                    <td class="whitespace-nowrap px-3 py-4 text-sm space-x-2">
+                        <a href="/customers/{{.ID}}/edit" class="text-indigo-600 hover:text-indigo-900">Edit</a>
+                        <button class="text-red-600 hover:text-red-900"
+                            hx-delete="/customers/{{.ID}}"
+                            hx-confirm="Are you sure you want to delete this customer?">Delete</button>
+                    </td>
+                </tr>
+                {{end}}
+            {{else}}
+                <tr>
+                    <td colspan="4" class="px-3 py-8 text-center text-sm text-gray-500">No customers found. <a href="/customers/new" class="text-indigo-600 hover:text-indigo-500">Create one</a>.</td>
+                </tr>
+            {{end}}
+        </tbody>
+    </table>
+</div>
+{{end}}

templates/dashboard.html

@@ -0,0 +1,76 @@
+{{define "content"}}
+<div class="space-y-6">
+    <h1 class="text-2xl font-bold text-gray-900">Dashboard</h1>
+
+    <!-- Summary Cards -->
+    <div class="grid grid-cols-1 gap-5 sm:grid-cols-2 lg:grid-cols-4">
+        <!-- Customers -->
+        <div class="overflow-hidden rounded-lg bg-white px-4 py-5 shadow sm:p-6">
+            <dt class="truncate text-sm font-medium text-gray-500">Total Customers</dt>
+            <dd class="mt-1 text-3xl font-semibold tracking-tight text-gray-900">{{.CustomerCount}}</dd>
+            <a href="/customers" class="mt-2 inline-block text-sm text-indigo-600 hover:text-indigo-500">View all &rarr;</a>
+        </div>
+
+        <!-- Open Orders -->
+        <div class="overflow-hidden rounded-lg bg-white px-4 py-5 shadow sm:p-6">
+            <dt class="truncate text-sm font-medium text-gray-500">Open Orders</dt>
+            <dd class="mt-1 text-3xl font-semibold tracking-tight text-gray-900">{{.OpenOrderCount}}</dd>
+            <a href="/orders" class="mt-2 inline-block text-sm text-indigo-600 hover:text-indigo-500">View all &rarr;</a>
+        </div>
+
+        <!-- Pending Invoices -->
+        <div class="overflow-hidden rounded-lg bg-white px-4 py-5 shadow sm:p-6">
+            <dt class="truncate text-sm font-medium text-gray-500">Pending Invoices</dt>
+            <dd class="mt-1 text-3xl font-semibold tracking-tight text-yellow-600">{{.PendingInvoices}}</dd>
+            <dd class="mt-1 text-sm text-gray-500">{{formatMoney .OutstandingAmount}} outstanding</dd>
+            <a href="/invoices?status=pending" class="mt-2 inline-block text-sm text-indigo-600 hover:text-indigo-500">View all &rarr;</a>
+        </div>
+
+        <!-- Revenue This Month -->
+        <div class="overflow-hidden rounded-lg bg-white px-4 py-5 shadow sm:p-6">
+            <dt class="truncate text-sm font-medium text-gray-500">Revenue This Month</dt>
+            <dd class="mt-1 text-3xl font-semibold tracking-tight text-green-600">{{formatMoney .RevenueThisMonth}}</dd>
+            <a href="/ledger/trial-balance" class="mt-2 inline-block text-sm text-indigo-600 hover:text-indigo-500">View ledger &rarr;</a>
+        </div>
+    </div>
+
+    <!-- Quick Actions -->
+    <div class="rounded-lg bg-white shadow p-6">
+        <h2 class="text-lg font-medium text-gray-900 mb-4">Quick Actions</h2>
+        <div class="flex flex-wrap gap-3">
+            <a href="/customers/new" class="inline-flex items-center rounded-md bg-indigo-600 px-3 py-2 text-sm font-semibold text-white shadow-sm hover:bg-indigo-500">
+                + New Customer
+            </a>
+            <a href="/orders/new" class="inline-flex items-center rounded-md bg-indigo-600 px-3 py-2 text-sm font-semibold text-white shadow-sm hover:bg-indigo-500">
+                + New Order
+            </a>
+            <a href="/ledger/journal/new" class="inline-flex items-center rounded-md bg-indigo-600 px-3 py-2 text-sm font-semibold text-white shadow-sm hover:bg-indigo-500">
+                + Journal Entry
+            </a>
+        </div>
+    </div>
+
+    <!-- Order Status Summary -->
+    <div class="rounded-lg bg-white shadow p-6">
+        <h2 class="text-lg font-medium text-gray-900 mb-4">Order Status Summary</h2>
+        <div class="grid grid-cols-2 gap-4 sm:grid-cols-4">
+            <div class="text-center">
+                <div class="text-2xl font-bold text-gray-500">{{.OpenOrderCount}}</div>
+                <div class="text-sm text-gray-500">Draft / Confirmed</div>
+            </div>
+            <div class="text-center">
+                <div class="text-2xl font-bold text-green-600">{{.FulfilledOrders}}</div>
+                <div class="text-sm text-gray-500">Fulfilled</div>
+            </div>
+            <div class="text-center">
+                <div class="text-2xl font-bold text-yellow-600">{{.PendingInvoices}}</div>
+                <div class="text-sm text-gray-500">Pending Invoices</div>
+            </div>
+            <div class="text-center">
+                <div class="text-2xl font-bold text-green-600">{{formatMoney .RevenueThisMonth}}</div>
+                <div class="text-sm text-gray-500">Monthly Revenue</div>
+            </div>
+        </div>
+    </div>
+</div>
+{{end}}

templates/invoices/detail.html

@@ -0,0 +1,67 @@
+{{define "content"}}
+<div class="space-y-6">
+    <div class="sm:flex sm:items-center sm:justify-between">
+        <div>
+            <h1 class="text-2xl font-bold text-gray-900">{{.Invoice.InvoiceNumber}}</h1>
+            <p class="mt-1 text-sm text-gray-500">{{.Invoice.CustomerName}}</p>
+        </div>
+        <div class="flex items-center space-x-3">
+            <a href="/invoices" class="text-sm text-gray-500 hover:text-gray-700">&larr; All Invoices</a>
+            {{if eq .Invoice.Status "pending"}}
+            <button class="rounded-md bg-green-600 px-3 py-2 text-sm font-semibold text-white shadow-sm hover:bg-green-500"
+                hx-post="/invoices/{{.Invoice.ID}}/pay"
+                hx-confirm="Mark this invoice as paid? This will create a GL journal entry.">
+                Mark as Paid
+            </button>
+            {{end}}
+        </div>
+    </div>
+
+    <div class="bg-white shadow sm:rounded-lg">
+        <div class="px-4 py-5 sm:p-6">
+            <dl class="grid grid-cols-1 gap-x-4 gap-y-6 sm:grid-cols-3">
+                <div>
+                    <dt class="text-sm font-medium text-gray-500">Invoice Number</dt>
+                    <dd class="mt-1 text-sm text-gray-900">{{.Invoice.InvoiceNumber}}</dd>
+                </div>
+                <div>
+                    <dt class="text-sm font-medium text-gray-500">Customer</dt>
+                    <dd class="mt-1 text-sm text-gray-900">
+                        <a href="/customers/{{.Invoice.CustomerID}}" class="text-indigo-600 hover:text-indigo-900">{{.Invoice.CustomerName}}</a>
+                    </dd>
+                </div>
+                <div>
+                    <dt class="text-sm font-medium text-gray-500">Status</dt>
+                    <dd class="mt-1">{{statusBadge .Invoice.Status}}</dd>
+                </div>
+                <div>
+                    <dt class="text-sm font-medium text-gray-500">Amount</dt>
+                    <dd class="mt-1 text-2xl font-semibold text-gray-900">{{formatMoney .Invoice.Amount}}</dd>
+                </div>
+                <div>
+                    <dt class="text-sm font-medium text-gray-500">Due Date</dt>
+                    <dd class="mt-1 text-sm text-gray-900">{{formatDate .Invoice.DueDate}}</dd>
+                </div>
+                {{if .Invoice.PaidDate.Valid}}
+                <div>
+                    <dt class="text-sm font-medium text-gray-500">Paid Date</dt>
+                    <dd class="mt-1 text-sm text-gray-900">{{formatDate .Invoice.PaidDate.String}}</dd>
+                </div>
+                {{end}}
+                {{if .Invoice.OrderID.Valid}}
+                <div>
+                    <dt class="text-sm font-medium text-gray-500">Order</dt>
+                    <dd class="mt-1 text-sm text-gray-900">
+                        <a href="/orders/{{.Invoice.OrderID.Int64}}" class="text-indigo-600 hover:text-indigo-900">Order #{{.Invoice.OrderID.Int64}}</a>
+                    </dd>
+                </div>
+                {{end}}
+                <div>
+                    <dt class="text-sm font-medium text-gray-500">Created</dt>
+                    <dd class="mt-1 text-sm text-gray-900">{{.Invoice.CreatedAt.Format "Jan 02, 2006 3:04 PM"}}</dd>
+                </div>
+            </dl>
+        </div>
+    </div>
+</div>
+{{end}}

templates/invoices/list.html

@@ -0,0 +1,67 @@
+{{define "content"}}
+<div class="space-y-6">
+    <div class="sm:flex sm:items-center sm:justify-between">
+        <h1 class="text-2xl font-bold text-gray-900">Invoices</h1>
+    </div>
+
+    <!-- Status Filter -->
+    <div class="flex space-x-2">
+        <a href="/invoices"
+            class="{{if eq .FilterStatus ""}}bg-indigo-100 text-indigo-700{{else}}bg-white text-gray-700 hover:bg-gray-50{{end}} rounded-md px-3 py-1.5 text-sm font-medium ring-1 ring-inset ring-gray-300">All</a>
+        <a href="/invoices?status=pending"
+            class="{{if eq .FilterStatus "pending"}}bg-indigo-100 text-indigo-700{{else}}bg-white text-gray-700 hover:bg-gray-50{{end}} rounded-md px-3 py-1.5 text-sm font-medium ring-1 ring-inset ring-gray-300">Pending</a>
+        <a href="/invoices?status=paid"
+            class="{{if eq .FilterStatus "paid"}}bg-indigo-100 text-indigo-700{{else}}bg-white text-gray-700 hover:bg-gray-50{{end}} rounded-md px-3 py-1.5 text-sm font-medium ring-1 ring-inset ring-gray-300">Paid</a>
+    </div>
+
+    <div id="invoice-table">
+        {{template "invoice-table" .}}
+    </div>
+</div>
+{{end}}
+
+{{define "invoice-table"}}
+<div class="overflow-hidden bg-white shadow ring-1 ring-black ring-opacity-5 sm:rounded-lg">
+    <table class="min-w-full divide-y divide-gray-300">
+        <thead class="bg-gray-50">
+            <tr>
+                <th class="py-3.5 pl-4 pr-3 text-left text-sm font-semibold text-gray-900">Invoice #</th>
+                <th class="px-3 py-3.5 text-left text-sm font-semibold text-gray-900">Customer</th>
+                <th class="px-3 py-3.5 text-left text-sm font-semibold text-gray-900">Status</th>
+                <th class="px-3 py-3.5 text-left text-sm font-semibold text-gray-900">Due Date</th>
+                <th class="px-3 py-3.5 text-right text-sm font-semibold text-gray-900">Amount</th>
+                <th class="px-3 py-3.5 text-left text-sm font-semibold text-gray-900">Actions</th>
+            </tr>
+        </thead>
+        <tbody class="divide-y divide-gray-200 bg-white">
+            {{if .Invoices}}
+                {{range .Invoices}}
+                <tr class="hover:bg-gray-50">
+                    <td class="whitespace-nowrap py-4 pl-4 pr-3 text-sm font-medium text-indigo-600">
+                        <a href="/invoices/{{.ID}}">{{.InvoiceNumber}}</a>
+                    </td>
+                    <td class="whitespace-nowrap px-3 py-4 text-sm text-gray-900">
+                        <a href="/customers/{{.CustomerID}}" class="hover:text-indigo-600">{{.CustomerName}}</a>
+                    </td>
+                    <td class="whitespace-nowrap px-3 py-4 text-sm">{{statusBadge .Status}}</td>
+                    <td class="whitespace-nowrap px-3 py-4 text-sm text-gray-500">{{formatDate .DueDate}}</td>
+                    <td class="whitespace-nowrap px-3 py-4 text-sm text-gray-900 text-right">{{formatMoney .Amount}}</td>
+                    <td class="whitespace-nowrap px-3 py-4 text-sm">
+                        <a href="/invoices/{{.ID}}" class="text-indigo-600 hover:text-indigo-900">View</a>
+                        {{if eq .Status "pending"}}
+                        <button class="ml-2 text-green-600 hover:text-green-900"
+                            hx-post="/invoices/{{.ID}}/pay"
+                            hx-confirm="Mark this invoice as paid?">Mark Paid</button>
+                        {{end}}
+                    </td>
+                </tr>
+                {{end}}
+            {{else}}
+                <tr>
+                    <td colspan="6" class="px-3 py-8 text-center text-sm text-gray-500">No invoices found. Invoices are auto-generated when orders are fulfilled.</td>
+                </tr>
+            {{end}}
+        </tbody>
+    </table>
+</div>
+{{end}}

templates/layout.html

@@ -0,0 +1,63 @@
+{{define "layout"}}
+<!DOCTYPE html>
+<html lang="en" class="h-full bg-gray-50">
+<head>
+    <meta charset="UTF-8">
+    <meta name="viewport" content="width=device-width, initial-scale=1.0">
+    <title>{{.Title}} - ERP System</title>
+    <script src="https://unpkg.com/htmx.org@2.0.4"></script>
+    <script src="https://cdn.tailwindcss.com"></script>
+    <style>
+        .htmx-indicator { display: none; }
+        .htmx-request .htmx-indicator { display: inline-block; }
+        .htmx-request.htmx-indicator { display: inline-block; }
+    </style>
+</head>
+<body class="h-full" hx-boost="true">
+    <div class="min-h-full">
+        <!-- Navigation -->
+        <nav class="bg-indigo-600 shadow-lg">
+            <div class="mx-auto max-w-7xl px-4 sm:px-6 lg:px-8">
+                <div class="flex h-16 items-center justify-between">
+                    <div class="flex items-center">
+                        <a href="/" class="text-white font-bold text-xl tracking-tight">ERP System</a>
+                        <div class="ml-10 flex items-baseline space-x-4">
+                            <a href="/" class="{{if eq .ActivePage "dashboard"}}bg-indigo-700 text-white{{else}}text-indigo-200 hover:bg-indigo-500 hover:text-white{{end}} rounded-md px-3 py-2 text-sm font-medium">Dashboard</a>
+                            <a href="/customers" class="{{if eq .ActivePage "customers"}}bg-indigo-700 text-white{{else}}text-indigo-200 hover:bg-indigo-500 hover:text-white{{end}} rounded-md px-3 py-2 text-sm font-medium">Customers</a>
+                            <a href="/orders" class="{{if eq .ActivePage "orders"}}bg-indigo-700 text-white{{else}}text-indigo-200 hover:bg-indigo-500 hover:text-white{{end}} rounded-md px-3 py-2 text-sm font-medium">Orders</a>
+                            <a href="/invoices" class="{{if eq .ActivePage "invoices"}}bg-indigo-700 text-white{{else}}text-indigo-200 hover:bg-indigo-500 hover:text-white{{end}} rounded-md px-3 py-2 text-sm font-medium">Invoices</a>
+                            <div class="relative group">
+                                <button class="{{if eq .ActivePage "ledger"}}bg-indigo-700 text-white{{else}}text-indigo-200 hover:bg-indigo-500 hover:text-white{{end}} rounded-md px-3 py-2 text-sm font-medium inline-flex items-center">
+                                    General Ledger
+                                    <svg class="ml-1 h-4 w-4" fill="currentColor" viewBox="0 0 20 20"><path fill-rule="evenodd" d="M5.293 7.293a1 1 0 011.414 0L10 10.586l3.293-3.293a1 1 0 111.414 1.414l-4 4a1 1 0 01-1.414 0l-4-4a1 1 0 010-1.414z" clip-rule="evenodd"/></svg>
+                                </button>
+                                <div class="absolute left-0 z-10 mt-1 w-48 origin-top-left rounded-md bg-white shadow-lg ring-1 ring-black ring-opacity-5 hidden group-hover:block">
+                                    <div class="py-1">
+                                        <a href="/ledger/accounts" class="block px-4 py-2 text-sm text-gray-700 hover:bg-gray-100" hx-boost="true">Chart of Accounts</a>
+                                        <a href="/ledger/journal" class="block px-4 py-2 text-sm text-gray-700 hover:bg-gray-100" hx-boost="true">Journal Entries</a>
+                                        <a href="/ledger/trial-balance" class="block px-4 py-2 text-sm text-gray-700 hover:bg-gray-100" hx-boost="true">Trial Balance</a>
+                                    </div>
+                                </div>
+                            </div>
+                        </div>
+                    </div>
+                    <div class="flex items-center space-x-4">
+                        <span class="text-indigo-200 text-sm">{{.Username}}</span>
+                        <form method="POST" action="/logout" hx-post="/logout">
+                            <button type="submit" class="text-indigo-200 hover:text-white text-sm font-medium">Logout</button>
+                        </form>
+                    </div>
+                </div>
+            </div>
+        </nav>
+
+        <!-- Main content -->
+        <main>
+            <div class="mx-auto max-w-7xl px-4 py-6 sm:px-6 lg:px-8">
+                {{template "content" .}}
+            </div>
+        </main>
+    </div>
+</body>
+</html>
+{{end}}

templates/ledger/chart_of_accounts.html

@@ -0,0 +1,34 @@
+{{define "content"}}
+<div class="space-y-6">
+    <div class="sm:flex sm:items-center sm:justify-between">
+        <h1 class="text-2xl font-bold text-gray-900">Chart of Accounts</h1>
+        <div class="flex space-x-3">
+            <a href="/ledger/journal" class="text-sm text-indigo-600 hover:text-indigo-500">Journal Entries</a>
+            <a href="/ledger/trial-balance" class="text-sm text-indigo-600 hover:text-indigo-500">Trial Balance</a>
+        </div>
+    </div>
+
+    <div class="overflow-hidden bg-white shadow ring-1 ring-black ring-opacity-5 sm:rounded-lg">
+        <table class="min-w-full divide-y divide-gray-300">
+            <thead class="bg-gray-50">
+                <tr>
+                    <th class="py-3.5 pl-4 pr-3 text-left text-sm font-semibold text-gray-900">Code</th>
+                    <th class="px-3 py-3.5 text-left text-sm font-semibold text-gray-900">Name</th>
+                    <th class="px-3 py-3.5 text-left text-sm font-semibold text-gray-900">Type</th>
+                    <th class="px-3 py-3.5 text-right text-sm font-semibold text-gray-900">Balance</th>
+                </tr>
+            </thead>
+            <tbody class="divide-y divide-gray-200 bg-white">
+                {{range .Accounts}}
+                <tr class="hover:bg-gray-50">
+                    <td class="whitespace-nowrap py-4 pl-4 pr-3 text-sm font-mono font-medium text-gray-900">{{.Code}}</td>
+                    <td class="whitespace-nowrap px-3 py-4 text-sm text-gray-900">{{.Name}}</td>
+                    <td class="whitespace-nowrap px-3 py-4 text-sm">{{accountTypeBadge .Type}}</td>
+                    <td class="whitespace-nowrap px-3 py-4 text-sm text-gray-900 text-right font-mono">{{formatMoney .Balance}}</td>
+                </tr>
+                {{end}}
+            </tbody>
+        </table>
+    </div>
+</div>
+{{end}}

templates/ledger/journal_entries.html

@@ -0,0 +1,49 @@
+{{define "content"}}
+<div class="space-y-6">
+    <div class="sm:flex sm:items-center sm:justify-between">
+        <h1 class="text-2xl font-bold text-gray-900">Journal Entries</h1>
+        <div class="flex space-x-3">
+            <a href="/ledger/accounts" class="text-sm text-indigo-600 hover:text-indigo-500">Chart of Accounts</a>
+            <a href="/ledger/trial-balance" class="text-sm text-indigo-600 hover:text-indigo-500">Trial Balance</a>
+            <a href="/ledger/journal/new" class="inline-flex items-center rounded-md bg-indigo-600 px-3 py-2 text-sm font-semibold text-white shadow-sm hover:bg-indigo-500">
+                + New Entry
+            </a>
+        </div>
+    </div>
+
+    <div class="overflow-hidden bg-white shadow ring-1 ring-black ring-opacity-5 sm:rounded-lg">
+        <table class="min-w-full divide-y divide-gray-300">
+            <thead class="bg-gray-50">
+                <tr>
+                    <th class="py-3.5 pl-4 pr-3 text-left text-sm font-semibold text-gray-900">#</th>
+                    <th class="px-3 py-3.5 text-left text-sm font-semibold text-gray-900">Date</th>
+                    <th class="px-3 py-3.5 text-left text-sm font-semibold text-gray-900">Description</th>
+                    <th class="px-3 py-3.5 text-left text-sm font-semibold text-gray-900">Reference</th>
+                    <th class="px-3 py-3.5 text-right text-sm font-semibold text-gray-900">Debit</th>
+                    <th class="px-3 py-3.5 text-right text-sm font-semibold text-gray-900">Credit</th>
+                </tr>
+            </thead>
+            <tbody class="divide-y divide-gray-200 bg-white">
+                {{if .Entries}}
+                    {{range .Entries}}
+                    <tr class="hover:bg-gray-50">
+                        <td class="whitespace-nowrap py-4 pl-4 pr-3 text-sm font-medium text-indigo-600">
+                            <a href="/ledger/journal/{{.ID}}">{{.ID}}</a>
+                        </td>
+                        <td class="whitespace-nowrap px-3 py-4 text-sm text-gray-500">{{formatDate .EntryDate}}</td>
+                        <td class="px-3 py-4 text-sm text-gray-900">{{.Description}}</td>
+                        <td class="whitespace-nowrap px-3 py-4 text-sm text-gray-500">{{.Reference}}</td>
+                        <td class="whitespace-nowrap px-3 py-4 text-sm text-gray-900 text-right font-mono">{{formatMoney .TotalDebit}}</td>
+                        <td class="whitespace-nowrap px-3 py-4 text-sm text-gray-900 text-right font-mono">{{formatMoney .TotalCredit}}</td>
+                    </tr>
+                    {{end}}
+                {{else}}
+                    <tr>
+                        <td colspan="6" class="px-3 py-8 text-center text-sm text-gray-500">No journal entries yet. <a href="/ledger/journal/new" class="text-indigo-600 hover:text-indigo-500">Create one</a>.</td>
+                    </tr>
+                {{end}}
+            </tbody>
+        </table>
+    </div>
+</div>
+{{end}}

templates/ledger/journal_entry_detail.html

@@ -0,0 +1,63 @@
+{{define "content"}}
+<div class="space-y-6">
+    <div class="sm:flex sm:items-center sm:justify-between">
+        <div>
+            <h1 class="text-2xl font-bold text-gray-900">Journal Entry #{{.Entry.ID}}</h1>
+            <p class="mt-1 text-sm text-gray-500">{{formatDate .Entry.EntryDate}}</p>
+        </div>
+        <a href="/ledger/journal" class="text-sm text-gray-500 hover:text-gray-700">&larr; All Entries</a>
+    </div>
+
+    <div class="bg-white shadow sm:rounded-lg">
+        <div class="px-4 py-5 sm:p-6">
+            <dl class="grid grid-cols-1 gap-x-4 gap-y-6 sm:grid-cols-3 mb-6">
+                <div>
+                    <dt class="text-sm font-medium text-gray-500">Date</dt>
+                    <dd class="mt-1 text-sm text-gray-900">{{formatDate .Entry.EntryDate}}</dd>
+                </div>
+                <div>
+                    <dt class="text-sm font-medium text-gray-500">Description</dt>
+                    <dd class="mt-1 text-sm text-gray-900">{{.Entry.Description}}</dd>
+                </div>
+                <div>
+                    <dt class="text-sm font-medium text-gray-500">Reference</dt>
+                    <dd class="mt-1 text-sm text-gray-900">{{if .Entry.Reference}}{{.Entry.Reference}}{{else}}-{{end}}</dd>
+                </div>
+            </dl>
+
+            <h3 class="text-sm font-medium text-gray-900 mb-3">Lines</h3>
+            <table class="min-w-full divide-y divide-gray-300">
+                <thead>
+                    <tr>
+                        <th class="py-2 pr-3 text-left text-sm font-semibold text-gray-900">Account</th>
+                        <th class="px-3 py-2 text-right text-sm font-semibold text-gray-900">Debit</th>
+                        <th class="px-3 py-2 text-right text-sm font-semibold text-gray-900">Credit</th>
+                    </tr>
+                </thead>
+                <tbody class="divide-y divide-gray-200">
+                    {{range .Entry.Lines}}
+                    <tr>
+                        <td class="py-2 pr-3 text-sm text-gray-900">
+                            <span class="font-mono text-gray-500">{{.AccountCode}}</span> {{.AccountName}}
+                        </td>
+                        <td class="px-3 py-2 text-sm text-gray-900 text-right font-mono">
+                            {{if gt .Debit 0.0}}{{formatMoney .Debit}}{{else}}-{{end}}
+                        </td>
+                        <td class="px-3 py-2 text-sm text-gray-900 text-right font-mono">
+                            {{if gt .Credit 0.0}}{{formatMoney .Credit}}{{else}}-{{end}}
+                        </td>
+                    </tr>
+                    {{end}}
+                </tbody>
+                <tfoot>
+                    <tr class="border-t-2 border-gray-900">
+                        <td class="py-2 pr-3 text-sm font-semibold text-gray-900">Totals</td>
+                        <td class="px-3 py-2 text-sm font-semibold text-gray-900 text-right font-mono">{{formatMoney .Entry.TotalDebit}}</td>
+                        <td class="px-3 py-2 text-sm font-semibold text-gray-900 text-right font-mono">{{formatMoney .Entry.TotalCredit}}</td>
+                    </tr>
+                </tfoot>
+            </table>
+        </div>
+    </div>
+</div>
+{{end}}

templates/ledger/journal_entry_form.html

@@ -0,0 +1,106 @@
+{{define "content"}}
+<div class="space-y-6">
+    <div class="sm:flex sm:items-center sm:justify-between">
+        <h1 class="text-2xl font-bold text-gray-900">New Journal Entry</h1>
+        <a href="/ledger/journal" class="text-sm text-gray-500 hover:text-gray-700">&larr; Back</a>
+    </div>
+
+    {{if .Error}}
+    <div class="rounded-md bg-red-50 p-4">
+        <div class="text-sm text-red-700">{{.Error}}</div>
+    </div>
+    {{end}}
+
+    <div class="bg-white shadow sm:rounded-lg">
+        <form class="space-y-6 p-6" method="POST" action="/ledger/journal" hx-post="/ledger/journal" id="je-form">
+            <div class="grid grid-cols-1 gap-6 sm:grid-cols-3">
+                <div>
+                    <label for="entry_date" class="block text-sm font-medium text-gray-700">Date *</label>
+                    <input type="date" name="entry_date" id="entry_date" required value="{{.Today}}"
+                        class="mt-1 block w-full rounded-md border border-gray-300 px-3 py-2 shadow-sm focus:border-indigo-500 focus:outline-none focus:ring-indigo-500 sm:text-sm">
+                </div>
+                <div>
+                    <label for="description" class="block text-sm font-medium text-gray-700">Description *</label>
+                    <input type="text" name="description" id="description" required
+                        class="mt-1 block w-full rounded-md border border-gray-300 px-3 py-2 shadow-sm focus:border-indigo-500 focus:outline-none focus:ring-indigo-500 sm:text-sm">
+                </div>
+                <div>
+                    <label for="reference" class="block text-sm font-medium text-gray-700">Reference</label>
+                    <input type="text" name="reference" id="reference"
+                        class="mt-1 block w-full rounded-md border border-gray-300 px-3 py-2 shadow-sm focus:border-indigo-500 focus:outline-none focus:ring-indigo-500 sm:text-sm">
+                </div>
+            </div>
+
+            <!-- Journal Lines -->
+            <div>
+                <h3 class="text-sm font-medium text-gray-700 mb-3">Lines (debits must equal credits)</h3>
+                <div id="journal-lines" class="space-y-3">
+                    <!-- Line 1 -->
+                    <div class="grid grid-cols-1 gap-3 sm:grid-cols-3 journal-line">
+                        <div>
+                            <select name="account_id" required
+                                class="block w-full rounded-md border border-gray-300 px-3 py-2 shadow-sm focus:border-indigo-500 focus:outline-none focus:ring-indigo-500 sm:text-sm">
+                                <option value="">Select Account</option>
+                                {{range .Accounts}}
+                                <option value="{{.ID}}">{{.Code}} - {{.Name}}</option>
+                                {{end}}
+                            </select>
+                        </div>
+                        <div>
+                            <input type="number" name="debit" placeholder="Debit" step="0.01" min="0" value="0"
+                                class="block w-full rounded-md border border-gray-300 px-3 py-2 shadow-sm focus:border-indigo-500 focus:outline-none focus:ring-indigo-500 sm:text-sm">
+                        </div>
+                        <div>
+                            <input type="number" name="credit" placeholder="Credit" step="0.01" min="0" value="0"
+                                class="block w-full rounded-md border border-gray-300 px-3 py-2 shadow-sm focus:border-indigo-500 focus:outline-none focus:ring-indigo-500 sm:text-sm">
+                        </div>
+                    </div>
+                    <!-- Line 2 -->
+                    <div class="grid grid-cols-1 gap-3 sm:grid-cols-3 journal-line">
+                        <div>
+                            <select name="account_id" required
+                                class="block w-full rounded-md border border-gray-300 px-3 py-2 shadow-sm focus:border-indigo-500 focus:outline-none focus:ring-indigo-500 sm:text-sm">
+                                <option value="">Select Account</option>
+                                {{range .Accounts}}
+                                <option value="{{.ID}}">{{.Code}} - {{.Name}}</option>
+                                {{end}}
+                            </select>
+                        </div>
+                        <div>
+                            <input type="number" name="debit" placeholder="Debit" step="0.01" min="0" value="0"
+                                class="block w-full rounded-md border border-gray-300 px-3 py-2 shadow-sm focus:border-indigo-500 focus:outline-none focus:ring-indigo-500 sm:text-sm">
+                        </div>
+                        <div>
+                            <input type="number" name="credit" placeholder="Credit" step="0.01" min="0" value="0"
+                                class="block w-full rounded-md border border-gray-300 px-3 py-2 shadow-sm focus:border-indigo-500 focus:outline-none focus:ring-indigo-500 sm:text-sm">
+                        </div>
+                    </div>
+                </div>
+
+                <button type="button" onclick="addLine()" class="mt-3 text-sm text-indigo-600 hover:text-indigo-500">+ Add another line</button>
+            </div>
+
+            <div class="flex justify-end space-x-3">
+                <a href="/ledger/journal"
+                    class="rounded-md bg-white px-3 py-2 text-sm font-semibold text-gray-900 shadow-sm ring-1 ring-inset ring-gray-300 hover:bg-gray-50">Cancel</a>
+                <button type="submit"
+                    class="rounded-md bg-indigo-600 px-3 py-2 text-sm font-semibold text-white shadow-sm hover:bg-indigo-500">
+                    Create Entry
+                </button>
+            </div>
+        </form>
+    </div>
+</div>
+
+<script>
+function addLine() {
+    const container = document.getElementById('journal-lines');
+    const firstLine = container.querySelector('.journal-line');
+    const newLine = firstLine.cloneNode(true);
+    // Reset values
+    newLine.querySelectorAll('select').forEach(s => s.value = '');
+    newLine.querySelectorAll('input').forEach(i => i.value = '0');
+    container.appendChild(newLine);
+}
+</script>
+{{end}}

templates/ledger/trial_balance.html

@@ -0,0 +1,61 @@
+{{define "content"}}
+<div class="space-y-6">
+    <div class="sm:flex sm:items-center sm:justify-between">
+        <h1 class="text-2xl font-bold text-gray-900">Trial Balance</h1>
+        <div class="flex space-x-3">
+            <a href="/ledger/accounts" class="text-sm text-indigo-600 hover:text-indigo-500">Chart of Accounts</a>
+            <a href="/ledger/journal" class="text-sm text-indigo-600 hover:text-indigo-500">Journal Entries</a>
+        </div>
+    </div>
+
+    <div class="overflow-hidden bg-white shadow ring-1 ring-black ring-opacity-5 sm:rounded-lg">
+        <table class="min-w-full divide-y divide-gray-300">
+            <thead class="bg-gray-50">
+                <tr>
+                    <th class="py-3.5 pl-4 pr-3 text-left text-sm font-semibold text-gray-900">Code</th>
+                    <th class="px-3 py-3.5 text-left text-sm font-semibold text-gray-900">Account Name</th>
+                    <th class="px-3 py-3.5 text-left text-sm font-semibold text-gray-900">Type</th>
+                    <th class="px-3 py-3.5 text-right text-sm font-semibold text-gray-900">Debit</th>
+                    <th class="px-3 py-3.5 text-right text-sm font-semibold text-gray-900">Credit</th>
+                </tr>
+            </thead>
+            <tbody class="divide-y divide-gray-200 bg-white">
+                {{range .Rows}}
+                {{if or (gt .Debit 0.0) (gt .Credit 0.0)}}
+                <tr class="hover:bg-gray-50">
+                    <td class="whitespace-nowrap py-4 pl-4 pr-3 text-sm font-mono font-medium text-gray-900">{{.Code}}</td>
+                    <td class="whitespace-nowrap px-3 py-4 text-sm text-gray-900">{{.Name}}</td>
+                    <td class="whitespace-nowrap px-3 py-4 text-sm">{{accountTypeBadge .Type}}</td>
+                    <td class="whitespace-nowrap px-3 py-4 text-sm text-gray-900 text-right font-mono">
+                        {{if gt .Debit 0.0}}{{formatMoney .Debit}}{{else}}-{{end}}
+                    </td>
+                    <td class="whitespace-nowrap px-3 py-4 text-sm text-gray-900 text-right font-mono">
+                        {{if gt .Credit 0.0}}{{formatMoney .Credit}}{{else}}-{{end}}
+                    </td>
+                </tr>
+                {{end}}
+                {{end}}
+            </tbody>
+            <tfoot>
+                <tr class="bg-gray-50 border-t-2 border-gray-900">
+                    <td colspan="3" class="py-4 pl-4 pr-3 text-sm font-semibold text-gray-900">Totals</td>
+                    <td class="px-3 py-4 text-sm font-semibold text-gray-900 text-right font-mono">{{formatMoney .TotalDebit}}</td>
+                    <td class="px-3 py-4 text-sm font-semibold text-gray-900 text-right font-mono">{{formatMoney .TotalCredit}}</td>
+                </tr>
+                <tr class="bg-gray-50">
+                    <td colspan="3" class="py-2 pl-4 pr-3 text-sm text-gray-500">Difference (should be $0.00)</td>
+                    <td colspan="2" class="px-3 py-2 text-sm text-right font-mono {{if eq .TotalDebit .TotalCredit}}text-green-600{{else}}text-red-600 font-bold{{end}}">
+                        {{formatMoney (sub .TotalDebit .TotalCredit)}}
+                    </td>
+                </tr>
+            </tfoot>
+        </table>
+    </div>
+
+    {{if not .Rows}}
+    <div class="text-center py-8 text-sm text-gray-500">
+        No transactions recorded yet. The trial balance will populate as journal entries are created.
+    </div>
+    {{end}}
+</div>
+{{end}}

templates/login.html

@@ -0,0 +1,50 @@
+<!DOCTYPE html>
+<html lang="en" class="h-full bg-gray-50">
+<head>
+    <meta charset="UTF-8">
+    <meta name="viewport" content="width=device-width, initial-scale=1.0">
+    <title>Login - ERP System</title>
+    <script src="https://unpkg.com/htmx.org@2.0.4"></script>
+    <script src="https://cdn.tailwindcss.com"></script>
+</head>
+<body class="h-full">
+    <div class="flex min-h-full items-center justify-center py-12 px-4 sm:px-6 lg:px-8">
+        <div class="w-full max-w-md space-y-8">
+            <div>
+                <h1 class="text-center text-3xl font-bold tracking-tight text-indigo-600">ERP System</h1>
+                <h2 class="mt-2 text-center text-lg text-gray-600">Sign in to your account</h2>
+            </div>
+
+            {{if .Error}}
+            <div class="rounded-md bg-red-50 p-4">
+                <div class="flex">
+                    <div class="text-sm text-red-700">{{.Error}}</div>
+                </div>
+            </div>
+            {{end}}
+
+            <form class="mt-8 space-y-6" method="POST" action="/login" hx-post="/login">
+                <div class="space-y-4 rounded-md shadow-sm">
+                    <div>
+                        <label for="username" class="block text-sm font-medium text-gray-700">Username</label>
+                        <input id="username" name="username" type="text" required
+                            class="mt-1 block w-full rounded-md border border-gray-300 px-3 py-2 shadow-sm focus:border-indigo-500 focus:outline-none focus:ring-indigo-500 sm:text-sm"
+                            placeholder="admin">
+                    </div>
+                    <div>
+                        <label for="password" class="block text-sm font-medium text-gray-700">Password</label>
+                        <input id="password" name="password" type="password" required
+                            class="mt-1 block w-full rounded-md border border-gray-300 px-3 py-2 shadow-sm focus:border-indigo-500 focus:outline-none focus:ring-indigo-500 sm:text-sm"
+                            placeholder="admin123">
+                    </div>
+                </div>
+
+                <button type="submit"
+                    class="group relative flex w-full justify-center rounded-md bg-indigo-600 px-3 py-2 text-sm font-semibold text-white hover:bg-indigo-500 focus-visible:outline focus-visible:outline-2 focus-visible:outline-offset-2 focus-visible:outline-indigo-600">
+                    Sign in
+                </button>
+            </form>
+        </div>
+    </div>
+</body>
+</html>

templates/orders/detail.html

@@ -0,0 +1,147 @@
+{{define "content"}}
+<div class="space-y-6">
+    <div class="sm:flex sm:items-center sm:justify-between">
+        <div>
+            <h1 class="text-2xl font-bold text-gray-900">Order #{{.Order.ID}}</h1>
+            <p class="mt-1 text-sm text-gray-500">{{.Order.CustomerName}} &middot; {{formatDate .Order.OrderDate}}</p>
+        </div>
+        <div class="flex items-center space-x-3">
+            <a href="/orders" class="text-sm text-gray-500 hover:text-gray-700">&larr; All Orders</a>
+            {{if eq .Order.Status "draft"}}
+                <a href="/orders/{{.Order.ID}}/edit"
+                    class="rounded-md bg-white px-3 py-2 text-sm font-semibold text-gray-900 shadow-sm ring-1 ring-inset ring-gray-300 hover:bg-gray-50">Edit</a>
+                <button class="rounded-md bg-blue-600 px-3 py-2 text-sm font-semibold text-white shadow-sm hover:bg-blue-500"
+                    hx-post="/orders/{{.Order.ID}}/confirm"
+                    hx-confirm="Confirm this order?">Confirm</button>
+                <button class="rounded-md bg-red-600 px-3 py-2 text-sm font-semibold text-white shadow-sm hover:bg-red-500"
+                    hx-post="/orders/{{.Order.ID}}/cancel"
+                    hx-confirm="Cancel this order?">Cancel</button>
+            {{end}}
+            {{if eq .Order.Status "confirmed"}}
+                <button class="rounded-md bg-green-600 px-3 py-2 text-sm font-semibold text-white shadow-sm hover:bg-green-500"
+                    hx-post="/orders/{{.Order.ID}}/fulfill"
+                    hx-confirm="Fulfill this order? This will generate an invoice and GL entries.">Fulfill</button>
+                <button class="rounded-md bg-red-600 px-3 py-2 text-sm font-semibold text-white shadow-sm hover:bg-red-500"
+                    hx-post="/orders/{{.Order.ID}}/cancel"
+                    hx-confirm="Cancel this order?">Cancel</button>
+            {{end}}
+        </div>
+    </div>
+
+    <!-- Order Info -->
+    <div class="bg-white shadow sm:rounded-lg">
+        <div class="px-4 py-5 sm:p-6">
+            <dl class="grid grid-cols-1 gap-x-4 gap-y-6 sm:grid-cols-4">
+                <div>
+                    <dt class="text-sm font-medium text-gray-500">Customer</dt>
+                    <dd class="mt-1 text-sm text-gray-900"><a href="/customers/{{.Order.CustomerID}}" class="text-indigo-600 hover:text-indigo-900">{{.Order.CustomerName}}</a></dd>
+                </div>
+                <div>
+                    <dt class="text-sm font-medium text-gray-500">Date</dt>
+                    <dd class="mt-1 text-sm text-gray-900">{{formatDate .Order.OrderDate}}</dd>
+                </div>
+                <div>
+                    <dt class="text-sm font-medium text-gray-500">Status</dt>
+                    <dd class="mt-1">{{statusBadge .Order.Status}}</dd>
+                </div>
+                <div>
+                    <dt class="text-sm font-medium text-gray-500">Total</dt>
+                    <dd class="mt-1 text-lg font-semibold text-gray-900">{{formatMoney .Order.TotalAmount}}</dd>
+                </div>
+                {{if .Order.Notes}}
+                <div class="sm:col-span-4">
+                    <dt class="text-sm font-medium text-gray-500">Notes</dt>
+                    <dd class="mt-1 text-sm text-gray-900">{{.Order.Notes}}</dd>
+                </div>
+                {{end}}
+            </dl>
+        </div>
+    </div>
+
+    <!-- Order Lines -->
+    <div id="order-lines-section">
+        {{template "order-lines" .Order}}
+    </div>
+</div>
+{{end}}
+
+{{define "order-lines"}}
+<div class="bg-white shadow sm:rounded-lg">
+    <div class="px-4 py-5 sm:p-6">
+        <h2 class="text-lg font-medium text-gray-900 mb-4">Line Items</h2>
+
+        <table class="min-w-full divide-y divide-gray-300 mb-4">
+            <thead>
+                <tr>
+                    <th class="py-2 pr-3 text-left text-sm font-semibold text-gray-900">Description</th>
+                    <th class="px-3 py-2 text-right text-sm font-semibold text-gray-900">Qty</th>
+                    <th class="px-3 py-2 text-right text-sm font-semibold text-gray-900">Unit Price</th>
+                    <th class="px-3 py-2 text-right text-sm font-semibold text-gray-900">Total</th>
+                    {{if eq .Status "draft"}}
+                    <th class="px-3 py-2 text-sm font-semibold text-gray-900"></th>
+                    {{end}}
+                </tr>
+            </thead>
+            <tbody class="divide-y divide-gray-200">
+                {{range .Lines}}
+                <tr>
+                    <td class="py-2 pr-3 text-sm text-gray-900">{{.Description}}</td>
+                    <td class="px-3 py-2 text-sm text-gray-900 text-right">{{printf "%.0f" .Quantity}}</td>
+                    <td class="px-3 py-2 text-sm text-gray-900 text-right">{{formatMoney .UnitPrice}}</td>
+                    <td class="px-3 py-2 text-sm text-gray-900 text-right">{{formatMoney .LineTotal}}</td>
+                    {{if eq $.Status "draft"}}
+                    <td class="px-3 py-2 text-sm text-right">
+                        <button class="text-red-600 hover:text-red-900"
+                            hx-delete="/orders/{{$.ID}}/lines/{{.ID}}"
+                            hx-target="#order-lines-section"
+                            hx-confirm="Remove this line?">Remove</button>
+                    </td>
+                    {{end}}
+                </tr>
+                {{else}}
+                <tr>
+                    <td colspan="5" class="py-4 text-center text-sm text-gray-500">No line items yet.</td>
+                </tr>
+                {{end}}
+            </tbody>
+            <tfoot>
+                <tr class="border-t-2 border-gray-900">
+                    <td colspan="3" class="py-2 pr-3 text-sm font-semibold text-gray-900 text-right">Total</td>
+                    <td class="px-3 py-2 text-sm font-semibold text-gray-900 text-right">{{formatMoney .TotalAmount}}</td>
+                    {{if eq .Status "draft"}}<td></td>{{end}}
+                </tr>
+            </tfoot>
+        </table>
+
+        {{if eq .Status "draft"}}
+        <!-- Add Line Form -->
+        <form class="mt-4 p-4 bg-gray-50 rounded-lg"
+            hx-post="/orders/{{.ID}}/lines"
+            hx-target="#order-lines-section"
+            hx-swap="innerHTML">
+            <h3 class="text-sm font-medium text-gray-700 mb-3">Add Line Item</h3>
+            <div class="grid grid-cols-1 gap-3 sm:grid-cols-4">
+                <div class="sm:col-span-2">
+                    <input type="text" name="description" placeholder="Description" required
+                        class="block w-full rounded-md border border-gray-300 px-3 py-2 shadow-sm focus:border-indigo-500 focus:outline-none focus:ring-indigo-500 sm:text-sm">
+                </div>
+                <div>
+                    <input type="number" name="quantity" placeholder="Qty" value="1" min="1" step="1" required
+                        class="block w-full rounded-md border border-gray-300 px-3 py-2 shadow-sm focus:border-indigo-500 focus:outline-none focus:ring-indigo-500 sm:text-sm">
+                </div>
+                <div>
+                    <input type="number" name="unit_price" placeholder="Unit Price" value="0.00" min="0" step="0.01" required
+                        class="block w-full rounded-md border border-gray-300 px-3 py-2 shadow-sm focus:border-indigo-500 focus:outline-none focus:ring-indigo-500 sm:text-sm">
+                </div>
+            </div>
+            <div class="mt-3">
+                <button type="submit"
+                    class="rounded-md bg-indigo-600 px-3 py-2 text-sm font-semibold text-white shadow-sm hover:bg-indigo-500">
+                    Add Line
+                </button>
+            </div>
+        </form>
+        {{end}}
+    </div>
+</div>
+{{end}}

templates/orders/form.html

@@ -0,0 +1,60 @@
+{{define "content"}}
+<div class="space-y-6">
+    <div class="sm:flex sm:items-center sm:justify-between">
+        <h1 class="text-2xl font-bold text-gray-900">{{if .IsNew}}New Order{{else}}Edit Order #{{.Order.ID}}{{end}}</h1>
+        <a href="{{if .IsNew}}/orders{{else}}/orders/{{.Order.ID}}{{end}}" class="text-sm text-gray-500 hover:text-gray-700">&larr; Back</a>
+    </div>
+
+    {{if .Error}}
+    <div class="rounded-md bg-red-50 p-4">
+        <div class="text-sm text-red-700">{{.Error}}</div>
+    </div>
+    {{end}}
+
+    <div class="bg-white shadow sm:rounded-lg">
+        <form class="space-y-6 p-6"
+            {{if .IsNew}}
+                method="POST" action="/orders" hx-post="/orders"
+            {{else}}
+                method="POST" action="/orders/{{.Order.ID}}" hx-put="/orders/{{.Order.ID}}"
+            {{end}}>
+
+            <div class="grid grid-cols-1 gap-6 sm:grid-cols-2">
+                <div>
+                    <label for="customer_id" class="block text-sm font-medium text-gray-700">Customer *</label>
+                    <select name="customer_id" id="customer_id" required
+                        class="mt-1 block w-full rounded-md border border-gray-300 px-3 py-2 shadow-sm focus:border-indigo-500 focus:outline-none focus:ring-indigo-500 sm:text-sm">
+                        <option value="">Select a customer</option>
+                        {{range .Customers}}
+                        <option value="{{.ID}}" {{if eq .ID $.Order.CustomerID}}selected{{end}}>{{.Name}}</option>
+                        {{end}}
+                    </select>
+                </div>
+
+                <div>
+                    <label for="order_date" class="block text-sm font-medium text-gray-700">Order Date</label>
+                    <input type="date" name="order_date" id="order_date" value="{{.Order.OrderDate}}"
+                        class="mt-1 block w-full rounded-md border border-gray-300 px-3 py-2 shadow-sm focus:border-indigo-500 focus:outline-none focus:ring-indigo-500 sm:text-sm">
+                </div>
+            </div>
+
+            <div>
+                <label for="notes" class="block text-sm font-medium text-gray-700">Notes</label>
+                <textarea name="notes" id="notes" rows="3"
+                    class="mt-1 block w-full rounded-md border border-gray-300 px-3 py-2 shadow-sm focus:border-indigo-500 focus:outline-none focus:ring-indigo-500 sm:text-sm">{{.Order.Notes}}</textarea>
+            </div>
+
+            <p class="text-sm text-gray-500">{{if .IsNew}}You can add line items after creating the order.{{else}}Line items can be managed from the order detail page.{{end}}</p>
+
+            <div class="flex justify-end space-x-3">
+                <a href="{{if .IsNew}}/orders{{else}}/orders/{{.Order.ID}}{{end}}"
+                    class="rounded-md bg-white px-3 py-2 text-sm font-semibold text-gray-900 shadow-sm ring-1 ring-inset ring-gray-300 hover:bg-gray-50">Cancel</a>
+                <button type="submit"
+                    class="rounded-md bg-indigo-600 px-3 py-2 text-sm font-semibold text-white shadow-sm hover:bg-indigo-500">
+                    {{if .IsNew}}Create Order{{else}}Update Order{{end}}
+                </button>
+            </div>
+        </form>
+    </div>
+</div>
+{{end}}

templates/orders/list.html

@@ -0,0 +1,69 @@
+{{define "content"}}
+<div class="space-y-6">
+    <div class="sm:flex sm:items-center sm:justify-between">
+        <h1 class="text-2xl font-bold text-gray-900">Orders</h1>
+        <a href="/orders/new" class="inline-flex items-center rounded-md bg-indigo-600 px-3 py-2 text-sm font-semibold text-white shadow-sm hover:bg-indigo-500">
+            + New Order
+        </a>
+    </div>
+
+    <!-- Status Filter -->
+    <div class="flex space-x-2">
+        <a href="/orders"
+            class="{{if eq .FilterStatus ""}}bg-indigo-100 text-indigo-700{{else}}bg-white text-gray-700 hover:bg-gray-50{{end}} rounded-md px-3 py-1.5 text-sm font-medium ring-1 ring-inset ring-gray-300">All</a>
+        <a href="/orders?status=draft"
+            class="{{if eq .FilterStatus "draft"}}bg-indigo-100 text-indigo-700{{else}}bg-white text-gray-700 hover:bg-gray-50{{end}} rounded-md px-3 py-1.5 text-sm font-medium ring-1 ring-inset ring-gray-300">Draft</a>
+        <a href="/orders?status=confirmed"
+            class="{{if eq .FilterStatus "confirmed"}}bg-indigo-100 text-indigo-700{{else}}bg-white text-gray-700 hover:bg-gray-50{{end}} rounded-md px-3 py-1.5 text-sm font-medium ring-1 ring-inset ring-gray-300">Confirmed</a>
+        <a href="/orders?status=fulfilled"
+            class="{{if eq .FilterStatus "fulfilled"}}bg-indigo-100 text-indigo-700{{else}}bg-white text-gray-700 hover:bg-gray-50{{end}} rounded-md px-3 py-1.5 text-sm font-medium ring-1 ring-inset ring-gray-300">Fulfilled</a>
+        <a href="/orders?status=cancelled"
+            class="{{if eq .FilterStatus "cancelled"}}bg-indigo-100 text-indigo-700{{else}}bg-white text-gray-700 hover:bg-gray-50{{end}} rounded-md px-3 py-1.5 text-sm font-medium ring-1 ring-inset ring-gray-300">Cancelled</a>
+    </div>
+
+    <div id="order-table">
+        {{template "order-table" .}}
+    </div>
+</div>
+{{end}}
+
+{{define "order-table"}}
+<div class="overflow-hidden bg-white shadow ring-1 ring-black ring-opacity-5 sm:rounded-lg">
+    <table class="min-w-full divide-y divide-gray-300">
+        <thead class="bg-gray-50">
+            <tr>
+                <th class="py-3.5 pl-4 pr-3 text-left text-sm font-semibold text-gray-900">Order #</th>
+                <th class="px-3 py-3.5 text-left text-sm font-semibold text-gray-900">Customer</th>
+                <th class="px-3 py-3.5 text-left text-sm font-semibold text-gray-900">Date</th>
+                <th class="px-3 py-3.5 text-left text-sm font-semibold text-gray-900">Status</th>
+                <th class="px-3 py-3.5 text-right text-sm font-semibold text-gray-900">Amount</th>
+                <th class="px-3 py-3.5 text-left text-sm font-semibold text-gray-900">Actions</th>
+            </tr>
+        </thead>
+        <tbody class="divide-y divide-gray-200 bg-white">
+            {{if .Orders}}
+                {{range .Orders}}
+                <tr class="hover:bg-gray-50">
+                    <td class="whitespace-nowrap py-4 pl-4 pr-3 text-sm font-medium text-indigo-600">
+                        <a href="/orders/{{.ID}}">#{{.ID}}</a>
+                    </td>
+                    <td class="whitespace-nowrap px-3 py-4 text-sm text-gray-900">
+                        <a href="/customers/{{.CustomerID}}" class="hover:text-indigo-600">{{.CustomerName}}</a>
+                    </td>
+                    <td class="whitespace-nowrap px-3 py-4 text-sm text-gray-500">{{formatDate .OrderDate}}</td>
+                    <td class="whitespace-nowrap px-3 py-4 text-sm">{{statusBadge .Status}}</td>
+                    <td class="whitespace-nowrap px-3 py-4 text-sm text-gray-900 text-right">{{formatMoney .TotalAmount}}</td>
+                    <td class="whitespace-nowrap px-3 py-4 text-sm">
+                        <a href="/orders/{{.ID}}" class="text-indigo-600 hover:text-indigo-900">View</a>
+                    </td>
+                </tr>
+                {{end}}
+            {{else}}
+                <tr>
+                    <td colspan="6" class="px-3 py-8 text-center text-sm text-gray-500">No orders found. <a href="/orders/new" class="text-indigo-600 hover:text-indigo-500">Create one</a>.</td>
+                </tr>
+            {{end}}
+        </tbody>
+    </table>
+</div>
+{{end}}