package main

import (
	"fmt"
	"log"
	"math/rand"
	"os"
	"strconv"
	"time"

	"erp_system/internal/database"

	_ "modernc.org/sqlite"
)

func main() {
	dbPath := "erp.db"
	if len(os.Args) > 1 {
		dbPath = os.Args[1]
	}

	log.Printf("Connecting to database at %s...", dbPath)
	// We can use the internal database package to initialize (runs migrations)
	db, err := database.Initialize(dbPath)
	if err != nil {
		log.Fatalf("Failed to initialize database: %v", err)
	}
	defer db.Close()

	// Configuration for generation
	const (
		numCustomers      = 500
		maxOrdersPerCust  = 15
		maxLinesPerOrder  = 8
		numJournalEntries = 100
	)

	log.Println("Starting data generation...")
	start := time.Now()

	tx, err := db.Begin()
	if err != nil {
		log.Fatalf("Failed to begin transaction: %v", err)
	}

	// 1. Customers
	customerIDs := make([]int64, 0, numCustomers)
	for i := 0; i < numCustomers; i++ {
		name := fmt.Sprintf("Customer %s %s", randomString(5), randomString(7))
		email := fmt.Sprintf("%s.%s@example.com", randomString(4), randomString(5))
		phone := fmt.Sprintf("555-%04d", rand.Intn(10000))
		address := fmt.Sprintf("%d %s St, City %s", rand.Intn(999), randomString(6), randomString(4))

		res, err := tx.Exec("INSERT INTO customers (name, email, phone, address) VALUES (?, ?, ?, ?)", name, email, phone, address)
		if err != nil {
			tx.Rollback()
			log.Fatalf("Failed to insert customer: %v", err)
		}
		id, _ := res.LastInsertId()
		customerIDs = append(customerIDs, id)
	}
	log.Printf("Generated %d customers", numCustomers)

	// 2. Orders and Lines and Invoices
	var orderCount, lineCount, invoiceCount int
	for _, custID := range customerIDs {
		numOrders := rand.Intn(maxOrdersPerCust)
		for j := 0; j < numOrders; j++ {
			// Create Order
			status := "draft"
			r := rand.Float32()
			if r > 0.7 {
				status = "fulfilled"
			} else if r > 0.4 {
				status = "confirmed"
			} else if r > 0.3 {
				status = "cancelled"
			}

			// Random date in last year
			orderDate := time.Now().AddDate(0, 0, -rand.Intn(365))

			res, err := tx.Exec("INSERT INTO orders (customer_id, status, order_date, notes) VALUES (?, ?, ?, ?)",
				custID, status, orderDate.Format("2006-01-02"), "Generated order")
			if err != nil {
				tx.Rollback()
				log.Fatalf("Failed to insert order: %v", err)
			}
			orderID, _ := res.LastInsertId()
			orderCount++

			// Create Order Lines
			numLines := rand.Intn(maxLinesPerOrder) + 1
			var totalAmount float64
			for k := 0; k < numLines; k++ {
				qty := float64(rand.Intn(10) + 1)
				price := float64(rand.Intn(100) + 10)
				desc := fmt.Sprintf("Product %s-%d", randomString(3), rand.Intn(100))
				lineTotal := qty * price
				totalAmount += lineTotal

				_, err := tx.Exec("INSERT INTO order_lines (order_id, description, quantity, unit_price, line_total) VALUES (?, ?, ?, ?, ?)",
					orderID, desc, qty, price, lineTotal)
				if err != nil {
					tx.Rollback()
					log.Fatalf("Failed to insert order line: %v", err)
				}
				lineCount++
			}

			// Update Order Total
			_, err = tx.Exec("UPDATE orders SET total_amount = ? WHERE id = ?", totalAmount, orderID)
			if err != nil {
				tx.Rollback()
				log.Fatalf("Failed to update order total: %v", err)
			}

			// Create Invoice if order is confirmed or fulfilled
			if status == "confirmed" || status == "fulfilled" {
				invoiceStatus := "pending"
				if rand.Float32() > 0.5 {
					invoiceStatus = "paid"
				}

				invNum := fmt.Sprintf("INV-%d-%d", orderID, rand.Intn(10000))
				dueDate := orderDate.AddDate(0, 1, 0) // Due in 30 days
				var paidDate interface{} = nil
				if invoiceStatus == "paid" {
					pd := dueDate.AddDate(0, 0, -rand.Intn(10))
					paidDate = pd.Format("2006-01-02")
				}

				_, err := tx.Exec("INSERT INTO invoices (order_id, customer_id, invoice_number, status, amount, due_date, paid_date) VALUES (?, ?, ?, ?, ?, ?, ?)",
					orderID, custID, invNum, invoiceStatus, totalAmount, dueDate.Format("2006-01-02"), paidDate)
				if err != nil {
					tx.Rollback()
					log.Fatalf("Failed to insert invoice: %v", err)
				}
				invoiceCount++
			}
		}
	}
	log.Printf("Generated %d orders, %d lines, %d invoices", orderCount, lineCount, invoiceCount)

	// 3. Journal Entries
	// Fetch account IDs first
	rows, err := tx.Query("SELECT id, code, type FROM gl_accounts")
	if err != nil {
		tx.Rollback()
		log.Fatalf("Failed to fetch accounts: %v", err)
	}
	defer rows.Close()

	type Account struct {
		ID   int64
		Code string
		Type string
	}
	var accounts []Account
	for rows.Next() {
		var a Account
		if err := rows.Scan(&a.ID, &a.Code, &a.Type); err != nil {
			log.Fatalf("Failed to scan account: %v", err)
		}
		accounts = append(accounts, a)
	}

	if len(accounts) >= 2 {
		for i := 0; i < numJournalEntries; i++ {
			date := time.Now().AddDate(0, 0, -rand.Intn(60)).Format("2006-01-02")
			desc := fmt.Sprintf("Journal Entry %d", i+1)

			res, err := tx.Exec("INSERT INTO journal_entries (entry_date, description, reference) VALUES (?, ?, ?)",
				date, desc, "GEN-"+strconv.Itoa(i))
			if err != nil {
				tx.Rollback()
				log.Fatalf("Failed to insert journal entry: %v", err)
			}
			jeID, _ := res.LastInsertId()

			// Simple balanced entry: 2 lines
			amount := float64(rand.Intn(5000) + 100)

			// Pick 2 random accounts
			idx1 := rand.Intn(len(accounts))
			idx2 := rand.Intn(len(accounts))
			for idx1 == idx2 {
				idx2 = rand.Intn(len(accounts))
			}

			// Debit line
			_, err = tx.Exec("INSERT INTO journal_lines (journal_entry_id, account_id, debit, credit) VALUES (?, ?, ?, ?)",
				jeID, accounts[idx1].ID, amount, 0)
			if err != nil {
				tx.Rollback()
				log.Fatalf("Failed to insert journal line 1: %v", err)
			}

			// Credit line
			_, err = tx.Exec("INSERT INTO journal_lines (journal_entry_id, account_id, debit, credit) VALUES (?, ?, ?, ?)",
				jeID, accounts[idx2].ID, 0, amount)
			if err != nil {
				tx.Rollback()
				log.Fatalf("Failed to insert journal line 2: %v", err)
			}
		}
	}
	log.Printf("Generated %d journal entries", numJournalEntries)

	if err := tx.Commit(); err != nil {
		log.Fatalf("Failed to commit transaction: %v", err)
	}

	log.Printf("Seeding completed in %v", time.Since(start))
}

func randomString(n int) string {
	var letters = []rune("abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ")
	b := make([]rune, n)
	for i := range b {
		b[i] = letters[rand.Intn(len(letters))]
	}
	return string(b)
}