package database

import (
	"billit/internal/models"
	"database/sql"
	"encoding/json"
	"fmt"
	"time"
)

// GetNextInvoiceNumber generates the next invoice ID in format PREFIX/MMM-YYYY/XXX and increments the counter
func (s *service) GetNextInvoiceNumber(userID string) (string, error) {
	var prefix string
	var counter int

	// Get current prefix and counter
	err := s.db.QueryRow(`SELECT COALESCE(invoice_prefix, 'INV'), COALESCE(invoice_counter, 0) FROM users WHERE id = ?`, userID).
		Scan(&prefix, &counter)
	if err != nil {
		return "", err
	}

	// Increment counter
	counter++

	// Update counter in database
	_, err = s.db.Exec(`UPDATE users SET invoice_counter = ? WHERE id = ?`, counter, userID)
	if err != nil {
		return "", err
	}

	// Generate formatted invoice ID: PREFIX/MMM-YYYY/XXX
	now := time.Now()
	humanReadableID := fmt.Sprintf("%s/%s-%d/%03d", prefix, now.Month().String()[:3], now.Year(), counter)

	return humanReadableID, nil
}

// CreateInvoice stores an invoice with UUID and human-readable ID for a user
func (s *service) CreateInvoice(id string, humanReadableID string, data interface{}, userID string) error {
	jsonData, err := json.Marshal(data)
	if err != nil {
		return err
	}
	_, err = s.db.Exec(`INSERT INTO invoices (id, human_readable_id, data, user_id) VALUES (?, ?, ?, ?)`, id, humanReadableID, string(jsonData), userID)
	return err
}

// GetInvoice retrieves an invoice by ID for a user
func (s *service) GetInvoice(id string, userID string) (*models.Invoice, error) {
	var inv models.Invoice
	err := s.db.QueryRow(`SELECT id, COALESCE(human_readable_id, ''), data, user_id, created_at FROM invoices WHERE id=? AND user_id=?`, id, userID).
		Scan(&inv.ID, &inv.HumanReadableID, &inv.Data, &inv.UserID, &inv.CreatedAt)
	if err == sql.ErrNoRows {
		return nil, nil
	}
	if err != nil {
		return nil, err
	}
	return &inv, nil
}

// GetAllInvoices retrieves all invoices for a user
func (s *service) GetAllInvoices(userID string) ([]models.Invoice, error) {
	rows, err := s.db.Query(`SELECT id, COALESCE(human_readable_id, ''), data, user_id, created_at FROM invoices WHERE user_id=? ORDER BY created_at DESC`, userID)
	if err != nil {
		return nil, err
	}
	defer rows.Close()

	var invoices []models.Invoice
	for rows.Next() {
		var inv models.Invoice
		if err := rows.Scan(&inv.ID, &inv.HumanReadableID, &inv.Data, &inv.UserID, &inv.CreatedAt); err != nil {
			return nil, err
		}
		invoices = append(invoices, inv)
	}
	return invoices, nil
}

// GetRecentInvoices returns the most recently generated invoices for a user
func (s *service) GetRecentInvoices(userID string, limit int) ([]models.Invoice, error) {
	rows, err := s.db.Query(`SELECT id, COALESCE(human_readable_id, ''), data, user_id, created_at FROM invoices WHERE user_id=? ORDER BY created_at DESC LIMIT ?`, userID, limit)
	if err != nil {
		return nil, err
	}
	defer rows.Close()

	var invoices []models.Invoice
	for rows.Next() {
		var inv models.Invoice
		if err := rows.Scan(&inv.ID, &inv.HumanReadableID, &inv.Data, &inv.UserID, &inv.CreatedAt); err != nil {
			return nil, err
		}
		invoices = append(invoices, inv)
	}
	return invoices, nil
}