package db

import (
	"fmt"
	"gestion/models"

	"gorm.io/gorm"
)

// AddProductInBasket ajoute un produit au panier de l'utilisateur
func (d *Database) AddProductInBasket(username, nameProduct string, quantity float64, category string) (*models.Panier, error) {
	var productResult struct {
		ID int `gorm:"column:id"`
	}
	err := d.GDB.Raw(`SELECT id FROM products WHERE LOWER(name) = LOWER(?) AND LOWER(category) = LOWER(?)`,
		nameProduct, category).Scan(&productResult).Error
	if err != nil {
		return nil, fmt.Errorf("erreur lors de la recherche du produit: %w", err)
	}
	if productResult.ID == 0 {
		return nil, fmt.Errorf("produit '%s' non trouvé dans la catégorie '%s'", nameProduct, category)
	}
	productID := productResult.ID

	price, err := d.GetProductPrice(nameProduct, category, quantity)
	if err != nil {
		return nil, fmt.Errorf("erreur récupération prix: %w", err)
	}

	var existing struct {
		ID       int     `gorm:"column:id"`
		Quantity float64 `gorm:"column:quantity"`
		Price    float64 `gorm:"column:price"`
	}
	d.GDB.Raw(`SELECT id, quantity, price FROM baskets WHERE username = ? AND product_id = ?`,
		username, productID).Scan(&existing)

	var basket models.Panier
	if existing.ID != 0 {
		newQuantity := existing.Quantity + quantity
		newPrice := existing.Price + price
		err = d.GDB.Raw(`
			UPDATE baskets SET quantity = ?, price = ?, created_at = CURRENT_TIMESTAMP
			WHERE id = ? RETURNING id, username, product_id, quantity, price, created_at`,
			newQuantity, newPrice, existing.ID).Scan(&basket).Error
		if err != nil {
			return nil, fmt.Errorf("erreur lors de la mise à jour du panier: %w", err)
		}
	} else {
		err = d.GDB.Raw(`
			INSERT INTO baskets (username, product_id, quantity, price, created_at)
			VALUES (?, ?, ?, ?, CURRENT_TIMESTAMP)
			RETURNING id, username, product_id, quantity, price, created_at`,
			username, productID, quantity, price).Scan(&basket).Error
		if err != nil {
			return nil, fmt.Errorf("erreur lors de l'ajout au panier: %w", err)
		}
	}
	return &basket, nil
}

// GetProductPrice récupère le prix réel d'un produit pour une quantité donnée (legacy)
func (d *Database) GetProductPrice(name, category string, quantity float64) (float64, error) {
	var result struct {
		Price float64 `gorm:"column:price"`
	}
	err := d.GDB.Raw(`
		SELECT price
		FROM product_prices pp
		INNER JOIN products p ON pp.product_id = p.id
		WHERE LOWER(p.name) = LOWER(?)
		  AND LOWER(p.category) = LOWER(?)
		  AND pp.quantity <= ?
		ORDER BY pp.quantity DESC
		LIMIT 1`, name, category, quantity).Scan(&result).Error
	if err != nil || result.Price == 0 {
		return 0, fmt.Errorf("prix produit introuvable pour %f %s: %w", quantity, name, err)
	}
	return result.Price, nil
}

func (d *Database) GetProductStock(name, category string) (float64, error) {
	var result struct {
		Stock float64 `gorm:"column:stock"`
	}
	err := d.GDB.Raw(`SELECT stock FROM products WHERE LOWER(name) = LOWER(?) AND LOWER(category) = LOWER(?)`,
		name, category).Scan(&result).Error
	if err != nil {
		return 0, fmt.Errorf("produit non trouvé: %w", err)
	}
	return result.Stock, nil
}

func (d *Database) DecrementProductStock(name, category string, quantity float64) error {
	result := d.GDB.Exec(`
		UPDATE products SET stock = stock - ?
		WHERE LOWER(name) = LOWER(?) AND LOWER(category) = LOWER(?) AND stock >= ?`,
		quantity, name, category, quantity)
	if result.Error != nil {
		return fmt.Errorf("erreur mise à jour stock: %w", result.Error)
	}
	if result.RowsAffected == 0 {
		return fmt.Errorf("stock insuffisant pour le produit")
	}
	return nil
}

// GetAllProductsInBasket récupère tous les produits du panier d'un utilisateur
func (d *Database) GetAllProductsInBasket(username string) ([]models.Panier, error) {
	var baskets []models.Panier
	err := d.GDB.Raw(`
		SELECT b.id, b.username, b.product_id, b.quantity, b.price, b.created_at,
		       p.name as product_name, p.category, p.description
		FROM baskets b
		INNER JOIN products p ON b.product_id = p.id
		WHERE b.username = ?
		ORDER BY b.created_at DESC`, username).Scan(&baskets).Error
	if err != nil {
		return nil, fmt.Errorf("erreur lors de la récupération du panier: %w", err)
	}
	return baskets, nil
}

func (d *Database) DecrementAndAddToBasket(username string, productID int, quantity float64) (*models.Panier, error) {
	var basket models.Panier
	err := d.GDB.Transaction(func(tx *gorm.DB) error {
		result := tx.Exec(`UPDATE products SET stock = stock - ? WHERE id = ? AND stock >= ?`,
			quantity, productID, quantity)
		if result.Error != nil {
			return fmt.Errorf("erreur stock: %w", result.Error)
		}
		if result.RowsAffected == 0 {
			return fmt.Errorf("stock insuffisant")
		}

		var priceResult struct {
			Price float64 `gorm:"column:price"`
		}
		if err := tx.Raw(`
            SELECT price FROM product_prices
            WHERE product_id = ? AND quantity <= ? AND active_price = true
            ORDER BY quantity DESC LIMIT 1`,
			productID, quantity).Scan(&priceResult).Error; err != nil || priceResult.Price == 0 {
			return fmt.Errorf("prix introuvable pour product_id=%d qty=%.3f", productID, quantity)
		}

		var existing struct {
			ID       int     `gorm:"column:id"`
			Quantity float64 `gorm:"column:quantity"`
			Price    float64 `gorm:"column:price"`
		}
		tx.Raw(`SELECT id, quantity, price FROM baskets WHERE username = ? AND product_id = ?`,
			username, productID).Scan(&existing)

		if existing.ID != 0 {
			return tx.Raw(`
                UPDATE baskets SET quantity = ?, price = ?, created_at = CURRENT_TIMESTAMP
                WHERE id = ? RETURNING id, username, product_id, quantity, price, created_at`,
				existing.Quantity+quantity, existing.Price+priceResult.Price,
				existing.ID).Scan(&basket).Error
		}
		return tx.Raw(`
            INSERT INTO baskets (username, product_id, quantity, price, created_at)
            VALUES (?, ?, ?, ?, CURRENT_TIMESTAMP)
            RETURNING id, username, product_id, quantity, price, created_at`,
			username, productID, quantity, priceResult.Price).Scan(&basket).Error
	})
	if err != nil {
		return nil, err
	}
	return &basket, nil
}

// DeleteProductFromBasket supprime un produit spécifique du panier et restitue le stock.
func (d *Database) DeleteProductFromBasket(basketID int) error {
	return d.GDB.Transaction(func(tx *gorm.DB) error {
		var item struct {
			ProductID int     `gorm:"column:product_id"`
			Quantity  float64 `gorm:"column:quantity"`
		}
		if err := tx.Raw(`SELECT product_id, quantity FROM baskets WHERE id = ?`, basketID).Scan(&item).Error; err != nil {
			return fmt.Errorf("produit non trouvé dans le panier")
		}
		if item.ProductID == 0 {
			return fmt.Errorf("produit non trouvé dans le panier")
		}

		if err := tx.Exec(`UPDATE products SET stock = stock + ? WHERE id = ?`,
			item.Quantity, item.ProductID).Error; err != nil {
			return fmt.Errorf("erreur restitution stock: %w", err)
		}

		result := tx.Exec(`DELETE FROM baskets WHERE id = ?`, basketID)
		if result.Error != nil {
			return fmt.Errorf("erreur lors de la suppression du produit: %w", result.Error)
		}
		if result.RowsAffected == 0 {
			return fmt.Errorf("produit non trouvé dans le panier")
		}
		return nil
	})
}

// ClearBasket vide complètement le panier d'un utilisateur et restitue les stocks.
func (d *Database) ClearBasket(username string) error {
	return d.GDB.Transaction(func(tx *gorm.DB) error {
		if err := tx.Exec(`
			UPDATE products p
			SET stock = stock + b.quantity
			FROM baskets b
			WHERE b.username = ? AND b.product_id = p.id`, username).Error; err != nil {
			return fmt.Errorf("erreur restitution stock: %w", err)
		}
		if err := tx.Exec(`DELETE FROM baskets WHERE username = ?`, username).Error; err != nil {
			return fmt.Errorf("erreur lors du vidage du panier: %w", err)
		}
		return nil
	})
}

// ClearBasketOnCheckout vide le panier après commande validée SANS restituer le stock.
func (d *Database) ClearBasketOnCheckout(username string) error {
	return d.GDB.Exec(`DELETE FROM baskets WHERE username = ?`, username).Error
}

// GetBasketTotal calcule le montant total du panier d'un utilisateur
func (d *Database) GetBasketTotal(username string) (float64, error) {
	var result struct {
		Total float64 `gorm:"column:total"`
	}
	err := d.GDB.Raw(`SELECT COALESCE(SUM(price), 0) as total FROM baskets WHERE username = ?`,
		username).Scan(&result).Error
	if err != nil {
		return 0, fmt.Errorf("erreur lors du calcul du total: %w", err)
	}
	return result.Total, nil
}

// GetBasketItemCount compte le nombre d'items dans le panier
func (d *Database) GetBasketItemCount(username string) (int, error) {
	var result struct {
		Count int `gorm:"column:count"`
	}
	err := d.GDB.Raw(`SELECT COUNT(*) as count FROM baskets WHERE username = ?`,
		username).Scan(&result).Error
	if err != nil {
		return 0, fmt.Errorf("erreur lors du comptage des items: %w", err)
	}
	return result.Count, nil
}

func (d *Database) UpdateBasketItemQuantity(basketID int, newQuantity float64) error {
	if newQuantity <= 0 {
		return fmt.Errorf("quantité invalide")
	}
	return d.GDB.Transaction(func(tx *gorm.DB) error {
		var item struct {
			ProductID int     `gorm:"column:product_id"`
			Quantity  float64 `gorm:"column:quantity"`
		}
		if err := tx.Raw(`SELECT product_id, quantity FROM baskets WHERE id = ? FOR UPDATE`, basketID).Scan(&item).Error; err != nil {
			return fmt.Errorf("produit non trouvé: %w", err)
		}
		if item.ProductID == 0 {
			return fmt.Errorf("panier item introuvable: %d", basketID)
		}

		diff := newQuantity - item.Quantity

		if diff > 0 {
			result := tx.Exec(`UPDATE products SET stock = stock - ? WHERE id = ? AND stock >= ?`,
				diff, item.ProductID, diff)
			if result.Error != nil {
				return fmt.Errorf("erreur stock: %w", result.Error)
			}
			if result.RowsAffected == 0 {
				return fmt.Errorf("stock insuffisant")
			}
		} else if diff < 0 {
			if err := tx.Exec(`UPDATE products SET stock = stock + ? WHERE id = ?`,
				-diff, item.ProductID).Error; err != nil {
				return fmt.Errorf("erreur stock: %w", err)
			}
		}

		if err := tx.Exec(`UPDATE baskets SET quantity = ? WHERE id = ?`,
			newQuantity, basketID).Error; err != nil {
			return fmt.Errorf("erreur panier: %w", err)
		}
		return nil
	})
}

func (d *Database) GetBasketItemOwner(basketID int) (string, error) {
	var username string
	err := d.GDB.Raw(`SELECT username FROM baskets WHERE id = ?`, basketID).Scan(&username).Error
	if err != nil {
		return "", err
	}
	if username == "" {
		return "", fmt.Errorf("article non trouvé")
	}
	return username, nil
}

func (d *Database) GetBasketItems(username string) ([]map[string]any, error) {
	var items []map[string]any
	if err := d.GDB.Raw(`SELECT product_id, quantity::float8 as quantity, price::float8 as price FROM baskets WHERE username = ?`,
		username).Scan(&items).Error; err != nil {
		return nil, err
	}
	return items, nil
}