package models

import (
	"database/sql"
	"encoding/json"
	"fmt"
)

type Cart_Item struct {
	Product_ID int
	Variant_ID int
	Quantity   int
}

type Cart_Item_Detail struct {
	Product_ID int
	Variant_ID int
	Quantity   int
	Name       string
	Size       string
	Price      int
	Image_URL  string
	Subtotal   int
}

type Cart map[string]Cart_Item

func cart_key(product_id, variant_id int) string {
	return fmt.Sprintf("%d_%d", product_id, variant_id)
}

func Parse_Cart(cart_json string) (Cart, error) {
	if cart_json == "" {
		return make(Cart), nil
	}

	var cart Cart
	if err := json.Unmarshal([]byte(cart_json), &cart); err != nil {
		return nil, err
	}
	return cart, nil
}

func Serialize_Cart(cart Cart) (string, error) {
	data, err := json.Marshal(cart)
	if err != nil {
		return "", err
	}
	return string(data), nil
}

func Add_To_Cart(cart Cart, product_id, variant_id, quantity int) Cart {
	key := cart_key(product_id, variant_id)
	if existing, ok := cart[key]; ok {
		existing.Quantity += quantity
		cart[key] = existing
	} else {
		cart[key] = Cart_Item{
			Product_ID: product_id,
			Variant_ID: variant_id,
			Quantity:   quantity,
		}
	}
	return cart
}

func Update_Cart_Quantity(cart Cart, product_id, variant_id, quantity int) Cart {
	key := cart_key(product_id, variant_id)
	if _, ok := cart[key]; ok {
		cart[key] = Cart_Item{
			Product_ID: product_id,
			Variant_ID: variant_id,
			Quantity:   quantity,
		}
	}
	return cart
}

func Remove_From_Cart(cart Cart, product_id, variant_id int) Cart {
	key := cart_key(product_id, variant_id)
	delete(cart, key)
	return cart
}

func Count_Cart_Items(cart Cart) int {
	total := 0
	for _, item := range cart {
		total += item.Quantity
	}
	return total
}

func Get_Cart_Items_With_Details(db *sql.DB, cart Cart) ([]Cart_Item_Detail, error) {
	var items []Cart_Item_Detail

	for _, item := range cart {
		variant, err := Get_Variant_By_ID(db, item.Variant_ID)
		if err != nil {
			return nil, err
		}
		if variant == nil {
			continue
		}

		items = append(items, Cart_Item_Detail{
			Product_ID: item.Product_ID,
			Variant_ID: item.Variant_ID,
			Quantity:   item.Quantity,
			Name:       variant.Product_Name,
			Size:       variant.Size,
			Price:      variant.Price,
			Image_URL:  variant.Image_URL,
			Subtotal:   variant.Price * item.Quantity,
		})
	}

	return items, nil
}

func Get_Cart_Total(items []Cart_Item_Detail) int {
	total := 0
	for _, item := range items {
		total += item.Subtotal
	}
	return total
}