package logic

import (
	"context"
	"errors"

	"healthapi/internal/model"
	"healthapi/internal/svc"
	"healthapi/internal/types"
	"healthapi/pkg/errorx"

	"github.com/zeromicro/go-zero/core/logx"
	"gorm.io/gorm"
)

type AddCartLogic struct {
	logx.Logger
	ctx    context.Context
	svcCtx *svc.ServiceContext
}

func NewAddCartLogic(ctx context.Context, svcCtx *svc.ServiceContext) *AddCartLogic {
	return &AddCartLogic{
		Logger: logx.WithContext(ctx),
		ctx:    ctx,
		svcCtx: svcCtx,
	}
}

func (l *AddCartLogic) AddCart(req *types.AddCartReq) (resp *types.CartItem, err error) {
	userID, err := GetUserIDFromCtx(l.ctx)
	if err != nil {
		return nil, errorx.ErrUnauthorized
	}

	// 验证商品存在且上架
	var product model.Product
	if err := l.svcCtx.DB.First(&product, req.ProductID).Error; err != nil {
		return nil, errorx.NewCodeError(404, "商品不存在")
	}
	if !product.IsActive {
		return nil, errorx.NewCodeError(400, "商品已下架")
	}

	price := product.Price
	stock := product.Stock
	skuName := ""
	image := product.MainImage

	// 如果有 SKU，验证 SKU
	if req.SkuID > 0 {
		var sku model.ProductSku
		if err := l.svcCtx.DB.First(&sku, req.SkuID).Error; err != nil {
			return nil, errorx.NewCodeError(404, "商品规格不存在")
		}
		if sku.ProductID != req.ProductID {
			return nil, errorx.NewCodeError(400, "商品规格不匹配")
		}
		if !sku.IsActive {
			return nil, errorx.NewCodeError(400, "该规格已下架")
		}
		price = sku.Price
		stock = sku.Stock
		skuName = sku.Name
		if sku.Image != "" {
			image = sku.Image
		}
	}

	// 检查库存
	if stock < req.Quantity {
		return nil, errorx.NewCodeError(400, "库存不足")
	}

	// 检查是否已在购物车中
	var existingItem model.CartItem
	query := l.svcCtx.DB.Where("user_id = ? AND product_id = ?", userID, req.ProductID)
	if req.SkuID > 0 {
		query = query.Where("sku_id = ?", req.SkuID)
	} else {
		query = query.Where("sku_id = 0 OR sku_id IS NULL")
	}

	if err := query.First(&existingItem).Error; err == nil {
		// 已存在，更新数量
		newQty := existingItem.Quantity + req.Quantity
		if newQty > stock {
			return nil, errorx.NewCodeError(400, "库存不足")
		}
		existingItem.Quantity = newQty
		l.svcCtx.DB.Save(&existingItem)

		resp = &types.CartItem{
			ID:          uint(existingItem.ID),
			ProductID:   existingItem.ProductID,
			SkuID:       existingItem.SkuID,
			ProductName: product.Name,
			SkuName:     skuName,
			Image:       image,
			Price:       price,
			Quantity:    existingItem.Quantity,
			Selected:    existingItem.Selected,
			Stock:       stock,
		}
		return resp, nil
	} else if !errors.Is(err, gorm.ErrRecordNotFound) {
		return nil, err
	}

	// 新增购物车项
	cartItem := model.CartItem{
		UserID:    userID,
		ProductID: req.ProductID,
		SkuID:     req.SkuID,
		Quantity:  req.Quantity,
		Selected:  true,
	}
	if err := l.svcCtx.DB.Create(&cartItem).Error; err != nil {
		return nil, err
	}

	resp = &types.CartItem{
		ID:          uint(cartItem.ID),
		ProductID:   cartItem.ProductID,
		SkuID:       cartItem.SkuID,
		ProductName: product.Name,
		SkuName:     skuName,
		Image:       image,
		Price:       price,
		Quantity:    cartItem.Quantity,
		Selected:    cartItem.Selected,
		Stock:       stock,
	}
	return resp, nil
}