// 功能描述：按购物车或收藏关联分类推荐真实在售商品；版本：1.0.0。
package user

import (
	"git.apinb.com/bsm-sdk/core/errcode"
	"git.apinb.com/bsm-sdk/core/infra"
	"git.apinb.com/heqiapp/platforms/backend/api/internal/impl"
	common "git.apinb.com/heqiapp/platforms/backend/api/internal/logic/common"
	"git.apinb.com/heqiapp/platforms/backend/api/internal/models"
	"github.com/gin-gonic/gin"
	"gorm.io/gorm"
	"gorm.io/gorm/clause"
)

// Recommendations 排除本人已入购物车商品，收藏场景另排除已收藏；相同分类优先，其余按最近更新排序。
func Recommendations(ctx *gin.Context) {
	account, ok := common.UserAccount(ctx)
	if !ok {
		return
	}
	var request struct {
		Source string `form:"source,default=cart" binding:"oneof=cart favorites"`
		Page   int    `form:"page,default=1" binding:"gte=1,lte=10000"`
		Size   int    `form:"page_size,default=2" binding:"gte=1,lte=20"`
	}
	if ctx.ShouldBindQuery(&request) != nil {
		infra.Response.Error(ctx, errcode.ErrInvalidArgument)
		return
	}
	query := impl.DBService.Where("status = ? AND stock_quantity > 0", common.StatusEnable).
		Where("NOT EXISTS (SELECT 1 FROM ec_cart c WHERE c.ec_product_id = ec_product.id AND c.user_account_id = ? AND c.status = ? AND c.deleted_at IS NULL)", account.ID, common.StatusEnable)
	table := "ec_cart"
	if request.Source == "favorites" {
		table = "ec_favorite"
		query = query.Where("NOT EXISTS (SELECT 1 FROM ec_favorite f WHERE f.ec_product_id = ec_product.id AND f.user_account_id = ? AND f.status = ? AND f.deleted_at IS NULL)", account.ID, common.StatusEnable)
	}
	// 表名来自固定枚举，用户输入不拼接进SQL；归属只使用JWT对应的内部账户键。
	rank := "CASE WHEN EXISTS (SELECT 1 FROM " + table + " r JOIN ec_product p ON p.id = r.ec_product_id WHERE r.user_account_id = ? AND r.status = ? AND r.deleted_at IS NULL AND p.ec_category_id = ec_product.ec_category_id) THEN 0 ELSE 1 END"
	var products []models.EcProduct
	if err := query.Clauses(clause.OrderBy{Expression: gorm.Expr(rank+", ec_product.updated_at desc, ec_product.identity", account.ID, common.StatusEnable)}).Offset((request.Page - 1) * request.Size).Limit(request.Size + 1).Find(&products).Error; err != nil {
		infra.Response.Error(ctx, err)
		return
	}
	values, err := recommendationValues(impl.DBService, products)
	if err != nil {
		infra.Response.Error(ctx, err)
		return
	}
	respondClientPage(ctx, clientPage{Number: request.Page, Size: request.Size}, values)
}

// recommendationValues 批量读取主图和分类，公开结果只包含展示和下单所需字段。
func recommendationValues(db *gorm.DB, products []models.EcProduct) ([]gin.H, error) {
	result := make([]gin.H, 0, len(products))
	if len(products) == 0 {
		return result, nil
	}
	ids := make([]uint64, 0, len(products))
	categoryIDs := []uint64{}
	seen := map[uint64]bool{}
	for _, p := range products {
		ids = append(ids, p.ID)
		if !seen[p.EcCategoryID] {
			seen[p.EcCategoryID] = true
			categoryIDs = append(categoryIDs, p.EcCategoryID)
		}
	}
	var images []models.EcProductImage
	if err := db.Where("ec_product_id IN ? AND status = ?", ids, common.StatusEnable).Order("is_cover desc, sort_no, identity").Find(&images).Error; err != nil {
		return nil, err
	}
	imageMap := map[uint64]string{}
	for _, i := range images {
		if _, ok := imageMap[i.EcProductID]; !ok {
			imageMap[i.EcProductID] = i.ImageURI
		}
	}
	var categories []models.EcCategory
	if err := db.Where("id IN ? AND status = ?", categoryIDs, common.StatusEnable).Find(&categories).Error; err != nil {
		return nil, err
	}
	categoryMap := map[uint64]string{}
	for _, c := range categories {
		categoryMap[c.ID] = c.Name
	}
	for _, p := range products {
		result = append(result, gin.H{"identity": p.Identity, "name": p.Name, "price_amount": p.PriceAmount, "stock_quantity": p.StockQuantity, "image_url": imageMap[p.ID], "category_name": categoryMap[p.EcCategoryID]})
	}
	return result, nil
}