package handler

import (
	"fmt"
	"net/http"
	"strings"

	"github.com/gin-gonic/gin"
	"gorm.io/gorm"

	"github.com/wangjia/jiu/backend/internal/model"
)

// 默认话术（保质期/储存方式空时使用）
const (
	defaultShelfLife = "无限期（适饮）"
	defaultStorage   = "阴凉干燥、避光保存"
)

type PublicHandler struct {
	db *gorm.DB
}

func NewPublicHandler(db *gorm.DB) *PublicHandler {
	return &PublicHandler{db: db}
}

// GetProduct GET /api/v1/public/products/:public_id (no auth)
func (h *PublicHandler) GetProduct(c *gin.Context) {
	publicID := c.Param("public_id")

	var product model.Product
	if err := h.db.Where("public_id = ? AND deleted_at IS NULL", publicID).
		Preload("Images").
		Preload("Origin").
		Preload("ShelfLife").
		Preload("Storage").
		Preload("DescriptionDoc").
		First(&product).Error; err != nil {
		c.JSON(http.StatusNotFound, gin.H{"error": "not found"})
		return
	}

	// Fetch shop public info
	var shop model.Shop
	shopData := gin.H{}
	if err := h.db.Where("id = ?", product.ShopID).First(&shop).Error; err == nil {
		shopData = gin.H{
			"name":           shop.Name,
			"code":           shop.Code,
			"address":        shop.Address,
			"phone":          shop.Phone,
			"business_hours": shop.BusinessHours,
		}
	}

	// Fetch latest inventory batch for this product
	var inv model.Inventory
	batchData := gin.H(nil)
	if err := h.db.Where("product_id = ? AND quantity > 0 AND deleted_at IS NULL", product.ID).
		Order("created_at DESC").
		First(&inv).Error; err == nil {
		var pdStr *string
		if inv.ProductionDate != nil {
			s := inv.ProductionDate.Time.Format("2006-01-02")
			pdStr = &s
		}
		batchData = gin.H{
			"production_date": pdStr,
			"batch_no":        inv.BatchNo,
			"in_stock_date":   inv.CreatedAt.Format("2006-01-02"),
		}
	}

	// 产地：空串表示无，前端不展示该行
	origin := ""
	if product.Origin != nil {
		origin = product.Origin.Name
	}

	// 保质期：无关联时用默认话术
	shelfLife := defaultShelfLife
	if product.ShelfLife != nil {
		shelfLife = product.ShelfLife.Name
	}

	// 储存方式：无关联时用默认话术
	storage := defaultStorage
	if product.Storage != nil {
		storage = product.Storage.Name
	}

	// 介绍三级回退：描述文档 → 旧 Description → 通用中性兜底
	descTitle, descBody, descKeywords := buildDescription(product)

	c.JSON(http.StatusOK, gin.H{
		"data": gin.H{
			"id":                product.ID,
			"name":              product.Name,
			"series":            product.Series,
			"spec":              product.Spec,
			"brand":             product.Brand,
			"unit":              product.Unit,
			"description":       descBody,
			"description_title": descTitle,
			"description_keywords": descKeywords,
			"origin":            origin,
			"shelf_life":        shelfLife,
			"storage":           storage,
			"images":            product.Images,
			"shop":              shopData,
			"batch":             batchData,
		},
	})
}

// buildDescription 商品介绍三级回退逻辑
// 1. DescriptionDoc.Content（结构化介绍文档）
// 2. Product.Description（旧自由文本）
// 3. 通用中性兜底（用真实字段拼，不含品牌专属词）
func buildDescription(p model.Product) (title, body string, keywords []string) {
	// 1. 描述文档
	if p.DescriptionDoc != nil && p.DescriptionDoc.Content != "" {
		return p.DescriptionDoc.Title, p.DescriptionDoc.Content, buildKeywords(p)
	}

	// 2. 旧 Description 自由文本
	if p.Description != "" {
		return "商品介绍", p.Description, buildKeywords(p)
	}

	// 3. 通用中性兜底
	parts := make([]string, 0, 4)
	if p.Brand != "" && p.Name != "" {
		parts = append(parts, fmt.Sprintf("%s%s", p.Brand, p.Name))
	} else if p.Name != "" {
		parts = append(parts, p.Name)
	}
	if p.Series != "" {
		parts = append(parts, fmt.Sprintf("%s系列", p.Series))
	}
	if p.Spec != "" {
		parts = append(parts, fmt.Sprintf("规格%s", p.Spec))
	}
	intro := strings.Join(parts, "，")
	if intro != "" {
		intro += "。"
	}
	intro += "本商品由门店正品供应，支持扫码验真，请认准官方渠道。"

	return "商品介绍", intro, buildKeywords(p)
}

// buildKeywords 从真实商品属性派生关键词 chips
func buildKeywords(p model.Product) []string {
	kws := make([]string, 0, 4)
	if p.Brand != "" {
		kws = append(kws, p.Brand)
	}
	if p.Series != "" {
		kws = append(kws, p.Series)
	}
	kws = append(kws, "正品保障", "扫码验真")
	return kws
}

// GetRelease GET /api/v1/public/release (no auth)
func (h *PublicHandler) GetRelease(c *gin.Context) {
	cfg, err := loadVersionConfig()
	if err != nil {
		c.JSON(http.StatusOK, gin.H{
			"version":       "1.0.0",
			"release_notes": "",
			"download_urls": gin.H{"web": "https://jiu.51yanmei.com/app"},
		})
		return
	}
	c.JSON(http.StatusOK, gin.H{
		"version":       cfg.Version,
		"release_notes": cfg.ReleaseNotes,
		"download_urls": cfg.DownloadURLs,
	})
}