package handler

import (
	"errors"
	"fmt"
	"html"
	"net/http"
	"strconv"
	"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)
// 数据装配走 loadPublicProduct（与 SSR 商品页共用，公开字段口径单一实现）。
func (h *PublicHandler) GetProduct(c *gin.Context) {
	d, err := h.loadPublicProduct(c.Param("public_id"))
	if err != nil {
		c.JSON(http.StatusNotFound, gin.H{"error": "not found"})
		return
	}
	product := d.Product

	shopData := gin.H{}
	if d.HasShop {
		shopData = gin.H{
			"name":           d.Shop.Name,
			"code":           d.Shop.Code,
			"address":        d.Shop.Address,
			"phone":          d.Shop.Phone,
			"business_hours": d.Shop.BusinessHours,
			"wechat_id":      d.Shop.WechatID,
		}
	}

	batchData := gin.H(nil)
	if d.Batch != nil {
		var pdStr *string
		if d.Batch.ProductionDate != nil {
			s := d.Batch.ProductionDate.Time.Format("2006-01-02")
			pdStr = &s
		}
		batchData = gin.H{
			"production_date": pdStr,
			"batch_no":        d.Batch.BatchNo,
			"in_stock_date":   d.Batch.CreatedAt.Format("2006-01-02"),
			"quantity":        d.Batch.Quantity,
		}
	}

	c.JSON(http.StatusOK, gin.H{
		"data": gin.H{
			"id":                   product.ID,
			"name":                 product.Name,
			"code":                 product.Code,
			"barcode":              product.Barcode,
			"series":               product.Series,
			"spec":                 product.Spec,
			"brand":                product.Brand,
			"unit":                 product.Unit,
			"sale_price":           product.SalePrice,
			"description":          d.DescBody,
			"description_title":    d.DescTitle,
			"description_keywords": d.Keywords,
			"origin":               d.Origin,
			"shelf_life":           d.ShelfLife,
			"storage":              d.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"},
			"changelog":     []changelogEntry{},
		})
		return
	}
	c.JSON(http.StatusOK, gin.H{
		"version":       cfg.Version,
		"release_notes": cfg.ReleaseNotes,
		"download_urls": cfg.DownloadURLs,
		"changelog":     changelogOrEmpty(cfg.Changelog),
	})
}

type publicProductImage struct {
	URL string `json:"url"`
}

type publicProductResp struct {
	ID        uint64               `json:"id"`
	PublicID  string               `json:"public_id"`
	Code      string               `json:"code"`
	Name      string               `json:"name"`
	Series    string               `json:"series"`
	Spec      string               `json:"spec"`
	Brand     string               `json:"brand"`
	Unit      string               `json:"unit"`
	SalePrice float64              `json:"sale_price"`
	Quantity  float64              `json:"quantity"`
	Images    []publicProductImage `json:"images"`
}

// ListShopProducts GET /api/v1/public/shops/:shop_code/products (no auth)
func (h *PublicHandler) ListShopProducts(c *gin.Context) {
	shopCode := c.Param("shop_code")

	var shop model.Shop
	if err := h.db.Where("code = ? AND deleted_at IS NULL", shopCode).First(&shop).Error; err != nil {
		if errors.Is(err, gorm.ErrRecordNotFound) {
			c.JSON(http.StatusNotFound, gin.H{"error": "shop not found"})
			return
		}
		c.JSON(http.StatusInternalServerError, gin.H{"error": err.Error()})
		return
	}

	page, _ := strconv.Atoi(c.DefaultQuery("page", "1"))
	pageSize, _ := strconv.Atoi(c.DefaultQuery("page_size", "20"))
	if page < 1 {
		page = 1
	}
	// 上限 20（2026-07 反爬收紧：客户端固定传 20，调大只方便爬全店）
	if pageSize < 1 || pageSize > 20 {
		pageSize = 20
	}

	// 查询装配走 queryShopProducts（与 SSR 店铺页共用）；API 不开放 keyword（现状不变）
	listData, total, err := h.queryShopProducts(shop.ID, page, pageSize, "")
	if err != nil {
		c.JSON(http.StatusInternalServerError, gin.H{"error": err.Error()})
		return
	}

	c.JSON(http.StatusOK, gin.H{
		"data":      listData,
		"total":     total,
		"page":      page,
		"page_size": pageSize,
	})
}

// ProductPage 已 SSR 化，实现移至 public_page.go（2026-07-07 公开页去 Flutter 化）。

// buildOGTitle 生成商品的分享标题：品牌 + 商品名（品牌已含在名字中时不重复）+ 系列。
func buildOGTitle(product model.Product) string {
	title := product.Name
	if product.Brand != "" && !strings.Contains(product.Name, product.Brand) {
		title = product.Brand + title
	}
	if product.Series != "" {
		title = title + "（" + product.Series + "）"
	}
	return title
}

// buildProductOG 构造基础 Open Graph meta 标签字符串。
// 所有值经 html.EscapeString 转义，防止 XSS 或破坏 HTML 结构。
// 无图片时不输出 og:image 行。
func buildProductOG(product model.Product, shopName, publicURL string) string {
	title := buildOGTitle(product)

	// og:description：系列（度数/香型）· 规格（容量/单位）| 门店名正品
	var specParts []string
	if product.Series != "" {
		specParts = append(specParts, product.Series)
	}
	if product.Spec != "" {
		specParts = append(specParts, product.Spec)
	}
	desc := strings.Join(specParts, " · ")
	suffix := "正品"
	if shopName != "" {
		suffix = shopName + suffix
	}
	if desc != "" {
		desc = desc + "\n" + suffix
	} else {
		desc = suffix
	}

	// og:site_name
	siteName := "岩美酒库"
	if shopName != "" {
		siteName = shopName + " · " + siteName
	}

	// og:url：指向 SSR 短链（公开页规范入口）
	pageURL := publicURL + "/product/" + product.PublicID

	var sb strings.Builder
	sb.WriteString("\n")
	sb.WriteString(`  <meta property="og:type" content="website">` + "\n")
	sb.WriteString(`  <meta property="og:site_name" content="` + html.EscapeString(siteName) + `">` + "\n")
	sb.WriteString(`  <meta property="og:url" content="` + html.EscapeString(pageURL) + `">` + "\n")
	sb.WriteString(`  <meta property="og:title" content="` + html.EscapeString(title) + `">` + "\n")
	sb.WriteString(`  <meta property="og:description" content="` + html.EscapeString(desc) + `">` + "\n")
	// og:image：仅有图片时输出
	if len(product.Images) > 0 && product.Images[0].URL != "" {
		imgURL := publicURL + product.Images[0].URL
		sb.WriteString(`  <meta property="og:image" content="` + html.EscapeString(imgURL) + `">` + "\n")
	}
	return sb.String()
}