package handler

import (
	"fmt"
	"image"
	_ "image/jpeg"
	_ "image/png"
	"net/http"
	"os"
	"path/filepath"
	"strconv"

	"github.com/disintegration/imaging"
	"github.com/gin-gonic/gin"
	"github.com/google/uuid"
	"gorm.io/gorm"

	"github.com/wangjia/jiu/backend/config"
	"github.com/wangjia/jiu/backend/internal/middleware"
	"github.com/wangjia/jiu/backend/internal/model"
	"github.com/wangjia/jiu/backend/internal/util"
)

type ProductImageHandler struct {
	db *gorm.DB
}

func NewProductImageHandler(db *gorm.DB) *ProductImageHandler {
	return &ProductImageHandler{db: db}
}

// Upload POST /api/v1/products/:id/images
func (h *ProductImageHandler) Upload(c *gin.Context) {
	shopID := middleware.GetShopID(c)
	productID, err := strconv.ParseUint(c.Param("id"), 10, 64)
	if err != nil {
		c.JSON(http.StatusBadRequest, gin.H{"error": "invalid product id"})
		return
	}

	// Verify product belongs to shop
	var product model.Product
	if err := h.db.Where("id = ? AND shop_id = ? AND deleted_at IS NULL", productID, shopID).
		First(&product).Error; err != nil {
		c.JSON(http.StatusNotFound, gin.H{"error": "product not found"})
		return
	}

	// Check image count limit
	var count int64
	h.db.Model(&model.ProductImage{}).Where("product_id = ? AND shop_id = ?", productID, shopID).Count(&count)
	if count >= 5 {
		c.JSON(http.StatusBadRequest, gin.H{"error": "最多上传 5 张图片"})
		return
	}

	// Parse multipart (1MB limit)
	if err := c.Request.ParseMultipartForm(1 << 20); err != nil {
		c.JSON(http.StatusBadRequest, gin.H{"error": "文件超过 1MB 限制"})
		return
	}

	file, _, err := c.Request.FormFile("file")
	if err != nil {
		c.JSON(http.StatusBadRequest, gin.H{"error": "请上传文件（field: file）"})
		return
	}
	defer file.Close()

	// Validate image format via decoding
	img, _, err := image.Decode(file)
	if err != nil {
		c.JSON(http.StatusBadRequest, gin.H{"error": "仅支持 JPEG/PNG 图片"})
		return
	}

	// Resize if needed (max 1200px on either dimension, preserve aspect ratio)
	resized := imaging.Fit(img, 1200, 1200, imaging.Lanczos)

	// Prepare output path
	filename := uuid.New().String() + ".jpg"
	subdir := fmt.Sprintf("%s/products/%d", config.C.Storage.UploadDir, productID)
	if err := os.MkdirAll(subdir, 0755); err != nil {
		c.JSON(http.StatusInternalServerError, gin.H{"error": "存储目录创建失败"})
		return
	}
	fullPath := filepath.Join(subdir, filename)

	// Save as JPEG with quality 85
	if err := imaging.Save(resized, fullPath, imaging.JPEGQuality(85)); err != nil {
		c.JSON(http.StatusInternalServerError, gin.H{"error": "图片保存失败"})
		return
	}

	// Relative URL served by Nginx / dev static handler
	relURL := fmt.Sprintf("/images/products/%d/%s", productID, filename)

	pi := model.ProductImage{
		ProductID: productID,
		ShopID:    shopID,
		URL:       relURL,
	}
	if err := h.db.Create(&pi).Error; err != nil {
		os.Remove(fullPath)
		c.JSON(http.StatusInternalServerError, gin.H{"error": err.Error()})
		return
	}

	util.RespondCreated(c, pi)
}

// Delete DELETE /api/v1/products/:id/images/:image_id
func (h *ProductImageHandler) Delete(c *gin.Context) {
	shopID := middleware.GetShopID(c)
	productID, err := strconv.ParseUint(c.Param("id"), 10, 64)
	if err != nil {
		c.JSON(http.StatusBadRequest, gin.H{"error": "invalid product id"})
		return
	}
	imageID, err := strconv.ParseUint(c.Param("image_id"), 10, 64)
	if err != nil {
		c.JSON(http.StatusBadRequest, gin.H{"error": "invalid image id"})
		return
	}

	var pi model.ProductImage
	if err := h.db.Where("id = ? AND product_id = ? AND shop_id = ?", imageID, productID, shopID).
		First(&pi).Error; err != nil {
		c.JSON(http.StatusNotFound, gin.H{"error": "not found"})
		return
	}

	// Delete file from disk
	filename := filepath.Base(pi.URL)
	fullPath := filepath.Join(config.C.Storage.UploadDir, fmt.Sprintf("products/%d/%s", productID, filename))
	os.Remove(fullPath)

	if err := h.db.Delete(&pi).Error; err != nil {
		c.JSON(http.StatusInternalServerError, gin.H{"error": err.Error()})
		return
	}

	c.JSON(http.StatusOK, gin.H{"message": "deleted"})
}