package handler

import (
	"crypto/md5"
	"encoding/hex"
	"fmt"
	"io"
	"photowall/internal/config"
	"photowall/internal/middleware"
	"photowall/internal/model"
	"photowall/pkg/response"
	"path/filepath"
	"strings"
	"time"

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

type UploadHandler struct {
	db *gorm.DB
}

func NewUploadHandler(db *gorm.DB) *UploadHandler {
	return &UploadHandler{db: db}
}

// Upload POST /api/upload
// 通用文件上传，MD5去重，返回可访问的 URL。type 参数：class(毕业照)/photo(个人照片)/avatar
func (h *UploadHandler) Upload(c *gin.Context) {
	userID := middleware.CurrentUserID(c)
	uploadType := c.DefaultPostForm("type", "photo")

	allowedDirs := map[string]string{
		"class":  "classes",
		"photo":  "photos",
		"avatar": "avatars",
	}
	subDir, ok := allowedDirs[uploadType]
	if !ok {
		subDir = "photos"
	}

	file, err := c.FormFile("file")
	if err != nil {
		response.BadRequest(c, "请选择要上传的文件")
		return
	}

	// 限制大小 10MB
	if file.Size > 10*1024*1024 {
		response.BadRequest(c, "文件大小不能超过 10MB")
		return
	}

	// 校验图片格式
	ext := strings.ToLower(filepath.Ext(file.Filename))
	allowedExts := map[string]bool{".jpg": true, ".jpeg": true, ".png": true, ".gif": true, ".webp": true}
	if !allowedExts[ext] {
		response.BadRequest(c, "仅支持 JPG/PNG/GIF/WEBP 格式")
		return
	}

	// 打开文件计算 MD5
	src, err := file.Open()
	if err != nil {
		response.Internal(c, "文件读取失败")
		return
	}
	defer src.Close()

	hash := md5.New()
	if _, err := io.Copy(hash, src); err != nil {
		response.Internal(c, "文件MD5计算失败")
		return
	}
	fileMd5 := hex.EncodeToString(hash.Sum(nil))

	// MD5 去重：已存在则返回已有路径
	var existing model.UploadFile
	if err := h.db.Where("md5 = ?", fileMd5).First(&existing).Error; err == nil {
		// 引用次数+1
		h.db.Model(&existing).Update("ref_count", gorm.Expr("ref_count + 1"))
		response.OK(c, gin.H{
			"url":       existing.FileUrl,
			"filename":  existing.FileName,
			"size":      existing.FileSize,
			"md5":       fileMd5,
			"duplicate": true,
			"message":   "文件已存在，使用已有路径",
		})
		return
	}

	// 新文件：保存到磁盘
	src.Seek(0, io.SeekStart) // 重置文件指针
	now := time.Now().Format("20060102")
	filename := fmt.Sprintf("%s_%d_%s%s", now, userID, uuid.New().String()[:8], ext)
	relPath := filepath.Join(subDir, filename)
	fullPath := filepath.Join(config.C.UploadDir, relPath)

	if err := c.SaveUploadedFile(file, fullPath); err != nil {
		response.Internal(c, "文件保存失败："+err.Error())
		return
	}

	// 记录到文件表
	url := "/uploads/" + strings.ReplaceAll(relPath, "\\", "/")
	record := model.UploadFile{
		Md5:        fileMd5,
		FilePath:   relPath,
		FileUrl:    url,
		FileName:   filename,
		FileSize:   file.Size,
		FileType:   uploadType,
		UploaderID: userID,
		RefCount:   1,
	}
	h.db.Create(&record)

	response.OK(c, gin.H{
		"url":       url,
		"filename":  filename,
		"size":      file.Size,
		"md5":       fileMd5,
		"duplicate": false,
	})
}