package upload

import (
	"fmt"
	"io"
	"mime/multipart"
	"os"
	"path/filepath"
	"strings"
	"time"

	"photography-backend/internal/config"
)

// UploadService 文件上传服务
type UploadService struct {
	config    *config.Config
	uploadDir string
	baseURL   string
}

// UploadResult 上传结果
type UploadResult struct {
	Filename     string `json:"filename"`
	OriginalName string `json:"original_name"`
	FilePath     string `json:"file_path"`
	FileURL      string `json:"file_url"`
	FileSize     int64  `json:"file_size"`
	MimeType     string `json:"mime_type"`
}

// NewUploadService 创建文件上传服务
func NewUploadService(cfg *config.Config) *UploadService {
	uploadDir := cfg.Storage.Local.BasePath
	if uploadDir == "" {
		uploadDir = "./uploads"
	}
	
	baseURL := cfg.Storage.Local.BaseURL
	if baseURL == "" {
		baseURL = fmt.Sprintf("http://localhost:%d/uploads", cfg.App.Port)
	}
	
	// 确保上传目录存在
	os.MkdirAll(uploadDir, 0755)
	
	// 创建子目录
	subdirs := []string{"photos", "thumbnails", "temp"}
	for _, subdir := range subdirs {
		os.MkdirAll(filepath.Join(uploadDir, subdir), 0755)
	}
	
	return &UploadService{
		config:    cfg,
		uploadDir: uploadDir,
		baseURL:   baseURL,
	}
}

// UploadPhoto 上传照片
func (s *UploadService) UploadPhoto(file multipart.File, header *multipart.FileHeader) (*UploadResult, error) {
	// 验证文件类型
	if !s.isValidImageType(header.Header.Get("Content-Type")) {
		return nil, fmt.Errorf("不支持的文件类型: %s", header.Header.Get("Content-Type"))
	}
	
	// 验证文件大小
	if header.Size > s.config.Upload.MaxFileSize {
		return nil, fmt.Errorf("文件大小超过限制: %d bytes", header.Size)
	}
	
	// 生成唯一文件名
	filename := s.generateUniqueFilename(header.Filename)
	
	// 保存文件到 photos 目录
	photoPath := filepath.Join(s.uploadDir, "photos", filename)
	
	// 创建目标文件
	dst, err := os.Create(photoPath)
	if err != nil {
		return nil, fmt.Errorf("创建文件失败: %w", err)
	}
	defer dst.Close()
	
	// 复制文件内容
	_, err = io.Copy(dst, file)
	if err != nil {
		return nil, fmt.Errorf("保存文件失败: %w", err)
	}
	
	// 构造文件URL
	fileURL := fmt.Sprintf("%s/photos/%s", s.baseURL, filename)
	
	return &UploadResult{
		Filename:     filename,
		OriginalName: header.Filename,
		FilePath:     photoPath,
		FileURL:      fileURL,
		FileSize:     header.Size,
		MimeType:     header.Header.Get("Content-Type"),
	}, nil
}

// DeletePhoto 删除照片
func (s *UploadService) DeletePhoto(filename string) error {
	// 删除原图
	photoPath := filepath.Join(s.uploadDir, "photos", filename)
	if err := os.Remove(photoPath); err != nil && !os.IsNotExist(err) {
		return fmt.Errorf("删除文件失败: %w", err)
	}
	
	// 删除缩略图
	thumbnailPath := filepath.Join(s.uploadDir, "thumbnails", filename)
	os.Remove(thumbnailPath) // 忽略错误，因为缩略图可能不存在
	
	return nil
}

// GetPhotoURL 获取照片URL
func (s *UploadService) GetPhotoURL(filename string) string {
	return fmt.Sprintf("%s/photos/%s", s.baseURL, filename)
}

// isValidImageType 验证是否为有效的图片类型
func (s *UploadService) isValidImageType(mimeType string) bool {
	allowedTypes := s.config.Upload.AllowedTypes
	if len(allowedTypes) == 0 {
		// 默认允许的图片类型
		allowedTypes = []string{
			"image/jpeg",
			"image/jpg", 
			"image/png",
			"image/gif",
			"image/webp",
			"image/tiff",
		}
	}
	
	for _, allowedType := range allowedTypes {
		if mimeType == allowedType {
			return true
		}
	}
	return false
}

// generateUniqueFilename 生成唯一文件名
func (s *UploadService) generateUniqueFilename(originalName string) string {
	ext := filepath.Ext(originalName)
	timestamp := time.Now().Unix()
	
	// 清理原文件名
	baseName := strings.TrimSuffix(originalName, ext)
	baseName = strings.ReplaceAll(baseName, " ", "_")
	
	return fmt.Sprintf("%s_%d%s", baseName, timestamp, ext)
}

// GetUploadStats 获取上传统计信息
func (s *UploadService) GetUploadStats() (map[string]interface{}, error) {
	photosDir := filepath.Join(s.uploadDir, "photos")
	
	var totalFiles int
	var totalSize int64
	
	err := filepath.Walk(photosDir, func(path string, info os.FileInfo, err error) error {
		if err != nil {
			return err
		}
		if !info.IsDir() {
			totalFiles++
			totalSize += info.Size()
		}
		return nil
	})
	
	if err != nil {
		return nil, err
	}
	
	return map[string]interface{}{
		"total_files": totalFiles,
		"total_size":  totalSize,
		"upload_dir":  s.uploadDir,
		"base_url":    s.baseURL,
	}, nil
}