package services

import (
	"context"
	"crypto/md5"
	"encoding/hex"
	"fmt"
	"io"
	"mime/multipart"
	"os"
	"path/filepath"
	"strings"
	"time"

	"server/models"

	"github.com/qiniu/go-sdk/v7/auth/qbox"
	"github.com/qiniu/go-sdk/v7/storage"
)

// StorageService 存储服务接口
type StorageService interface {
	Upload(file multipart.File, header *multipart.FileHeader) (*UploadResult, error)
	GetPublicURL(key string) string
	Delete(key string) error
}

// UploadResult 上传结果
type UploadResult struct {
	URL      string // 完整访问URL
	Key      string // 存储key/路径
	Size     int64  // 文件大小
	MD5      string // 文件MD5
	MimeType string // 文件类型
}

// LocalStorage 本地存储实现
type LocalStorage struct {
	BaseDir string // 基础目录，默认 "uploads"
	BaseURL string // 基础URL，默认 "/"
}

// NewLocalStorage 创建本地存储服务
func NewLocalStorage() *LocalStorage {
	return &LocalStorage{
		BaseDir: "uploads",
		BaseURL: "/",
	}
}

// Upload 上传文件到本地
func (s *LocalStorage) Upload(file multipart.File, header *multipart.FileHeader) (*UploadResult, error) {
	// 生成存储路径
	ext := filepath.Ext(header.Filename)
	datePath := time.Now().Format("2006/01/02")
	fileName := fmt.Sprintf("%d%s", time.Now().UnixNano(), ext)
	savePath := filepath.Join(datePath, fileName)
	
	// 创建目录
	destDir := filepath.Join(s.BaseDir, filepath.FromSlash(datePath))
	if err := os.MkdirAll(destDir, 0755); err != nil {
		return nil, fmt.Errorf("创建目录失败: %w", err)
	}
	
	// 保存文件
	destPath := filepath.Join(s.BaseDir, filepath.FromSlash(savePath))
	dst, err := os.Create(destPath)
	if err != nil {
		return nil, fmt.Errorf("创建文件失败: %w", err)
	}
	defer dst.Close()
	
	// 计算MD5并复制文件
	hash := md5.New()
	size, err := io.Copy(io.MultiWriter(dst, hash), file)
	if err != nil {
		_ = os.Remove(destPath)
		return nil, fmt.Errorf("保存文件失败: %w", err)
	}
	
	md5Sum := hex.EncodeToString(hash.Sum(nil))
	webURL := s.BaseURL + strings.ReplaceAll(filepath.ToSlash(destPath), "\\", "/")
	
	return &UploadResult{
		URL:      webURL,
		Key:      savePath,
		Size:     size,
		MD5:      md5Sum,
		MimeType: header.Header.Get("Content-Type"),
	}, nil
}

// GetPublicURL 获取公开访问URL
func (s *LocalStorage) GetPublicURL(key string) string {
	return s.BaseURL + filepath.ToSlash(filepath.Join(s.BaseDir, key))
}

// Delete 删除本地文件
func (s *LocalStorage) Delete(key string) error {
	filePath := filepath.Join(s.BaseDir, filepath.FromSlash(key))
	return os.Remove(filePath)
}

// QiniuStorage 七牛云存储实现
type QiniuStorage struct {
	AccessKey string
	SecretKey string
	Bucket    string
	Domain    string
	Region    string
}

// NewQiniuStorage 创建七牛云存储服务
func NewQiniuStorage(cfg *models.StorageConfig) *QiniuStorage {
	return &QiniuStorage{
		AccessKey: cfg.QiniuAccessKey,
		SecretKey: cfg.QiniuSecretKey,
		Bucket:    cfg.QiniuBucket,
		Domain:    cfg.QiniuDomain,
		Region:    cfg.QiniuRegion,
	}
}

// getZone 根据区域代码获取存储区域
func (s *QiniuStorage) getZone() *storage.Region {
	switch s.Region {
	case "z0":
		return &storage.ZoneHuadong
	case "z1":
		return &storage.ZoneHuabei
	case "z2":
		return &storage.ZoneHuanan
	case "na0":
		return &storage.ZoneBeimei
	case "as0":
		return &storage.ZoneXinjiapo
	case "cn-east-2":
		return &storage.ZoneHuadongZheJiang2
	default:
		return &storage.ZoneHuadong // 默认华东
	}
}

// Upload 上传文件到七牛云
func (s *QiniuStorage) Upload(file multipart.File, header *multipart.FileHeader) (*UploadResult, error) {
	// 生成存储key
	ext := filepath.Ext(header.Filename)
	datePath := time.Now().Format("2006/01/02")
	fileName := fmt.Sprintf("%d%s", time.Now().UnixNano(), ext)
	key := filepath.ToSlash(filepath.Join(datePath, fileName))
	
	// 创建上传凭证
	mac := qbox.NewMac(s.AccessKey, s.SecretKey)
	putPolicy := storage.PutPolicy{
		Scope: s.Bucket,
	}
	upToken := putPolicy.UploadToken(mac)
	
	// 配置上传参数
	cfg := storage.Config{
		Region:        s.getZone(),
		UseHTTPS:      true,
		UseCdnDomains: false,
	}
	
	// 创建表单上传器
	formUploader := storage.NewFormUploader(&cfg)
	ret := storage.PutRet{}
	putExtra := storage.PutExtra{}
	
	// 计算文件大小和MD5
	tmpFile, err := os.CreateTemp("", "qiniu_upload_*")
	if err != nil {
		return nil, fmt.Errorf("创建临时文件失败: %w", err)
	}
	defer os.Remove(tmpFile.Name())
	defer tmpFile.Close()
	
	hash := md5.New()
	size, err := io.Copy(io.MultiWriter(tmpFile, hash), file)
	if err != nil {
		return nil, fmt.Errorf("读取文件失败: %w", err)
	}
	md5Sum := hex.EncodeToString(hash.Sum(nil))
	
	// 重置文件指针
	if _, err := tmpFile.Seek(0, 0); err != nil {
		return nil, fmt.Errorf("重置文件指针失败: %w", err)
	}
	
	// 执行上传
	err = formUploader.Put(context.Background(), &ret, upToken, key, tmpFile, size, &putExtra)
	if err != nil {
		return nil, fmt.Errorf("上传到七牛云失败: %w", err)
	}
	
	// 构建完整URL
	domain := strings.TrimRight(s.Domain, "/")
	url := fmt.Sprintf("%s/%s", domain, ret.Key)
	
	return &UploadResult{
		URL:      url,
		Key:      ret.Key,
		Size:     size,
		MD5:      md5Sum,
		MimeType: header.Header.Get("Content-Type"),
	}, nil
}

// GetPublicURL 获取七牛云公开访问URL
func (s *QiniuStorage) GetPublicURL(key string) string {
	domain := strings.TrimRight(s.Domain, "/")
	return fmt.Sprintf("%s/%s", domain, key)
}

// Delete 删除七牛云文件
func (s *QiniuStorage) Delete(key string) error {
	mac := qbox.NewMac(s.AccessKey, s.SecretKey)
	cfg := storage.Config{
		Region:   s.getZone(),
		UseHTTPS: true,
	}
	
	bucketManager := storage.NewBucketManager(mac, &cfg)
	err := bucketManager.Delete(s.Bucket, key)
	if err != nil {
		return fmt.Errorf("删除七牛云文件失败: %w", err)
	}
	return nil
}

// GetStorageService 根据配置获取存储服务
func GetStorageService() (StorageService, error) {
	cfg, err := models.GetStorageConfig()
	if err != nil {
		// 默认使用本地存储
		return NewLocalStorage(), nil
	}
	
	switch cfg.StorageType {
	case "qiniu":
		if cfg.QiniuAccessKey == "" || cfg.QiniuSecretKey == "" || 
		   cfg.QiniuBucket == "" || cfg.QiniuDomain == "" {
			return nil, fmt.Errorf("七牛云配置不完整")
		}
		return NewQiniuStorage(cfg), nil
	case "local":
		return NewLocalStorage(), nil
	default:
		return NewLocalStorage(), nil
	}
}