backend/internal/logic/fileStorage/upload_video_logic.go

package fileStorage

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

	"backend/internal/svc"
	"backend/internal/types"

	"github.com/google/uuid"
	"github.com/zeromicro/go-zero/core/logx"
)

type UploadVideoLogic struct {
	logx.Logger
	ctx    context.Context
	svcCtx *svc.ServiceContext
}

func NewUploadVideoLogic(ctx context.Context, svcCtx *svc.ServiceContext) *UploadVideoLogic {
	return &UploadVideoLogic{
		Logger: logx.WithContext(ctx),
		ctx:    ctx,
		svcCtx: svcCtx,
	}
}

func (l *UploadVideoLogic) UploadVideo(req *types.UploadVideoReq, file multipart.File, header *multipart.FileHeader) (resp *types.UploadResp, err error) {
	// 驗證文件大小（100MB 限制）
	const maxVideoSize = 100 << 20 // 100MB
	if header.Size > maxVideoSize {
		return nil, fmt.Errorf("video size exceeds 100MB limit")
	}

	// 讀取文件內容
	videoData, err := io.ReadAll(file)
	if err != nil {
		return nil, fmt.Errorf("failed to read file: %w", err)
	}

	// 驗證實際文件大小
	if int64(len(videoData)) > maxVideoSize {
		return nil, fmt.Errorf("video size exceeds 100MB limit")
	}

	// 檢測視頻 MIME 類型
	mimeType := l.detectVideoType(videoData, header)
	if mimeType == "" {
		// 從文件名推斷
		ext := strings.ToLower(filepath.Ext(header.Filename))
		mimeType = l.getMimeTypeFromExtension(ext)
		if mimeType == "" {
			return nil, fmt.Errorf("unsupported video format")
		}
	}

	// 生成唯一文件名
	fileExt := filepath.Ext(header.Filename)
	if fileExt == "" {
		fileExt = l.getExtensionFromMimeType(mimeType)
	}
	fileName := fmt.Sprintf("%s%s", uuid.New().String(), fileExt)
	objectPath := fmt.Sprintf("videos/%d/%s", time.Now().Year(), fileName)

	// 上傳到 S3
	fileStorageUC := l.svcCtx.FileStorageUC
	if err := fileStorageUC.UploadFromData(l.ctx, videoData, objectPath, mimeType); err != nil {
		return nil, fmt.Errorf("failed to upload video: %w", err)
	}

	// 獲取公開 URL
	fileUrl := fileStorageUC.GetPublicURL(l.ctx, objectPath)

	return &types.UploadResp{
		FileUrl:  fileUrl,
		FileSize: int64(len(videoData)),
		MimeType: mimeType,
	}, nil
}

// detectVideoType 檢測視頻類型（通過 magic bytes）
func (l *UploadVideoLogic) detectVideoType(data []byte, header *multipart.FileHeader) string {
	if len(data) < 12 {
		return ""
	}

	// 檢查常見視頻格式的 magic bytes
	// MP4: ftyp box 通常在開頭
	if len(data) >= 12 {
		// MP4/MOV: 通常以 ftyp 開頭
		if string(data[4:8]) == "ftyp" {
			if strings.Contains(string(data[8:12]), "mp4") || strings.Contains(string(data[8:12]), "isom") {
				return "video/mp4"
			}
			if strings.Contains(string(data[8:12]), "qt") {
				return "video/quicktime"
			}
		}
	}

	// AVI: RIFF...AVI
	if len(data) >= 12 && string(data[0:4]) == "RIFF" && string(data[8:12]) == "AVI " {
		return "video/x-msvideo"
	}

	// WebM: webm
	if len(data) >= 4 && string(data[0:4]) == "\x1a\x45\xdf\xa3" {
		return "video/webm"
	}

	// 從 Content-Type header 獲取
	if header != nil && len(header.Header) > 0 {
		contentType := header.Header.Get("Content-Type")
		if contentType != "" && strings.HasPrefix(contentType, "video/") {
			return contentType
		}
	}

	return ""
}

// getMimeTypeFromExtension 根據文件擴展名獲取 MIME 類型
func (l *UploadVideoLogic) getMimeTypeFromExtension(ext string) string {
	ext = strings.ToLower(ext)
	switch ext {
	case ".mp4":
		return "video/mp4"
	case ".mov":
		return "video/quicktime"
	case ".avi":
		return "video/x-msvideo"
	case ".webm":
		return "video/webm"
	case ".mkv":
		return "video/x-matroska"
	case ".flv":
		return "video/x-flv"
	case ".wmv":
		return "video/x-ms-wmv"
	default:
		return ""
	}
}

// getExtensionFromMimeType 根據 MIME 類型獲取文件擴展名
func (l *UploadVideoLogic) getExtensionFromMimeType(mimeType string) string {
	switch mimeType {
	case "video/mp4":
		return ".mp4"
	case "video/quicktime":
		return ".mov"
	case "video/x-msvideo":
		return ".avi"
	case "video/webm":
		return ".webm"
	case "video/x-matroska":
		return ".mkv"
	case "video/x-flv":
		return ".flv"
	case "video/x-ms-wmv":
		return ".wmv"
	default:
		return ".mp4"
	}
}