chore: refresh gramsrv public release

internal/app/files/video_thumbnail.go

@@ -0,0 +1,132 @@
+package files
+
+import (
+	"context"
+	"fmt"
+	"os"
+	"os/exec"
+	"strings"
+	"time"
+)
+
+const (
+	videoThumbnailTimeout       = 5 * time.Second
+	videoThumbnailMaxInputBytes = 200 << 20 // 200MB；更大文件本阶段跳过 fallback，避免阻塞发送。
+	videoThumbnailMaxConcurrent = 2
+)
+
+// VideoThumbnailer 从视频字节中抽取静态缩略图。实现必须可失败降级，不影响原发送流程。
+type VideoThumbnailer interface {
+	Extract(ctx context.Context, data []byte, mimeType string) ([]byte, error)
+}
+
+// FFmpegVideoThumbnailer 使用本机 ffmpeg 抽取第一帧 JPEG。
+type FFmpegVideoThumbnailer struct {
+	path    string
+	timeout time.Duration
+	slots   chan struct{}
+}
+
+// NewFFmpegVideoThumbnailer 返回基于 PATH 中 ffmpeg 的抽帧器。
+func NewFFmpegVideoThumbnailer() (*FFmpegVideoThumbnailer, error) {
+	path, err := exec.LookPath("ffmpeg")
+	if err != nil {
+		return nil, err
+	}
+	return &FFmpegVideoThumbnailer{
+		path:    path,
+		timeout: videoThumbnailTimeout,
+		slots:   make(chan struct{}, videoThumbnailMaxConcurrent),
+	}, nil
+}
+
+// Extract 抽取第一帧并输出 JPEG bytes。
+func (t *FFmpegVideoThumbnailer) Extract(ctx context.Context, data []byte, mimeType string) ([]byte, error) {
+	if t == nil || t.path == "" {
+		return nil, fmt.Errorf("ffmpeg thumbnailer unavailable")
+	}
+	if len(data) == 0 {
+		return nil, fmt.Errorf("empty video data")
+	}
+	if len(data) > videoThumbnailMaxInputBytes {
+		return nil, fmt.Errorf("video too large for thumbnail fallback: %d bytes", len(data))
+	}
+	select {
+	case t.slots <- struct{}{}:
+		defer func() { <-t.slots }()
+	case <-ctx.Done():
+		return nil, ctx.Err()
+	}
+
+	runCtx, cancel := context.WithTimeout(ctx, t.timeout)
+	defer cancel()
+
+	input, err := os.CreateTemp("", "telesrv-video-*"+videoTempExt(mimeType))
+	if err != nil {
+		return nil, fmt.Errorf("create temp video: %w", err)
+	}
+	inputPath := input.Name()
+	defer os.Remove(inputPath)
+	if _, err := input.Write(data); err != nil {
+		input.Close()
+		return nil, fmt.Errorf("write temp video: %w", err)
+	}
+	if err := input.Close(); err != nil {
+		return nil, fmt.Errorf("close temp video: %w", err)
+	}
+
+	output, err := os.CreateTemp("", "telesrv-video-thumb-*.jpg")
+	if err != nil {
+		return nil, fmt.Errorf("create temp thumbnail: %w", err)
+	}
+	outputPath := output.Name()
+	output.Close()
+	defer os.Remove(outputPath)
+
+	cmd := exec.CommandContext(
+		runCtx,
+		t.path,
+		"-hide_banner",
+		"-loglevel", "error",
+		"-y",
+		"-i", inputPath,
+		"-map", "0:v:0",
+		"-frames:v", "1",
+		"-an",
+		"-vf", "scale=320:320:force_original_aspect_ratio=decrease",
+		"-q:v", "3",
+		outputPath,
+	)
+	stderr, err := cmd.CombinedOutput()
+	if runCtx.Err() != nil {
+		return nil, runCtx.Err()
+	}
+	if err != nil {
+		msg := strings.TrimSpace(string(stderr))
+		if msg != "" {
+			return nil, fmt.Errorf("ffmpeg extract thumbnail: %w: %s", err, msg)
+		}
+		return nil, fmt.Errorf("ffmpeg extract thumbnail: %w", err)
+	}
+	thumb, err := os.ReadFile(outputPath)
+	if err != nil {
+		return nil, fmt.Errorf("read thumbnail: %w", err)
+	}
+	if len(thumb) == 0 {
+		return nil, fmt.Errorf("ffmpeg produced empty thumbnail")
+	}
+	return thumb, nil
+}
+
+func videoTempExt(mimeType string) string {
+	switch strings.ToLower(strings.TrimSpace(mimeType)) {
+	case "video/mp4":
+		return ".mp4"
+	case "video/quicktime":
+		return ".mov"
+	case "video/webm":
+		return ".webm"
+	default:
+		return ".bin"
+	}
+}