1 files changed, 111 insertions, 0 deletions
diff --git a/internal/thumbnail/generator.go b/internal/thumbnail/generator.go
new file mode 100644
index 0000000..20aa391
--- /dev/null
+++ b/internal/thumbnail/generator.go
@@ -0,0 +1,111 @@
+package thumbnail
+
+import (
+	"context"
+	"fmt"
+	"os/exec"
+	"path/filepath"
+	"strconv"
+	"strings"
+	"time"
+)
+
+type Generator struct {
+	ffmpegPath string
+}
+
+func NewGenerator() *Generator {
+	return &Generator{
+		ffmpegPath: "ffmpeg",
+	}
+}
+
+func (g *Generator) Generate(ctx context.Context, videoPath string) (string, error) {
+	duration, err := g.probeVideoDuration(ctx, videoPath)
+	if err != nil {
+		return "", fmt.Errorf("probe video duration: %w", err)
+	}
+
+	timestamp := duration * time.Duration(thumbnailPercent) / 100
+	thumbnailPath := g.getThumbnailPath(videoPath)
+
+	if err := g.extractFrame(ctx, videoPath, thumbnailPath, timestamp); err != nil {
+		return "", fmt.Errorf("extract frame: %w", err)
+	}
+
+	return thumbnailPath, nil
+}
+
+func (g *Generator) probeVideoDuration(ctx context.Context, videoPath string) (time.Duration, error) {
+	args := []string{
+		"-v", "error",
+		"-show_entries", "format=duration",
+		"-of", "default=noprint_wrappers=1:nokey=1",
+		videoPath,
+	}
+
+	ctx, cancel := context.WithTimeout(ctx, 15*time.Second)
+	defer cancel()
+
+	cmd := exec.CommandContext(ctx, "ffprobe", args...)
+	output, err := cmd.Output()
+	if err != nil {
+		return 0, err
+	}
+
+	seconds, err := strconv.ParseFloat(strings.TrimSpace(string(output)), 64)
+	if err != nil {
+		return 0, err
+	}
+
+	return time.Duration(seconds * float64(time.Second)), nil
+}
+
+func (g *Generator) extractFrame(ctx context.Context, videoPath, thumbnailPath string, timestamp time.Duration) error {
+	thumbnailDir := filepath.Dir(thumbnailPath)
+	if err := ensureDir(thumbnailDir); err != nil {
+		return err
+	}
+
+	timestampSec := timestamp.Seconds()
+	timestampStr := fmt.Sprintf("%.3f", timestampSec)
+
+	args := []string{
+		"-ss", timestampStr,
+		"-i", videoPath,
+		"-vframes", "1",
+		"-vf", fmt.Sprintf("scale=%d:%d", thumbnailWidth, thumbnailHeight),
+		"-y",
+		thumbnailPath,
+	}
+
+	ctx, cancel := context.WithTimeout(ctx, 30*time.Second)
+	defer cancel()
+
+	cmd := exec.CommandContext(ctx, g.ffmpegPath, args...)
+	if err := cmd.Run(); err != nil {
+		return err
+	}
+
+	return nil
+}
+
+func (g *Generator) getThumbnailPath(videoPath string) string {
+	dir := filepath.Dir(videoPath)
+	thumbnailDir := filepath.Join(dir, thumbnailDir)
+
+	filename := filepath.Base(videoPath)
+	ext := filepath.Ext(filename)
+	name := strings.TrimSuffix(filename, ext)
+
+	return filepath.Join(thumbnailDir, name+"."+thumbnailFormat)
+}
+
+func ensureDir(path string) error {
+	if _, err := exec.LookPath("mkdir"); err == nil {
+		cmd := exec.Command("mkdir", "-p", path)
+		return cmd.Run()
+	}
+
+	return fmt.Errorf("mkdir not found")
+}