add new youtubedl dependency

downloader/vendor/github.com/kkdai/youtube/v2/transcript.go

@@ -0,0 +1,214 @@
+package youtube
+
+import (
+	"context"
+	"encoding/json"
+	"errors"
+	"fmt"
+	"strconv"
+	"strings"
+)
+
+var (
+	ErrTranscriptDisabled = errors.New("transcript is disabled on this video")
+)
+
+// TranscriptSegment is a single transcipt segment spanning a few milliseconds.
+type TranscriptSegment struct {
+	// Text is the transcipt text.
+	Text string `json:"text"`
+
+	// StartMs is the start timestamp in ms.
+	StartMs int `json:"offset"`
+
+	// OffsetText e.g. '4:00'.
+	OffsetText string `json:"offsetText"`
+
+	// Duration the transcript segment spans in ms.
+	Duration int `json:"duration"`
+}
+
+func (tr TranscriptSegment) String() string {
+	return tr.OffsetText + " - " + strings.TrimSpace(tr.Text)
+}
+
+type VideoTranscript []TranscriptSegment
+
+func (vt VideoTranscript) String() string {
+	var str string
+	for _, tr := range vt {
+		str += tr.String() + "\n"
+	}
+
+	return str
+}
+
+// GetTranscript fetches the video transcript if available.
+//
+// Not all videos have transcripts, only relatively new videos.
+// If transcripts are disabled or not available, ErrTranscriptDisabled is returned.
+func (c *Client) GetTranscript(video *Video, lang string) (VideoTranscript, error) {
+	return c.GetTranscriptCtx(context.Background(), video, lang)
+}
+
+// GetTranscriptCtx fetches the video transcript if available.
+//
+// Not all videos have transcripts, only relatively new videos.
+// If transcripts are disabled or not available, ErrTranscriptDisabled is returned.
+func (c *Client) GetTranscriptCtx(ctx context.Context, video *Video, lang string) (VideoTranscript, error) {
+	c.assureClient()
+
+	if video == nil || video.ID == "" {
+		return nil, fmt.Errorf("no video provided")
+	}
+
+	body, err := c.transcriptDataByInnertube(ctx, video.ID, lang)
+	if err != nil {
+		return nil, err
+	}
+
+	transcript, err := parseTranscript(body)
+	if err != nil {
+		return nil, err
+	}
+
+	return transcript, nil
+}
+
+func parseTranscript(body []byte) (VideoTranscript, error) {
+	var resp transcriptResp
+	if err := json.Unmarshal(body, &resp); err != nil {
+		return nil, err
+	}
+
+	if len(resp.Actions) > 0 {
+		// Android client response
+		if app := resp.Actions[0].AppSegment; app != nil {
+			return getSegments(app)
+		}
+
+		// Web client response
+		if web := resp.Actions[0].WebSegment; web != nil {
+			return nil, fmt.Errorf("not implemented")
+		}
+	}
+
+	return nil, ErrTranscriptDisabled
+}
+
+type segmenter interface {
+	ParseSegments() []TranscriptSegment
+}
+
+func getSegments(f segmenter) (VideoTranscript, error) {
+	if segments := f.ParseSegments(); len(segments) > 0 {
+		return segments, nil
+	}
+
+	return nil, ErrTranscriptDisabled
+}
+
+// transcriptResp is the JSON structure as returned by the transcript API.
+type transcriptResp struct {
+	Actions []struct {
+		AppSegment *appData `json:"elementsCommand"`
+		WebSegment *webData `json:"updateEngagementPanelAction"`
+	} `json:"actions"`
+}
+
+type appData struct {
+	TEC struct {
+		Args struct {
+			ListArgs struct {
+				Ow struct {
+					InitialSeg []struct {
+						TranscriptSegment struct {
+							StartMs string `json:"startMs"`
+							EndMs   string `json:"endMs"`
+							Text    struct {
+								String struct {
+									// Content is the actual transctipt text
+									Content string `json:"content"`
+								} `json:"elementsAttributedString"`
+							} `json:"snippet"`
+							StartTimeText struct {
+								String struct {
+									// Content is the fomratted timestamp, e.g. '4:00'
+									Content string `json:"content"`
+								} `json:"elementsAttributedString"`
+							} `json:"startTimeText"`
+						} `json:"transcriptSegmentRenderer"`
+					} `json:"initialSegments"`
+				} `json:"overwrite"`
+			} `json:"transformTranscriptSegmentListArguments"`
+		} `json:"arguments"`
+	} `json:"transformEntityCommand"`
+}
+
+func (s *appData) ParseSegments() []TranscriptSegment {
+	rawSegments := s.TEC.Args.ListArgs.Ow.InitialSeg
+	segments := make([]TranscriptSegment, 0, len(rawSegments))
+
+	for _, segment := range rawSegments {
+		startMs, _ := strconv.Atoi(segment.TranscriptSegment.StartMs)
+		endMs, _ := strconv.Atoi(segment.TranscriptSegment.EndMs)
+
+		segments = append(segments, TranscriptSegment{
+			Text:       segment.TranscriptSegment.Text.String.Content,
+			StartMs:    startMs,
+			OffsetText: segment.TranscriptSegment.StartTimeText.String.Content,
+			Duration:   endMs - startMs,
+		})
+	}
+
+	return segments
+}
+
+type webData struct {
+	Content struct {
+		TR struct {
+			Body struct {
+				TBR struct {
+					Cues []struct {
+						Transcript struct {
+							FormattedStartOffset struct {
+								SimpleText string `json:"simpleText"`
+							} `json:"formattedStartOffset"`
+							Cues []struct {
+								TranscriptCueRenderer struct {
+									Cue struct {
+										SimpleText string `json:"simpleText"`
+									} `json:"cue"`
+									StartOffsetMs string `json:"startOffsetMs"`
+									DurationMs    string `json:"durationMs"`
+								} `json:"transcriptCueRenderer"`
+							} `json:"cues"`
+						} `json:"transcriptCueGroupRenderer"`
+					} `json:"cueGroups"`
+				} `json:"transcriptSearchPanelRenderer"`
+			} `json:"content"`
+		} `json:"transcriptRenderer"`
+	} `json:"content"`
+}
+
+func (s *webData) ParseSegments() []TranscriptSegment {
+	// TODO: doesn't actually work now, check json.
+	cues := s.Content.TR.Body.TBR.Cues
+	segments := make([]TranscriptSegment, 0, len(cues))
+
+	for _, s := range cues {
+		formatted := s.Transcript.FormattedStartOffset.SimpleText
+		segment := s.Transcript.Cues[0].TranscriptCueRenderer
+		start, _ := strconv.Atoi(segment.StartOffsetMs)
+		duration, _ := strconv.Atoi(segment.DurationMs)
+
+		segments = append(segments, TranscriptSegment{
+			Text:       segment.Cue.SimpleText,
+			StartMs:    start,
+			OffsetText: formatted,
+			Duration:   duration,
+		})
+	}
+
+	return segments
+}