download cmd handles playlist & video

client.go

@@ -72,7 +72,7 @@ func (c *Client) GetPlaylist(url string) (*Playlist, error) {
 // for these videos. Playlist entries cannot be downloaded, as they lack all the required metadata, but
 // can be used to enumerate all IDs, Authors, Titles, etc.
 func (c *Client) GetPlaylistContext(ctx context.Context, url string) (*Playlist, error) {
-	id, err := extractPlaylistID(url)
+	id, err := ExtractPlaylistID(url)
 	if err != nil {
 		return nil, fmt.Errorf("extractPlaylistID failed: %w", err)
 	}

cmd/youtubedr/download.go

@@ -5,19 +5,65 @@ import (
 	"fmt"
 	"log"
 	"os/exec"
+	"strconv"
 	"strings"
 
+	"github.com/kkdai/youtube/v2"
 	"github.com/spf13/cobra"
 )
 
+var (
+	errNotID = fmt.Errorf("cannot detect ID in given input")
+)
+
 // downloadCmd represents the download command
 var downloadCmd = &cobra.Command{
 	Use:     "download",
-	Short:   "Downloads a video from youtube",
+	Short:   "Downloads a video or a playlist from youtube",
 	Example: `youtubedr -o "Campaign Diary".mp4 https://www.youtube.com/watch\?v\=XbNghLqsVwU`,
 	Args:    cobra.ExactArgs(1),
 	Run: func(cmd *cobra.Command, args []string) {
-		exitOnError(download(args[0]))
+		if playlistID, err := youtube.ExtractPlaylistID(args[0]); err != nil {
+			videoID, err := youtube.ExtractVideoID(args[0])
+			if err != nil {
+				exitOnError(errNotID)
+			}
+			log.Printf(
+				"download video %s to directory %s\n",
+				videoID,
+				outputDir,
+			)
+			exitOnError(download(videoID))
+		} else {
+			playlist, err := getDownloader().GetPlaylist(playlistID)
+			if err != nil {
+				exitOnError(err)
+			}
+			log.Printf(
+				"download %d videos from playlist %s to directory %s\n",
+				len(playlist.Videos),
+				playlist.ID,
+				outputDir,
+			)
+			var errors []error
+			outputFileOrigin := outputFile
+			for i, v := range playlist.Videos {
+				if len(outputFileOrigin) != 0 {
+					index := v.Index
+					if len(index) == 0 {
+						// In case video does not contain index
+						index = strconv.Itoa(i)
+					}
+					outputFile = fmt.Sprintf("%s-%s", outputFile, index)
+				}
+				if err := download(v.ID); err != nil {
+					errors = append(errors, err)
+				}
+			}
+			if len(errors) > 0 {
+				exitOnErrors(errors)
+			}
+		}
 	},
 }
 
@@ -30,7 +76,7 @@ var (
 func init() {
 	rootCmd.AddCommand(downloadCmd)
 
-	downloadCmd.Flags().StringVarP(&outputFile, "filename", "o", "", "The output file, the default is genated by the video title.")
+	downloadCmd.Flags().StringVarP(&outputFile, "filename", "o", "", "The output file, the default is generated from the video title.")
 	downloadCmd.Flags().StringVarP(&outputDir, "directory", "d", ".", "The output directory.")
 	addQualityFlag(downloadCmd.Flags())
 	addMimeTypeFlag(downloadCmd.Flags())
@@ -42,8 +88,6 @@ func download(id string) error {
 		return err
 	}
 
-	log.Println("download to directory", outputDir)
-
 	if strings.HasPrefix(outputQuality, "hd") {
 		if err := checkFFMPEG(); err != nil {
 			return err

cmd/youtubedr/main.go

@@ -15,3 +15,12 @@ func exitOnError(err error) {
 		os.Exit(1)
 	}
 }
+
+func exitOnErrors(errors []error) {
+	for _, err := range errors {
+		fmt.Fprintln(os.Stderr, err)
+	}
+	if len(errors) != 0 {
+		os.Exit(1)
+	}
+}

playlist.go

@@ -34,12 +34,13 @@ type Playlist struct {
 
 type PlaylistEntry struct {
 	ID       string
+	Index    string
 	Title    string
 	Author   string
 	Duration time.Duration
 }
 
-func extractPlaylistID(url string) (string, error) {
+func ExtractPlaylistID(url string) (string, error) {
 	if playlistIDRegex.Match([]byte(url)) {
 		return url, nil
 	}
@@ -128,10 +129,11 @@ func (p *Playlist) UnmarshalJSON(b []byte) (err error) {
 
 type videosJSONExtractor struct {
 	Renderer *struct {
-		ID       string   `json:"videoId"`
-		Title    withRuns `json:"title"`
-		Author   withRuns `json:"shortBylineText"`
-		Duration string   `json:"lengthSeconds"`
+		ID       string    `json:"videoId"`
+		Index    indexText `json:"index"`
+		Title    withRuns  `json:"title"`
+		Author   withRuns  `json:"shortBylineText"`
+		Duration string    `json:"lengthSeconds"`
 	} `json:"playlistVideoRenderer"`
 }
 
@@ -142,6 +144,7 @@ func (vje videosJSONExtractor) PlaylistEntry() *PlaylistEntry {
 	}
 	return &PlaylistEntry{
 		ID:       vje.Renderer.ID,
+		Index:    vje.Renderer.Index.String(),
 		Title:    vje.Renderer.Title.String(),
 		Author:   vje.Renderer.Author.String(),
 		Duration: time.Second * time.Duration(ds),
@@ -154,9 +157,17 @@ type withRuns struct {
 	} `json:"runs"`
 }
 
+type indexText struct {
+	SimpleText string `json:"simpleText"`
+}
+
 func (wr withRuns) String() string {
 	if len(wr.Runs) > 0 {
 		return wr.Runs[0].Text
 	}
 	return ""
 }
+
+func (it indexText) String() string {
+	return it.SimpleText
+}

playlist_test.go

@@ -65,7 +65,7 @@ func TestYoutube_extractPlaylistID(t *testing.T) {
 
 	for _, v := range tests {
 		t.Run(v.name, func(t *testing.T) {
-			id, err := extractPlaylistID(v.url)
+			id, err := ExtractPlaylistID(v.url)
 
 			assert.Equal(t, v.expectedError, err)
 			assert.Equal(t, v.expectedID, id)