add support for descengind playlists

Author: matejdro

README.md

@@ -78,6 +78,7 @@ vimeo = [ # Multiple keys will be rotated.
   update_period = "12h" # How often query for updates, examples: "60m", "4h", "2h45m"
   quality = "high" # or "low"
   format = "video" # or "audio"
+  playlist_sort = "asc" # or "desc", which will fetch playlist items from the end
   # custom.cover_art_quality use "high" or "low" to special cover image quality from channel cover default is equal with "quality" and disable when custom.cover_art was set.
   # custom = { title = "Level1News", description = "News sections of Level1Techs, in a podcast feed!", author = "Level1Tech", cover_art = "{IMAGE_URL}", cover_art_quality = "high", category = "TV", subcategories = ["Documentary", "Tech News"], explicit = true, lang = "en" } # Optional feed customizations
   # max_height = 720 # Optional maximal height of video, example: 720, 1080, 1440, 2160, ...

pkg/builder/youtube.go

@@ -330,11 +330,14 @@ func (yt *YouTubeBuilder) queryVideoDescriptions(ctx context.Context, playlist m
 	return nil
 }
 
-// Cost: (3 units + 5 units) * X pages = 8 units per page
+// Cost:
+// ASC mode = (3 units + 5 units) * X pages = 8 units per page
+// DESC mode = 3 units * (number of pages in the entire playlist) + 5 units
 func (yt *YouTubeBuilder) queryItems(ctx context.Context, feed *model.Feed) error {
 	var (
-		token string
-		count int
+		token       string
+		count       int
+		allSnippets []*youtube.PlaylistItemSnippet
 	)
 
 	for {
@@ -346,25 +349,39 @@ func (yt *YouTubeBuilder) queryItems(ctx context.Context, feed *model.Feed) erro
 		token = pageToken
 
 		if len(items) == 0 {
-			return nil
+			break
 		}
 
 		// Extract playlist snippets
-		snippets := map[string]*youtube.PlaylistItemSnippet{}
 		for _, item := range items {
-			snippets[item.Snippet.ResourceId.VideoId] = item.Snippet
+			allSnippets = append(allSnippets, item.Snippet)
 			count++
 		}
 
-		// Query video descriptions from the list of ids
-		if err := yt.queryVideoDescriptions(ctx, snippets, feed); err != nil {
-			return err
+		if (feed.PlaylistSort != model.SortingDesc && count >= feed.PageSize) || token == "" {
+			break
 		}
+	}
 
-		if count >= feed.PageSize || token == "" {
-			return nil
+	if len(allSnippets) > feed.PageSize {
+		if feed.PlaylistSort != model.SortingDesc {
+			allSnippets = allSnippets[:feed.PageSize]
+		} else {
+			allSnippets = allSnippets[len(allSnippets)-feed.PageSize:]
 		}
 	}
+
+	snippets := map[string]*youtube.PlaylistItemSnippet{}
+	for _, snippet := range allSnippets {
+		snippets[snippet.ResourceId.VideoId] = snippet
+	}
+
+	// Query video descriptions from the list of ids
+	if err := yt.queryVideoDescriptions(ctx, snippets, feed); err != nil {
+		return err
+	}
+
+	return nil
 }
 
 func (yt *YouTubeBuilder) Build(ctx context.Context, cfg *config.Feed) (*model.Feed, error) {
@@ -374,13 +391,14 @@ func (yt *YouTubeBuilder) Build(ctx context.Context, cfg *config.Feed) (*model.F
 	}
 
 	feed := &model.Feed{
-		ItemID:    info.ItemID,
-		Provider:  info.Provider,
-		LinkType:  info.LinkType,
-		Format:    cfg.Format,
-		Quality:   cfg.Quality,
-		PageSize:  cfg.PageSize,
-		UpdatedAt: time.Now().UTC(),
+		ItemID:       info.ItemID,
+		Provider:     info.Provider,
+		LinkType:     info.LinkType,
+		Format:       cfg.Format,
+		Quality:      cfg.Quality,
+		PageSize:     cfg.PageSize,
+		PlaylistSort: cfg.PlaylistSort,
+		UpdatedAt:    time.Now().UTC(),
 	}
 
 	if feed.PageSize == 0 {

pkg/config/config.go

@@ -45,6 +45,8 @@ type Feed struct {
 	YouTubeDLArgs []string `toml:"youtube_dl_args"`
 	// Included in OPML file
 	OPML bool `toml:"opml"`
+	// Playlist sort
+	PlaylistSort model.Sorting `toml:"playlist_sort"`
 }
 
 type Filters struct {
@@ -237,5 +239,9 @@ func (c *Config) applyDefaults(configPath string) {
 		if feed.PageSize == 0 {
 			feed.PageSize = model.DefaultPageSize
 		}
+
+		if feed.PlaylistSort == "" {
+			feed.PlaylistSort = model.SortingAsc
+		}
 	}
 }

pkg/config/config_test.go

@@ -40,6 +40,7 @@ timeout = 15
   format = "audio"
   quality = "low"
   filters = { title = "regex for title here" }
+  playlist_sort = "desc"
   clean = { keep_last = 10 }
   	[feeds.XYZ.custom]
 	cover_art = "http://img"
@@ -80,6 +81,7 @@ timeout = 15
 	assert.EqualValues(t, "low", feed.Quality)
 	assert.EqualValues(t, "regex for title here", feed.Filters.Title)
 	assert.EqualValues(t, 10, feed.Clean.KeepLast)
+	assert.EqualValues(t, model.SortingDesc, feed.PlaylistSort)
 
 	assert.EqualValues(t, "http://img", feed.Custom.CoverArt)
 	assert.EqualValues(t, "high", feed.Custom.CoverArtQuality)

pkg/model/feed.go

@@ -20,6 +20,14 @@ const (
 	FormatVideo = Format("video")
 )
 
+// Playlist sorting style
+type Sorting string
+
+const (
+	SortingDesc = Sorting("desc")
+	SortingAsc  = Sorting("asc")
+)
+
 type Episode struct {
 	// ID of episode
 	ID          string        `json:"id"`
@@ -54,6 +62,7 @@ type Feed struct {
 	ItemURL         string     `json:"item_url"` // Platform specific URL
 	Episodes        []*Episode `json:"-"`        // Array of episodes
 	UpdatedAt       time.Time  `json:"updated_at"`
+	PlaylistSort    Sorting    `json:"playlist_sort"`
 }
 
 type EpisodeStatus string