Rewrite extract_item and extract_items functions
This commit completely rewrites the extract_item and extract_items function. Before this commit these two function were an unreadable mess. The extract_item function was a lengthy if-elsif chain while the extract_items function contained an incomprehensible mess of .try, else and ||. With this commit both of these functions have been pulled into a separate file with the internal logic being moved to a few classes. This significantly reduces the size of these two methods, enhances readability and makes adding new extraction/parse rules much simpler. See diff for details.pull/2059/head
syeopite
4 years ago
parent
48a518b252
commit
a027fbf7af
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# This file contains helper methods to parse the Youtube API json data into
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# neat little packages we can use
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# Tuple of Parsers/Extractors so we can easily cycle through them.
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private ITEM_CONTAINER_EXTRACTOR = {
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YoutubeTabsExtractor.new,
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SearchResultsExtractor.new,
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ContinuationExtractor.new
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}
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private ITEM_PARSERS = {
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VideoParser.new,
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ChannelParser.new,
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GridPlaylistParser.new,
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PlaylistParser.new,
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}
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private struct AuthorFallback
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property name, id
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def initialize(@name : String? = nil, @id : String? = nil)
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end
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end
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# The following are the parsers for parsing raw item data into neatly packaged structs.
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# They're accessed through the process() method which validates the given data as applicable
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# to their specific struct and then use the internal parse() method to assemble the struct
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# specific to their category.
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private class ItemParser
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# Base type for all item parsers.
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def process(item : JSON::Any, author_fallback : AuthorFallback)
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end
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private def parse(item_contents : JSON::Any, author_fallback : AuthorFallback)
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end
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end
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private class VideoParser < ItemParser
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def process(item, author_fallback)
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if item_contents = (item["videoRenderer"]? || item["gridVideoRenderer"]?)
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return self.parse(item_contents, author_fallback)
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end
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end
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private def parse(item_contents, author_fallback)
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video_id = item_contents["videoId"].as_s
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title = item_contents["title"].try { |t| t["simpleText"]?.try &.as_s || t["runs"]?.try &.as_a.map(&.["text"].as_s).join("") } || ""
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author_info = item_contents["ownerText"]?.try &.["runs"]?.try &.as_a?.try &.[0]?
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author = author_info.try &.["text"].as_s || author_fallback.name || ""
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author_id = author_info.try &.["navigationEndpoint"]?.try &.["browseEndpoint"]["browseId"].as_s || author_fallback.id || ""
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published = item_contents["publishedTimeText"]?.try &.["simpleText"]?.try { |t| decode_date(t.as_s) } || Time.local
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view_count = item_contents["viewCountText"]?.try &.["simpleText"]?.try &.as_s.gsub(/\D+/, "").to_i64? || 0_i64
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description_html = item_contents["descriptionSnippet"]?.try { |t| parse_content(t) } || ""
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length_seconds = item_contents["lengthText"]?.try &.["simpleText"]?.try &.as_s.try { |t| decode_length_seconds(t) } ||
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item_contents["thumbnailOverlays"]?.try &.as_a.find(&.["thumbnailOverlayTimeStatusRenderer"]?).try &.["thumbnailOverlayTimeStatusRenderer"]?
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.try &.["text"]?.try &.["simpleText"]?.try &.as_s.try { |t| decode_length_seconds(t) } || 0
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live_now = false
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paid = false
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premium = false
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premiere_timestamp = item_contents["upcomingEventData"]?.try &.["startTime"]?.try { |t| Time.unix(t.as_s.to_i64) }
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item_contents["badges"]?.try &.as_a.each do |badge|
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b = badge["metadataBadgeRenderer"]
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case b["label"].as_s
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when "LIVE NOW"
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live_now = true
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when "New", "4K", "CC"
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# TODO
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when "Premium"
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paid = true
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# TODO: Potentially available as item_contents["topStandaloneBadge"]["metadataBadgeRenderer"]
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premium = true
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else nil # Ignore
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end
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end
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SearchVideo.new({
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title: title,
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id: video_id,
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author: author,
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ucid: author_id,
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published: published,
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views: view_count,
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description_html: description_html,
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length_seconds: length_seconds,
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live_now: live_now,
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paid: paid,
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premium: premium,
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premiere_timestamp: premiere_timestamp,
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})
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end
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end
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private class ChannelParser < ItemParser
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def process(item, author_fallback)
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if item_contents = item["channelRenderer"]?
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return self.parse(item_contents, author_fallback)
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end
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end
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private def parse(item_contents, author_fallback)
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author = item_contents["title"]["simpleText"]?.try &.as_s || author_fallback.name || ""
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author_id = item_contents["channelId"]?.try &.as_s || author_fallback.id || ""
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author_thumbnail = item_contents["thumbnail"]["thumbnails"]?.try &.as_a[0]?.try &.["url"]?.try &.as_s || ""
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subscriber_count = item_contents["subscriberCountText"]?.try &.["simpleText"]?.try &.as_s.try { |s| short_text_to_number(s.split(" ")[0]) } || 0
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auto_generated = false
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auto_generated = true if !item_contents["videoCountText"]?
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video_count = item_contents["videoCountText"]?.try &.["runs"].as_a[0]?.try &.["text"].as_s.gsub(/\D/, "").to_i || 0
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description_html = item_contents["descriptionSnippet"]?.try { |t| parse_content(t) } || ""
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SearchChannel.new({
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author: author,
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ucid: author_id,
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author_thumbnail: author_thumbnail,
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subscriber_count: subscriber_count,
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video_count: video_count,
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description_html: description_html,
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auto_generated: auto_generated,
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})
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end
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end
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private class GridPlaylistParser < ItemParser
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def process(item, author_fallback)
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if item_contents = item["gridPlaylistRenderer"]?
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return self.parse(item_contents, author_fallback)
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end
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end
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private def parse(item_contents, author_fallback)
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title = item_contents["title"]["runs"].as_a[0]?.try &.["text"].as_s || ""
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plid = item_contents["playlistId"]?.try &.as_s || ""
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video_count = item_contents["videoCountText"]["runs"].as_a[0]?.try &.["text"].as_s.gsub(/\D/, "").to_i || 0
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playlist_thumbnail = item_contents["thumbnail"]["thumbnails"][0]?.try &.["url"]?.try &.as_s || ""
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SearchPlaylist.new({
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title: title,
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id: plid,
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author: author_fallback.name || "",
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ucid: author_fallback.id || "",
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video_count: video_count,
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videos: [] of SearchPlaylistVideo,
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thumbnail: playlist_thumbnail,
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})
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end
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end
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private class PlaylistParser < ItemParser
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def process(item, author_fallback)
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if item_contents = item["playlistRenderer"]?
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return self.parse(item_contents, author_fallback)
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end
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end
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def parse(item_contents, author_fallback)
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title = item_contents["title"]["simpleText"]?.try &.as_s || ""
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plid = item_contents["playlistId"]?.try &.as_s || ""
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video_count = item_contents["videoCount"]?.try &.as_s.to_i || 0
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playlist_thumbnail = item_contents["thumbnails"].as_a[0]?.try &.["thumbnails"]?.try &.as_a[0]?.try &.["url"].as_s || ""
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author_info = item_contents["shortBylineText"]?.try &.["runs"]?.try &.as_a?.try &.[0]?
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author = author_info.try &.["text"].as_s || author_fallback.name || ""
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author_id = author_info.try &.["navigationEndpoint"]?.try &.["browseEndpoint"]["browseId"].as_s || author_fallback.id || ""
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videos = item_contents["videos"]?.try &.as_a.map do |v|
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v = v["childVideoRenderer"]
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v_title = v["title"]["simpleText"]?.try &.as_s || ""
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v_id = v["videoId"]?.try &.as_s || ""
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v_length_seconds = v["lengthText"]?.try &.["simpleText"]?.try { |t| decode_length_seconds(t.as_s) } || 0
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SearchPlaylistVideo.new({
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title: v_title,
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id: v_id,
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length_seconds: v_length_seconds,
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})
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end || [] of SearchPlaylistVideo
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# TODO: item_contents["publishedTimeText"]?
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SearchPlaylist.new({
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title: title,
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id: plid,
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author: author,
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ucid: author_id,
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video_count: video_count,
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videos: videos,
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thumbnail: playlist_thumbnail,
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})
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end
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end
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# The following are the extractors for extracting an array of items from
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# the internal Youtube API's JSON response. The result is then packaged into
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# a structure we can more easily use via the parsers above. Their internals are
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# identical to the item parsers.
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private class ItemsContainerExtractor
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def process(item : Hash(String, JSON::Any))
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end
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private def extract(target : JSON::Any)
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end
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end
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private class YoutubeTabsExtractor < ItemsContainerExtractor
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def process(initial_data)
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if target = initial_data["twoColumnBrowseResultsRenderer"]?
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self.extract(target)
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end
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end
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private def extract(target)
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raw_items = [] of JSON::Any
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selected_tab = extract_selected_tab(target["tabs"])
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content = selected_tab["tabRenderer"]["content"]
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content["sectionListRenderer"]["contents"].as_a.each do | renderer_container |
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renderer_container = renderer_container["itemSectionRenderer"]
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renderer_container_contents = renderer_container["contents"].as_a[0]
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# Shelf renderer usually refer to a category and would need special handling once
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# An extractor for categories are added. But for now it is just used to
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# extract items for the trending page
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if items_container = renderer_container_contents["shelfRenderer"]?
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if items_container["content"]["expandedShelfContentsRenderer"]?
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items_container = items_container["content"]["expandedShelfContentsRenderer"]
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end
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elsif items_container = renderer_container_contents["gridRenderer"]?
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else
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items_container = renderer_container_contents
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end
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items_container["items"].as_a.each do | item |
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raw_items << item
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end
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end
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return raw_items
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end
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end
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private class SearchResultsExtractor < ItemsContainerExtractor
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def process(initial_data)
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if target = initial_data["twoColumnSearchResultsRenderer"]?
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self.extract(target)
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end
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end
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private def extract(target)
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raw_items = [] of JSON::Any
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content = target["primaryContents"]
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renderer = content["sectionListRenderer"]["contents"].as_a[0]["itemSectionRenderer"]
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raw_items = renderer["contents"].as_a
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return raw_items
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end
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end
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private class ContinuationExtractor < ItemsContainerExtractor
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def process(initial_data)
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if target = initial_data["continuationContents"]?
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self.extract(target)
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end
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end
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private def extract(target)
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raw_items = [] of JSON::Any
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if content = target["gridContinuation"]?
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raw_items = content["items"].as_a
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end
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return raw_items
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end
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end
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def extract_item(item : JSON::Any, author_fallback : String? = nil, author_id_fallback : String? = nil)
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# Parses an item from Youtube's JSON response into a more usable structure.
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# The end result can either be a SearchVideo, SearchPlaylist or SearchChannel.
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author_fallback = AuthorFallback.new(author_fallback, author_id_fallback)
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# Cycles through all of the item parsers and attempt to parse the raw YT JSON data.
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# Each parser automatically validates the data given to see if the data is
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# applicable to itself. If not nil is returned and the next parser is attemped.
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ITEM_PARSERS.each do |parser|
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result = parser.process(item, author_fallback)
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if !result.nil?
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return result
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end
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end
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# TODO radioRenderer, showRenderer, shelfRenderer, horizontalCardListRenderer, searchPyvRenderer
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end
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def extract_items(initial_data : Hash(String, JSON::Any), author_fallback : String? = nil, author_id_fallback : String? = nil)
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items = [] of SearchItem
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initial_data = initial_data["contents"]?.try &.as_h || initial_data["response"]?.try &.as_h || initial_data
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# This is identicial to the parser cyling of extract_item().
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ITEM_CONTAINER_EXTRACTOR.each do | extractor |
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results = extractor.process(initial_data)
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if !results.nil?
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results.each do | item |
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parsed_result = extract_item(item, author_fallback, author_id_fallback)
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if !parsed_result.nil?
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items << parsed_result
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end
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end
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end
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end
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return items
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end
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