Extract channel routes (#2227)

* Extract primary channel routes from invidious.cr

Also removes timedtext_video stub since all it does is redirect to the
homepage. However, Invidious's 404 handler already does this.

--
As the template for the channel about page doesn't exist yet, the
behavior for the /channel/:ucid/about endpoint has been changed to be
the same as what's currently present on Invidious

(cherry picked from commit 8fad19d8057d7d22e3de27ebbc88a9978c1df27b)

* Manually extract brand_redirect from 1b569bbc99207cae7c20aa285f42477ae361dd30

This commit manually extracts the brand_redirect function from the
commit mentioned.

However, the redirect to the  `.../about` endpoint is removed due to the
fact that it doesn't exist yet.

This commit is also mainly just a bridge for the next few cherry picks from
\#2215

* Update brand_redirect to use youtubei resolve_url

(cherry picked from commit 53335fe7cfdfac392365b7cac447bc7cc6478134)

* Add additional channel endpoints to brand_redirect

(cherry picked from commit 8fc6f3add637dabb09b2034f4d82fc3d039ba15c)

* Add separate handler for /profile endpoint

* Add /channel/:ucid/home route

* Document all channel brand_urls

2 files changed, 190 insertions, 211 deletions

diff --git a/src/invidious.cr b/src/invidious.cr
index 89292f05..1d183637 100644
--- a/src/invidious.cr
+++ b/src/invidious.cr
@@ -309,6 +309,24 @@ Invidious::Routing.get "/", Invidious::Routes::Misc, :home
 Invidious::Routing.get "/privacy", Invidious::Routes::Misc, :privacy
 Invidious::Routing.get "/licenses", Invidious::Routes::Misc, :licenses
 
+Invidious::Routing.get "/channel/:ucid", Invidious::Routes::Channels, :home
+Invidious::Routing.get "/channel/:ucid/home", Invidious::Routes::Channels, :home
+Invidious::Routing.get "/channel/:ucid/videos", Invidious::Routes::Channels, :videos
+Invidious::Routing.get "/channel/:ucid/playlists", Invidious::Routes::Channels, :playlists
+Invidious::Routing.get "/channel/:ucid/community", Invidious::Routes::Channels, :community
+Invidious::Routing.get "/channel/:ucid/about", Invidious::Routes::Channels, :about
+
+["", "/videos", "/playlists", "/community", "/about"].each do |path|
+  # /c/LinusTechTips
+  Invidious::Routing.get "/c/:user#{path}", Invidious::Routes::Channels, :brand_redirect
+  # /user/linustechtips | Not always the same as /c/
+  Invidious::Routing.get "/user/:user#{path}", Invidious::Routes::Channels, :brand_redirect
+  # /attribution_link?a=anything&u=/channel/UCZYTClx2T1of7BRZ86-8fow
+  Invidious::Routing.get "/attribution_link#{path}", Invidious::Routes::Channels, :brand_redirect
+  # /profile?user=linustechtips
+  Invidious::Routing.get "/profile/#{path}", Invidious::Routes::Channels, :profile
+end
+
 Invidious::Routing.get "/watch", Invidious::Routes::Watch, :handle
 Invidious::Routing.get "/watch/:id", Invidious::Routes::Watch, :redirect
 Invidious::Routing.get "/shorts/:id", Invidious::Routes::Watch, :redirect
@@ -1618,217 +1636,6 @@ end
   end
 end
 
-# YouTube appears to let users set a "brand" URL that
-# is different from their username, so we convert that here
-get "/c/:user" do |env|
-  locale = LOCALES[env.get("preferences").as(Preferences).locale]?
-
-  user = env.params.url["user"]
-
-  response = YT_POOL.client &.get("/c/#{user}")
-  html = XML.parse_html(response.body)
-
-  ucid = html.xpath_node(%q(//link[@rel="canonical"])).try &.["href"].split("/")[-1]
-  next env.redirect "/" if !ucid
-
-  env.redirect "/channel/#{ucid}"
-end
-
-# Legacy endpoint for /user/:username
-get "/profile" do |env|
-  user = env.params.query["user"]?
-  if !user
-    env.redirect "/"
-  else
-    env.redirect "/user/#{user}"
-  end
-end
-
-get "/attribution_link" do |env|
-  if query = env.params.query["u"]?
-    url = URI.parse(query).request_target
-  else
-    url = "/"
-  end
-
-  env.redirect url
-end
-
-# Page used by YouTube to provide captioning widget, since we
-# don't support it we redirect to '/'
-get "/timedtext_video" do |env|
-  env.redirect "/"
-end
-
-get "/user/:user" do |env|
-  user = env.params.url["user"]
-  env.redirect "/channel/#{user}"
-end
-
-get "/user/:user/videos" do |env|
-  user = env.params.url["user"]
-  env.redirect "/channel/#{user}/videos"
-end
-
-get "/user/:user/about" do |env|
-  user = env.params.url["user"]
-  env.redirect "/channel/#{user}"
-end
-
-get "/channel/:ucid/about" do |env|
-  ucid = env.params.url["ucid"]
-  env.redirect "/channel/#{ucid}"
-end
-
-get "/channel/:ucid" do |env|
-  locale = LOCALES[env.get("preferences").as(Preferences).locale]?
-
-  user = env.get? "user"
-  if user
-    user = user.as(User)
-    subscriptions = user.subscriptions
-  end
-  subscriptions ||= [] of String
-
-  ucid = env.params.url["ucid"]
-
-  page = env.params.query["page"]?.try &.to_i?
-  page ||= 1
-
-  continuation = env.params.query["continuation"]?
-
-  sort_by = env.params.query["sort_by"]?.try &.downcase
-
-  begin
-    channel = get_about_info(ucid, locale)
-  rescue ex : ChannelRedirect
-    next env.redirect env.request.resource.gsub(ucid, ex.channel_id)
-  rescue ex
-    next error_template(500, ex)
-  end
-
-  if channel.auto_generated
-    sort_options = {"last", "oldest", "newest"}
-    sort_by ||= "last"
-
-    items, continuation = fetch_channel_playlists(channel.ucid, channel.author, continuation, sort_by)
-    items.uniq! do |item|
-      if item.responds_to?(:title)
-        item.title
-      elsif item.responds_to?(:author)
-        item.author
-      end
-    end
-    items = items.select(&.is_a?(SearchPlaylist)).map(&.as(SearchPlaylist))
-    items.each { |item| item.author = "" }
-  else
-    sort_options = {"newest", "oldest", "popular"}
-    sort_by ||= "newest"
-
-    count, items = get_60_videos(channel.ucid, channel.author, page, channel.auto_generated, sort_by)
-    items.reject! &.paid
-
-    env.set "search", "channel:#{channel.ucid} "
-  end
-
-  templated "channel"
-end
-
-get "/channel/:ucid/videos" do |env|
-  locale = LOCALES[env.get("preferences").as(Preferences).locale]?
-
-  ucid = env.params.url["ucid"]
-  params = env.request.query
-
-  if !params || params.empty?
-    params = ""
-  else
-    params = "?#{params}"
-  end
-
-  env.redirect "/channel/#{ucid}#{params}"
-end
-
-get "/channel/:ucid/playlists" do |env|
-  locale = LOCALES[env.get("preferences").as(Preferences).locale]?
-
-  user = env.get? "user"
-  if user
-    user = user.as(User)
-    subscriptions = user.subscriptions
-  end
-  subscriptions ||= [] of String
-
-  ucid = env.params.url["ucid"]
-
-  continuation = env.params.query["continuation"]?
-
-  sort_by = env.params.query["sort_by"]?.try &.downcase
-  sort_by ||= "last"
-
-  begin
-    channel = get_about_info(ucid, locale)
-  rescue ex : ChannelRedirect
-    next env.redirect env.request.resource.gsub(ucid, ex.channel_id)
-  rescue ex
-    next error_template(500, ex)
-  end
-
-  if channel.auto_generated
-    next env.redirect "/channel/#{channel.ucid}"
-  end
-
-  items, continuation = fetch_channel_playlists(channel.ucid, channel.author, continuation, sort_by)
-  items = items.select { |item| item.is_a?(SearchPlaylist) }.map { |item| item.as(SearchPlaylist) }
-  items.each { |item| item.author = "" }
-
-  env.set "search", "channel:#{channel.ucid} "
-  templated "playlists"
-end
-
-get "/channel/:ucid/community" do |env|
-  locale = LOCALES[env.get("preferences").as(Preferences).locale]?
-
-  user = env.get? "user"
-  if user
-    user = user.as(User)
-    subscriptions = user.subscriptions
-  end
-  subscriptions ||= [] of String
-
-  ucid = env.params.url["ucid"]
-
-  thin_mode = env.params.query["thin_mode"]? || env.get("preferences").as(Preferences).thin_mode
-  thin_mode = thin_mode == "true"
-
-  continuation = env.params.query["continuation"]?
-  # sort_by = env.params.query["sort_by"]?.try &.downcase
-
-  begin
-    channel = get_about_info(ucid, locale)
-  rescue ex : ChannelRedirect
-    next env.redirect env.request.resource.gsub(ucid, ex.channel_id)
-  rescue ex
-    next error_template(500, ex)
-  end
-
-  if !channel.tabs.includes? "community"
-    next env.redirect "/channel/#{channel.ucid}"
-  end
-
-  begin
-    items = JSON.parse(fetch_channel_community(ucid, continuation, locale, "json", thin_mode))
-  rescue ex : InfoException
-    env.response.status_code = 500
-    error_message = ex.message
-  rescue ex
-    next error_template(500, ex)
-  end
-
-  env.set "search", "channel:#{channel.ucid} "
-  templated "community"
-end
-
 # API Endpoints
 
 get "/api/v1/stats" do |env|
diff --git a/src/invidious/routes/channels.cr b/src/invidious/routes/channels.cr
new file mode 100644
index 00000000..9876936f
--- /dev/null
+++ b/src/invidious/routes/channels.cr
@@ -0,0 +1,172 @@
+class Invidious::Routes::Channels < Invidious::Routes::BaseRoute
+  def home(env)
+    self.videos(env)
+  end
+
+  def videos(env)
+    data = self.fetch_basic_information(env)
+    if !data.is_a?(Tuple)
+      return data
+    end
+    locale, user, subscriptions, continuation, ucid, channel = data
+
+    page = env.params.query["page"]?.try &.to_i?
+    page ||= 1
+
+    sort_by = env.params.query["sort_by"]?.try &.downcase
+
+    if channel.auto_generated
+      sort_options = {"last", "oldest", "newest"}
+      sort_by ||= "last"
+
+      items, continuation = fetch_channel_playlists(channel.ucid, channel.author, continuation, sort_by)
+      items.uniq! do |item|
+        if item.responds_to?(:title)
+          item.title
+        elsif item.responds_to?(:author)
+          item.author
+        end
+      end
+      items = items.select(&.is_a?(SearchPlaylist)).map(&.as(SearchPlaylist))
+      items.each { |item| item.author = "" }
+    else
+      sort_options = {"newest", "oldest", "popular"}
+      sort_by ||= "newest"
+
+      count, items = get_60_videos(channel.ucid, channel.author, page, channel.auto_generated, sort_by)
+      items.reject! &.paid
+    end
+
+    templated "channel"
+  end
+
+  def playlists(env)
+    data = self.fetch_basic_information(env)
+    if !data.is_a?(Tuple)
+      return data
+    end
+    locale, user, subscriptions, continuation, ucid, channel = data
+
+    sort_options = {"last", "oldest", "newest"}
+    sort_by = env.params.query["sort_by"]?.try &.downcase
+    sort_by ||= "last"
+
+    if channel.auto_generated
+      return env.redirect "/channel/#{channel.ucid}"
+    end
+
+    items, continuation = fetch_channel_playlists(channel.ucid, channel.author, continuation, sort_by)
+    items = items.select { |item| item.is_a?(SearchPlaylist) }.map { |item| item.as(SearchPlaylist) }
+    items.each { |item| item.author = "" }
+
+    templated "playlists"
+  end
+
+  def community(env)
+    data = self.fetch_basic_information(env)
+    if !data.is_a?(Tuple)
+      return data
+    end
+    locale, user, subscriptions, continuation, ucid, channel = data
+
+    thin_mode = env.params.query["thin_mode"]? || env.get("preferences").as(Preferences).thin_mode
+    thin_mode = thin_mode == "true"
+
+    continuation = env.params.query["continuation"]?
+    # sort_by = env.params.query["sort_by"]?.try &.downcase
+
+    if !channel.tabs.includes? "community"
+      return env.redirect "/channel/#{channel.ucid}"
+    end
+
+    begin
+      items = JSON.parse(fetch_channel_community(ucid, continuation, locale, "json", thin_mode))
+    rescue ex : InfoException
+      env.response.status_code = 500
+      error_message = ex.message
+    rescue ex
+      return error_template(500, ex)
+    end
+
+    templated "community"
+  end
+
+  def about(env)
+    data = self.fetch_basic_information(env)
+    if !data.is_a?(Tuple)
+      return data
+    end
+    locale, user, subscriptions, continuation, ucid, channel = data
+
+    env.redirect "/channel/#{ucid}"
+  end
+
+  # Redirects brand url channels to a normal /channel/:ucid route
+  def brand_redirect(env)
+    locale = LOCALES[env.get("preferences").as(Preferences).locale]?
+
+    # /attribution_link endpoint needs both the `a` and `u` parameter
+    # and in order to avoid detection from YouTube we should only send the required ones
+    # without any of the additional url parameters that only Invidious uses.
+    yt_url_params = URI::Params.encode(env.params.query.to_h.select(["a", "u", "user"]))
+
+    # Retrieves URL params that only Invidious uses
+    invidious_url_params = URI::Params.encode(env.params.query.to_h.select!(["a", "u", "user"]))
+
+    begin
+      resolved_url = YoutubeAPI.resolve_url("https://youtube.com#{env.request.path}#{yt_url_params.size > 0 ? "?#{yt_url_params}" : ""}")
+      ucid = resolved_url["endpoint"]["browseEndpoint"]["browseId"]
+    rescue ex : InfoException | KeyError
+      raise InfoException.new(translate(locale, "This channel does not exist."))
+    end
+
+    selected_tab = env.request.path.split("/")[-1]
+    if ["home", "videos", "playlists", "community", "channels", "about"].includes? selected_tab
+      url = "/channel/#{ucid}/#{selected_tab}"
+    else
+      url = "/channel/#{ucid}"
+    end
+
+    env.redirect url
+  end
+
+  # Handles redirects for the /profile endpoint
+  def profile(env)
+    # The /profile endpoint is special. If passed into the resolve_url
+    # endpoint YouTube would return a sign in page instead of an /channel/:ucid
+    # thus we'll add an edge case and handle it here.
+
+    uri_params = env.params.query.size > 0 ? "?#{env.params.query}" : ""
+
+    user = env.params.query["user"]?
+    if !user
+      raise InfoException.new("This channel does not exist.")
+    else
+      env.redirect "/user/#{user}#{uri_params}"
+    end
+  end
+
+  private def fetch_basic_information(env)
+    locale = LOCALES[env.get("preferences").as(Preferences).locale]?
+
+    user = env.get? "user"
+    if user
+      user = user.as(User)
+      subscriptions = user.subscriptions
+    end
+    subscriptions ||= [] of String
+
+    ucid = env.params.url["ucid"]
+    continuation = env.params.query["continuation"]?
+
+    begin
+      channel = get_about_info(ucid, locale)
+    rescue ex : ChannelRedirect
+      return env.redirect env.request.resource.gsub(ucid, ex.channel_id)
+    rescue ex
+      return error_template(500, ex)
+    end
+
+    return {locale, user, subscriptions, continuation, ucid, channel}
+  end
+end