Add YouTube iCalendar endpoint. It should make it possible to subscri…

…be to channels in calendar applications and get notified on upcoming live streams, and easily find recent videos.

app.rb

@@ -235,6 +235,58 @@
   end
 end
 
+get "/youtube/:channel_id/:username.ics" do
+  @channel_id = params[:channel_id]
+  @username = params[:username]
+
+  # The API is really inconsistent in listing scheduled live streams, but the RSS endpoint seems to consistently list them, so experiment with using that
+  response = HTTP.get("https://www.youtube.com/feeds/videos.xml?channel_id=#{@channel_id}")
+  raise(GoogleError, response) if !response.success?
+  doc = Nokogiri::XML(response.body)
+  ids = doc.xpath("//yt:videoId").map(&:text)
+
+  response = Google.get("/youtube/v3/videos", query: { part: "snippet,liveStreamingDetails,contentDetails", id: ids.join(",") })
+  raise(GoogleError, response) if !response.success?
+  @data = response.json["items"]
+
+  if params.has_key?(:eventType)
+    eventTypes = params[:eventType].split(",")
+    eventType_completed = eventTypes.include?("completed")
+    eventType_live = eventTypes.include?("live")
+    eventType_upcoming = eventTypes.include?("upcoming")
+    @data.select! do |v|
+      v.has_key?("liveStreamingDetails") && (
+        (eventType_completed && v["liveStreamingDetails"].has_key?("actualEndTime")) ||
+        (eventType_live      && v["liveStreamingDetails"].has_key?("actualStartTime")    && !v["liveStreamingDetails"].has_key?("actualEndTime")) ||
+        (eventType_upcoming  && v["liveStreamingDetails"].has_key?("scheduledStartTime") && !v["liveStreamingDetails"].has_key?("actualStartTime"))
+      )
+    end
+  end
+
+  if params.has_key?(:q)
+    @query = params[:q]
+    q = @query.downcase
+    @data.select! { |v| v["snippet"]["title"].downcase.include?(q) }
+    @title = "\"#{@query}\" from #{@username}"
+  else
+    @title = "#{@username} on YouTube"
+  end
+
+  @data.sort_by! do |video|
+    if video.has_key?("liveStreamingDetails")
+      Time.parse(video["liveStreamingDetails"]["actualStartTime"] || video["liveStreamingDetails"]["scheduledStartTime"])
+    else
+      Time.parse(video["snippet"]["publishedAt"])
+    end
+  end.reverse!
+
+  @data.map do |video|
+    video["snippet"]["description"].grep_urls
+  end.flatten.tap { |urls| URL.resolve(urls) }
+
+  erb :"youtube.ics"
+end
+
 get "/youtube/:channel_id/:username" do
   @channel_id = params[:channel_id]
   playlist_id = "UU" + @channel_id[2..]

config/application.rb

@@ -1,6 +1,7 @@
 # frozen_string_literal: true
 
 ENV["APP_ENV"] ||= ENV["RACK_ENV"] || "development"
+ENV["APP_VERSION"] ||= ENV["HEROKU_RELEASE_VERSION"] || "unknown"
 
 require "bundler/setup"
 Bundler.require(:default, ENV["APP_ENV"])

views/youtube.ics.erb

@@ -0,0 +1,55 @@
+<%- content_type :ics -%>
+BEGIN:VCALENDAR
+PRODID:-//RSSBox//RSSBox <%= ENV["APP_VERSION"] %>//EN
+VERSION:2.0
+CALSCALE:GREGORIAN
+METHOD:PUBLISH
+X-WR-CALNAME:<%= @title %>
+X-WR-CALDESC:https://www.youtube.com/channel/<%= @channel_id %><%= Addressable::URI.new(path: "/search", query: "query=#{@query}").normalize.to_s if @query %>
+
+<%-
+@data.each do |video|
+  duration = video["contentDetails"]["duration"].parse_pt
+  title = video["snippet"]["title"].to_line
+  url = "https://www.youtube.com/watch?v=#{video["id"]}"
+  description = if duration > 0
+    "Duration: #{duration.to_duration}"
+  end
+  published_at = Time.parse(video["snippet"]["publishedAt"])
+
+  if video.has_key?("liveStreamingDetails")
+    dtstart = Time.parse(video["liveStreamingDetails"]["actualStartTime"] || video["liveStreamingDetails"]["scheduledStartTime"])
+    dtend = if video["liveStreamingDetails"]["actualEndTime"]
+      Time.parse(video["liveStreamingDetails"]["actualEndTime"])
+    else
+      [Time.now, dtstart].max + 7200
+    end
+    if video["liveStreamingDetails"].has_key?("actualEndTime")
+    elsif video["liveStreamingDetails"].has_key?("actualStartTime")
+      title += " (started)"
+    elsif video["liveStreamingDetails"].has_key?("scheduledStartTime")
+      title += " (scheduled)"
+    end
+  else
+    dtstart = published_at
+    dtend = published_at + duration
+  end
+
+  dtstart = dtstart.strftime("%Y%m%dT%H%M%SZ")
+  dtend = dtend.strftime("%Y%m%dT%H%M%SZ")
+  published_at = published_at.strftime("%Y%m%dT%H%M%SZ")
+-%>
+BEGIN:VEVENT
+UID:video-<%= video["id"] %>@youtube.com
+DTSTART:<%= dtstart %>
+DTEND:<%= dtend %>
+DTSTAMP:<%= published_at %>
+CREATED:<%= published_at %>
+LAST-MODIFIED:<%= published_at %>
+SUMMARY:<%= title %>
+LOCATION:<%= url %>
+DESCRIPTION:<%= description %>
+END:VEVENT
+
+<%- end -%>
+END:VCALENDAR