feat: Add job to download captions

apps/cf/config/config.exs

@@ -14,25 +14,6 @@ config :cf,
   soft_limitations_period: 15 * 60,
   hard_limitations_period: 3 * 60 * 60
 
-# Configure scheduler
-config :cf, CF.Scheduler,
-  # Run only one instance across cluster
-  global: true,
-  debug_logging: false,
-  jobs: [
-    # credo:disable-for-lines:10
-    # Actions analysers
-    # Every minute
-    {"*/1 * * * *", {CF.Jobs.Reputation, :update, []}},
-    # Every day
-    {"@daily", {CF.Jobs.Reputation, :reset_daily_limits, []}},
-    # Every minute
-    {"*/1 * * * *", {CF.Jobs.Flags, :update, []}},
-    # Various updaters
-    # Every 5 minutes
-    {"*/5 * * * *", {CF.Jobs.Moderation, :update, []}}
-  ]
-
 # Configure mailer
 config :cf, CF.Mailer, adapter: Bamboo.MailgunAdapter
 

apps/cf/config/test.exs

@@ -14,9 +14,6 @@ config :cf,
 # Print only warnings and errors during test
 config :logger, level: :warn
 
-# Disable CRON tasks on test
-config :cf, CF.Scheduler, jobs: []
-
 # Mails
 config :cf, CF.Mailer, adapter: Bamboo.TestAdapter
 

apps/cf/lib/videos/captions_fetcher.ex

@@ -3,5 +3,6 @@ defmodule CF.Videos.CaptionsFetcher do
   Fetch captions for videos.
   """
 
-  @callback fetch(DB.Schema.Video.t()) :: {:ok, DB.Schema.VideoCaption.t()} | {:error, binary()}
+  @callback fetch(DB.Schema.Video.t()) ::
+              {:ok, %{raw: String.t(), parsed: String.t(), format: String.t()}} | {:error, term()}
 end

apps/cf/lib/videos/captions_fetcher_test.ex

@@ -7,9 +7,16 @@ defmodule CF.Videos.CaptionsFetcherTest do
 
   @impl true
   def fetch(_video) do
-    captions = %DB.Schema.VideoCaption{
-      content: "__TEST-CONTENT__",
-      format: "xml"
+    captions = %{
+      raw: "__TEST-CONTENT__",
+      format: "custom",
+      parsed: [
+        %{
+          "text" => "__TEST-CONTENT__",
+          "start" => 0.0,
+          "duration" => 1.0
+        }
+      ]
     }
 
     {:ok, captions}

apps/cf/lib/videos/captions_fetcher_youtube.ex

@@ -1,38 +1,134 @@
 defmodule CF.Videos.CaptionsFetcherYoutube do
   @moduledoc """
   A captions fetcher for YouTube.
+  Based upon https://github.com/Valian/youtube-captions, but adapted with Httpoison.
   """
 
   @behaviour CF.Videos.CaptionsFetcher
 
+  require Logger
+
   @impl true
   def fetch(%{youtube_id: youtube_id, language: language}) do
-    with {:ok, content} <- fetch_captions_content(youtube_id, language) do
-      captions = %DB.Schema.VideoCaption{
-        content: content,
-        format: "xml"
-      }
-
-      {:ok, captions}
+    with {:ok, data} <- fetch_youtube_data(youtube_id),
+         {:ok, caption_tracks} <- parse_caption_tracks(data),
+         {:ok, transcript_url} <- find_transcript_url(caption_tracks, language),
+         {:ok, transcript_data} <- fetch_transcript(transcript_url) do
+      {:ok,
+       %{
+         raw: transcript_data,
+         parsed: process_transcript(transcript_data),
+         format: "xml"
+       }}
     end
   end
 
-  defp fetch_captions_content(video_id, locale) do
-    case HTTPoison.get("http://video.google.com/timedtext?lang=#{locale}&v=#{video_id}") do
-      {:ok, %HTTPoison.Response{status_code: 200, body: ""}} ->
-        {:error, :not_found}
+  defp fetch_youtube_data(video_id) do
+    url = "https://www.youtube.com/watch?v=#{video_id}"
 
-      {:ok, %HTTPoison.Response{status_code: 200, body: body}} ->
+    case HTTPoison.get(url, []) do
+      {:ok, %HTTPoison.Response{body: body}} ->
         {:ok, body}
 
-      {:ok, %HTTPoison.Response{status_code: 404}} ->
-        {:error, :not_found}
+      {:error, %HTTPoison.Error{reason: reason}} ->
+        {:error, "Failed to fetch YouTube video #{url}: #{inspect(reason)}"}
+    end
+  end
+
+  defp parse_caption_tracks(data) do
+    captions_regex = ~r/"captionTracks":(?<data>\[.*?\])/
+
+    case Regex.named_captures(captions_regex, data) do
+      %{"data" => data} -> {:ok, Jason.decode!(data)}
+      _ -> {:error, :not_found}
+    end
+  end
+
+  defp find_transcript_url(caption_tracks, lang) do
+    case Enum.find(caption_tracks, &Regex.match?(~r".#{lang}", &1["vssId"])) do
+      nil ->
+        {:error, :language_not_found}
+
+      %{"baseUrl" => base_url} ->
+        {:ok, base_url}
+
+      _data ->
+        {:error, :language_url_not_found}
+    end
+  end
 
-      {:ok, %HTTPoison.Response{status_code: _}} ->
-        {:error, :unknown}
+  defp fetch_transcript(base_url) do
+    case HTTPoison.get(base_url, []) do
+      {:ok, %HTTPoison.Response{body: body}} ->
+        {:ok, body}
 
       {:error, %HTTPoison.Error{reason: reason}} ->
-        {:error, reason}
+        {:error, "Failed to fetch transcript: #{inspect(reason)}"}
     end
   end
+
+  defp process_transcript(transcript) do
+    transcript
+    |> String.replace(~r/^<\?xml version="1.0" encoding="utf-8"\?><transcript>/, "")
+    |> String.replace("</transcript>", "")
+    |> String.split("</text>")
+    |> Enum.filter(&(String.trim(&1) != ""))
+    |> Enum.map(&process_line/1)
+  end
+
+  defp process_line(line) do
+    %{"start" => start} = Regex.named_captures(~r/start="(?<start>[\d.]+)"/, line)
+    %{"dur" => dur} = Regex.named_captures(~r/dur="(?<dur>[\d.]+)"/, line)
+
+    text =
+      line
+      |> String.replace("&amp;", "&")
+      |> String.replace(~r/<text.+>/, "")
+      |> String.replace(~r"</?[^>]+(>|$)", "")
+      |> HtmlEntities.decode()
+      |> String.trim()
+
+    %{start: parse_float(start), duration: parse_float(dur), text: text}
+  end
+
+  defp parse_float(val) do
+    {num, _} = Float.parse(val)
+    num
+  end
+
+  # Below is an implementation using the official YouTube API, but it requires OAuth2 authentication.
+  # It is left here for reference, in case we loose access to the unofficial API.
+  # defp fetch_captions_content_with_official_api(video_id, locale) do
+  #   # TODO: Continue dev here. See https://www.perplexity.ai/search/Can-you-show-jioyCtw.S4yrL8mlIBdqGg
+  #   {:ok, token} = Goth.Token.for_scope("https://www.googleapis.com/auth/youtube.force-ssl")
+  #   conn = YouTubeConnection.new(token.token)
+  # {:ok, captions} = GoogleApi.YouTube.V3.Api.Captions.youtube_captions_list(conn, ["snippet"], video_id, [])
+  # {
+  #   "kind": "youtube#captionListResponse",
+  #   "etag": "kMTAKpyU_VGu7GxgEnxXHqcuEXM",
+  #   "items": [
+  #     {
+  #       "kind": "youtube#caption",
+  #       "etag": "tWo68CIcRRFZA0oXPt8HGxCYia4",
+  #       "id": "AUieDaZJxYug0L5YNAw_31GbXz73b0CPXCDFlsPNSNe7KQvuv1g",
+  #       "snippet": {
+  #         "videoId": "v2IoEhuho2k",
+  #         "lastUpdated": "2024-06-16T18:45:12.56697Z",
+  #         "trackKind": "asr",
+  #         "language": "fr",
+  #         "name": "",
+  #         "audioTrackType": "unknown",
+  #         "isCC": false,
+  #         "isLarge": false,
+  #         "isEasyReader": false,
+  #         "isDraft": false,
+  #         "isAutoSynced": false,
+  #         "status": "serving"
+  #       }
+  #     }
+  #   ]
+  # }
+  # caption_id = List.first(captions.items).id # TODO inspect to pick the right caption
+  # {:ok, caption} = GoogleApi.YouTube.V3.Api.Captions.youtube_captions_download(conn, caption_id, [])
+  # end
 end

apps/cf/lib/videos/videos.ex

@@ -3,6 +3,8 @@ defmodule CF.Videos do
   The boundary for the Videos system.
   """
 
+  require Logger
+
   import Ecto.Query, warn: false
   import CF.Videos.MetadataFetcher
   import CF.Videos.CaptionsFetcher
@@ -167,15 +169,42 @@ defmodule CF.Videos do
   iex> download_captions(video)
   """
   def download_captions(video = %Video{}) do
-    with {:ok, captions} <- @captions_fetcher.fetch(video) do
-      captions
-      |> VideoCaption.changeset(%{video_id: video.id})
-      |> Repo.insert()
-
-      {:ok, captions}
+    # Try to fetch new captions
+    existing_captions = get_existing_captions(video)
+    captions_base = if existing_captions, do: existing_captions, else: %VideoCaption{}
+
+    case @captions_fetcher.fetch(video) do
+      {:ok, captions} ->
+        captions_base
+        |> VideoCaption.changeset(Map.merge(captions, %{video_id: video.id}))
+        |> Repo.insert_or_update()
+
+      # If no Youtube caption found, insert a dummy entry in DB to prevent retrying for 30 days
+      {:error, :not_found} ->
+        unless existing_captions do
+          Repo.insert(%DB.Schema.VideoCaption{
+            video_id: video.id,
+            raw: "",
+            parsed: "",
+            format: "xml"
+          })
+        end
+
+        {:error, :not_found}
+
+      result ->
+        result
     end
   end
 
+  defp get_existing_captions(video) do
+    VideoCaption
+    |> where([vc], vc.video_id == ^video.id)
+    |> order_by(desc: :inserted_at)
+    |> limit(1)
+    |> Repo.one()
+  end
+
   defp get_metadata_fetcher(video_url) do
     if Application.get_env(:cf, :use_test_video_metadata_fetcher) do
       &MetadataFetcher.Test.fetch_video_metadata/1

apps/cf/test/videos/videos_test.exs

@@ -68,7 +68,15 @@ defmodule CF.VideosTest do
 
       {:ok, captions} = Videos.download_captions(video)
 
-      assert captions.content == "__TEST-CONTENT__"
+      assert captions.raw == "__TEST-CONTENT__"
+
+      assert captions.parsed == [
+               %{
+                 "text" => "__TEST-CONTENT__",
+                 "start" => 0.0,
+                 "duration" => 1.0
+               }
+             ]
     end
   end
 end

apps/cf_jobs/config/config.exs

@@ -8,6 +8,7 @@ config :cf_jobs, CF.Jobs.Scheduler,
   jobs: [
     # Reputation
     update_reputations: [
+      # every 20 minutes
       schedule: {:extended, "*/20"},
       task: {CF.Jobs.Reputation, :update, []},
       overlap: false
@@ -19,21 +20,31 @@ config :cf_jobs, CF.Jobs.Scheduler,
     ],
     # Moderation
     update_moderation: [
+      # every 5 minutes
       schedule: "*/5 * * * *",
       task: {CF.Jobs.Moderation, :update, []},
       overlap: false
     ],
     # Flags
     update_flags: [
+      # every minute
       schedule: "*/1 * * * *",
       task: {CF.Jobs.Flags, :update, []},
       overlap: false
     ],
     # Notifications
     create_notifications: [
+      # every 5 seconds
       schedule: {:extended, "*/5"},
       task: {CF.Jobs.CreateNotifications, :update, []},
       overlap: false
+    ],
+    # Captions
+    download_captions: [
+      # every 10 minutes
+      schedule: "*/10 * * * *",
+      task: {CF.Jobs.DownloadCaptions, :update, []},
+      overlap: false
     ]
   ]
 

apps/cf_jobs/lib/application.ex

@@ -10,13 +10,15 @@ defmodule CF.Jobs.Application do
     :timer.sleep(1000)
 
     env = Application.get_env(:cf, :env)
+
     # Define workers and child supervisors to be supervised
     children = [
       # Jobs
       worker(CF.Jobs.Reputation, []),
       worker(CF.Jobs.Flags, []),
       worker(CF.Jobs.Moderation, []),
-      worker(CF.Jobs.CreateNotifications, [])
+      worker(CF.Jobs.CreateNotifications, []),
+      worker(CF.Jobs.DownloadCaptions, [])
     ]
 
     # Do not start scheduler in tests