From b2f5b1eb68382079f4d88792b8f3f79635125254 Mon Sep 17 00:00:00 2001
From: syeopite <syeopite@syeopite.dev>
Date: Thu, 13 Jun 2024 10:56:18 -0700
Subject: [PATCH] Add logic to fetch transcripts from label

Although available this method should be discouraged as it requires
an extra request to YouTube to get caption data in order to
map label -> language code and auto-generated status, which are needed
to fetch transcripts.
---
 src/invidious/routes/api/v1/videos.cr | 23 ++++++++++++++++++++++-
 1 file changed, 22 insertions(+), 1 deletion(-)

diff --git a/src/invidious/routes/api/v1/videos.cr b/src/invidious/routes/api/v1/videos.cr
index 03fdc49b..85a208c7 100644
--- a/src/invidious/routes/api/v1/videos.cr
+++ b/src/invidious/routes/api/v1/videos.cr
@@ -421,10 +421,11 @@ module Invidious::Routes::API::V1::Videos
 
     id = env.params.url["id"]
     lang = env.params.query["lang"]?
+    label = env.params.query["label"]?
     auto_generated = env.params.query["autogen"]? ? true : false
 
     # Return all available transcript options when none is given
-    if !lang
+    if !label && !lang
       begin
         video = get_video(id)
       rescue ex : NotFoundException
@@ -462,6 +463,26 @@ module Invidious::Routes::API::V1::Videos
       return response
     end
 
+    # If lang is not given then we attempt to fetch
+    # the transcript through the given label
+    if lang.nil?
+      begin
+        video = get_video(id)
+      rescue ex : NotFoundException
+        return error_json(404, ex)
+      rescue ex
+        return error_json(500, ex)
+      end
+
+      target_transcript = video.captions.select(&.name.== label)
+      if target_transcript.empty?
+        return error_json(404, NotFoundException.new("Requested transcript does not exist"))
+      else
+        target_transcript = target_transcript[0]
+        lang, auto_generated = target_transcript.language_code, target_transcript.auto_generated
+      end
+    end
+
     params = Invidious::Videos::Transcript.generate_param(id, lang, auto_generated)
 
     begin