update fetch_community_post_comments protobuf to match currently used protobuf, add sort_by option

src/invidious/channels/community.cr

@@ -24,6 +24,15 @@ def fetch_channel_community(ucid, cursor, locale, format, thin_mode)
   return extract_channel_community(items, ucid: ucid, locale: locale, format: format, thin_mode: thin_mode)
 end
 
+def decode_ucid_from_post_protobuf(params)
+  decoded_protobuf = params.try { |i| URI.decode_www_form(i) }
+  .try { |i| Base64.decode(i) }
+  .try { |i| IO::Memory.new(i) }
+  .try { |i| Protodec::Any.parse(i) }
+
+  return decoded_protobuf.try(&.["56:0:embedded"]["2:0:string"].as_s)
+end
+
 def fetch_channel_community_post(ucid, post_id, locale, format, thin_mode)
   object = {
     "56:embedded" => {

src/invidious/comments/youtube.cr

@@ -16,34 +16,38 @@ module Invidious::Comments
     return parse_youtube(id, response, format, locale, thin_mode, sort_by)
   end
 
-  def fetch_community_post_comments(ucid, post_id)
+  def fetch_community_post_comments(ucid, post_id, sort_by = "top")
     object = {
-      "2:string"    => "community",
+      "2:string"    => "posts",
-      "25:embedded" => {
-        "22:string" => post_id,
-      },
-      "45:embedded" => {
-        "2:varint" => 1_i64,
-        "3:varint" => 1_i64,
-      },
       "53:embedded" => {
         "4:embedded" => {
           "6:varint"  => 0_i64,
-          "27:varint" => 1_i64,
+          "15:varint" => 2_i64,
+          "25:varint" => 0_i64,
           "29:string" => post_id,
           "30:string" => ucid,
         },
+        "7:varint" => 0_i64,
         "8:string" => "comments-section",
       },
     }
 
+    case sort_by
+    when "top"
+      object["53:embedded"].as(Hash)["4:embedded"].as(Hash)["6:varint"] = 0_i64
+    when "new", "newest"
+      object["53:embedded"].as(Hash)["4:embedded"].as(Hash)["6:varint"] = 1_i64
+    else # top
+      object["53:embedded"].as(Hash)["4:embedded"].as(Hash)["6:varint"] = 0_i64
+    end
+
     object_parsed = object.try { |i| Protodec::Any.cast_json(i) }
       .try { |i| Protodec::Any.from_json(i) }
       .try { |i| Base64.urlsafe_encode(i) }
 
     object2 = {
       "80226972:embedded" => {
-        "2:string" => ucid,
+        "2:string" => "FEcomment_post_detail_page_web_top_level",
         "3:string" => object_parsed,
       },
     }

src/invidious/routes/api/v1/channels.cr

@@ -436,7 +436,7 @@ module Invidious::Routes::API::V1::Channels
     if ucid.nil?
       response = YoutubeAPI.resolve_url("https://www.youtube.com/post/#{id}")
       return error_json(400, "Invalid post ID") if response["error"]?
-      ucid = response.dig("endpoint", "browseEndpoint", "browseId").as_s
+      ucid = decode_ucid_from_post_protobuf(response.dig("endpoint", "browseEndpoint", "params").as_s)
     else
       ucid = ucid.to_s
     end
@@ -460,13 +460,15 @@ module Invidious::Routes::API::V1::Channels
 
     format = env.params.query["format"]?
     format ||= "json"
+    sort_by = env.params.query["sort_by"]?.try &.downcase
+    sort_by ||= "top"
 
     continuation = env.params.query["continuation"]?
 
     case continuation
     when nil, ""
       ucid = env.params.query["ucid"]
-      comments = Comments.fetch_community_post_comments(ucid, id)
+      comments = Comments.fetch_community_post_comments(ucid, id, sort_by: sort_by)
     else
       comments = YoutubeAPI.browse(continuation: continuation)
     end

src/invidious/routes/channels.cr

@@ -284,7 +284,7 @@ module Invidious::Routes::Channels
       response = YoutubeAPI.resolve_url("https://www.youtube.com/post/#{id}")
       return error_template(400, "Invalid post ID") if response["error"]?
 
-      ucid = response.dig("endpoint", "browseEndpoint", "browseId").as_s
+      ucid = decode_ucid_from_post_protobuf(response.dig("endpoint", "browseEndpoint", "params").as_s)
       post_response = fetch_channel_community_post(ucid, id, locale, "json", thin_mode)
     end