Add subscribe button to channel page

src/invidious.cr

@@ -939,6 +939,14 @@ get "/videoplayback*" do |env|
 end
 
 get "/channel/:ucid" do |env|
+  authorized = env.get? "authorized"
+  if authorized
+    sid = env.get("sid").as(String)
+
+    subscriptions = PG_DB.query_one?("SELECT subscriptions FROM users WHERE id = $1", sid, as: Array(String))
+  end
+  subscriptions ||= [] of String
+
   ucid = env.params.url["ucid"]
 
   page = env.params.query["page"]?.try &.to_i

src/views/channel.ecr

@@ -3,6 +3,27 @@
 <% end %>
 
 <h1><%= author %></h1>
+<% if authorized %>
+    <% if subscriptions.includes? ucid %>
+    <p>
+        <a href="/subscription_ajax?action_remove_subscriptions=1&c=<%= ucid %>">
+            <b>Unsubscribe from <%= author %></b>
+        </a>
+    </p>
+    <% else %>
+    <p>
+        <a href="/subscription_ajax?action_create_subscription_to_channel=1&c=<%= ucid %>">
+            <b>Subscribe to <%= author %></b>
+        </a>
+    </p>
+    <% end %>
+<% else %>
+    <p>
+        <a href="/login">
+            <b>Login to subscribe to <%= author %></b>
+        </a>
+    </p>
+<% end %>
 <% videos.each_slice(4) do |slice| %>
 <div class="pure-g">
     <% slice.each do |video| %>