Fix local storyboard requests on Crystal >= 1.16.0

src/ext/kemal_static_file_handler.cr

@@ -191,5 +191,13 @@ module Kemal
         end
       end
     end
+
+    # See https://github.com/crystal-lang/crystal/issues/15788
+    #
+    # URL fragments also aren't passed along but there isn't an easy way
+    # to retrieve that at the moment.
+    private def redirect_to(context, path)
+      context.response.redirect URI.new(path: URI.encode_path(path.to_s), query: context.request.query)
+    end
   end
 end

src/invidious/helpers/handlers.cr

@@ -50,7 +50,30 @@ class Kemal::ExceptionHandler
 
   private def call_exception_with_status_code(context : HTTP::Server::Context, exception : Exception, status_code : Int32)
     return if context.response.closed?
-    return if exclude_match? context
+
+    # Invidious excludes the status code error handlers from running on the api routes
+    # meaning that we are unable to redirect /api/v1/storyboards/sb/... to the right location
+    # within a 404 handler. As a quick fix we'll match it here.
+    #
+    # For future reference this is also why the API will always return a 200 status code
+    # even when a route could not be found.
+    #
+    # TODO: In the future there should be dedicated status code error handlers for the api.
+    #
+    if exclude_match?(context)
+      if status_code == 404
+        # Only necessary on Crystal versions >= 1.16.0
+        {% if compare_versions(Crystal::VERSION, "1.16.0") >= 0 %}
+          if HOST_URL.empty? && context.request.path.starts_with?("/api/v1/storyboards/sb")
+            return context.redirect "#{context.request.path[19..]}?#{context.params.query}", status_code: 302
+          end
+
+          return
+        {% end %}
+      end
+
+      return
+    end
 
     if !Kemal.config.error_handlers.empty? && Kemal.config.error_handlers.has_key?(status_code)
       context.response.content_type = "text/html" unless context.response.headers.has_key?("Content-Type")

src/invidious/routes/errors.cr

@@ -1,9 +1,20 @@
 module Invidious::Routes::ErrorRoutes
   def self.error_404(env)
-    # Workaround for #3117
-    if HOST_URL.empty? && env.request.path.starts_with?("/v1/storyboards/sb")
-      return env.redirect "#{env.request.path[15..]}?#{env.params.query}"
-    end
+    # Workaround for #3117 on versions prior to 1.16.0
+    #
+    # Crystal 1.16.0 fixed the parsing of some weird-looking paths
+    # meaning that `//api/v1/storyboards/sb/i/...` will no longer
+    # get parsed into a request target of `/v1/storyboards/sb/i/...`
+    #
+    # This also means that we won't be able to handle the logic here
+    # because status code error handles are disabled for the API routes
+
+    # We only need to include this workaround on versions prior to 1.16.0
+    {% if compare_versions(Crystal::VERSION, "1.16.0") < 0 %}
+      if HOST_URL.empty? && env.request.path.starts_with?("/v1/storyboards/sb")
+        return env.redirect "#{env.request.path[15..]}?#{env.params.query}"
+      end
+    {% end %}
 
     if md = env.request.path.match(/^\/(?<id>([a-zA-Z0-9_-]{11})|(\w+))$/)
       item = md["id"]