Change syntax for routes with filename

Previously, the filename was URL-encoded, thus each / was replaced with %2F. This caused issues with some Apache2 configuration, smartly mingling with the URL to either encode it a second time (resulting in %252F) or decoding it (generating a real /). However, for authenticated file downloads with the JWT, we hardly require a byte-by-byte matching. With these changes, the URL parameter is no longer URL-encoded, so that Apache2 won't break our implementation any longer.

Further, we use this opportunity to get rid of the unnecessary .json extension for those filename routes, simplifying the routes generated and doing some further cleanup.

config/routes.rb

@@ -1,7 +1,5 @@
 # frozen_string_literal: true
 
-FILENAME_REGEXP = /.+/ unless Kernel.const_defined?(:FILENAME_REGEXP)
-
 Rails.application.routes.draw do
   resources :community_solutions, only: %i[index edit update]
   resources :error_template_attributes
@@ -67,7 +65,7 @@ Rails.application.routes.draw do
       get :shell
       post 'shell', as: :execute_command, action: :execute_command
       get :list_files, as: :list_files_in
-      get 'download/:filename', as: :download_file_from, constraints: {filename: FILENAME_REGEXP}, action: :download_arbitrary_file, controller: 'live_streams'
+      get 'download/*filename', as: :download_file_from, action: :download_arbitrary_file, controller: 'live_streams', format: false # Admin file-system access to runners
       get :statistics
       post :sync_to_runner_management
     end
@@ -131,8 +129,8 @@ Rails.application.routes.draw do
   namespace :code_ocean do
     resources :files, only: %i[create destroy]
   end
-  get '/uploads/files/:id/:filename', to: 'code_ocean/files#show_protected_upload', as: :protected_upload, constraints: {filename: FILENAME_REGEXP}
-  get '/uploads/render_files/:id/:filename', to: 'code_ocean/files#render_protected_upload', as: :render_protected_upload, constraints: {filename: FILENAME_REGEXP}
+  get '/uploads/files/:id/*filename', to: 'code_ocean/files#show_protected_upload', as: :protected_upload, format: false # View file, e.g., when implementing or viewing an exercise
+  get '/uploads/render_files/:id/*filename', to: 'code_ocean/files#render_protected_upload', as: :render_protected_upload, format: false # Render action with embedded files, i.e., images in user-created HTML
 
   resources :file_types
 
@@ -154,14 +152,14 @@ Rails.application.routes.draw do
 
   resources :submissions, only: %i[create index show] do
     member do
-      get 'download', as: :download, action: :download
-      get 'download/:filename', as: :download_file, constraints: {filename: FILENAME_REGEXP}, action: :download_file
-      get 'download_stream/:filename', as: :download_stream_file, constraints: {filename: FILENAME_REGEXP}, action: :download_submission_file, controller: 'live_streams'
-      get 'render/:filename', as: :render, constraints: {filename: FILENAME_REGEXP}, action: :render_file
-      get 'run/:filename', as: :run, constraints: {filename: FILENAME_REGEXP}, action: :run
+      get 'download', as: :download, action: :download # Full submission download with RemoteEvaluationMapping
+      get 'download/*filename', as: :download_file, action: :download_file, format: false # Single file download, currently not used in the frontend (but working)
+      get 'download_stream/*filename', as: :download_stream_file, action: :download_submission_file, controller: 'live_streams', format: false # Access runner artifacts
+      get 'render/*filename', as: :render, action: :render_file, format: false
+      get 'run/*filename', as: :run, action: :run, format: false
       get :score
       get :statistics
-      get 'test/:filename', as: :test, constraints: {filename: FILENAME_REGEXP}, action: :test
+      get 'test/*filename', as: :test, action: :test, format: false
       get :finalize
     end
   end