Support uploads using the put saver

TiddlyWiki's upload.js saver is old and deprecated so let's see if
we can switch to using the put saver.

Includes:
- A bogus WebDAV header to convince TiddlyWiki that the put
  saver is usable
- A new controller method and route for the "put" saves
- Clear the url from $:/UploadURL when serving a site to make
  sure TW doesn't try to use the upload saver

There's a related PR for TiddlyWiki that exposes the error messages
to the user, see TiddlyWiki/TiddlyWiki5#6589

Issue: #148

rails/app/controllers/tiddlywiki_controller.rb

@@ -7,7 +7,7 @@ class TiddlywikiController < ApplicationController
   before_action :find_site
 
   # TiddlyWiki can't provide the token for saving so we need to skip it
-  skip_before_action :verify_authenticity_token, only: :save
+  skip_before_action :verify_authenticity_token, only: [:upload_save, :put_save]
 
   # Rails wants a token for options requests, which TiddlyWiki similarly can't provide
   skip_before_action :verify_authenticity_token,
@@ -20,6 +20,9 @@ class TiddlywikiController < ApplicationController
   def serve
     return site_not_available unless site_visible?
 
+    # Convince TiddlyWiki it can use the put saver
+    dummy_webdav_header if request.options? && @site.enable_put_saver?
+
     etag_header
 
     # Avoid site download for head or options requests
@@ -92,7 +95,8 @@ def download
     download_html_content(@site.download_content, @site.name)
   end
 
-  def save
+  # Using the "upload" saver
+  def upload_save
     begin
       if site_saveable?
         @site.file_upload(params[:userfile])
@@ -108,6 +112,24 @@ def save
     end
   end
 
+  # Using the "put" saver
+  def put_save
+    begin
+      if site_saveable?
+        @site.file_upload(request.body)
+        @site.increment_save_count
+        head 204
+      else
+        err_message = "If this is your site please log in at #{main_site_url} and try again."
+        render status: 403, plain: err_message
+      end
+    rescue => e
+      # Todo: Should probably give a generic "Save failed!" message, and log the real problem
+      err_message = "#{e.class.name} #{e.message}"
+      render status: 500, plain: err_message
+    end
+  end
+
   private
 
   def update_view_count_and_access_timestamp
@@ -200,4 +222,9 @@ def cors_headers
     response.set_header 'Access-Control-Allow-Headers', 'X-Requested-With'
   end
 
+  # TiddlyWiki just checks if the header exists so the value doesn't matter
+  def dummy_webdav_header
+    response.set_header 'dav', "Dummy WebDAV header to enable TiddlyWiki's PUT saver"
+  end
+
 end

rails/app/models/site.rb

@@ -56,7 +56,8 @@ def looks_valid?
   end
 
   def html_content(signed_in_user: nil)
-    th_file.apply_tiddlyhost_mods(name, signed_in_user: signed_in_user).to_html
+    th_file.apply_tiddlyhost_mods(name,
+      signed_in_user: signed_in_user, enable_put_saver: enable_put_saver).to_html
   end
 
   def json_data(opts={})

rails/config/routes.rb

@@ -29,7 +29,8 @@
     get '/favicon.ico', to: 'tiddlywiki#favicon'
     get '/download', to: 'tiddlywiki#download'
 
-    post '/', to: 'tiddlywiki#save'
+    post '/', to: 'tiddlywiki#upload_save'
+    put '/', to: 'tiddlywiki#put_save'
   end
 
   #

rails/lib/th_file.rb

@@ -38,17 +38,22 @@ def self.from_empty(empty_type)
     from_file(empty_path(empty_type))
   end
 
-  def apply_tiddlyhost_mods(site_name, for_download: false, signed_in_user: nil)
+  def apply_tiddlyhost_mods(site_name, for_download: false, enable_put_saver: false, signed_in_user: nil)
     if is_tw5?
 
-      upload_url = if !for_download
-        # The url for uploads is the same as the site url
-        Settings.subdomain_site_url(site_name)
-      else
-        # Clear $:/UploadURL so the save button in the downloaded file will not try
-        # to use upload.js. It should use another save method, probably download to file.
+      upload_url = if for_download || enable_put_saver
+        # Clear $:/UploadURL for downloads so the save button in the downloaded
+        # file will not try to use upload.js. It should use another save
+        # method, probably download to file.
+        #
         # Todo: Consider if we should do that also when signed_in_user is nil.
+        #
+        # Clear $:/UploadURL when using the put saver otherwise TW will
+        # prioritize the upload saver
         ""
+      else
+        # The url for uploads is the same as the site url
+        Settings.subdomain_site_url(site_name)
       end
 
       if !for_download && signed_in_user