Add yaml support (#7)

rswag-api/lib/open_api/rswag/api/middleware.rb

@@ -1,4 +1,6 @@
 require 'json'
+require 'yaml'
+require 'rack/mime'
 
 module OpenApi
   module Rswag
@@ -15,13 +17,15 @@ module OpenApi
           filename = "#{@config.resolve_swagger_root(env)}/#{path}"
 
           if env['REQUEST_METHOD'] == 'GET' && File.file?(filename)
-            swagger = load_json(filename)
+            swagger = parse_file(filename)
             @config.swagger_filter.call(swagger, env) unless @config.swagger_filter.nil?
+            mime = Rack::Mime.mime_type(::File.extname(path), 'text/plain')
+            body = unload_swagger(filename, swagger)
 
             return [
               '200',
-              { 'Content-Type' => 'application/json' },
-              [ JSON.dump(swagger) ]
+              { 'Content-Type' => 'mine' },
+              [ body ]
             ]
           end
 
@@ -30,9 +34,29 @@ module OpenApi
 
         private
 
+        def parse_file(filename)
+          if /\.ya?ml$/ === filename
+            load_yaml(filename)
+          else
+            load_json(filename)
+          end
+        end
+
+        def load_yaml(filename)
+          YAML.safe_load(File.read(filename))
+        end
+
         def load_json(filename)
           JSON.parse(File.read(filename))
         end
+
+        def unload_swagger(filename, swagger)
+          if /\.ya?ml$/ === filename
+            YAML.dump(swagger)
+          else
+            JSON.dump(swagger)
+          end
+        end
       end
     end
   end