require 'oj'

module Useless
  module Doc
    module Serialization
      module Dump

        # Converts a hash to a JSON representation.
        #
        # @param [Hash, String] hash the hash to be converted.
        #
        # @raise [ArgumentError] if json is not a Hash, String or IO.
        #
        # @return [String] a JSON representation corresponding to the
        #   specified hash.
        #
        def self.hash_to_json(hash)
          hash.is_a?(String) ? hash : Oj.dump(hash)
        end

        # Converts +Doc::Resource+ instance to a JSON representation.
        #
        # @param [Doc::Resource] resource the resource to be converted to JSON.
        #
        # @return [String] a JSON representation of the specified resource.
        #
        def self.resource(resource)
          if resource
            hash_to_json \
              'path' => resource.path,
              'description' => resource.description,
              'requests' => resource.requests.map { |request| request(request) }
          end
        end

        # @api private
        def self.request(request)
          if request
            hash_to_json \
              'method' => request.method,
              'description' => request.description,
              'authentication_required' => request.authentication_required,
              'parameters' => request.parameters.map { |parameter| request_parameter(parameter) },
              'headers' => request.headers.map { |header| header(header) },
              'body' => body(request.body),
              'responses' => request.responses.map { |response| response(response) }
          end
        end

        # @api private
        def self.response(response)
          if response
            hash_to_json \
              'code' => response.code,
              'description' => response.description,
              'headers' => response.headers.map { |header| header(header) },
              'body' => body(response.body)
          end
        end

        # @api private
        def self.request_parameter(parameter)
          if parameter
            hash_to_json \
              'type' => parameter.type,
              'key' => parameter.key,
              'required' => parameter.required,
              'default' => parameter.default,
              'description' => parameter.description
          end
        end

        # @api private
        def self.header(header)
          if header
            hash_to_json \
              'key' => header.key,
              'description' => header.description
          end
        end

        # @api private
        def self.response_status(status)
          if status
            hash_to_json \
              'code' => status.code,
              'description' => status.description
          end
        end

        # @api private
        def self.body(body)
          if body
            hash_to_json \
              'content_type' => body.content_type,
              'attributes' => body.attributes.map { |attribute| body_attribute(attribute) }
          end
        end

        # @api private
        def self.body_attribute(attribute)
          if attribute
            hash_to_json \
              'key' => attribute.key,
              'type' => attribute.type,
              'required' => attribute.required,
              'default' => attribute.default,
              'description' => attribute.description
          end
        end

      end
    end
  end
end