rest/interceptor/mime.js

/*
 * Copyright 2012-2014 the original author or authors
 * @license MIT, see LICENSE.txt for details
 *
 * @author Scott Andrews
 */

(function (define) {
	'use strict';

	define(function (require) {

		var interceptor, mime, registry, noopConverter, when;

		interceptor = require('../interceptor');
		mime = require('../mime');
		registry = require('../mime/registry');
		when = require('when');

		noopConverter = {
			read: function (obj) { return obj; },
			write: function (obj) { return obj; }
		};

		/**
		 * MIME type support for request and response entities.  Entities are
		 * (de)serialized using the converter for the MIME type.
		 *
		 * Request entities are converted using the desired converter and the
		 * 'Accept' request header prefers this MIME.
		 *
		 * Response entities are converted based on the Content-Type response header.
		 *
		 * @param {Client} [client] client to wrap
		 * @param {string} [config.mime='text/plain'] MIME type to encode the request
		 *   entity
		 * @param {string} [config.accept] Accept header for the request
		 * @param {Client} [config.client=<request.originator>] client passed to the
		 *   converter, defaults to the client originating the request
		 * @param {Registry} [config.registry] MIME registry, defaults to the root
		 *   registry
		 * @param {boolean} [config.permissive] Allow an unkown request MIME type
		 *
		 * @returns {Client}
		 */
		return interceptor({
			init: function (config) {
				config.registry = config.registry || registry;
				return config;
			},
			request: function (request, config) {
				var type, headers;

				headers = request.headers || (request.headers = {});
				type = mime.parse(headers['Content-Type'] = headers['Content-Type'] || config.mime || 'text/plain');
				headers.Accept = headers.Accept || config.accept || type.raw + ', application/json;q=0.8, text/plain;q=0.5, */*;q=0.2';

				if (!('entity' in request)) {
					return request;
				}

				return config.registry.lookup(type).otherwise(function () {
					// failed to resolve converter
					if (config.permissive) {
						return noopConverter;
					}
					throw 'mime-unknown';
				}).then(function (converter) {
					var client = config.client || request.originator;

					return when.attempt(converter.write, request.entity, { client: client, request: request, mime: type, registry: config.registry })
						.otherwise(function() {
							throw 'mime-serialization';
						})
						.then(function(entity) {
							request.entity = entity;
							return request;
						});
				});
			},
			response: function (response, config) {
				if (!(response.headers && response.headers['Content-Type'] && response.entity)) {
					return response;
				}

				var type = mime.parse(response.headers['Content-Type']);

				return config.registry.lookup(type).otherwise(function () { return noopConverter; }).then(function (converter) {
					var client = config.client || response.request && response.request.originator;

					return when.attempt(converter.read, response.entity, { client: client, response: response, mime: type, registry: config.registry })
						.otherwise(function (e) {
							response.error = 'mime-deserialization';
							response.cause = e;
							throw response;
						})
						.then(function (entity) {
							response.entity = entity;
							return response;
						});
				});
			}
		});

	});

}(
	typeof define === 'function' && define.amd ? define : function (factory) { module.exports = factory(require); }
	// Boilerplate for AMD and Node
));