var isFunction = Y.Lang.isFunction;
/**
* <p>Provides a JSONPRequest class for repeated JSONP calls, and a convenience
* method Y.jsonp(url, callback) to instantiate and send a JSONP request.</p>
*
* <p>Both the constructor as well as the convenience function take two
* parameters: a url string and a callback.</p>
*
* <p>The url provided must include the placeholder string
* "{callback}" which will be replaced by a dynamically
* generated routing function to pass the data to your callback function.
* An example url might look like
* "http://example.com/service?callback={callback}".</p>
*
* <p>The second parameter can be a callback function that accepts the JSON
* payload as its argument, or a configuration object supporting the keys:</p>
* <ul>
* <li>on - map of callback subscribers
* <ul>
* <li>success - function handler for successful transmission</li>
* <li>failure - function handler for failed transmission</li>
* <li>timeout - function handler for transactions that timeout</li>
* </ul>
* </li>
* <li>format - override function for inserting the proxy name in the url</li>
* <li>timeout - the number of milliseconds to wait before giving up</li>
* <li>context - becomes <code>this</code> in the callbacks</li>
* <li>args - array of subsequent parameters to pass to the callbacks</li>
* <li>allowCache - use the same proxy name for all requests? (boolean)</li>
* </ul>
*
* @module jsonp
* @class JSONPRequest
* @constructor
* @param url {String} the url of the JSONP service
* @param callback {Object|Function} the default callback configuration or
* success handler
*/
function JSONPRequest() {
this._init.apply(this, arguments);
}
JSONPRequest.prototype = {
/**
* Set up the success and failure handlers and the regex pattern used
* to insert the temporary callback name in the url.
*
* @method _init
* @param url {String} the url of the JSONP service
* @param callback {Object|Function} Optional success callback or config
* object containing success and failure functions and
* the url regex.
* @protected
*/
_init : function (url, callback) {
this.url = url;
/**
* Map of the number of requests currently pending responses per
* generated proxy. Used to ensure the proxy is not flushed if the
* request times out and there is a timeout handler and success
* handler, and used by connections configured to allowCache to make
* sure the proxy isn't deleted until the last response has returned.
*
* @property _requests
* @private
* @type {Object}
*/
this._requests = {};
/**
* Map of the number of timeouts received from the destination url
* by generated proxy. Used to ensure the proxy is not flushed if the
* request times out and there is a timeout handler and success
* handler, and used by connections configured to allowCache to make
* sure the proxy isn't deleted until the last response has returned.
*
* @property _timeouts
* @private
* @type {Object}
*/
this._timeouts = {};
// Accept a function, an object, or nothing
callback = (isFunction(callback)) ?
{ on: { success: callback } } :
callback || {};
var subs = callback.on || {};
if (!subs.success) {
subs.success = this._defaultCallback(url, callback);
}
// Apply defaults and store
this._config = Y.merge({
context: this,
args : [],
format : this._format,
allowCache: false
}, callback, { on: subs });
},
/**
* Override this method to provide logic to default the success callback if
* it is not provided at construction. This is overridden by jsonp-url to
* parse the callback from the url string.
*
* @method _defaultCallback
* @param url {String} the url passed at construction
* @param config {Object} (optional) the config object passed at
* construction
* @return {Function}
*/
_defaultCallback: function () {},
/**
* Issues the JSONP request.
*
* @method send
* @param args* {any} any additional arguments to pass to the url formatter
* beyond the base url and the proxy function name
* @chainable
*/
send : function () {
var self = this,
args = Y.Array(arguments, 0, true),
config = self._config,
proxy = self._proxy || Y.guid(),
url;
// TODO: support allowCache as time value
if (config.allowCache) {
self._proxy = proxy;
}
if (self._requests[proxy] === undefined) {
self._requests[proxy] = 0;
}
if (self._timeouts[proxy] === undefined) {
self._timeouts[proxy] = 0;
}
self._requests[proxy]++;
Y.log('sending ' + proxy);
args.unshift(self.url, 'YUI.Env.JSONP.' + proxy);
url = config.format.apply(self, args);
if (!config.on.success) {
Y.log("No success handler defined. Aborting JSONP request.", "warn", "jsonp");
return self;
}
function wrap(fn, isTimeout) {
return (isFunction(fn)) ?
function (data) {
var execute = true,
counter = '_requests';
//if (config.allowCache) {
// A lot of wrangling to make sure timeouts result in
// fewer success callbacks, but the proxy is properly
// cleaned up.
if (isTimeout) {
++self._timeouts[proxy];
--self._requests[proxy];
Y.log(proxy + ' timed out - timeouts(' + self._timeouts[proxy] + ') requests(' + self._requests[proxy] + ')');
} else {
if (!self._requests[proxy]) {
execute = false;
counter = '_timeouts';
}
--self[counter][proxy];
Y.log(proxy + ' response received - timeouts(' + self._timeouts[proxy] + ') requests(' + self._requests[proxy] + ')');
}
//}
if (!self._requests[proxy] && !self._timeouts[proxy]) {
Y.log('deleting ' + proxy);
delete YUI.Env.JSONP[proxy];
}
if (execute) {
fn.apply(config.context, [data].concat(config.args));
}
} :
null;
}
// Temporary un-sandboxed function alias
// TODO: queuing
YUI.Env.JSONP[proxy] = wrap(config.on.success);
Y.Get.script(url, {
onFailure : wrap(config.on.failure),
onTimeout : wrap(config.on.timeout, true),
timeout : config.timeout,
charset : config.charset,
attributes: config.attributes
});
return self;
},
/**
* Default url formatter. Looks for callback= in the url and appends it
* if not present. The supplied proxy name will be assigned to the query
* param. Override this method by passing a function as the
* "format" property in the config object to the constructor.
*
* @method _format
* @param url { String } the original url
* @param proxy {String} the function name that will be used as a proxy to
* the configured callback methods.
* @param args* {any} additional args passed to send()
* @return {String} fully qualified JSONP url
* @protected
*/
_format: function (url, proxy) {
return url.replace(/\{callback\}/, proxy);
}
};
Y.JSONPRequest = JSONPRequest;
/**
*
* @method jsonp
* @param url {String} the url of the JSONP service with the {callback}
* placeholder where the callback function name typically goes.
* @param c {Function|Object} Callback function accepting the JSON payload
* as its argument, or a configuration object (see above).
* @param args* {any} additional arguments to pass to send()
* @return {JSONPRequest}
* @static
* @for YUI
*/
Y.jsonp = function (url,c) {
var req = new Y.JSONPRequest(url,c);
return req.send.apply(req, Y.Array(arguments, 2, true));
};
if (!YUI.Env.JSONP) {
YUI.Env.JSONP = {};
}
