WSClient.js

/*

	WSClient.js

	Copyright(C) 2015  Carlos Pineda Guerrero
	carlospinedag@m4gm.com
	twitter.com/m4gmCloud

	This program is free software: you can redistribute it and/or modify
	it under the terms of the GNU General Public License as published by
	the Free Software Foundation, either version 3 of the License, or
	(at your option) any later version.

	This program is distributed in the hope that it will be useful,
	but WITHOUT ANY WARRANTY; without even the implied warranty of
	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
	GNU General Public License for more details.

	You should have received a copy of the GNU General Public License
	along with this program.  If not, see <http://www.gnu.org/licenses/>.

*/


function WSClient(url)
{
	this.url = url;
	this.post = function(operation,args,callback)
	{
		var request = new XMLHttpRequest();
		var body = "";
		var pairs = [];
		var name;
		try
		{
			for (name in args)
			{
				var value = args[name];
				if (typeof value !== "string") value = JSON.stringify(value);
				pairs.push(name + '=' + encodeURI(value).replace(/=/g,'%3D').replace(/&/g,'%26').replace(/%20/g,'+'));
			}
			body = pairs.join('&');
			request.open('POST', url + '/' + operation);
			request.setRequestHeader('Content-Type','application/x-www-form-urlencoded');
			request.setRequestHeader('Content-Length',body.length);
			request.responseType = 'json';
			request.onload = function()
			{
				if (callback != null) callback(request.status,resolveReferences(request.response));
			}
			request.send(body);
		}
		catch (e)
		{
			alert("Error: " + e.message);
		}
	}
}

// http://stackoverflow.com/questions/15312529/resolve-circular-references-from-json-object

function resolveReferences(json)
{
	if (typeof json === 'string') json = JSON.parse(json);

	var byid = {}, // all objects by id
	refs = []; // references to objects that could not be resolved

	json = (function recurse(obj, prop, parent)
	{
		if (typeof obj !== 'object' || !obj) // a primitive value
			return obj;
		if (Object.prototype.toString.call(obj) === '[object Array]')
		{
			for (var i = 0; i < obj.length; i++)
			// check also if the array element is not a primitive value
			if (typeof obj[i] !== 'object' || !obj[i]) // a primitive value
				continue;
			else if ("$ref" in obj[i])
				obj[i] = recurse(obj[i], i, obj);
			else
				obj[i] = recurse(obj[i], prop, obj);
			return obj;
		}
		if ("$ref" in obj)
		{
			// a reference
			var ref = obj.$ref;
			if (ref in byid) return byid[ref];
			// else we have to make it lazy:
			refs.push([parent, prop, ref]);
			return;
		}
		else if ("$id" in obj)
		{
			var id = obj.$id;
			delete obj.$id;
			if ("$values" in obj) // an array
				obj = obj.$values.map(recurse);
			else // a plain object
				for (var prop in obj)
					obj[prop] = recurse(obj[prop], prop, obj);
			byid[id] = obj;
		}
		return obj;
	})(json); // run it!

	for (var i = 0; i < refs.length; i++)
	{
		// resolve previously unknown references
		var ref = refs[i];
		ref[0][ref[1]] = byid[ref[2]];
		// Notice that this throws if you put in a reference at top-level
	}
	return json;
}