/*
	Copyright (c) 2004-2006, The Dojo Foundation
	All Rights Reserved.

	Licensed under the Academic Free License version 2.1 or above OR the
	modified BSD license. For more information on Dojo licensing, see:

		http://dojotoolkit.org/community/licensing.shtml
*/

dojo.provide("dojo.rpc.RpcService");
dojo.require("dojo.io.*");
dojo.require("dojo.json");
dojo.require("dojo.lang.func");
dojo.require("dojo.Deferred");

dojo.rpc.RpcService = function(url){
	// summary
	// constructor for rpc base class
	if(url){
		this.connect(url);
	}
}

dojo.lang.extend(dojo.rpc.RpcService, {

	strictArgChecks: true,
	serviceUrl: "",

	parseResults: function(obj){
		// summary
		// parse the results coming back from an rpc request.  
   		// this base implementation, just returns the full object
		// subclasses should parse and only return the actual results
		return obj;
	},

	errorCallback: function(/* dojo.Deferred */ deferredRequestHandler){
		// summary
		// create callback that calls the Deferres errback method
		return function(type, e){
			deferredRequestHandler.errback(new Error(e.message));
		}
	},

	resultCallback: function(/* dojo.Deferred */ deferredRequestHandler){
		// summary
		// create callback that calls the Deferred's callback method
		var tf = dojo.lang.hitch(this, 
			function(type, obj, e){
				if (obj["error"]!=null) {
					var err = new Error(obj.error);
					err.id = obj.id;
					deferredRequestHandler.errback(err);
				} else {
					var results = this.parseResults(obj);
					deferredRequestHandler.callback(results); 
				}
			}
		);
		return tf;
	},


	generateMethod: function(/*string*/ method, /*array*/ parameters, /*string*/ url){
		// summary
		// generate the local bind methods for the remote object
		return dojo.lang.hitch(this, function(){
			var deferredRequestHandler = new dojo.Deferred();

			// if params weren't specified, then we can assume it's varargs
			if( (this.strictArgChecks) &&
				(parameters != null) &&
				(arguments.length != parameters.length)
			){
				// put error stuff here, no enough params
				dojo.raise("Invalid number of parameters for remote method.");
			} else {
				this.bind(method, arguments, deferredRequestHandler, url);
			}

			return deferredRequestHandler;
		});
	},

	processSmd: function(/*json*/ object){
		// summary
		// callback method for reciept of a smd object.  Parse the smd and
		// generate functions based on the description
		dojo.debug("RpcService: Processing returned SMD.");
		if(object.methods){
			dojo.lang.forEach(object.methods, function(m){
				if(m && m["name"]){
					dojo.debug("RpcService: Creating Method: this.", m.name, "()");
					this[m.name] = this.generateMethod(	m.name,
														m.parameters, 
														m["url"]||m["serviceUrl"]||m["serviceURL"]);
					if(dojo.lang.isFunction(this[m.name])){
						dojo.debug("RpcService: Successfully created", m.name, "()");
					}else{
						dojo.debug("RpcService: Failed to create", m.name, "()");
					}
				}
			}, this);
		}

		this.serviceUrl = object.serviceUrl||object.serviceURL;
		dojo.debug("RpcService: Dojo RpcService is ready for use.");
	},

	connect: function(/*String*/ smdUrl){
		// summary
		// connect to a remote url and retrieve a smd object
		dojo.debug("RpcService: Attempting to load SMD document from:", smdUrl);
		dojo.io.bind({
			url: smdUrl,
			mimetype: "text/json",
			load: dojo.lang.hitch(this, function(type, object, e){ return this.processSmd(object); }),
			sync: true
		});		
	}
});