var publishPicker = {
		"1" : function ( envelope ) {
			if ( !envelope ) {
				throw new Error( "publishing from the 'global' postal.publish call requires a valid envelope." );
			}
			envelope.channel = envelope.channel || DEFAULT_CHANNEL;
			envelope.timeStamp = new Date();
			postal.configuration.bus.publish( envelope );
			return envelope;
		},
		"2" : function ( topic, data ) {
			var envelope = { channel : DEFAULT_CHANNEL, topic : topic, timeStamp : new Date(), data : data };
			postal.configuration.bus.publish( envelope );
			return envelope;
		},
		"3" : function ( channel, topic, data ) {
			var envelope = { channel : channel, topic : topic, timeStamp : new Date(), data : data };
			postal.configuration.bus.publish( envelope );
			return envelope;
		}
	},
	channelPicker = {
		"1" : function ( chn ) {
			var channel = chn, topic, options = {};
			if ( Object.prototype.toString.call( channel ) === "[object String]" ) {
				channel = DEFAULT_CHANNEL;
				topic = chn;
			}
			else {
				channel = chn.channel || DEFAULT_CHANNEL;
				topic = chn.topic;
				options = chn.options || options;
			}
			return new postal.channelTypes[ options.type || "local" ]( channel, topic );
		},
		"2" : function ( chn, tpc ) {
			var channel = chn, topic = tpc, options = {};
			if ( Object.prototype.toString.call( tpc ) === "[object Object]" ) {
				channel = DEFAULT_CHANNEL;
				topic = chn;
				options = tpc;
			}
			return new postal.channelTypes[ options.type || "local" ]( channel, topic );
		},
		"3" : function ( channel, topic, options ) {
			return new postal.channelTypes[ options.type || "local" ]( channel, topic );
		}
	},
	sessionInfo = {};

// save some setup time, albeit tiny
localBus.subscriptions[SYSTEM_CHANNEL] = {};

var postal = {
	configuration : {
		bus : localBus,
		resolver : bindingsResolver,
		DEFAULT_CHANNEL : DEFAULT_CHANNEL,
		DEFAULT_PRIORITY : DEFAULT_PRIORITY,
		DEFAULT_DISPOSEAFTER : DEFAULT_DISPOSEAFTER,
		SYSTEM_CHANNEL : SYSTEM_CHANNEL
	},

	channelTypes : {
		local : ChannelDefinition
	},

	channel : function () {
		var len = arguments.length;
		if ( channelPicker[len] ) {
			return channelPicker[len].apply( this, arguments );
		}
	},

	subscribe : function ( options ) {
		var callback = options.callback,
			topic = options.topic,
			channel = options.channel || DEFAULT_CHANNEL;
		return new SubscriptionDefinition( channel, topic, callback );
	},

	publish : function () {
		var len = arguments.length;
		if ( publishPicker[len] ) {
			return publishPicker[len].apply( this, arguments );
		}
	},

	addWireTap : function ( callback ) {
		return this.configuration.bus.addWireTap( callback );
	},

	linkChannels : function ( sources, destinations ) {
		var result = [];
		if ( !_.isArray( sources ) ) {
			sources = [sources];
		}
		if ( !_.isArray( destinations ) ) {
			destinations = [destinations];
		}
		_.each( sources, function ( source ) {
			var sourceTopic = source.topic || "*";
			_.each( destinations, function ( destination ) {
				var destChannel = destination.channel || DEFAULT_CHANNEL;
				result.push(
					postal.subscribe( {
						channel : source.channel || DEFAULT_CHANNEL,
						topic : source.topic || "*",
						callback : function ( data, env ) {
							var newEnv = env;
							newEnv.topic = _.isFunction( destination.topic ) ? destination.topic( env.topic ) : destination.topic || env.topic;
							newEnv.channel = destChannel;
							newEnv.data = data;
							postal.publish( newEnv );
						}
					} )
				);
			} );
		} );
		return result;
	},

	utils : {
		getSubscribersFor : function () {
			var channel = arguments[ 0 ],
				tpc = arguments[ 1 ],
				result = [];
			if ( arguments.length === 1 ) {
				if ( Object.prototype.toString.call( channel ) === "[object String]" ) {
					channel = postal.configuration.DEFAULT_CHANNEL;
					tpc = arguments[ 0 ];
				}
				else {
					channel = arguments[ 0 ].channel || postal.configuration.DEFAULT_CHANNEL;
					tpc = arguments[ 0 ].topic;
				}
			}
			if ( postal.configuration.bus.subscriptions[ channel ] &&
			     postal.configuration.bus.subscriptions[ channel ].hasOwnProperty( tpc ) ) {
				result = postal.configuration.bus.subscriptions[ channel ][ tpc ];
			}
			return result;
		},

		reset : function () {
			postal.configuration.bus.reset();
			postal.configuration.resolver.reset();
		}
	}
};