http://play.elevatorsaga.com/

elevator.js

{
	init: function (elevators, floors)
	{
		var requestQueue = [];
		var request = function (floor, direction)
		{
			requestQueue.push({
				floor: floor,
				direction: direction
			});
			requestQueue = _.sortBy(requestQueue, 'floor');
		}
		var getRequest = function ()
		{
			var nextRequest = _.last(requestQueue);
			_.remove(requestQueue, nextRequest);
			return nextRequest;
		}
		var findRequest = function (floor, direction)
		{
			var validRequests = _.remove(requestQueue, {
				floor: floor,
				direction: direction
			});
			return _.size(validRequests) > 0;
		}
		var setIndicator = function (elevator, direction)
		{
			if (_.isUndefined(direction))
			{
				elevator.goingUpIndicator(true);
				elevator.goingDownIndicator(true);
			}
			else if (direction === 'up')
			{
				elevator.goingUpIndicator(true);
				elevator.goingDownIndicator(false);
			}
			else if (direction === 'down')
			{
				elevator.goingDownIndicator(true);
				elevator.goingUpIndicator(false);
			}
		}
		_.each(elevators,
			function (elevator)
			{
				elevator.on('idle',
					function ()
					{
						var nextRequest = getRequest();
						if (_.isUndefined(nextRequest))
						{
							if (elevator.currentFloor() === 0)
							{
								setIndicator(elevator, 'up');
								elevator.goToFloor(0);
							}
							else
							{
								setIndicator(elevator, 'down');
								elevator.goToFloor(0);
							}
							return;
						}
						elevator.goToFloor(nextRequest.floor);
					}
				);
				elevator.on('stopped_at_floor',
					function (floorNum)
					{
						if (_.isEmpty(elevator.destinationQueue))
						{
							setIndicator(elevator);
						}
					}
				);
				elevator.on('passing_floor',
					function (floorNum, direction)
					{
						if (elevator.loadFactor() >= 1)
						{
							return;
						}
						var floorHasRequest = findRequest(floorNum, direction);
						if (!floorHasRequest)
						{
							return;
						}
						elevator.destinationQueue.unshift(floorNum);
						elevator.checkDestinationQueue();
					}
				);
				elevator.on('floor_button_pressed',
					function (floorNum)
					{
						elevator.goToFloor(floorNum);
						if (floorNum > elevator.currentFloor())
						{
							setIndicator(elevator, 'up');
							elevator.destinationQueue = _(elevator.destinationQueue)
							.sortBy(
								function (num) {
									return num;
								}
							)
							.uniq()
							.value();
						}
						else
						{
							setIndicator(elevator, 'down');
							elevator.destinationQueue = _(elevator.destinationQueue)
							.sortBy(
								function (num) {
									return -num;
								}
							)
							.uniq()
							.value();
						}
						elevator.checkDestinationQueue();
					}
				);
			}
		);
		_.each(floors,
			function (floor)
			{
				floor.on('up_button_pressed',
					function ()
					{
						request(floor.floorNum(), 'up');
					}
				);
				floor.on('down_button_pressed',
					function ()
					{
						request(floor.floorNum(), 'down');
					}
				);
			}
		);
	},
	update: _.noop
}