elevator-saga/elevator.js

eval({
	init: function(elevators, floors) {
		// Get elevator/building info
		const elevatorCount = elevators.length,
		      floorCount    = floors.length,
		      bottomFloor   = 0,
		      topFloor      = floorCount - 1;

		console.clear();
		("Starting (" + floorCount + " floors; " + elevatorCount + " elevator" + (floorCount == 1) ? "s" : "" + ")...");

		// Direction constants
		const UP   = 0,
		      DOWN = 1,
		      IDLE = 2;

		// Rest floor constants
		const LOW  = 0,
		      MED  = 1,
		      HIGH = 2;

		// Data structure for floor requests
		const requests = [new Set(), new Set()];

		// ----
		// Functions
		// ----

		// getClosestFloor takes a floor, a list of floors, an optional
		// list of ignored floors, and an optional direction. It
		// returns the closest floor from that list in the given
		// direction that is not part of the ignored floors list. Ties
		// are broken by even/oddness of the current floor.
		function getClosestFloor(currentFloor, floorList, ignoredFloors = new Set(), direction = IDLE) {
			const isEven = (currentFloor % 2 == 0);

			let closestFloor = currentFloor,
			    distance     = floorCount,
			    newDistance  = distance;

			floorList.forEach(function(floorNum) {
				const direction = getDirection(currentFloor, floorNum);
				newDistance = Math.abs(currentFloor - floorNum);

				if (newDistance < distance && newDistance > 0 && !(ignoredFloors.has(floorNum))) {
					closestFloor = floorNum;
					distance = newDistance;
				} else if (newDistance == distance && !(ignoredFloors.has(floorNum))) {
					if (isEven && direction == UP) {
						closestFloor = floorNum;
					} else if (!isEven && direction == DOWN) {
						closestFloor = floorNum;
					}
				}
			});

			if (closestFloor != currentFloor) {
				return closestFloor;
			} else {
				throw new Error("No floor in selected direction");
			}
		}

		// getNextFloor chooses the best destination for an elevator
		// when given the index of the elevator, along with all
		// destinations, requests, and rest floors.
		function getNextFloor(elevators, elevatorIndex, destinations, requests, restFloors) {
			let elevator = elevators[elevatorIndex],
			    floorNum = restFloors[MED];

			if (requests[UP].size == 0 && requests[DOWN].size == 0 && destinations.size == 0) {
				// No people; send to rest floor
			} else if (destinations.size == 0) {
				// No destinations; send to pick up passengers
				try {
					floorNum = getClosestFloor(elevator.currentFloor(), new Set([...requests[UP], ...requests[DOWN]]));
				} catch (e) {
					console.log("ERROR: Requests set was empty");
				}
			} else {
				// Prioritize dropping off current passengers
				try {
					floorNum = getClosestFloor(elevator.currentFloor(), destinations);
				} catch (e) {
					console.log("ERROR: Destinations set was empty");
				}
			}

			return floorNum;
		}

		// getClosestElevator takes a floor number and returns the
		// index of the closest elevator.
		function getClosestElevator(floorNum) {
			let closestElevator = 0,
			    distance        = floorCount,
			    newDistance     = distance;

			elevators.forEach(function(elevator, elevatorIndex) {
				newDistance = Math.abs(elevator.currentFloor() - floorNum);
				if (newDistance < distance) {
					distance = newDistance;
					closestElevator = elevatorIndex;
				}
			});

			//console.log("Closest is elevator[" + closestElevator + "]")
			return closestElevator;
		}

		// getDirection get the direction (up or down) that an elevator
		// will need to travel to get to a specified floor
		function getDirection(currentFloor, floorNum) {
			const distance = currentFloor - floorNum;
			let direction = IDLE;

			if (distance > 0 || currentFloor == topFloor) {
				direction = DOWN;
			} else if (distance < 0 || currentFloor == bottomFloor) {
				direction = UP;
			}

			return direction;
		}

		// setDirection changes the indicator lights on a specified
		// elevator to match the given direction.
		function setDirection(elevator, direction) {
			switch (direction) {
			case UP:
				elevator.goingUpIndicator(true);
				elevator.goingDownIndicator(false);
				break;
			case DOWN:
				elevator.goingUpIndicator(false);
				elevator.goingDownIndicator(true);
				break;
			default:
				elevator.goingUpIndicator(true);
				elevator.goingDownIndicator(true);
			}
		}

		// ----
		// Floors
		// ----

		floors.forEach(function(floor) {
			floor.on("up_button_pressed", function() {
				//console.log("> Up request on floor[" + floor.level + "]");
				requests[UP].add(floor.level);
			});
			floor.on("down_button_pressed", function() {
				//console.log("> Down request on floor[" + floor.level + "]");
				requests[DOWN].add(floor.level);
			});
		});

		// ----
		// Elevators
		// ----

		elevators.forEach(function(elevator, elevatorIndex) {
			// Elevator info and variables
			const restFloors = [
				elevatorIndex * Math.floor(floorCount / (elevatorCount + 1)),
				(elevatorIndex + 1) * Math.floor(floorCount / (elevatorCount + 1)),
				(elevatorIndex + 2) * Math.floor(floorCount / (elevatorCount + 1))
			];

			let destinations = new Set(),
			    nextFloor = restFloors[LOW];

			// Start
			setDirection(elevator, UP); // Starts on the ground floor, must be going up
			console.log("> Elevator[" + elevatorIndex + "] rest floors are " + restFloors[LOW] + ", " + restFloors[MED] + ", and " + restFloors[HIGH] + ". Starting at " + restFloors[LOW] + ".");
			elevator.goToFloor(nextFloor); // Nearest rest floor

			// Idle
			elevator.on("idle", function() {
				//console.log("> Elevator[" + elevatorIndex + "] is idle")
				nextFloor = getNextFloor(elevators, elevatorIndex, destinations, requests, restFloors);
				elevator.goToFloor(nextFloor);
			});

			// Passing
			elevator.on("passing_floor", function(floorNum, direction) {
				if (destinations.has(floorNum) ||
				   (elevator.loadFactor() < 1 &&
				   (elevator.destinationDirection() == "up" && requests[UP].has(floorNum)) ||
				   (elevator.destinationDirection() == "down" && requests[DOWN].has(floorNum)))) {
					elevator.goToFloor(floorNum, true);
				}
			});

			// Buttons
			elevator.on("floor_button_pressed", function(floorNum) {
				//console.log("> Pressed floor[" + floorNum + "] on elevator[" + elevatorIndex + "]");
				destinations.add(floorNum);
			});

			// Stopped
			elevator.on("stopped_at_floor", function(floorNum) {
				//console.log("> elevator[" + elevatorIndex + "] stopped at floor[" + floorNum + "]");
				let isNext = (elevator.currentFloor() == nextFloor);

				destinations.delete(floorNum);

				if (isNext) {
					nextFloor = getNextFloor(elevators, elevatorIndex, destinations, requests, restFloors);
					setDirection(elevator, getDirection(elevator.currentFloor(), nextFloor));
				}

				if (elevator.goingUpIndicator() == true) {
					requests[UP].delete(floorNum);
				}

				if (elevator.goingDownIndicator() == true) {
					requests[DOWN].delete(floorNum);
				}

				if (isNext) {
					elevator.goToFloor(nextFloor);
				}
			});
		});
	},

	update: function(dt, elevators, floors) {}
});