Elevator Saga

ElevatorSaga.js

{
    init: function(elevators, floors) {
        const priorities = {
            CAPACITY: 'CAPACITY',
            DISTANCE: 'DISTANCE',
            WAITING: 'WAITING'
        }
        const priority = priorities.DISTANCE
        const needsPickup = floors.reduce((acc, floor) => {
            acc[floor.floorNum()] = {
                waiting: 0,
                lastVisit: Date.now()
            }
            return acc
        }, {})
        
        function pickNextFloor(currentFloor = 0) {
            return (floors
                .map(floor => {
                    const floorNum = floor.floorNum()
                    return {
                        floor: floorNum,
                        distance: Math.abs(currentFloor - floorNum),
                        numWaiting: needsPickup[floorNum].waiting,
                        lastVisit: needsPickup[floorNum].lastVisit
                    }
                })
                .filter(floor => floor.numWaiting > 0)
                .sort((a, b) => {
                    switch (priority) {
                        case priorities.CAPACITY:
                            return a.numWaiting - b.numWaiting

                        case priorities.WAITING:
                            return a.lastVisit - b.lastVisit

                        case priorities.DISTANCE:
                            return a.distance - b.distance

                        default:
                            return (a.waiting + a.distance) - (b.waiting + b.distance)
                    }
                })[0] || {}).floor
        }
        
        function queueFloor(floorNum) {
            needsPickup[floorNum].waiting++
            console.log('queueFloor', floorNum, needsPickup)
            elevators.forEach(elevator => elevator.processQueue())
        }

        elevators.forEach(elevator => {
            elevator.processQueue = function() {
                console.log('processing queue', elevator)
                if (elevator.destinationQueue.length === 0) {
                    const nextStop = pickNextFloor(elevator.currentFloor())
                    if (typeof nextStop === 'number') elevator.goToFloor(nextStop)
                }
            }
            
            elevator.on('stopped_at_floor', floorNumber => {
                needsPickup[floorNumber].waiting = 0
                needsPickup[floorNumber].lastVisit = Date.now()
                elevator.destinationQueue = elevator.destinationQueue.filter(stop => stop !== floorNumber)
                const floorDistances = elevator.destinationQueue.map(floor => {
                    return {
                        floor,
                        distance: Math.abs(floorNumber - floor),
                        numWaiting: needsPickup[floor].waiting,
                        lastVisit: needsPickup[floor].lastVisit
                    }
                })
                elevator.destinationQueue = floorDistances
                    .sort((a, b) => {
                        switch (priority) {
                            case priorities.CAPACITY:
                                return a.numWaiting - b.numWaiting
                                
                            case priorities.WAITING:
                                return a.lastVisit - b.lastVisit
                                
                            case priorities.DISTANCE:
                                return a.distance - b.distance
                                
                            default:
                                return (a.waiting + a.distance) - (b.waiting + b.distance)
                        }
                    })
                    .map(({ floor }) => floor)
                elevator.checkDestinationQueue()
                elevator.processQueue()
            })
            
            elevator.on('floor_button_pressed', elevator.goToFloor)
        })
        
        floors.forEach(floor => {
            const queueThisFloor = () => queueFloor(floor.floorNum())
            floor.on('up_button_pressed', queueThisFloor)
            floor.on('down_button_pressed', queueThisFloor)
        })
    },
    update: function(dt, elevators, floors) {
        // We normally don't need to do anything here
    }
}