Generated by XState Viz: https://xstate.js.org/viz

machine.js

const tickEvent = (gear) => ({ type: 'TICK', gear })

const trainMachine = Machine(
  {
    id: 'train',
    initial: 'inactive',
    context: {
      position: {
        x: 0,
        y: 0,
      },
      power: 0,
      speed: 0,
      tickStream: null,
    },
    on: {
      ACTIVATE: '.active',
      DEACTIVATE: '.inactive',
    },
    states: {
      inactive: {
        invoke: ctx => ctx.tickStream.map(tickEvent),
        on: {
          TICK: { actions: ['slowDown', 'updatePosition'], cond: 'isMoving' },
        },
      },
      active: {
        invoke: ctx => ctx.tickStream.map(tickEvent),
        on: {
          TICK: {
            actions: ['updatePower', 'updateSpeed', 'updatePosition'],
          },
        },
      },
    },
  },
  {
    actions: {
      updatePower: assign({
        power: (_, ev) => {
          switch (ev.gear) {
            case 'neutral':
              return 0
            case 'forward':
              return 1
            case 'reverse':
              return -1
          }
        },
      }),
      updateSpeed: assign({
        speed: ctx => Phaser.Math.Clamp(ctx.speed + ctx.power, -1, 3),
      }),
      updatePosition: assign({ position: ctx => {} }),
      slowDown: assign({ speed: ctx => Phaser.Math.MinSub(ctx.speed, 0.1, 0) }),
    },
    guards: {
      isMoving: (ctx) => ctx.speed !== 0,
    },
  },
)