State machine for a car engine

CarEngineStateMachine.ts

import { createMachine, assign } from "xstate";

interface Context {
  maxGears: number;
  fuelLevel: number;
  currentGear: number;
}

const engineCarMachine = createMachine<Context>(
  {
    id: "fetch",
    initial: "ENGINE_OFF",
    context: {
      maxGears: 6,
      fuelLevel: 0,
      currentGear: 0,
    },
    states: {
      ENGINE_OFF: {
        on: {
          FILL_FUEL: {
            actions: assign({
              fuelLevel: 100,
            }),
          },
          START_ENGINE: {
            target: "ENGINE_ON",
          },
        },
      },
      ENGINE_ON: {
        on: {
          TURN_OFF_ENGINE: {
            target: "ENGINE_OFF",
          },
          UP_GEAR: {
            cond: 'canUpGear',
            target: "ENGINE_ON",
            actions: assign((context) => ({
              currentGear: context.currentGear + 1
            }))
          },
          DOWN_GEAR: {
            cond: 'canDownGear',
            target: "ENGINE_ON",
            actions: assign((context) => ({
              currentGear: context.currentGear - 1
            }))
          },
        },
      },
    },
  },
  {
    guards: {
      canUpGear: (context, event) =>
        context.currentGear < context.maxGears,
      canDownGear: (context, event) =>
        context.currentGear > 0,
    },
  }
);