order plan statechart https://xstate.js.org/viz/?gist=d0faf22bb431308e9daa731a55bde469

machine.js

  // Available variables:
  // - Machine
  // - interpret
  // - assign
  // - send
  // - sendParent
  // - spawn
  // - raise
  // - actions
  // - XState (all XState exports)
  
  const fetchMachine = Machine({
    id: 'order-plan',
  initial: 'idle',
  context: {
    plan: undefined,
    user: undefined,
    error: undefined,
  },
  states: {
    idle: {
      on: {
        CHOOSE_PLAN: {
          target: 'ready',
          actions: assign({
            plan: (_, event) => event.data,
          }),
        },
      },
    },
    ready: {
      on: {
        CHECKOUT: 'waiting',
        CHANGE_PLAN: {
          target: 'ready',
          actions: assign({
            plan: (_, event) => event.data,
          }),
        },
      },
    },
    waiting: {
      invoke: {
        src: 'checkout',
        onDone: {
          target: 'done',
          actions: assign({
            result: (_, event) => event.data,
          }),
        },
        onError: {
          target: 'error',
          actions: assign({
            error: (_, event) => event.data,
          }),
        },
      },
    },
    error: {
      on: {
        CHECKOUT: 'waiting',
        CHANGE_PLAN: {
          target: 'ready',
          actions: assign({
            plan: (_, event) => event.data,
          }),
        },
      },
    },
    done: {
      on: {
        CHECKOUT: 'waiting',
        CHANGE_PLAN: {
          target: 'ready',
          actions: assign({
            plan: (_, event) => event.data,
          }),
        },
        SAVE_PAYMENT: 'finish',
      },
    },
    finish: {
      type: 'final',
      entry: 'goNextPage',
    },
  },
  });