Managing application state in production applications is crucial. and with finite state machine we can have error-free applications.

export const authMachine =
  createMachine({
    id: 'authMachine',
    initial: 'LOGGED_OUT',
    context: {
      userProfile: null,
      cognitoUserProfile: null,
      platform: undefined,
    },
    states: {
      LOGGED_OUT: {
        on: {
          login: {
            target: 'LOGGED_IN',
            actions: assign({
              cognitoUserProfile: (context, event) => event.data,
            }),
          },
        },
      },
      LOGGED_IN: {
        initial: 'USER_PROFILE_CHECK',
        states: {
          USER_PROFILE_CHECK: {
            invoke: {
              // check if user is added to DB
              src: context => {
                return new Promise(async (resolve, reject) => {
              },
              onDone: {
                target: 'USER_PROFILE_PRESENT',
                actions: assign({
                  userProfile: (context, event) => event.data,
                }),
              },
              // if not added transit to USER_PROFILE_ABSENT
              onError: {
                target: 'USER_PROFILE_ABSENT',
                actions: (context, event) => {
                  console.log('USER_PROFILE_ABSENT', event.value);
                },
              },
            },
          },
          USER_PROFILE_PRESENT: {},
          USER_PROFILE_ABSENT: {
            invoke: {
              // Add user to DB
              src: () => {},
              // if added set machine context and transit to USER_PROFILE_PRESENT
              onDone: {target: 'USER_PROFILE_PRESENT', action: () => {}},
            },
          },
        },
        on: {
          logout: {
            target: 'LOGGED_OUT',
            actions: assign(() => {
              return {
                userProfile: null,
                cognitoUserProfile: null,
              };
            }),
          },
        },
      },
    },
  });