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

machine.js

const LOGGED_IN = 'LOGGED_IN';
const LOGGED_OUT = 'LOGGED_OUT';
const SOFT_LOGGED_IN = 'SOFT_LOGGED_IN';

const res = { locals: {} };

const fetchMachine = Machine(
  {
    id: 'authentication',
    initial: 'idle',
    context: {
      allowLoggedOut: true,
      allowSoftLoggedIn: false,
      cookieValue: null,
      id: null,
      loginState: null,
      language: null,
    },
    states: {
      idle: {
        on: {
          HAS_COOKIE: {
            target: 'fetchLoginState',
            action: 'storeCookie',
          },
          NO_COOKIE: [
            {
              target: 'redirectToLoginApp',
              cond: 'loggedInRequired',
            },
            {
              target: 'proceed',
              cond: 'loggedOutAllowed',
            },
          ],
        },
      },
      fetchLoginState: {
        invoke: {
          id: 'get-login-state',
          src: 'fetchLoginState',
          onDone: [
            {
              target: '.retrievedLoginState',
              action: 'storeUserData',
            },
          ],
        },
        states: {
          retrievedLoginState: {
            on: {
              '': [
                {
                  target: '.loggedIn',
                  cond: 'isLoggedIn',
                },
                {
                  target: '.validateSoftLoggedIn',
                  cond: 'isSoftLoggedIn',
                },
                {
                  target: '#authentication.retry',
                  cond: 'isLoggedOut',
                },
              ],
            },
            states: {
              loggedIn: [
                {
                  target: '#authentication.proceed',
                  action: 'assignUserDataToResponse',
                },
              ],
              validateSoftLoggedIn: [
                {
                  cond: 'softLoggedInAllowed',
                  target: '#authentication.proceed',
                  action: 'assignUserDataToResponse',
                },
                {
                  cond: 'softLoggedInForbidden',
                  target: '#authentication.redirectToLoginApp',
                },
              ],
            },
          },
        },
      },

      redirectToLoginApp: {
        final: true,
      },
      proceed: {
        final: true,
      },
      retry: {
        final: true,
      },
    },
  },
  {
    guards: {
      loggedInRequired: (context) => context.allowLoggedOut === false,
      loggedOutAllowed: (context) => context.allowLoggedOut === true,
      softLoggedInForbidden: (context) => context.allowSoftLoggedIn === false,

      isLoggedIn: (context) => context.loginState === LOGGED_IN,
      isLoggedOut: (context) => context.loginState === LOGGED_OUT,
      isSoftLoggedIn: (context) => context.loginState === SOFT_LOGGED_IN,
    },

    actions: {
      storeCookie: assign({ cookieValue: (_, event) => event.cookieValue }),
      storeUserData: assign({
        id: (_, event) => event.id,
        loginState: (_, event) => event.loginState,
        language: (_, event) => event.language,
      }),
      assignUserDataToResponse: (context) =>
        Object.assign(res.locals, {
          id: context.id,
          loginState: context.loginState,
          authenticated: context.loginState === LOGGED_IN,
          language: context.language,
        }),
    },

    services: {
      fetchLoginState: {
        src: (context) => {
          // fetch login state with `context.cookieValue`...
          // return `<loginState>`, `<language>` & `<id>`...
        },
      },
    },
  }
);