auth - local storage middleware

import agent from './agent';

function isPromise(v) {
  return v && typeof v.then === 'function';
}

const promiseMiddleware = store => next => action => {
  // if the action's payload is a promise, trigger this middleware
  if (isPromise(action.payload)) {
    // trigger UI's loading state
    store.dispatch({ type: 'ASYNC_START', subtype: action.type });
    // let promise succeed/fail
    action.payload.then(
      // if it succeeds, mutate payload into the promised data and
      // dispatch action to store
      res => {
        action.payload = res;
        store.dispatch(action);
      },
      // failure => set an error flag on action and mutate payload into
      // the error message. dispatch action to store
      error => {
        action.error = true;
        action.payload = error.response.body;
        store.dispatch(action);
      }
    );

    return;
  }

  // if the action payload is not a promise, send the action over to the next middleware
  // or dispatch it to the store if this is the last middleware in the chain
  next(action);
}

const localStorageMiddleware = store => next => action => {
  // set the token if we have it
  if (action.type === 'REGISTER' || action.type === 'LOGIN') {
    if (!action.error) {
      window.localStorage.setItem('jwt', action.payload.user.token);
      // pass the token to the HTTP client so we can use it to make calls where we need
      // authentication.
      agent.setToken(action.payload.user.token);
    }
  }
  // if we're logging out, clear the authentication token from local storage and the http client
  else if (action.type === 'LOGOUT') {
    window.localStorage.setItem('jwt', '');
    agent.setToken(null);
  }
  next(action);
};

export {
  localStorageMiddleware,
  promiseMiddleware
};