Middleware for Asynchronous Data Persistence

// Define an async persistence middleware function
const asyncDataPersistenceMiddleware = store => next => action => {
  if (action.type === 'PERSIST_COURSE_PROGRESS') {
    // Perform the asynchronous persistence (e.g., API call)
    saveCourseProgress(action.payload).then(
      response => store.dispatch({ type: 'COURSE_PROGRESS_SAVED', payload: response }),
      error => store.dispatch({ type: 'COURSE_PROGRESS_SAVE_FAILED', payload: error })
    );
  } else if (action.type === 'LOAD_COURSE_CONTENT') {
    // Perform the asynchronous content loading
    loadCourseContent(action.payload).then(
      content => store.dispatch({ type: 'COURSE_CONTENT_LOADED', payload: content }),
      error => store.dispatch({ type: 'COURSE_CONTENT_LOAD_FAILED', payload: error })
    );
  }

  // Continue to the next middleware
  return next(action);
}

// Function to save course progress to the server
async function saveCourseProgress(progress) {
  // API call to persist course progress
  // Return a Promise that resolves or rejects based on the API response
  return fetch('/api/save-progress', {
    method: 'POST',
    headers: { 'Content-Type': 'application/json' },
    body: JSON.stringify(progress)
  }).then(response => response.json());
}

// Function to load course content from the server
async function loadCourseContent(courseId) {
  // API call to load course content
  // Return a Promise that resolves or rejects based on the API response
  return fetch(`/api/load-content/${courseId}`).then(response => response.json());
}

// Example of applying the middleware to the Redux store
import { applyMiddleware, createStore } from 'redux';
import rootReducer from './reducers';

// Create the Redux store and apply the middleware
const store = createStore(
  rootReducer,
  applyMiddleware(asyncDataPersistenceMiddleware)
);