Reducers for Educational Modules

Demonstrate how to write reducers to update the state based on course progression actions, ensuring immutability and proper state transitions.

const courseReducer = (state, action) => {
  switch (action.type) {
    // Start a new module
    case 'START_MODULE':
      return {
        ...state,
        currentModule: action.moduleId,
        modules: {
          ...state.modules,
          [action.moduleId]: {
            ...state.modules[action.moduleId],
            started: true,
            completed: false
          }
        }
      };

    // Mark the current module as completed
    case 'COMPLETE_MODULE':
      return {
        ...state,
        modules: {
          ...state.modules,
          [action.moduleId]: {
            ...state.modules[action.moduleId],
            completed: true
          }
        }
      };

    // Reset the progress of the module
    case 'RESET_MODULE':
      return {
        ...state,
        modules: {
          ...state.modules,
          [action.moduleId]: {
            ...state.modules[action.moduleId],
            started: false,
            completed: false
          }
        }
      };

    // Default case to return the current state
    default:
      return state;
  }
};

This code defines a reducer for managing state transitions in an educational course system. It handles actions for starting a module, completing it, and resetting a module's progress. The reducer maintains immutability by returning a new state object each time, using the spread operator to copy the existing state and update only the necessary parts.