import { TUTORIAL_SUCCESS, TUTORIAL_ERROR, TUTORIAL_CHANGE, TUTORIAL_XML, TUTORIAL_ID, TUTORIAL_STEP } from '../actions/types';

import tutorials from '../data/tutorials.json';

const initialStatus = () => {
  if(window.localStorage.getItem('status')){
    var status = JSON.parse(window.localStorage.getItem('status'));
    var existingTutorialIds = tutorials.map((tutorial, i) => {
      var tutorialsId = tutorial.id;
      var statusIndex = status.findIndex(status => status.id === tutorialsId);
      if(statusIndex > -1){
        var tasks = tutorial.steps.filter(step => step.type === 'task');
        var existingTaskIds = tasks.map((task, j) => {
          var tasksId = task.id;
          if(status[statusIndex].tasks.findIndex(task => task.id === tasksId) === -1){
            // task does not exist
            status[statusIndex].tasks.push({id: tasksId});
          }
          return tasksId;
        });
        // deleting old tasks which do not longer exist
        if(existingTaskIds.length > 0){
          status[statusIndex].tasks = status[statusIndex].tasks.filter(task => existingTaskIds.indexOf(task.id) > -1);
        }
      }
      else{
        status.push({id: tutorialsId, tasks: tutorial.steps.filter(step => step.type === 'task').map(task => {return {id: task.id};})});
      }
      return tutorialsId;
    });
    // deleting old tutorials which do not longer exist
    if(existingTutorialIds.length > 0){
      status = status.filter(status => existingTutorialIds.indexOf(status.id) > -1);
    }
    return status;
  }
  // window.localStorage.getItem('status') does not exist
  return tutorials.map(tutorial => {return {id: tutorial.id, tasks: tutorial.steps.filter(step => step.type === 'task').map(task => {return {id: task.id};})};});
};

const initialState = {
  status: initialStatus(),
  currentId: null,
  activeStep: 0,
  change: 0
};

export default function(state = initialState, action){
  switch(action.type){
    case TUTORIAL_SUCCESS:
    case TUTORIAL_ERROR:
    case TUTORIAL_XML:
      // update locale storage - sync with redux store
      window.localStorage.setItem('status', JSON.stringify(action.payload));
      return {
        ...state,
        status: action.payload
      };
    case TUTORIAL_CHANGE:
      return {
        ...state,
        change: state.change += 1
      }
    case TUTORIAL_ID:
      return {
        ...state,
        currentId: action.payload
      }
    case TUTORIAL_STEP:
      return {
        ...state,
        activeStep: action.payload
      }
    default:
      return state;
  }
}
