Coursemology/coursemology2

import { produce } from 'immer';

import actions, { defaultPastAnswersDisplayed } from '../../constants';

export default function (state = {}, action) {
  switch (action.type) {
    case actions.FETCH_SUBMISSION_SUCCESS: {
      if (action.payload.history) {
        return {
          ...state,
          ...action.payload.history.questions.reduce(
            (obj, question) => ({
              ...obj,
              [question.id]: {
                pastAnswersLoaded: false,
                isLoading: false,
                answerIds: question.answerIds,
              },
            }),
            {},
          ),
        };
      }
      return state;
    }
    case actions.SELECT_PAST_ANSWERS: {
      const { questionId, answerIds } = action.payload;
      return {
        ...state,
        [questionId]: {
          ...state[questionId],
          selected: answerIds,
        },
      };
    }
    case actions.GET_PAST_ANSWERS_REQUEST: {
      const { questionId } = action.payload;
      return {
        ...state,
        [questionId]: {
          ...state[questionId],
          isLoading: true,
        },
      };
    }
    case actions.GET_PAST_ANSWERS_SUCCESS: {
      const { questionId, answers } = action.payload;
      const answerIds = answers.map((answer) => answer.id);
      const selected = answerIds.slice(0, defaultPastAnswersDisplayed);
      return {
        ...state,
        [questionId]: {
          ...state[questionId],
          answerIds,
          selected,
          pastAnswersLoaded: true,
          isLoading: false,
        },
      };
    }
    case actions.GET_PAST_ANSWERS_FAILURE: {
      const { questionId } = action.payload;
      return {
        ...state,
        [questionId]: {
          ...state[questionId],
          isLoading: false,
        },
      };
    }
    case actions.SAVE_ANSWER_SUCCESS:
    case actions.AUTOGRADE_SUCCESS: {
      const { questionId, latestAnswer } = action.payload;

      if (latestAnswer) {
        return produce(state, (draft) => {
          const question = draft[questionId];
          const answerIds = question.answerIds;
          // Ensure that the id is not being repeatedly added
          if (answerIds.indexOf(latestAnswer.id) === -1) {
            answerIds.unshift(latestAnswer.id);
          }
          // Allow selection of at most 10 answers
          if (answerIds.length > 10) {
            answerIds.pop();
          }
          // Reset the selected answers to the first
          const selected = answerIds.slice(0, defaultPastAnswersDisplayed);
          draft[questionId].answerIds = answerIds;
          draft[questionId].selected = selected;
        });
      }
      return state;
    }
    default:
      return state;
  }
}