/**
 * Factory used to create reducer and actions to perfom fetch functions.
 * @module fetch.factory
 * @member redux/factories
 */

export const fetchActionConstants = (reducerId) => ({
  FETCH_REQUEST: `${reducerId}::FETCH_REQUEST`,
  FETCH_SUCCESS: `${reducerId}::FETCH_SUCCESS`,
  FETCH_FAILURE: `${reducerId}::FETCH_FAILURE`,
  FETCH_RESET: `${reducerId}::FETCH_RESET`,
})

const DEFAULT_STATE = {
  isFetching: false,
  error: undefined,
  lastUpdated: undefined,
  data: undefined,
}

// ======================================
// Reducer factory
// ======================================
const defaultDataFormatter = payload => payload.data

/**
 * @param {string} reducerId - a unique name to identify the reducer
 * @param {Object} options - Reducer configuration.
    {
      iniData?: undefined, // initial value for data field of state
      dataFormatter?: payload => payload.data, // Function called after succes fetch GET to assign
                                               // a new value
    }
 * to data field of state.
 * @returns {Function} reducer for fetch with GET method
 */
export default (
  reducerId,
  {
    iniData = undefined,
    dataFormatter = defaultDataFormatter,
  } = {}
) => {
  // Action constants
  const {
    FETCH_REQUEST, FETCH_SUCCESS, FETCH_FAILURE, FETCH_RESET,
  } = fetchActionConstants(reducerId)

  // Initial state
  const initialState = {
    ...DEFAULT_STATE,
    data: iniData,
  }

  // Return the fetch reducer
  return (state = initialState, action) => {
    const { type, payload } = action
    switch (type) {
      case FETCH_REQUEST:
        return {
          ...state,
          isFetching: true,
          error: undefined,
        }
      case FETCH_SUCCESS:
        return {
          ...state,
          isFetching: false,
          error: undefined,
          lastUpdated: payload.receivedAt,
          data: dataFormatter(payload),
        }
      case FETCH_FAILURE:
        return {
          ...state,
          isFetching: false,
          error: payload,
        }
      case FETCH_RESET:
        return initialState
      default:
        return state
    }
  }
}

// ======================================
// Action creators
// ======================================
export const fetchRequest = (type) => ({ type })

export const fetchSuccess = (type, response: { data, headers?}) => ({
  type,
  payload: {
    data: response.data,
    headers: response.headers,
    receivedAt: new Date(),
  },
})

export const fetchFailure = (type, error) => ({
  type,
  payload: error,
  error: true,
})

export const resetFetch = (type) => ({ type })