import { Reducer } from 'redux';
import {
    FETCH_START,
    FETCH_END,
    FETCH_ERROR,
    FETCH_CANCEL,
} from '../../actions/fetchActions';

type State = number;

const loadingReducer: Reducer<State> = (previousState = 0, { type }) => {
    switch (type) {
        case FETCH_START:
            return previousState + 1;
        case FETCH_END:
        case FETCH_ERROR:
        case FETCH_CANCEL:
            return Math.max(previousState - 1, 0);
        default:
            return previousState;
    }
};

export default loadingReducer;