number-munchers/reducers/board/grid.reducer.js

const Immutable = require('immutable');

import * as GridActions from '../../actions/board/grid.actions';
import { SETTINGS } from '../../App';
import Values from '../Values';

const reducer = (state = [], action) => {
    if (action.type !== GridActions.GRID_ACTION) {
        return state;
    }

    switch (action.action) {
        case GridActions.GENERATE:
            return Values.generate(action.count, action.level);

        case GridActions.UPDATE:
            const results = Immutable.List(state);
            const index = action.y * SETTINGS.GRID_HEIGHT + action.x;
            const valid = Values.validate(state[index], action.level);

            if (valid) {
                return results.set(index, '').toArray();
            }
            break;
    }

    return state;
};

export default reducer;