chess/web/static/js/reducers/chess-board.js

import Immutable from "immutable";
import { Map } from "immutable";

import defaultState from "../store/default-state";
import movePiece from "./move-piece";

const chessBoardReducer = (state = defaultState, action) => {
  switch (action.type) {
    case "SET_BOARD":
      return Immutable.fromJS(state)
        .set("board", action.board)
        .set("selectedSquare", null)
        .toJS();

    case "SET_GAME_ID":
      return Immutable.fromJS(state)
        .set("gameId", action.gameId)
        .toJS();

    case "MOVE_PIECE":
      return Immutable.fromJS(state)
        .set("board", movePiece(state.board))
        .set("selectedSquare", null)
        .toJS();

    case "SELECT_PIECE":
      return Immutable.fromJS(state)
        .set("selectedSquare", action.coords)
        .toJS();

    default:
      return state;
  }
}

export default chessBoardReducer;