Add basic networking capabilities.

Include package-lock.json in git. Add server file. Start moving Board
backend into its own file (currently a lot of duplicate code between
board.js and backend.js).

server.js

@@ -0,0 +1,57 @@
+const {Board, Piece} = require('./src/backend');
+
+const express = require("express");
+const http = require("http");
+const socketIo = require("socket.io");
+
+const port = process.env.PORT || 4001;
+
+const app = express();
+
+const server = http.createServer(app);
+
+const io = socketIo(server, {
+  cors: {
+    cors: true,
+    origins: ["http://192.168.1.7:3000"],
+  }
+});
+
+let interval;
+
+let board = new Board();
+
+let sockets = [];
+
+io.on("connection", (socket) => {
+  sockets.push(socket);
+  console.log("New client connected");
+  if (interval) {
+    clearInterval(interval);
+  }
+  getApiAndEmit(socket);
+  //interval = setInterval(() => getApiAndEmit(socket), 5000);
+  socket.on("disconnect", () => {
+    // TODO sockets.remove(socket)
+    console.log("Client disconnected");
+    clearInterval(interval);
+  });
+
+  socket.on("move", (move) => {
+    console.log("Received move");
+    if(move && board.makeMove(move.from, move.to) == 0) {
+      for (s of sockets) {
+        getApiAndEmit(s);
+      }
+    }
+  });
+});
+
+const getApiAndEmit = socket => {
+  const response = board.textFromState();
+  console.log(response);
+  // Emitting a new message. Will be consumed by the client
+  socket.emit("FromAPI", response);
+};
+
+server.listen(port, () => console.log(`Listening on port ${port}`));

src/backend.js

@@ -0,0 +1,578 @@
+const BLACK = 0; const WHITE = 1;
+
+const PAWN = 0;
+const ROOK = 1;
+const KNIGHT = 2;
+const BISHOP = 3;
+const QUEEN = 4;
+const KING = 5;
+
+const EMPTY = -1;
+
+const SHUFFLING_ENABLED = 0;
+
+function getAllSettings() {
+  return [SHUFFLING_ENABLED];
+}
+
+function settingText(setting) {
+  switch(setting) {
+    case SHUFFLING_ENABLED:
+      return "Shuffle Back Row";
+    default:
+      return "";
+  }
+}
+
+function range(n) {
+  return Array.from(Array(n).keys());
+}
+
+function imageFromPiece(piece) {
+  if (piece && piece.type >= 0) {
+    const image = piece.color === WHITE ? piece.type : piece.type + 6;
+    return Images[image];
+  }
+  return null;
+}
+
+class Piece {
+  constructor(color, type) {
+    this.color = color;
+    this.type = type;
+    this.passantable = false;
+    this.moves = 0;
+  }
+
+  setType(type) {
+    this.type = type;
+  }
+
+  getInfoText() {
+    if(this.moves === 1) {
+      return "Has made 1 move"
+    } else {
+      return "Has made " + this.moves + " moves"
+    }
+  }
+
+  isEmpty() {
+    return this.type === EMPTY;
+  }
+
+  isFull() {
+    return !this.isEmpty();
+  }
+
+  isBlack() {
+    return this.color === BLACK;
+  }
+
+  isWhite() {
+    return this.color === WHITE;
+  }
+
+  isEnemyOf(piece) {
+    if (this.color === EMPTY || piece.color === EMPTY) {
+      return false;
+    } else {
+      return this.color !== piece.color;
+    }
+  }
+
+  isFriendOf(piece) {
+    if (this.color === EMPTY || piece.color === EMPTY) {
+      return false;
+    } else {
+      return this.color === piece.color;
+    }
+  }
+
+  is(type) {
+    return this.type === type;
+  }
+
+  hasMoved() {
+    return this.moves !== 0;
+  }
+
+  hasntMoved() {
+    return !this.hasMoved();
+  }
+}
+
+class Board {
+  constructor(props) {
+    this.state = (props && props.text) ?
+      this.stateFromText(props.text) : this.originalState();
+  }
+
+  setHand(hand) {
+    // setState
+    this.state.hand = hand;
+  }
+
+  clone() {
+    let board = new Board();
+    board.state.squares = this.state.squares.slice();
+    board.state.blackIsNext = this.state.blackIsNext;
+    board.state.hand = {
+      heldPiece: this.state.hand.heldPiece,
+    };
+    return board;
+  }
+
+  stateFromText(text) {
+    text = text.replace(/[\n]+/g, '');
+    const squares = text.substring(1);
+    return {
+      hand: {
+        heldPiece: null,
+      },
+      blackIsNext: text[0].toUpperCase() === 'B',
+      squares: squares.split('').map(c => {
+        const type = c.toLowerCase();
+        const color = c === type ? WHITE : BLACK;
+        switch (type) {
+          case 'r':
+            return new Piece(color, ROOK);
+          case 'n':
+            return new Piece(color, KNIGHT);
+          case 'b':
+            return new Piece(color, BISHOP);
+          case 'q':
+            return new Piece(color, QUEEN);
+          case 'k':
+            return new Piece(color, KING);
+          case 'p':
+            return new Piece(color, PAWN);
+          default:
+            return new Piece(EMPTY, EMPTY);
+        }
+      }),
+    };
+  }
+
+  shuffledBackRow() {
+    return "rnbqkbnr".split('').sort(() => Math.random() - 0.5).join('');
+  }
+
+  shuffledBackRowState() {
+    const backRow = this.shuffledBackRow();
+    const text = ["B", backRow, "pppppppp",
+      "________", "________", "________", "________",
+      "PPPPPPPP", backRow.toUpperCase()].join('');
+    return this.stateFromText(text);
+  }
+
+  textFromState() {
+    const turn = (this.state.blackIsNext? 'B' : 'W');
+    return turn + this.state.squares.map(square => {
+      if (!square) {
+        return '_';
+      }
+      let color = (c) => {
+        return square.color === BLACK ? c.toUpperCase() : c;
+      };
+      switch (square.type) {
+        case ROOK:
+          return color('r');
+        case KNIGHT:
+          return color('n');
+        case BISHOP:
+          return color('b');
+        case QUEEN:
+          return color('q');
+        case KING:
+          return color('k');
+        case PAWN:
+          return color('p');
+        default:
+          return '_';
+      }
+    }).join('');;
+  }
+
+  doReset() {
+    // setState
+    this.state = this.getSetting(SHUFFLING_ENABLED) ?
+      this.shuffledBackRowState() : this.originalState();
+    this.state.showPopup = false;
+  }
+
+  originalState() {
+    let squares = [];
+    const mainRow = [ROOK, KNIGHT, BISHOP, QUEEN, KING, BISHOP, KNIGHT, ROOK];
+    function add(num, color, type) {
+      for(let i = 0; i < num; i++) {
+        squares.push(new Piece(color, type));
+      }
+    }
+
+    mainRow.forEach(type => add(1, WHITE, type));
+    add(8, WHITE, PAWN);
+    add(32, EMPTY, EMPTY);
+    add(8, BLACK, PAWN);
+    mainRow.forEach(type => add(1, BLACK, type));
+
+    return ({
+      squares,
+      blackIsNext: true,
+      hand: {
+        heldPiece: null,
+      },
+      showPopup: false,
+      settings: {},
+    });
+  }
+
+  getXandY(i) {
+    const x = i % 8;
+    const y = Math.floor(i / 8);
+    return [x, y];
+  }
+
+  getIndex(x, y) {
+    return x + (y * 8);
+  }
+
+  isValidXY(x, y) {
+    return x < 8 && x >=0 && y < 8 && y >= 0;
+  }
+
+  squareCount() {
+    return this.state.squares.length;
+  }
+
+  pieceAtIndex(i) {
+    return i >= 0 && i < 64 ? this.state.squares[i] : null;
+  }
+
+  pieceAt(x, y) {
+    if (this.isValidXY(x, y)) {
+      return this.state.squares[this.getIndex(x, y)];
+    } else {
+      return new Piece(EMPTY, EMPTY);
+    }
+  }
+
+  getValidMovesAt(piece, x, y) {
+    let moves = [];
+    const tryAddMove = (x, y) => {
+      if (this.isValidXY(x, y)) {
+        if(this.pieceAt(x, y).isEmpty()) {
+          moves.push({x, y});
+          // Keep searching
+          return 0;
+        } else if (piece.isEnemyOf(this.pieceAt(x, y))) {
+          moves.push({x, y});
+        }
+        // Stop searching
+        return 1;
+      }
+    };
+    const addBunch = (xFunc, yFunc, isUp) => {
+      for (let i = 1; i < 8; i++) {
+        if(tryAddMove(xFunc(i), yFunc(i)) !== 0) {
+          break;
+        }
+      }
+    }
+
+    if (piece.is(PAWN)) {
+      const pieceIsBlack = piece.isBlack();
+      const shift = pieceIsBlack ? -1 : 1;
+      const startLine = pieceIsBlack ? 6 : 1;
+
+      // Check for en passant
+      const left = this.pieceAt(x - 1, y);
+      const right = this.pieceAt(x + 1, y);
+      if (left && left.passantable && left.isEnemyOf(piece)) {
+        moves.push({x: x - 1, y: y + shift, passant: {x: x - 1, y}})
+      }
+      if (right && right.passantable && right.isEnemyOf(piece)) {
+        moves.push({x: x + 1, y: y + shift, passant: {x: x + 1, y}})
+      }
+
+      if (this.pieceAt(x, y + shift).isEmpty()) {
+        moves.push({x, y: y + shift});
+        // Pawn moving two spaces becomes en-passantable
+        if (y === startLine && this.pieceAt(x, y + (shift * 2)).isEmpty()) {
+          moves.push({x, y: y + (shift * 2), passantable: true});
+        }
+      }
+      [x + 1, x - 1].forEach(x => {
+        const y2 = y + shift;
+        if (this.isValidXY(x, y2) && piece.isEnemyOf(this.pieceAt(x, y2))) {
+          moves.push({x, y: y2});
+        }
+      });
+    } else if (piece.is(ROOK)) {
+      addBunch(n => {return x;}, n => {return y + n;});
+      addBunch(n => {return x;}, n => {return y - n;});
+      addBunch(n => {return x + n;}, n => {return y;});
+      addBunch(n => {return x - n;}, n => {return y;});
+    } else if (piece.is(BISHOP)) {
+      addBunch(n => {return x + n;}, n => {return y + n;});
+      addBunch(n => {return x - n;}, n => {return y + n;});
+      addBunch(n => {return x + n;}, n => {return y - n;});
+      addBunch(n => {return x - n;}, n => {return y - n;});
+    } else if (piece.is(QUEEN)) {
+      const [rook, bishop] =
+        [new Piece(piece.color, ROOK), new Piece(piece.color, BISHOP)];
+      moves = moves.concat(this.getValidMovesAt(rook, x, y));
+      moves = moves.concat(this.getValidMovesAt(bishop, x, y));
+    } else if (piece.is(KNIGHT)) {
+      [
+        [2, 1], [2, -1], [-2, 1], [-2, -1],
+        [1, 2], [1, -2], [-1, 2], [-1, -2],
+      ].forEach(delta => tryAddMove(x + delta[0], y + delta[1]));
+    } else if (piece.is(KING)) {
+      [[1, 1], [1, -1], [-1, 1], [-1, -1], [0, 1], [0, -1], [1, 0], [-1, 0]]
+        .forEach(delta => tryAddMove(x + delta[0], y + delta[1]));
+      if (piece.hasntMoved()) {
+        const kingIndex = this.findIndex(piece);
+        const [x, y] = this.getXandY(kingIndex);
+
+        let leftRook = this.pieceAt(0, y);
+        if(leftRook.is(ROOK) && leftRook.hasntMoved()) {
+          // Check if spaces between rook and king are empty
+          if(this.pieceAt(1, y).isEmpty() &&
+            this.pieceAt(2, y).isEmpty() &&
+            this.pieceAt(3, y).isEmpty()) {
+            // Check if between space puts king in check
+            let board = this.clone();
+            board.state.squares[board.getIndex(x - 1, y)] = piece;
+            board.state.squares[kingIndex].isEmpty();
+            if(board.inCheck(piece) == null) {
+              moves.push({x: x - 2, y, castle: [x - 1, y]});
+            }
+          }
+        }
+
+        let rightRook = this.pieceAt(7, y);
+        if(rightRook.is(ROOK) && rightRook.hasntMoved()) {
+          // Check if spaces between rook and king are empty
+          if(this.pieceAt(5, y).isEmpty() &&
+            this.pieceAt(6, y).isEmpty()) {
+            // Check if between space puts king in check
+            let board = this.clone();
+            board.state.squares[board.getIndex(x + 1, y)] = piece;
+            board.state.squares[kingIndex].isEmpty();
+            if(board.inCheck(piece) == null) {
+              moves.push({x: x + 2, y, castle: [x + 1, y]});
+            }
+          }
+        }
+      }
+    }
+    return moves;
+  }
+
+  findIndex(piece) {
+    for(let i = 0; i < this.squareCount(); i++) {
+      const check = this.state.squares[i];
+      if(check.type === piece.type && check.color === piece.color) {
+        return i;
+      }
+    }
+    return null;
+  }
+
+  distanceBetween(i1, i2) {
+    const [pos1X, pos1Y] = this.getXandY(i1);
+    const [pos2X, pos2Y] = this.getXandY(i2);
+
+    let a = pos1X - pos2X;
+    a = a * a;
+
+    let b = pos1Y - pos2Y;
+    b = b * b;
+
+    return Math.sqrt(a + b);
+  }
+
+  inCheck(piece) {
+    const kingPos = this.getXandY(this.findIndex(piece));
+
+    for(let i = 0; i < this.squareCount(); i++) {
+      if(piece.isEnemyOf(this.pieceAtIndex(i))) {
+        const moves = this.getValidMoves(i);
+        for(let j = 0; j < moves.length; j++) {
+          if(moves[j].x === kingPos[0] && moves[j].y === kingPos[1]) {
+            return piece;
+          }
+        }
+      }
+    }
+
+    return null;
+  }
+
+  whoInCheck() {
+    const blackKing = this.inCheck(new Piece(BLACK, KING));
+    return blackKing ? blackKing : this.inCheck(new Piece(WHITE, KING));
+  }
+
+  checkmate() {
+    const checkedKing = this.whoInCheck();
+    if (checkedKing != null) {
+      // For each square
+      for(let i = 0; i < this.squareCount(); i++) {
+        const piece = this.pieceAtIndex(i);
+        // If that piece is on the checked team
+        if (piece != null && piece.isFriendOf(checkedKing)) {
+          // For each move of the above piece
+          const moves = this.getValidMoves(i)
+          for(const move of moves) {
+            // Copy the board
+            const board = this.clone();
+            const moveIndex = board.getIndex(move.x, move.y);
+            board.state.squares[moveIndex] = board.state.squares[i];
+            const check = board.inCheck(checkedKing);
+            if (check == null || check.color !== checkedKing.color) {
+              return false;
+            }
+          }
+        }
+      }
+      return true;
+    }
+
+    return false;
+  }
+
+  getValidMoves(source) {
+    const [x, y] = this.getXandY(source);
+
+    const piece = this.pieceAtIndex(source);
+    return this.getValidMovesAt(piece, x, y);
+  }
+
+  isValidMove(source, dest) {
+    const [destX, destY] = this.getXandY(dest);
+
+    for (const move of this.getValidMoves(source)) {
+      if (destX === move.x && destY === move.y) {
+        return move;
+      }
+    }
+
+    return null;
+  }
+
+  isHoldingPiece() {
+    return this.heldPiece() != null;
+  }
+
+  heldPiece() {
+    return (this.state && this.state.hand) ? this.state.hand.heldPiece : null;
+  }
+
+  makeMove(from, to) {
+    const squares = this.state.squares.slice();
+    const move = this.isValidMove(from, to)
+    if (move) {
+      if (move.passant) {
+        const i = this.getIndex(move.passant.x, move.passant.y);
+        squares[i] = new Piece(EMPTY, EMPTY);
+      }
+      if (move.castle) {
+        // .castle holds the position where the rook should end up
+        // King moved left
+        const rookX = move.castle[0] > move.x ? 0 : 7;
+        console.log("Replace " + move.castle + " with " + [rookX, move.castle[1]]);
+        const rookStart = this.getIndex(rookX, move.castle[1]);
+        const rookLanding = this.getIndex(move.castle[0], move.castle[1]);
+        squares[rookLanding] = squares[rookStart];
+        squares[rookStart] = new Piece(EMPTY, EMPTY);
+      }
+      // Remove existing passantable states
+      squares.forEach(square => {
+        if (square) {
+          square.passantable = false;
+        }
+      });
+      if (move.passantable) {
+        squares[from].passantable = true;
+      }
+      const y = this.getXandY(to)[1];
+      squares[to] = squares[from];
+      squares[from] = new Piece(EMPTY, EMPTY);
+      if (squares[to].type === PAWN && (y === 0 || y === 7)) {
+        squares[to].setType(QUEEN);
+      }
+      squares[to].moves++;
+      // setState
+      this.state.squares = squares;
+      this.state.blackIsNext = !this.state.blackIsNext;
+      this.state.hand.heldPiece = null;
+      return 0;
+    }
+    return 1;
+  }
+
+  handleClick(i) {
+    if (this.checkmate()) {
+      return;
+    }
+    if (this.isHoldingPiece()) {
+      // Copy the board
+      let board = this.clone();
+      board.state.squares[i] = board.state.squares[board.heldPiece()];
+      board.state.squares[this.heldPiece()] = new Piece(EMPTY, EMPTY);
+
+      const moversKing = this.state.blackIsNext ?
+        new Piece(BLACK, KING) : new Piece(WHITE, KING);
+      if (board.inCheck(moversKing) != null) {
+        return;
+      }
+      if (this.makeMove(this.heldPiece(), i) !== 0) {
+        this.setHand({
+            heldPiece: null,
+        });
+      }
+    } else if (this.state.squares[i].isFull()) {
+      const isSquareBlack = this.state.squares[i].isBlack();
+      if(isSquareBlack === this.state.blackIsNext) {
+        this.setHand({
+            heldPiece: i,
+        });
+      }
+    }
+  }
+
+  togglePopup() {
+    // setState
+    this.state.showPopup = !this.state.showPopup;
+  }
+
+  setSetting(name, value) {
+    let settings = this.state.settings;
+    settings[name] = value;
+    // setState
+    this.state.settings = settings;
+  }
+
+  getSetting(name) {
+    return this.state.settings[name];
+  }
+
+  toggleSetting(name) {
+    console.log("toggle " + settingText(name));
+    let settings = this.state.settings;
+    settings[name] = !settings[name];
+    console.log(settings[name]);
+    // setState
+    this.state.settings = settings;
+  }
+}
+
+module.exports = {
+  Board: Board,
+  Piece: Piece,
+}
+
+// export default Board;
+// export {Board, Piece};
+// export { BLACK, WHITE, PAWN, ROOK, KNIGHT, BISHOP, QUEEN, KING, EMPTY };

src/backend.test.js

@@ -0,0 +1,112 @@
+import Board from './backend';
+import * as game from './backend';
+
+it('detects friendship and enemyship', () => {
+  const black = new game.Piece(game.BLACK, game.KING);
+  const black2 = new game.Piece(game.BLACK, game.QUEEN);
+  const white = new game.Piece(game.WHITE, game.KING);
+  const white2 = new game.Piece(game.WHITE, game.QUEEN);
+  const empty = new game.Piece(game.EMPTY, game.EMPTY);
+  const empty2 = new game.Piece(game.EMPTY, game.EMPTY);
+
+  const truths = [
+    black.isFriendOf(black2),
+    white.isFriendOf(white2),
+
+    black.isEnemyOf(white),
+    white.isEnemyOf(black),
+  ];
+  for (const truth of truths) {
+    expect(truth).toBe(true);
+  }
+
+  const lies = [
+    black.isFriendOf(white), black.isFriendOf(empty),
+    white.isFriendOf(black), white.isFriendOf(empty),
+    empty.isFriendOf(white), empty.isFriendOf(black), empty.isFriendOf(empty2),
+
+    black.isEnemyOf(black2), black.isEnemyOf(empty),
+    white.isEnemyOf(white2), white.isEnemyOf(empty),
+    empty.isEnemyOf(white), empty.isEnemyOf(black), empty.isEnemyOf(empty2),
+  ];
+  for (const lie of lies) {
+    expect(lie).toBe(false);
+  }
+});
+
+it('is created correctly', () => {
+  const board = new Board();
+  const rows = ['B',
+    'rnbqkbnr',
+    'pppppppp',
+    '________',
+    '________',
+    '________',
+    '________',
+    'PPPPPPPP',
+    'RNBQKBNR'
+  ];
+  expect(board.textFromState()).toBe(rows.join(''));
+  for (const square of board.state.squares) {
+    expect(square.hasntMoved()).toBe(true);
+  }
+});
+
+it('is created from text correctly', () => {
+  const rows = ['B',
+    'pppppppp',
+    'pppppppp',
+    '________',
+    '________',
+    '________',
+    '________',
+    'PPPPPPPP',
+    'PPPPPPPP'
+  ];
+  const board = new Board({text: rows.join('')});
+  expect(board.textFromState()).toBe(rows.join(''));
+});
+
+it('detects an obvious checkmate', () => {
+  const rows = ['B',
+    'q_______',
+    'q______K',
+    'q_______',
+    '________',
+    '________',
+    '________',
+    '________',
+    'k_______'
+  ];
+  const board = new Board({text: rows.join('')});
+  const inCheck = board.whoInCheck();
+  expect(inCheck.type).toEqual(game.KING);
+  expect(inCheck.color).toEqual(game.BLACK);
+});
+
+it('detects basic castling', () => {
+  const startRows = ['B',
+    '____k___',
+    '________',
+    '________',
+    '________',
+    '________',
+    '________',
+    'PPPPPPPP',
+    'R___K__R'
+  ];
+  // const endRows = ['B',
+  //   '____k___',
+  //   '________',
+  //   '________',
+  //   '________',
+  //   '________',
+  //   '________',
+  //   'PPPPPPPP',
+  //   'R____RK_'
+  // ];
+  let board = new Board({text: startRows.join('')});
+  let move = board.isValidMove(60, 62);
+  expect(move.x).toBe(6);
+  expect(move.y).toBe(7);
+});

src/board.js

@@ -143,6 +143,9 @@ class Piece {
 class Board extends React.Component {
   constructor(props) {
     super(props);
+    if (props) {
+      this.onMove = props.onMove;
+    }
     this.state = (props && props.text) ?
       this.stateFromText(props.text) : this.originalState();
   }
@@ -554,6 +557,8 @@ class Board extends React.Component {
           heldPiece: null,
         }
       });
+      console.log("this.onMove({from, to});");
+      this.onMove({from, to});
       return 0;
     }
     return 1;

src/index.js

@@ -1,22 +1,45 @@
 import React from 'react';
 import ReactDOM from 'react-dom';
+import io from 'socket.io-client';
 
 import Board from './board';
 
 import './index.css';
 
 
+const ENDPOINT = "http://192.168.1.7:4001";
+
 class Game extends React.Component {
   constructor(props) {
     super(props);
-    this.state = { showPopup: false };
+    this.state = {
+      board: null,
+      socket: io(ENDPOINT),
+    };
+
+    this.state.socket.on("FromAPI", data => {
+      console.log(data);
+      this.setState({
+        board: null,
+      });
+      this.setState({
+        board: (
+          <Board
+           text={data}
+           onMove={(move) => {
+             console.log("ON MOVE");
+             this.state.socket.emit("move", move);
+          }}/>
+        ),
+      });
+    });
   }
 
   render() {
     return (
       <div className="game">
         <div className="game-board">
-          <Board />
+          {this.state.board}
         </div>
       </div>
     );