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<!doctype html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport"
content="width=device-width, user-scalable=no, initial-scale=1.0, maximum-scale=1.0, minimum-scale=1.0">
<meta http-equiv="X-UA-Compatible" content="ie=edge">
<title>Awesome Chess</title>
</head>
<style>
* {
padding: 0;
margin: 0;
box-sizing: border-box;
}
#app {
margin: 0 auto;
width: fit-content;
}
.board {
border: 2px solid black;
font-size: 20px;
user-select: none;
}
.board-field.black {
background: chocolate;
}
.board-field.white {
background: bisque;
}
.board-field {
text-align: center;
width: 1.5em;
border: 1px transparent;
height: 1.5em;
}
.lastmove {
border: 1px solid green;
}
#warn {
display: block;
position: fixed;
top: 25%;
left: 25%;
z-index: 10;
margin: 0 auto;
width: 50%;
background: coral;
border: crimson solid 1px;
}
.status {
text-align: center;
font-family: sans-serif;
}
.invisible {
display: none !important;
}
</style>
<body>
<div id="app">
<p class="status">You are <b>white</b></p>
</div>
<div id="warn" class="invisible">
Connection closed
</div>
<script>
class Board {
constructor(elem) {
this.socket = new WebSocket(`${location.protocol.includes('s') ? 'wss' : 'ws'}://${window.location.host}/socket`)
this.ended = false
this.boardState = {}
this.lastMove = ''
window.addEventListener('beforeunload', () => {
this.ended = false
})
this.socket.addEventListener('message', ev => {
const message = JSON.parse(ev.data)
console.log(message)
this.playerColor = message.player_color || this.playerColor
this.boardState = parseFEN(message.board)
this.lastMove = message.lastmove || ''
this.ended ||= message.event === 'game_over'
this.result = message.result
this.synchronizeBoard()
})
this.socket.addEventListener('close', () => {
if (!this.ended)
document.getElementById('warn').classList.remove('invisible')
})
let board = document.createElement("table")
board.className = "board"
this.fields = {};
for (let i = 7; i >= 0; i--) {
let row = document.createElement("tr")
row.className = "board-row"
for (let j = 0; j < 8; j++) {
let field = document.createElement("td")
field.className = "board-field " + (((i + j) % 2) === 0 ? 'black' : 'white');
let name = indiciesToFieldName(i, j)
field.innerText = name;
field.addEventListener("dragover", ev => ev.preventDefault())
field.addEventListener("drop", ev => {
ev.preventDefault()
this.playMove(ev.dataTransfer.getData("text"), name)
})
this.fields [name] = field
row.appendChild(field)
}
board.appendChild(row)
}
elem.appendChild(board)
this.turnIndicator = document.createElement('p')
this.turnIndicator.className = "turn-indicator status"
elem.appendChild(this.turnIndicator)
}
playMove(fromField, toField) {
if (!this.isPlayerTurn) return
let uci = fromField + toField
if (((toField[1] === '8' && this.playerColor === 'white')
|| (toField[2] === '1' && this.playerColor === 'black'))
&& (this.boardState[fromField].toUpperCase() === 'P')) {
uci += window.prompt('promote to what')
}
this.socket.send(JSON.stringify({
method: "move",
params: {
move: uci
}
}))
}
get canPlay() {
return this.isPlayerTurn && !this.ended
}
get isPlayerTurn() {
return this.playerColor === this.boardState.turn
}
synchronizeBoard() {
this.turnIndicator.innerHTML = `<b>${capitalize(this.boardState.turn)}</b>s turn`
if (this.ended) {
this.turnIndicator.innerHTML += `<p><b>${this.result}</b></p>`
}
for (let field in this.fields) {
const fieldDOM = this.fields[field]
fieldDOM.innerHTML = ""
if (this.boardState[field]) {
let piece = document.createElement("span")
piece.innerText = notationToPieceUnicode(this.boardState[field])
piece.addEventListener("dragstart", ev => {
ev.dataTransfer.setData("text", field)
})
piece.draggable = this.canPlay
fieldDOM.appendChild(piece)
}
fieldDOM.classList.remove('lastmove')
if (this.lastMove.includes(field)) {
fieldDOM.classList.add('lastmove')
}
}
}
}
function capitalize(thing) {
return thing.replace(/\b./, x => x.toUpperCase())
}
function indiciesToFieldName(row, col) {
return "abcdefgh".at(col) + (row + 1)
}
function parseFEN(notation) {
let row = 7;
let col = 0;
let board = {}
let s = 'position'
let error = c => {
console.log("Error while parsing notation")
console.log(board)
throw "Could not parse notation: " + c
}
for (let c of notation) {
if (s === 'position') {
if (c === '/') { // Next row on /
if (col !== 8) {
throw "Row not finished"
}
row--
col = 0
} else if ((c | 0) > 0) { // Skip n places on a number
col += (c | 0)
} else if (c === ' ') {
s = 'turn'
} else if ("KQRBNP".includes(c.toUpperCase())) {
board[indiciesToFieldName(row, col)] = c
col += 1
} else {
error(c)
}
} else if (s === 'turn') {
if (c === 'b') {
board.turn = 'black'
} else if (c === 'w') {
board.turn = 'white'
} else if (c === ' ') {
break
} else {
error(c)
}
} else {
error('Invalid state ' + s)
}
}
return board
}
function notationToPieceUnicode(notation) {
let white = "♔♕♖♗♘♙"
let black = "♚♛♜♝♞♟︎"
let names = "KQRBNP"
let index = names.indexOf(notation.toUpperCase())
if (index < 0) {
return null
}
return (notation < 'Z' ? white : black)[index];
}
const board = new Board(document.getElementById("app"));
</script>
</body>
</html>
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