const assets = [
  "wk.webp", "wq.webp", "wr.png", "wb.webp", "wn.png", "wp.png",
  "bk.webp", "bq.png", "br.webp", "bb.webp", "bn.webp", "bp.png"
].map(x => "./assets/pieces/" + x);
let hoveringPiece = -1;

const bitboards = [
  16n,
  8n,
  129n,
  36n,
  66n,
  65280n,
  1152921504606846976n,
  576460752303423488n,
  9295429630892703744n,
  2594073385365405696n,
  4755801206503243776n,
  71776119061217280n,
];
const WHITE_KING   =  0;
const WHITE_QUEEN  =  1;
const WHITE_ROOK   =  2;
const WHITE_BISHOP =  3;
const WHITE_KNIGHT =  4;
const WHITE_PAWN   =  5;
const BLACK_KING   =  6;
const BLACK_QUEEN  =  7;
const BLACK_ROOK   =  8;
const BLACK_BISHOP =  9;
const BLACK_KNIGHT = 10;
const BLACK_PAWN   = 11;

let counting_bitboard = 0n;
function trackBitboard(i, selected, output) {
  const mask = 1n << BigInt(i);
  if (selected) counting_bitboard |= mask;
  else counting_bitboard &= ~mask;
  output.textContent = counting_bitboard.toString();
}

function checkForPiece(square, bitIndex, set = true) {
  for (let i = 0; i < bitboards.length; i++) {
    const mask = bitboards[i];
    if ((mask >> BigInt(bitIndex)) & 1n) {
      if (set) square.style.backgroundImage = `url(${assets[i]})`;
      return i;
    }
  }
  return null;
}

function isYourTurn(piece) {
  if (turn == "w") return piece < 6;
  return piece >= 6;
}

const selectedAction = trackBitboard;

window.onkeydown = (e) => {
  if (e.key == 'b') {
    console.log(`
position.bitboards[WHITE_KING] = ${bitboards[0].toString()}ULL;
position.bitboards[WHITE_QUEEN] = ${bitboards[1].toString()}ULL;
position.bitboards[WHITE_ROOK] = ${bitboards[2].toString()}ULL;
position.bitboards[WHITE_BISHOP] = ${bitboards[3].toString()}ULL;
position.bitboards[WHITE_KNIGHT] = ${bitboards[4].toString()}ULL;
position.bitboards[WHITE_PAWN] = ${bitboards[5].toString()}ULL;
position.bitboards[BLACK_KING] = ${bitboards[6].toString()}ULL;
position.bitboards[BLACK_QUEEN] = ${bitboards[7].toString()}ULL;
position.bitboards[BLACK_ROOK] = ${bitboards[8].toString()}ULL;
position.bitboards[BLACK_BISHOP] = ${bitboards[9].toString()}ULL;
position.bitboards[BLACK_KNIGHT] = ${bitboards[10].toString()}ULL;
position.bitboards[BLACK_PAWN] = ${bitboards[11].toString()}ULL;
      `)
  }
}

let validMoves = {};
let renderingMoves = [];
let pickedUpFrom = -1;

function updateRenderingMoves() {
  for (let i = 0; i < 64; i++) {
    const square = document.getElementById(`square-${i}`);
    if (renderingMoves.includes(i)) square.children[0].classList.add("possible_move");
    else square.children[0].classList.remove("possible_move");
  }
}

function handleTransmission(data) {
  data = data.join("");
  for (let i = 0; i < data.length / 4; i++) {
    const moveData = data.slice(4 * i, 4 * i + 4);
    let from = parseInt(moveData.slice(0, 2));
    let to = parseInt(moveData.slice(2));

    console.log(from, to, moveData);

    if (validMoves[from] == undefined) validMoves[from] = []
    validMoves[from].push(to);
  }
}

function calculateFen() {
  let fen = ""
  let empty = 0;
  for (let i = 7; i >= 0; i--) {
    for (let j = 0; j < 8; j++) {
      const sqr = document.getElementById(`square-${8 * i + j}`).style.backgroundImage;
      if (sqr.length == 0 || sqr.includes("none")) {
        empty++;
        continue;
      }
      if (empty != 0) {
        fen += empty.toString();
      }
      empty = 0;
      let p = sqr[22];
      if (sqr[21] == "w") p = sqr[22].toUpperCase();
      fen += p;
    }
    if (empty != 0) {
      fen += empty.toString();
    }
    if (i == 0) continue;
    empty = 0;
    fen += "/";
  }
  return fen;
}

let turn = "w";
let castling = "KQkq";
let passant_square = "-";
let halfmove = 0;
let fullmove = 1;
let socket;
let old_fen = "rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1";
function checkMoveMade(pieceMoved) {
  let new_fen = calculateFen();
  if (new_fen == old_fen.split(" ")[0]) return;
  old_fen = new_fen;
  halfmove++;
  console.log(pieceMoved)
  if (pieceMoved == WHITE_PAWN || pieceMoved == BLACK_PAWN) halfmove = 0;
  if (turn == "b") fullmove++;
  turn = turn == "w" ? "b" : "w";
  old_fen = `${new_fen} ${turn} ${castling} ${passant_square} ${halfmove} ${fullmove}`;
  validMoves = {};
  console.log(old_fen);
  socket.send(old_fen);
}

function connectSocket() {
  socket = new WebSocket("ws://localhost:3456");
  let data = [];
  socket.onmessage = e => {
    console.log(e);
    if (e.data == "END-TRANSMISSION") {
      handleTransmission(data);
      data = [];
    } else {
      data.push(e.data);
    }
  }
  socket.onopen = () => {
    console.log(old_fen);
    socket.send(old_fen);
  }
  socket.onerror = e => {
    console.log("error", e);
  };
}

window.onload = () => {
  connectSocket();
  socket.onclose = e => {
    console.log("closed", e.code, e.reason);
  };

  const output = document.getElementById("output");
  const board = document.getElementById("board");
  for (let i = 0; i < 64; i++) {
    if (i % 8 == 0) {
      const label = document.createElement("div");
      label.classList.add("label");
      label.textContent = 8 - Math.round(i / 8);
      board.appendChild(label);
    }
    const square = document.createElement("div");
    square.classList.add("square");

    const renderingMoveMarker = document.createElement("div");
    renderingMoveMarker.classList.add("rendering_marker");
    square.appendChild(renderingMoveMarker);

    const shift = Math.floor(i / 8);
    square.classList.add((i + shift) % 2 ? "dark" : "light");
    const bitIndex = (i % 8) - 8 * Math.floor(i / 8) + 56;
    square.id = 'square-' + bitIndex.toString();
    checkForPiece(square, bitIndex);
    square.onclick = (e) => {
      if (e.ctrlKey) {
        const selected = square.classList.contains("selected");
        selectedAction(bitIndex, !selected, output);
        if (selected) square.classList.remove("selected");
        else square.classList.add("selected");
        return;
      }
      
      const piece = checkForPiece(square, bitIndex, false);
      const sqr_id = parseInt(square.id.slice(7));
      if (hoveringPiece == -1) {
        if (piece == null) return;
        if (!isYourTurn(piece)) return;
        if (validMoves[bitIndex]) renderingMoves = validMoves[bitIndex];
        setHoverpiece(piece);
        pickedUpFrom = sqr_id;
        square.style.backgroundImage = `none`;
        bitboards[piece] &= ~(1n << BigInt(bitIndex));
      } else {
        if (sqr_id != pickedUpFrom && !renderingMoves.includes(sqr_id)) return;
        renderingMoves = [];
        square.style.backgroundImage = `url(${assets[hoveringPiece]})`;
        if (piece) bitboards[piece] &= ~(1n << BigInt(bitIndex));
        bitboards[hoveringPiece] |= (1n << BigInt(bitIndex));
        setHoverpiece(-1);
      }
      console.log(piece, hoveringPiece, square, renderingMoves);
      updateRenderingMoves();
    };
    board.appendChild(square);
  }
  const label = document.createElement("div");
  label.classList.add("horizontal_label");
  board.appendChild(label);
  for (let i = 0; i < 8; i++)  {
    const label = document.createElement("div");
    label.classList.add("horizontal_label");
    label.textContent = ["a", "b", "c", "d", "e", "f", "g", "h"][i];
    board.appendChild(label);
  }

  const mouse = document.getElementById("mouse");
  function setHoverpiece(i) {
    let oldHoveringPiece = hoveringPiece;
    hoveringPiece = i;
    if (i < 0) {
      mouse.style.backgroundImage = `none`;
      checkMoveMade(oldHoveringPiece);
      return;
    }
    mouse.style.backgroundImage = `url(${assets[i]})`;
  }
  window.onmousemove = (e) => {
    const x = e.clientX;
    const y = e.clientY;
    mouse.style.left = x.toString() + 'px';
    mouse.style.top = y.toString() + 'px';
  }
}