'use strict';

const CpuGame = (() => {
  const SCORES_KEY = 'ttt-scores';
  const CPU_DELAY = 600;

  const state = {
    board: Array(9).fill(null),
    turn: 'X',
    gameOver: false,
    scores: { you: 0, opponent: 0, draws: 0 },
  };

  let cpuTimer = 0;

  function persistScores() {
    try {
      localStorage.setItem(SCORES_KEY, JSON.stringify(state.scores));
    } catch (e) { /* storage unavailable */ }
  }

  function loadScores() {
    try {
      const raw = localStorage.getItem(SCORES_KEY);
      if (raw) {
        const s = JSON.parse(raw);
        state.scores = {
          you: Number(s.you) || 0,
          opponent: Number(s.cpu || s.opponent) || 0,
          draws: Number(s.draws) || 0,
        };
      }
    } catch (e) { /* corrupted storage */ }
  }

  function handleMove(i) {
    if (state.gameOver || state.turn !== 'X' || state.board[i]) return;
    state.board[i] = 'X';
    App.renderMark(i, 'X');
    const result = App.checkWinner(state.board);
    if (result) {
      endRound(result);
      return;
    }
    state.turn = 'O';
    App.renderStatus('CPU is thinking…', 'thinking');
    cpuTimer = setTimeout(cpuMove, CPU_DELAY);
  }

  function cpuMove() {
    if (state.gameOver) return;
    const empty = [];
    state.board.forEach((v, i) => { if (v === null) empty.push(i); });
    if (!empty.length) return;
    const i = empty[Math.floor(Math.random() * empty.length)];
    state.board[i] = 'O';
    App.renderMark(i, 'O');
    const result = App.checkWinner(state.board);
    if (result) {
      endRound(result);
      return;
    }
    state.turn = 'X';
    App.renderStatus('Your turn', 'normal');
  }

  function endRound(result) {
    state.gameOver = true;
    let title;
    let key;
    if (result.winner === 'X') {
      key = 'you';
      title = 'You Win!';
      App.renderStatus('You win!', 'normal');
    } else if (result.winner === 'O') {
      key = 'opponent';
      title = 'CPU Wins';
      App.renderStatus('CPU wins', 'normal');
      document.getElementById('board').classList.add('shake');
    } else {
      key = 'draws';
      title = "It's a Draw";
      App.renderStatus("It's a draw", 'normal');
      document.getElementById('board').classList.add('pulse');
    }

    state.scores[key]++;
    persistScores();
    App.renderScores(state.scores);

    if (result.line) App.drawWinLine(result.line);

    setTimeout(() => {
      App.showOverlay(title);
      if (result.winner === 'X') App.burstConfetti();
    }, result.winner === 'draw' ? 400 : 600);
  }

  function newRound() {
    clearTimeout(cpuTimer);
    state.board = Array(9).fill(null);
    state.turn = 'X';
    state.gameOver = false;
    App.clearBoard();
    App.renderStatus('Your turn', 'normal');
  }

  function resetScores() {
    state.scores = { you: 0, opponent: 0, draws: 0 };
    persistScores();
    App.renderScores(state.scores);
    App.showToast('Scores reset');
  }

  function destroy() {
    clearTimeout(cpuTimer);
  }

  function init() {
    clearTimeout(cpuTimer);
    App.clearBoard();
    state.board = Array(9).fill(null);
    state.turn = 'X';
    state.gameOver = false;
    loadScores();
    App.renderScores(state.scores);
    App.renderStatus('Your turn', 'normal');
  }

  return { init, handleMove, newRound, resetScores, destroy };
})();