#!/usr/bin/env node
'use strict';

const readline = require('readline');

// --- Config ---
const W = 40, H = 20;
const TICK = 100; // ms per frame

// --- ANSI helpers ---
const ESC = '\x1b[';
const cls = () => process.stdout.write('\x1bc');
const hide = () => process.stdout.write(ESC + '?25l');
const show = () => process.stdout.write(ESC + '?25h');
const move = (x, y) => process.stdout.write(ESC + `${y};${x}H`);
const color = (code, s) => `\x1b[${code}m${s}\x1b[0m`;
const green  = s => color('32;1', s);
const yellow = s => color('33;1', s);
const red    = s => color('31;1', s);
const cyan   = s => color('36;1', s);
const white  = s => color('37;1', s);
const dim    = s => color('2', s);

// --- State ---
let snake, dir, nextDir, food, score, highScore = 0, running, timer;

function randPos() {
  return { x: 1 + Math.floor(Math.random() * (W - 2)), y: 1 + Math.floor(Math.random() * (H - 2)) };
}

function spawnFood() {
  let pos;
  do { pos = randPos(); }
  while (snake.some(s => s.x === pos.x && s.y === pos.y));
  food = pos;
}

function init() {
  const mid = { x: Math.floor(W / 2), y: Math.floor(H / 2) };
  snake = [mid, { x: mid.x - 1, y: mid.y }, { x: mid.x - 2, y: mid.y }];
  dir = { x: 1, y: 0 };
  nextDir = { x: 1, y: 0 };
  score = 0;
  spawnFood();
  running = true;
}

function drawBorder() {
  const top    = cyan('╔' + '═'.repeat(W - 2) + '╗');
  const bottom = cyan('╚' + '═'.repeat(W - 2) + '╝');
  move(1, 1); process.stdout.write(top);
  move(1, H); process.stdout.write(bottom);
  for (let row = 2; row < H; row++) {
    move(1, row);    process.stdout.write(cyan('║'));
    move(W, row);    process.stdout.write(cyan('║'));
  }
}

function drawStatus() {
  move(1, H + 1);
  process.stdout.write(
    white(' Score: ') + yellow(String(score).padEnd(6)) +
    white(' Best: ')  + yellow(String(highScore).padEnd(6)) +
    dim(' [←↑→↓] move  [q] quit')
  );
}

function drawGame() {
  // Clear interior
  for (let row = 2; row < H; row++) {
    move(2, row);
    process.stdout.write(' '.repeat(W - 2));
  }

  // Food
  move(food.x, food.y);
  process.stdout.write(red('◆'));

  // Snake
  snake.forEach((seg, i) => {
    move(seg.x, seg.y);
    process.stdout.write(i === 0 ? green('█') : green('▓'));
  });

  drawStatus();
}

function tick() {
  dir = nextDir;
  const head = { x: snake[0].x + dir.x, y: snake[0].y + dir.y };

  // Wall collision
  if (head.x <= 0 || head.x >= W || head.y <= 0 || head.y >= H) {
    return gameOver();
  }
  // Self collision
  if (snake.some(s => s.x === head.x && s.y === head.y)) {
    return gameOver();
  }

  snake.unshift(head);

  if (head.x === food.x && head.y === food.y) {
    score++;
    if (score > highScore) highScore = score;
    spawnFood();
  } else {
    snake.pop();
  }

  drawGame();
}

function gameOver() {
  running = false;
  clearInterval(timer);

  const msg = red('  GAME OVER  ');
  const sub = `  Score: ${yellow(String(score))}  `;
  const reLine = `  Press ${green('r')} to restart or ${red('q')} to quit  `;

  const cx = Math.floor(W / 2) - 12;
  const cy = Math.floor(H / 2) - 1;
  move(cx, cy);     process.stdout.write('┌' + '─'.repeat(28) + '┐');
  move(cx, cy + 1); process.stdout.write('│' + msg.padEnd(28 + msg.length - 13) + '│');
  move(cx, cy + 2); process.stdout.write('│' + sub.padEnd(28 + sub.length - 14) + '│');
  move(cx, cy + 3); process.stdout.write('│' + reLine.padEnd(28 + reLine.length - 27) + '│');
  move(cx, cy + 4); process.stdout.write('└' + '─'.repeat(28) + '┘');
}

function startGame() {
  cls();
  hide();
  init();
  drawBorder();
  drawGame();
  timer = setInterval(tick, TICK);
}

// --- Input ---
readline.emitKeypressEvents(process.stdin);
if (process.stdin.isTTY) process.stdin.setRawMode(true);

process.stdin.on('keypress', (_, key) => {
  if (!key) return;

  if (key.name === 'q' || (key.ctrl && key.name === 'c')) {
    clearInterval(timer);
    show();
    cls();
    move(1, 1);
    console.log(white('Thanks for playing! Final score: ') + yellow(String(score)));
    process.exit(0);
  }

  if (!running) {
    if (key.name === 'r') { startGame(); }
    return;
  }

  const moves = {
    up:    { x: 0,  y: -1 },
    down:  { x: 0,  y:  1 },
    left:  { x: -1, y:  0 },
    right: { x: 1,  y:  0 },
  };

  const next = moves[key.name];
  if (!next) return;

  // Prevent 180° reversal
  if (next.x === -dir.x && next.y === -dir.y) return;
  nextDir = next;
});

// --- Title screen ---
cls();
move(1, Math.floor(H / 2) - 3);
const logo = [
  ' ███████╗███╗  ██╗ █████╗ ██╗  ██╗███████╗',
  ' ██╔════╝████╗ ██║██╔══██╗██║ ██╔╝██╔════╝',
  ' ███████╗██╔██╗██║███████║█████╔╝ █████╗  ',
  ' ╚════██║██║╚████║██╔══██║██╔═██╗ ██╔══╝  ',
  ' ███████║██║ ╚███║██║  ██║██║  ██╗███████╗',
  ' ╚══════╝╚═╝  ╚══╝╚═╝  ╚═╝╚═╝  ╚═╝╚══════╝',
];
logo.forEach((line, i) => { move(1, Math.floor(H / 2) - 3 + i); process.stdout.write(green(line)); });
move(1, Math.floor(H / 2) + 4);
process.stdout.write(white('  Use ') + cyan('arrow keys') + white(' to move  ·  ') + yellow('eat ◆ to grow') + white('  ·  ') + red('q') + white(' to quit'));
move(1, Math.floor(H / 2) + 6);
process.stdout.write(white('         Press ') + green('any arrow key') + white(' to start...'));

// Start on first keypress
process.stdin.once('keypress', (_, key) => {
  if (key && (key.ctrl && key.name === 'c')) process.exit(0);
  startGame();
});