// Headless verifier for the Tetris Attack engine.
//   node tools/verifyTetrisAttack.js
// Exits non-zero if any check fails.
import { readFileSync } from 'node:fs';
import { fileURLToPath } from 'node:url';
import { dirname, join } from 'node:path';
import {
  COLS, ROWS, TUNING, mulberry32, newGame, step, trySwap, moveCursor,
  findMatchGroups, findClearingSwap, isSettled, remainingTargets,
  loadPuzzle, solvePuzzle, resolveFully, comboBonus, chainBonus,
} from '../src/games/tetrisattack/TetrisAttackLogic.js';

const __dirname = dirname(fileURLToPath(import.meta.url));

let failures = 0;
let checks = 0;
function check(name, cond, detail = '') {
  checks++;
  if (!cond) { failures++; console.log(`  ✗ ${name}${detail ? ' — ' + detail : ''}`); }
}
function section(t) { console.log(`\n${t}`); }

// Build a settled state from a bottom-first grid (for fixtures). Always places
// the explicit grid (via puzzle load) then retags the mode so endless/stageclear
// fixtures use the hand-authored board rather than a random fill.
function fromGrid(grid, mode = 'puzzle') {
  const s = newGame({ mode: 'puzzle', puzzle: { grid, maxMoves: 20 } });
  s.mode = mode;
  if (mode !== 'puzzle') s.riseRate = 0; // keep fixtures still unless a test opts in
  return s;
}
// Step until settled, recording the peak chain and all emitted event types.
function resolveRecord(state, rng = () => 0.5, cap = 3000) {
  let peakChain = 0;
  const types = new Set();
  let i = 0;
  while (i < cap) {
    const events = step(state, rng);
    for (const e of events) types.add(e.type);
    peakChain = Math.max(peakChain, state.chain);
    i++;
    if (isSettled(state) && state.chain === 0) break;
  }
  return { peakChain, types, ticks: i };
}

// ── 1. Match detection ──────────────────────────────────────────────────────
section('1. Match detection');
{
  const s = fromGrid(['rrr...']);
  const g = findMatchGroups(s.board);
  check('horizontal 3-run found', g.length === 1 && g[0].size === 3);

  const s2 = fromGrid(['g.....', 'g.....', 'g.....']);
  const g2 = findMatchGroups(s2.board);
  check('vertical 3-run found', g2.length === 1 && g2[0].size === 3);

  // L-shape merges into one group of 5
  const s3 = fromGrid(['b.....', 'b.....', 'bbb...']);
  const g3 = findMatchGroups(s3.board);
  check('L-shape is one group of 5', g3.length === 1 && g3[0].size === 5, JSON.stringify(g3.map(x => x.size)));

  const s4 = fromGrid(['ryg...']);
  check('no false match', findMatchGroups(s4.board).length === 0);
}

// ── 2. Basic clear + scoring ────────────────────────────────────────────────
section('2. Clear & scoring');
{
  const s = fromGrid(['rrr...']);
  const before = s.score;
  const rec = resolveRecord(s);
  check('clear removes matched panels', s.board.every((row) => row.every((p) => p === null || p.color !== 'red')));
  check('clear event fired', rec.types.has('clear'));
  check('pop event fired', rec.types.has('pop'));
  check('score increased by base*3', s.score - before === 3 * TUNING.BASE_PANEL, `got ${s.score - before}`);
  check('comboBonus(3)=0, (4)=20', comboBonus(3) === 0 && comboBonus(4) === 20);
  check('chainBonus(1)=0, (2)=50', chainBonus(1) === 0 && chainBonus(2) === 50);
}

// ── 3. Chain propagation ────────────────────────────────────────────────────
section('3. Chain propagation');
{
  // Bottom RRR clears; the g above col2 falls and completes GGG (cols 2,3,4).
  const s = fromGrid(['..g...', 'rrrgg.']);
  const rec = resolveRecord(s);
  check('chain reaches level 2', rec.peakChain >= 2, `peak ${rec.peakChain}`);
  check('chainEnd fired', rec.types.has('chainEnd'));
  check('board fully cleared by chain', s.board.every((row) => row.every((p) => p === null)));
}

// ── 4. Gravity: no floating panels ──────────────────────────────────────────
section('4. Gravity');
{
  // A panel with empty space beneath must fall to the floor.
  const s = fromGrid(['r.....', '......', '......']);
  // r is at top of a 3-tall region; resolve (no match) → it should rest on floor
  resolveRecord(s, () => 0.5, 200);
  const bottomHasR = s.board[ROWS - 1][0]?.color === 'red';
  check('lone panel falls to floor', bottomHasR, JSON.stringify(s.board.map(r => r[0]?.color ?? '.')));
  // invariant: no idle panel has an empty cell directly beneath it
  let floating = 0;
  for (let c = 0; c < COLS; c++) for (let r = 0; r < ROWS - 1; r++) {
    if (s.board[r][c] && !s.board[r + 1][c]) floating++;
  }
  check('no floating panels after settle', floating === 0, `${floating} floating`);
}

// ── 5. Cursor & swap ────────────────────────────────────────────────────────
section('5. Cursor & swap');
{
  const s = fromGrid(['ryr...', 'yyr...', 'rryyy.'], 'endless');
  // move cursor bounds
  s.cursor = { row: 0, col: 0 };
  moveCursor(s, 'left');
  check('cursor col clamps at 0', s.cursor.col === 0);
  for (let i = 0; i < 10; i++) moveCursor(s, 'right');
  check('cursor col clamps at COLS-2', s.cursor.col === COLS - 2);

  // a swap between two idle panels succeeds and exchanges them
  const s2 = fromGrid(['rg....'], 'endless');
  s2.cursor = { row: ROWS - 1, col: 0 };
  const a = s2.board[ROWS - 1][0].id;
  const ev = trySwap(s2);
  check('swap returns event', ev && ev.type === 'swap');
  check('swap exchanged cells', s2.board[ROWS - 1][1].id === a);

  // cannot swap a clearing panel
  const s3 = fromGrid(['rrr...'], 'endless');
  step(s3, () => 0.5); // starts the clear
  s3.cursor = { row: ROWS - 1, col: 0 };
  check('cannot swap mid-clear', trySwap(s3) === null);
}

// ── 6. Rise & emerge ────────────────────────────────────────────────────────
section('6. Rise & row emergence');
{
  const s = newGame({ mode: 'endless', rng: mulberry32(7) });
  s.riseRate = 0.34; // fast for the test
  const raised0 = s.rowsRaised;
  const bottomBefore = s.incoming.slice();
  let sawShift = false;
  for (let i = 0; i < 20; i++) {
    const ev = step(s, mulberry32(99 + i));
    if (ev.some((e) => e.type === 'rowShift')) sawShift = true;
  }
  check('rows emerge as the stack rises', s.rowsRaised > raised0 && sawShift);
  check('riseOffset stays in [0,1)', s.riseOffset >= 0 && s.riseOffset < 1, `${s.riseOffset}`);
}

// ── 7. Top-out / game over ──────────────────────────────────────────────────
section('7. Top-out');
{
  const s = newGame({ mode: 'endless', rng: mulberry32(3) });
  // fill the entire board so row 0 is occupied and nothing can clear
  for (let r = 0; r < ROWS; r++) for (let c = 0; c < COLS; c++) {
    s.board[r][c] = { color: 'red', id: 10000 + r * COLS + c, state: 'idle', chain: false };
  }
  // give it distinct colors to avoid instant clears masking the top-out
  const cols = ['red', 'yellow', 'green', 'cyan', 'purple', 'blue'];
  for (let r = 0; r < ROWS; r++) for (let c = 0; c < COLS; c++) s.board[r][c].color = cols[(r + c) % 6];
  let over = false;
  for (let i = 0; i < TUNING.PANIC_GRACE + 50 && !over; i++) {
    const ev = step(s, mulberry32(1 + i));
    if (ev.some((e) => e.type === 'gameOver')) over = true;
  }
  check('full board tops out', over && s.over);
}

// ── 8. Stage Clear win condition ────────────────────────────────────────────
section('8. Stage Clear');
{
  // one target row of 3 that clears immediately → win
  const s = newGame({ mode: 'stageclear', rng: mulberry32(5), stage: { speedLevel: 1, startRows: 0 } });
  // hand-place a single clearing target group
  for (let c = 0; c < 3; c++) s.board[ROWS - 1][c] = { color: 'green', id: c + 1, state: 'idle', chain: false, target: true };
  s.targetsTotal = 3;
  let won = false;
  for (let i = 0; i < 200 && !won; i++) {
    const ev = step(s, mulberry32(50 + i));
    if (ev.some((e) => e.type === 'win')) won = true;
  }
  check('clearing all targets wins the stage', won && s.won);
  check('no targets remain on win', remainingTargets(s) === 0);
}

// ── 9. Puzzle bank ──────────────────────────────────────────────────────────
section('9. Puzzle bank');
{
  const bankPath = join(__dirname, '..', 'data', 'tetrisattack-puzzles.json');
  const bank = JSON.parse(readFileSync(bankPath, 'utf8'));
  check('bank has puzzles', bank.puzzles.length >= 12, `${bank.puzzles.length}`);
  let solvable = 0;
  let optimal = 0;
  for (const p of bank.puzzles) {
    const sol = solvePuzzle({ grid: p.grid, maxMoves: p.maxMoves }, () => 0.5);
    if (sol) {
      solvable++;
      if (sol.length <= p.maxMoves) optimal++;
      // apply the solution and confirm the board empties
      const s = newGame({ mode: 'puzzle', puzzle: { grid: p.grid, maxMoves: p.maxMoves } });
      for (const mv of sol) { s.cursor = { row: mv.row, col: mv.col }; trySwap(s); resolveFully(s, () => 0.5); }
      const empty = s.board.every((row) => row.every((c) => c === null));
      if (!empty) { failures++; checks++; console.log(`  ✗ puzzle ${p.id} solution did not empty board`); }
      else checks++;
    }
  }
  check('every puzzle is solvable', solvable === bank.puzzles.length, `${solvable}/${bank.puzzles.length}`);
  check('every puzzle solvable within maxMoves', optimal === bank.puzzles.length, `${optimal}/${bank.puzzles.length}`);
}

// ── 10. Determinism ─────────────────────────────────────────────────────────
section('10. Determinism');
{
  const boardHash = (s) => s.board.map((row) => row.map((p) => (p ? p.color[0] : '.')).join('')).join('|');
  const run = (seed) => {
    const rng = mulberry32(seed);
    const s = newGame({ mode: 'endless', rng });
    const trace = [];
    for (let i = 0; i < 400; i++) {
      if (i % 5 === 0) { const mv = findClearingSwap(s); if (mv) { s.cursor = { row: mv.row, col: mv.col }; trySwap(s); } }
      step(s, rng);
      trace.push(`${s.score}:${boardHash(s)}`);
    }
    return trace.join(',');
  };
  check('seeded runs are identical', run(12345) === run(12345));
  check('different seeds differ', run(12345) !== run(999));
}

// ── 11. Monte-carlo self-play (invariants) ──────────────────────────────────
section('11. Self-play invariants');
{
  let games = 0, totalTicks = 0, gameOvers = 0, maxScore = 0, invariantBreaks = 0;
  for (let g = 0; g < 40; g++) {
    const seed = 1000 + g;
    const rng = mulberry32(seed);
    const s = newGame({ mode: 'endless', rng });
    let lastScore = 0;
    for (let t = 0; t < 1500 && !s.over; t++) {
      // occasionally act: make a clearing swap when one exists
      if (t % 5 === 0) {
        const mv = findClearingSwap(s);
        if (mv) { s.cursor = { row: mv.row, col: mv.col }; trySwap(s); }
      }
      step(s, rng);
      totalTicks++;
      // invariant: score never decreases
      if (s.score < lastScore) invariantBreaks++;
      lastScore = s.score;
      // invariant: cursor in bounds
      if (s.cursor.row < 0 || s.cursor.row >= ROWS || s.cursor.col < 0 || s.cursor.col > COLS - 2) invariantBreaks++;
      // invariant: when fully settled, no floating idle panels
      if (isSettled(s)) {
        for (let c = 0; c < COLS; c++) for (let r = 0; r < ROWS - 1; r++) {
          if (s.board[r][c] && s.board[r][c].state === 'idle' && !s.board[r + 1][c]) invariantBreaks++;
        }
      }
    }
    games++;
    if (s.over) gameOvers++;
    maxScore = Math.max(maxScore, s.score);
  }
  check('self-play produced no invariant breaks', invariantBreaks === 0, `${invariantBreaks} breaks`);
  check('self-play scored points', maxScore > 0, `max ${maxScore}`);
  console.log(`  (ran ${games} games, ${totalTicks} ticks, ${gameOvers} top-outs, peak score ${maxScore})`);
}

// ── Summary ─────────────────────────────────────────────────────────────────
console.log(`\n${failures === 0 ? '✓ ALL PASSED' : '✗ FAILURES'} — ${checks - failures}/${checks} checks passed`);
process.exit(failures ? 1 : 0);