import { Game, trace } from '../../src/core.js';
import { metrics, decisionTimeline, describeAction, describeResult, RATING_QUESTIONS } from '../../src/bench.js';
import { layout } from '../../src/geometry.js';
import { CanvasPainter, drawScene } from '../../src/renderer.js';
import { TILE_ATLAS } from '../../src/sprites.js';
import { exitTiming } from '../../src/exit-animation.js';
import { MOTION } from '../../src/design-tokens.js';

// Where the run files and the tile atlas live, relative to this page. The
// standalone kit builder (scripts/bench-kit.mjs) rewrites these two lines, so
// keep them as plain string literals.
const DATA = '../../bench/runs', ASSET_BASE = '../../';

const $ = id => document.getElementById(id);
const canvas = $('board'), context = canvas.getContext('2d'), painter = new CanvasPainter(context);
const reduced = matchMedia('(prefers-reduced-motion: reduce)').matches;
let runObj = null, game = null, cursor = 0, view, width, height, animation = null, turning = null, hint = null, path = null, frame = 0, liveTimer = null, clockFrame = 0;

// ---------- data ----------
// Data always refreshes; the checkbox only decides whether the cursor chases
// the newest step. Hiding the refresh behind a toggle meant a page opened from
// the dropdown sat at 0/0 while the agent played.
const following = () => $('live').checked;
// The board column carries no running commentary — the feed already says what
// happened, step by step. This line exists only for "the file is gone".
function notice(text) { const n = $('notice'); n.textContent = text || ''; n.hidden = !text; }
async function loadIndex({ keepSelection = false } = {}) {
  const res = await fetch(`${DATA}/index.json?t=` + Date.now()).catch(() => null);
  let index = [];
  try { index = res && res.ok ? await res.json() : []; } catch { return null; }
  index.sort((a, b) => (b.updatedAt || '').localeCompare(a.updatedAt || ''));
  const markup = index.length ? index.map(e => `<option value="${e.run}">${e.run} · ${e.level} · ${e.status} · ${e.steps} 步 · ${e.persona}/${e.model}</option>`).join('') : '<option value="">（还没有任何局：先用 scripts/bench.mjs start）</option>';
  // Rebuilding the list on every poll would fight the open dropdown; only
  // touch it when the options actually changed.
  if (markup !== $('run').innerHTML) {
    const selected = keepSelection ? $('run').value : null;
    $('run').innerHTML = markup;
    if (selected && index.some(e => e.run === selected)) $('run').value = selected;
  }
  return index;
}
let missing = 0;
async function loadRun(name, { keepCursor = false, fromStart = false } = {}) {
  let fresh;
  try {
    const res = await fetch(`${DATA}/${name}.json?t=` + Date.now());
    if (!res.ok) {
      // A stale index entry would otherwise 404 once a second forever.
      // Drop the board with the data: leaving `game` behind meant the next
      // resize redrew a run that no longer exists and read `runObj.steps`.
      if (++missing >= 3) { runObj = null; game = null; view = null; missing = 0; notice(`${DATA}/${name}.json 不见了（可能已删除）——从列表里另选一局。`); await loadIndex(); }
      else if (!keepCursor) notice(`读不到 ${DATA}/${name}.json`);
      return;
    }
    // The agent may be mid-write; a torn read just means "try again next tick".
    fresh = await res.json();
    missing = 0; notice('');
  } catch { return; }
  const sameRun = runObj && runObj.run === fresh.run;
  const changed = !sameRun || runObj.steps.length !== fresh.steps.length || runObj.status !== fresh.status || runObj.rating !== fresh.rating;
  runObj = fresh;
  if (changed) { renderSteps(); renderMetrics(); }
  // Hopping to a fresh run: watch it from the opening so the animations play.
  if (!sameRun || !keepCursor) rebuild(fromStart ? 0 : runObj.steps.length);
  else pump();
  // Keep the dropdown and the address bar on the run being watched. An auto-hop
  // lands on a run the select may not list yet, and a silent mismatch there
  // labels the board with somebody else's game.
  if (!sameRun) {
    if (![...$('run').options].some(o => o.value === runObj.run)) await loadIndex();
    $('run').value = runObj.run;
    const url = new URL(location.href); url.searchParams.set('run', runObj.run); history.replaceState(null, '', url);
  }
  syncUi();
  cancelAnimationFrame(clockFrame); paintClock();
  if (fromStart) pump();
}
// Following the agent: keep playing whatever steps have arrived until the
// cursor is caught up. draw() calls back here when an animation finishes, so a
// batch of several steps plays through instead of stalling after one.
function pump() {
  if (!following() || !runObj) return;
  if (animation || turning) return;
  if (cursor < runObj.steps.length) advance();
}

// ---------- replay ----------
function rebuild(n) {
  cancelAnimationFrame(frame); animation = null; turning = null; hint = null; path = null;
  game = new Game(runObj.level); cursor = 0;
  for (; cursor < n && cursor < runObj.steps.length; cursor++) applyModel(runObj.steps[cursor]);
  resize(); syncUi();
}
function applyModel(step) {
  const a = step.action;
  if (a.type === 'tap') game.tap(a.id);
  else if (a.type === 'rotate') game.rotate(a.direction);
  else if (a.type === 'undo') game.undo();
}
// Advance one step with the real animations.
function advance() {
  if (!runObj || cursor >= runObj.steps.length || animation || turning) return;
  const step = runObj.steps[cursor]; const a = step.action;
  hint = null; path = null;
  if (a.type === 'tap') {
    const result = game.tap(a.id);
    if (result.status === 'exit') animation = { route: result, start: performance.now(), duration: reduced ? 100 : exitTiming(result).duration };
    else if (result.travelPoints) animation = { route: result, start: performance.now(), duration: reduced ? 150 : MOTION.collisionMs };
  } else if (a.type === 'rotate') {
    game.rotate(a.direction);
    turning = { direction: a.direction, start: performance.now(), duration: reduced ? 100 : MOTION.rotationMs };
  } else if (a.type === 'undo') game.undo();
  else if (a.type === 'peek') { const tile = game.tiles.find(t => t.id === a.id); if (tile) { hint = tile.id; path = trace(game.level, tile, game.tiles); } }
  cursor++;
  syncUi(); draw();
}
function syncUi() {
  if (!game || !runObj) return;
  const behind = runObj.steps.length - cursor;
  $('feed-state').textContent = !following() ? '已暂停跟随' : pinned ? '已固定这一局' : runObj.status === 'playing' ? (behind > 0 ? `追 ${behind} 步` : '等待下一步') : '本局已结束';
  $('feed-state').style.color = following() && runObj.status === 'playing' ? 'var(--live-ink)' : 'var(--ink3)';
  $('who-model').textContent = runObj.model || 'unknown';
  $('who-agent').textContent = runObj.agent || '';
  $('who-level').textContent = `${runObj.level.id} · ${runObj.level.cells.length} 格 · ${runObj.level.tiles.length} 枚 · 人设 ${runObj.persona}`;
  // The jump-back button is the only replay control left: it appears exactly
  // when the view is not tracking the agent's live frontier, and says which
  // part of that it will resume — the newest step, or the newest run.
  const drifted = !following(), locked = pinned && following();
  $('end').hidden = !drifted && !locked;
  $('end').textContent = pinned ? '↩ 跟回最新一局' : '↩ 回到实时';
  document.querySelectorAll('#steps li').forEach((li, i) => li.classList.toggle('current', i === cursor - 1));
  scrollFeedTo(document.querySelector('#steps li.current'));
  renderScoreboard();
}

// Scroll the feed, never the page. scrollIntoView({block:'nearest'}) walks up
// every scroll container, so on a phone — where the feed sits below the fold —
// each new step yanked the clock off the top of the screen.
function scrollFeedTo(li) {
  if (!li) return;
  const box = $('steps'), b = box.getBoundingClientRect(), r = li.getBoundingClientRect();
  if (r.top < b.top) box.scrollTop += r.top - b.top;
  else if (r.bottom > b.bottom) box.scrollTop += r.bottom - b.bottom;
}

// ---------- scoreboard ----------
const STATUS = { playing: ['进行中', 'playing'], cleared: ['通关', 'cleared'], 'gave-up': ['放弃', 'gaveup'], budget: ['预算用尽', 'budget'] };
const pad = (n, w = 2) => String(n).padStart(w, '0');
// A stopwatch, not a duration: minutes:seconds.milliseconds, always the same width.
function stopwatch(ms) {
  if (ms == null || ms < 0) return '0:00.000';
  const m = Math.floor(ms / 60000), s = Math.floor(ms % 60000 / 1000);
  return `${m}:${pad(s)}.${pad(Math.floor(ms % 1000), 3)}`;
}
// metrics() re-solves the level, which is far too heavy to run on every clock
// frame; the numbers only change when a step lands.
let metricsCache = { key: null, value: null };
function runMetrics() {
  const key = `${runObj.run}:${runObj.steps.length}:${runObj.status}:${runObj.rating ? 1 : 0}`;
  if (metricsCache.key !== key) metricsCache = { key, value: metrics(runObj) };
  return metricsCache.value;
}
function renderScoreboard() {
  if (!runObj) return;
  const m = runMetrics(), total = runObj.level.tiles.length;
  const last = runObj.steps[runObj.steps.length - 1];
  const left = last ? last.remaining : total;
  // Rewound, every number here still describes the whole run while the board
  // beside it shows step N. Label the mismatch rather than let them contradict.
  const rewound = !following() && cursor < runObj.steps.length;
  const [label, cls] = rewound
    ? [`回看 ${cursor} / ${runObj.steps.length}`, 'rewound']
    : STATUS[runObj.status] || [runObj.status, ''];
  document.querySelector('.scoreboard').classList.toggle('rewound', rewound);
  $('sb-steps').textContent = m.steps;
  $('sb-budget').textContent = `/ ${runObj.budget}`;
  $('sb-decisions').textContent = m.decisions;
  $('sb-per').textContent = m.actionsPerDecision ? `· ${m.actionsPerDecision.toFixed(1)} 步/次` : '—';
  $('sb-cleared').textContent = total - left;
  $('sb-total').textContent = `/ ${total}`;
  $('sb-bar').style.width = `${Math.round((total - left) / Math.max(1, total) * 100)}%`;
  $('sb-dead').textContent = m.deadTaps;
  $('sb-rot').textContent = `· ${m.rotations} 转${m.minimumRotations != null ? ` / 最少 ${m.minimumRotations}` : ''}`;
  $('sb-status').textContent = label;
  $('sb-status').className = `pill ${cls}`;
}
// The clock is the point of the page: it runs while the agent is still playing,
// and freezes on the final time the moment the run ends.
function paintClock() {
  clockFrame = 0;
  if (!runObj) return;
  const started = runObj.startedAt ? Date.parse(runObj.startedAt) : null;
  const last = runObj.steps[runObj.steps.length - 1];
  const lastAt = last?.at ?? started;
  const live = runObj.status === 'playing';
  const now = Date.now();
  $('clock').textContent = stopwatch(started == null ? null : (live ? now : lastAt) - started);
  if (live && lastAt != null) {
    const thinking = now - lastAt;
    $('think').textContent = thinking >= 60000 ? stopwatch(thinking) : `${(thinking / 1000).toFixed(1)}s`;
    $('think').classList.toggle('hot', thinking > 15000);
    $('think-label').textContent = '本步思考';
  } else {
    $('think').textContent = last ? stopwatch(runMetrics().timing.maxDecisionMs) : '—';
    $('think').classList.remove('hot');
    $('think-label').textContent = '最长一步';
  }
  if (live) clockFrame = requestAnimationFrame(paintClock);
}
const secs = ms => ms == null ? '—' : ms >= 10000 ? `${(ms / 1000).toFixed(0)} s` : ms >= 1000 ? `${(ms / 1000).toFixed(1)} s` : `${ms} ms`;
function renderSteps() {
  // One badge per decision: how long the agent took before committing this batch.
  const latency = new Map(decisionTimeline(runObj).map(d => [d.from, d]));
  $('steps').innerHTML = runObj.steps.map(s => {
    const d = latency.get(s.n);
    const badge = d ? `<em title="这次决定用了多久（含读盘与进程启动）">${secs(d.ms)}${d.actions > 1 ? ` · 连做 ${d.actions} 步` : ''}</em>` : '';
    return `<li data-n="${s.n}"${d ? ' class="lead"' : ''}>${badge}<b>${describeAction(s.action)}</b> → ${describeResult(s.result)}${s.note ? `<i>${s.note}</i>` : ''}</li>`;
  }).join('');
  document.querySelectorAll('#steps li').forEach(li => li.onclick = () => { const n = Number(li.dataset.n); follow(false); rebuild(n); });
}
// The list is one tab stop; the arrows walk it. Without this the step rows are
// mouse-only, and removing the slider left keyboard users with no replay at all.
$('steps').onkeydown = e => {
  if (!runObj) return;
  const last = runObj.steps.length;
  const to = { ArrowDown: cursor + 1, ArrowRight: cursor + 1, ArrowUp: cursor - 1, ArrowLeft: cursor - 1, Home: 0, End: last }[e.key];
  if (to === undefined) return;
  e.preventDefault();
  const n = Math.max(0, Math.min(last, to));
  if (n === last) { follow(true); return; }
  follow(false); rebuild(n);
}
function renderMetrics() {
  const m = runMetrics();
  const t = m.timing;
  const perPiece = t.totalMs != null ? t.totalMs / runObj.level.tiles.length : null;
  $('timing').innerHTML = [
    ['总耗时', secs(t.totalMs)], ['决策次数', m.actionsPerDecision != null ? `${m.decisions}（${m.actionsPerDecision.toFixed(1)} 步/次）` : `${m.decisions}`],
    ['每次决策', `中位 ${secs(t.medianDecisionMs)} · 最长 ${secs(t.maxDecisionMs)}`],
    ['开局读盘', secs(t.firstDecisionMs)], ['每枚棋子', secs(perPiece == null ? null : Math.round(perPiece))],
    ...(t.thinkMs != null ? [['其中模型思考', secs(t.thinkMs)]] : []),
  ].map(([k, v]) => `<div><dt>${k}</dt><dd>${v}</dd></div>`).join('');
  const rows = [['状态', m.status], ['步数 / 预算', `${m.steps} / ${runObj.budget}`], ['动作 ÷ 棋子', m.actionsPerPiece?.toFixed(2)], ['点击 / 离场 / 空点', `${m.taps} / ${m.exits} / ${m.deadTaps}`], ['其中擦碰空点', m.grazeDeadTaps], ['最长连续空点', m.longestDeadStreak], ['旋转 / 有效 / 盲转', `${m.rotations} / ${m.effectiveRotations} / ${m.blindRotations}`], ['转错方向', m.wrongWayRotations], ['最长连续盲转', m.longestBlindStreak], ['进入卡住状态', m.stuckEntries], ['首次离场在第', m.stepsToFirstExit ?? '—'], ['撤销 / 查看', `${m.undos} / ${m.peeks}`], ['最少旋转（求解器）', m.minimumRotations ?? '—']];
  $('metrics').innerHTML = rows.map(([k, v]) => `<div><dt>${k}</dt><dd>${v}</dd></div>`).join('');
  $('rating').innerHTML = runObj.rating ? RATING_QUESTIONS.map(q => `<div><dt>${q.key}</dt><dd>${runObj.rating[q.key] ?? '—'}</dd></div>`).join('') : '<div><dt>尚未评分</dt><dd>—</dd></div>';
  if (runObj.status === 'gave-up') $('rating').insertAdjacentHTML('afterbegin', `<div class="giveup"><dt>放弃原因</dt><dd>${runObj.reason || '—'}</dd></div>`);
}

// ---------- drawing ----------
function draw(now = performance.now()) {
  cancelAnimationFrame(frame);
  if (!view || !game || !runObj) return;
  context.clearRect(0, 0, width, height);
  const state = { hint, path, reduced };
  if (animation) { const p = Math.min(1, (now - animation.start) / animation.duration); state.animation = { route: animation.route, progress: p }; if (p >= 1) animation = null; }
  if (turning) { const p = Math.min(1, (now - turning.start) / turning.duration); state.boardAngle = -turning.direction * Math.PI / 3 * Math.pow(1 - p, 3); if (p >= 1) turning = null; }
  drawScene(painter, game.level, game.tiles, view, state);
  if (animation || turning) frame = requestAnimationFrame(draw);
  else if (following() && cursor < runObj.steps.length) setTimeout(pump, 120);
}
function resize() {
  if (!game) return;
  const rect = canvas.getBoundingClientRect(), dpr = Math.min(devicePixelRatio || 1, 3);
  width = rect.width; height = rect.height;
  canvas.width = Math.round(width * dpr); canvas.height = Math.round(height * dpr);
  context.setTransform(dpr, 0, 0, dpr, 0, 0);
  view = layout(game.level.cells, width, height); draw();
}

// ---------- controls ----------
$('run').onchange = () => { pinned = true; loadRun($('run').value); };
$('reload').onclick = async () => { const index = await loadIndex(); if (runObj) $('run').value = runObj.run; else if (index?.[0]) loadRun(index[0].run); };
// Polling is unconditional — a page opened from the dropdown must still track a
// running game. `follow` only decides whether the page chases the agent: the
// newest step within this run, and the agent's next run once this one is done.
function follow(on) {
  $('live').checked = on;
  if (on) pinned = false;
  if (on && runObj) rebuild(runObj.steps.length);
  syncUi();
}
// Watching "the agent", not "one run": when our run has finished (or has gone
// quiet while another is clearly active), hop to whatever it started next.
const STALE_MS = 20000;
let lastChangeAt = Date.now();
// Picking a run from the dropdown pins it: auto-hop must not yank the viewer
// away from a game they deliberately opened. 「跟随最新」releases the pin.
let pinned = false;
function nextRun(index) {
  if (pinned || !following() || !runObj || !index?.length) return null;
  const mine = runObj.status !== 'playing' ? null : Date.now() - lastChangeAt;
  if (mine !== null && mine < STALE_MS) return null;
  const candidate = index.filter(e => e.run !== runObj.run && e.status === 'playing')
    .sort((a, b) => (b.updatedAt || '').localeCompare(a.updatedAt || ''))[0];
  if (!candidate) return null;
  return (candidate.updatedAt || '') > (runObj.updatedAt || '') ? candidate.run : null;
}
let tick = 0;
liveTimer = setInterval(async () => {
  if (runObj) {
    const before = runObj.steps.length;
    await loadRun(runObj.run, { keepCursor: true });
    if (runObj && runObj.steps.length !== before) lastChangeAt = Date.now();
  }
  if (tick++ % 2 === 0) {
    const index = await loadIndex({ keepSelection: true });
    const hop = nextRun(index);
    if (hop) {
      await loadRun(hop, { fromStart: true });
      lastChangeAt = Date.now();
    }
  }
}, 1000);
$('live').onchange = () => follow($('live').checked);
// Clicking a step in the feed is the whole replay control; this puts it back.
$('end').onclick = () => { follow(true); };
const atlas = new Image(); atlas.onload = () => { painter.atlas = atlas; draw(); }; atlas.src = ASSET_BASE + TILE_ATLAS;
new ResizeObserver(resize).observe(canvas);

const index = await loadIndex();
const wanted = new URLSearchParams(location.search).get('run');
if (wanted && index.some(e => e.run === wanted)) {
  $('run').value = wanted; await loadRun(wanted);
  // A link to a finished run is a replay link: don't let auto-hop drag the
  // viewer off to whatever happens to be playing. A link to a live run still
  // follows the agent into its next game, which is what `start` prints it for.
  if (runObj && runObj.status !== 'playing') pinned = true;
}
else if (index[0]) await loadRun(index[0].run);
// live=1 仍然接受（start 打印的链接带它），但跟随本来就是默认开的。
if (new URLSearchParams(location.search).get('live') === '0') follow(false);