// tlui.js — SCENEGOD timeline panel (Lane B). ALL DOM/canvas lives here;
// timeline.js stays headless. Mounts into #timeline, drives a Timeline.
//
// Layout: [scene bar] / [names column | ruler+canvas lanes]. One <canvas> for
// all lanes (decision: simpler than canvas-per-lane; hit-testing via a rebuilt
// hitbox list each draw). Time axis fits to width at zoom 1; Cmd/Ctrl+wheel
// zooms around the cursor, plain wheel is left to the page (scroll), and
// trackpad horizontal wheel pans when zoomed in.

const ROW_H = 28;
const RULER_H = 22;
const KEY_R = 5;

// ponytail: styles injected here, not written into Lane A's web/style.css —
// keeps Lane B inside its own files (orchestrator confirmed this is permanent).
const CSS = `
#timeline{display:flex;flex-direction:column;background:#161a20;color:#c9d1d9;font:12px/1.4 ui-monospace,Menlo,monospace;border-top:1px solid #2b323c;user-select:none}
#timeline .tl-bar{display:flex;gap:8px;align-items:center;padding:6px 8px;border-bottom:1px solid #2b323c}
#timeline .tl-bar input{background:#0d1117;border:1px solid #2b323c;color:#c9d1d9;padding:2px 6px;border-radius:3px;font:inherit}
#timeline .tl-bar input.name{width:150px}
#timeline .tl-bar input.num{width:56px}
#timeline .tl-bar select{background:#0d1117;border:1px solid #2b323c;color:#c9d1d9;padding:2px 4px;border-radius:3px;font:inherit}
#timeline .tl-bar label{display:flex;align-items:center;gap:3px;color:#8b949e;cursor:pointer}
#timeline .tl-bar button{background:#21262d;border:1px solid #2b323c;color:#c9d1d9;padding:3px 10px;border-radius:3px;cursor:pointer;font:inherit}
#timeline .tl-bar button:hover{background:#2b323c}
#timeline .tl-bar .spring{flex:1}
#timeline .tl-bar .clock{color:#7aa2f7;min-width:64px;text-align:right}
#timeline .tl-body{display:flex}
#timeline .tl-names{width:150px;flex:none;overflow:hidden;border-right:1px solid #2b323c;background:#12161c}
#timeline .tl-names .row{height:${ROW_H}px;display:flex;align-items:center;padding:0 8px;box-sizing:border-box;border-bottom:1px solid #1b2027;white-space:nowrap;overflow:hidden;text-overflow:ellipsis}
#timeline .tl-names .row.head{margin-top:${RULER_H}px}
#timeline .tl-names .row .k{color:#565f6b;margin-right:6px;font-size:10px}
#timeline .tl-names .row.sub{color:#8b949e;padding-left:20px;font-size:11px}
#timeline .tl-names .row input.gain{width:38px;margin-left:auto;background:#0d1117;border:1px solid #2b323c;color:#c9d1d9;font:10px ui-monospace;border-radius:3px;padding:1px 2px}
#timeline .tl-names .row button.lip{margin-left:4px;background:#21262d;border:1px solid #2b323c;border-radius:3px;color:#c9d1d9;cursor:pointer;font-size:11px;padding:0 4px}
#timeline .tl-names .row button.lip:hover{background:#2b323c}
#timeline .tl-lanes{flex:1;position:relative;overflow:hidden}
#timeline canvas{display:block;width:100%;height:100%}
.tl-menu{position:fixed;z-index:9999;background:#12161c;border:1px solid #2b323c;border-radius:4px;max-height:240px;overflow:auto;font:12px ui-monospace;color:#c9d1d9;min-width:160px}
.tl-menu .item{padding:4px 10px;cursor:pointer;white-space:nowrap}
.tl-menu .item:hover{background:#2b323c}
.tl-menu .empty{padding:6px 10px;color:#565f6b}
.tl-menu.tmpl{max-width:420px}
.tl-menu.tmpl .item{display:flex;gap:9px;align-items:flex-start;padding:8px 10px;white-space:normal;border-bottom:1px solid #1b2027}
.tl-menu.tmpl .item img{width:68px;height:42px;flex:none;object-fit:cover;border-radius:3px;background:#0d1117}
.tl-menu.tmpl .t{color:#e0e6ed}
.tl-menu.tmpl .d{color:#8b949e;font-size:11px;line-height:1.35;margin-top:2px}
.tl-help{position:fixed;left:50%;top:50%;transform:translate(-50%,-50%);z-index:10001;background:#12161c;border:1px solid #2b323c;border-radius:6px;box-shadow:0 10px 44px #000b;padding:14px 18px 16px;color:#c9d1d9;font:12px/1.5 ui-monospace,Menlo,monospace;max-width:min(880px,94vw);max-height:84vh;overflow:auto}
.tl-help h3{margin:0 0 2px;font-size:13px;color:#7aa2f7}
.tl-help .hint{color:#565f6b;margin-bottom:10px}
.tl-help .cols{display:flex;gap:28px;flex-wrap:wrap;align-items:flex-start}
.tl-help section{min-width:250px;flex:1}
.tl-help h4{margin:8px 0 4px;font-size:11px;color:#e0af68;letter-spacing:.07em}
/* SYNC9: dt was auto-width + nowrap, so long terms ("drag an animation onto a
   character") blew past the grid cell and the three columns overlapped. Cap the
   term column and let it wrap. */
.tl-help dl{display:grid;grid-template-columns:minmax(0,11em) minmax(0,1fr);gap:3px 12px;margin:0}
.tl-help dt{color:#57c99a;white-space:normal;overflow-wrap:anywhere}
.tl-help dd{margin:0;color:#8b949e}
.tl-help .close{position:absolute;top:6px;right:10px;background:none;border:0;color:#565f6b;font:14px ui-monospace;cursor:pointer}
.tl-help .close:hover{color:#c9d1d9}
.tl-toast{position:fixed;left:50%;bottom:18px;transform:translateX(-50%);z-index:10000;background:#12161c;border:1px solid #e0af68;color:#e0e6ed;padding:6px 14px;border-radius:4px;font:12px ui-monospace;max-width:70vw}
`;

export class TimelineUI {
  constructor(timeline, mountEl) {
    this.tl = timeline;
    this.stage = timeline.stage;
    this.el = typeof mountEl === 'string' ? document.querySelector(mountEl) : mountEl;
    // REVIEW-FIX: shared failure surface — timeline._fail (and any other module)
    // toasts through here instead of dying silently in the console.
    window.sgToast = (m) => this._toast(m);
    this._hits = [];
    this._drag = null;
    this._selKeys = [];        // box-selected keys: [{id, track, key}]
    this._snapOn = true;
    this._snapStep = 'frame';  // 'frame' | seconds string
    this._zoom = 1;            // 1 = fit-to-width; Cmd/Ctrl+wheel zooms
    this._panT = 0;            // left edge of the view, in seconds
    this._audioBuf = new Map();  // path -> decoded AudioBuffer
    this._audioSrcs = [];        // live BufferSourceNodes during playback
    this._wasPlaying = false;
    this._injectCSS();
    this._build();
    this.tl.onTick(() => {       // natural end-of-play stops audio (timeline auto-pauses)
      this.draw();
      if (this._wasPlaying && !this.tl.playing) this._audioStop();
      this._wasPlaying = this.tl.playing;
    });
    this.tl.onLoad(() => { this._syncRows(); this._refreshBar(); });  // SYNC1 #3a/#3b
    if (this.stage.onChange) this.stage.onChange(() => this._syncRows());
    this._syncRows();
    this.draw();
  }

  _refreshBar() {
    if (this.$name) this.$name.value = this.tl.scene.name || '';
    if (this.$dur) this.$dur.value = this.tl.duration;
  }

  _injectCSS() {
    if (document.getElementById('laneB-tl-css')) return;
    const s = document.createElement('style');
    s.id = 'laneB-tl-css';
    s.textContent = CSS;
    document.head.appendChild(s);
  }

  _build() {
    this.el.innerHTML = '';
    const bar = document.createElement('div');
    bar.className = 'tl-bar';
    bar.innerHTML = `
      <button data-act="play">▶</button>
      <span class="clock">0.00s</span>
      <input class="name" placeholder="scene name" value="${this.tl.scene.name || ''}">
      <span>dur</span><input class="num dur" type="number" min="0" step="0.5" value="${this.tl.duration}">
      <label><input type="checkbox" class="snap" checked> snap</label>
      <select class="snapstep" title="snap increment">
        <option value="frame">frame</option><option value="0.1">0.1s</option>
        <option value="0.25">0.25s</option><option value="1">1s</option></select>
      <button data-act="audio" title="add audio clip at playhead">🎵</button>
      <span class="spring"></span>
      <button data-act="help" title="keyboard shortcuts (?)">?</button>
      <button data-act="tmpl" title="start a new scene from a starter template">New…</button>
      <button data-act="save">Save</button>
      <button data-act="load">Load</button>`;
    this.el.appendChild(bar);
    this.$play = bar.querySelector('[data-act="play"]');
    this.$clock = bar.querySelector('.clock');
    this.$name = bar.querySelector('.name');
    this.$dur = bar.querySelector('.dur');
    this.$snap = bar.querySelector('.snap');
    this.$snapStep = bar.querySelector('.snapstep');
    this.$play.onclick = () => this._toggle();
    bar.querySelector('[data-act="save"]').onclick = () => this.save();
    bar.querySelector('[data-act="load"]').onclick = () => this.load(this.$name.value);
    this.$audioBtn = bar.querySelector('[data-act="audio"]');
    this.$audioBtn.onclick = () => this._pickAudio();
    this.$tmplBtn = bar.querySelector('[data-act="tmpl"]');
    this.$tmplBtn.onclick = () => this._pickTemplate();
    this.$helpBtn = bar.querySelector('[data-act="help"]');
    this.$helpBtn.onclick = () => this._toggleHelp();
    this.$dur.onchange = () => this.tl.setDuration(this.$dur.value);   // clamps + refreshes bar
    this.$name.onchange = () => { this.tl.scene.name = this.$name.value; };
    this.$snap.onchange = () => { this._snapOn = this.$snap.checked; };
    this.$snapStep.onchange = () => { this._snapStep = this.$snapStep.value; };

    const body = document.createElement('div');
    body.className = 'tl-body';
    this.$names = document.createElement('div'); this.$names.className = 'tl-names';
    const lanes = document.createElement('div'); lanes.className = 'tl-lanes';
    this.canvas = document.createElement('canvas');
    lanes.appendChild(this.canvas);
    body.appendChild(this.$names); body.appendChild(lanes);
    this.el.appendChild(body);
    this.lanesEl = lanes;

    this.canvas.addEventListener('mousedown', (e) => this._down(e));
    this.canvas.addEventListener('wheel', (e) => this._wheel(e), { passive: false });
    window.addEventListener('mousemove', (e) => this._move(e));
    window.addEventListener('mouseup', () => this._up());
    this.canvas.addEventListener('dblclick', (e) => this._dbl(e));
    this.canvas.addEventListener('contextmenu', (e) => this._ctx(e));
    window.addEventListener('keydown', (e) => this._key(e));
    window.addEventListener('resize', () => this.draw());
  }

  // rows: [{type:'transform'|'params'|'clip'|'cameras', id?, label}].
  // Built from the timeline's entities (authoritative for tracks) merged with
  // any stage entities not yet keyframed (dock-added but not in a loaded scene).
  _rows() {
    const rows = [];
    const list = [...this.tl.scene.entities];
    for (const se of this.stage.entities()) if (!list.find((e) => e.id === se.id)) list.push(se);
    for (const e of list) {
      rows.push({ type: 'transform', id: e.id, kind: e.kind, label: e.label || e.id });
      if (e.kind === 'character') rows.push({ type: 'clip', id: e.id, label: '↳ clips' });
      const paramable = (e.tracks?.params?.length > 0) || e.kind === 'camera' || e.kind === 'light';
      if (paramable) rows.push({ type: 'params', id: e.id, label: '↳ params' });
      // viseme lane only when the character actually has morph targets (M4-B)
      const hasMorphs = (e.tracks?.morphs?.length > 0) ||
        (e.kind === 'character' && this.stage.visemeTargets && (this.stage.visemeTargets(e.id) || []).length > 0);
      if (hasMorphs) rows.push({ type: 'morphs', id: e.id, label: '↳ visemes' });
    }
    rows.push({ type: 'cameras', label: 'Cameras' });
    for (const clip of (this.tl.scene.audio || [])) {
      rows.push({ type: 'audio', clip, label: '🎵 ' + (clip.path || '').split('/').pop() });
    }
    return rows;
  }

  _syncRows() {
    this.rows = this._rows();
    this.$names.innerHTML = '';
    this.rows.forEach((r, i) => {
      const d = document.createElement('div');
      const sub = r.type === 'clip' || r.type === 'params' || r.type === 'morphs' || r.type === 'audio';
      d.className = 'row' + (i === 0 ? ' head' : '') + (sub ? ' sub' : '');
      if (r.type === 'transform') d.innerHTML = `<span class="k">${(r.kind || '?')[0].toUpperCase()}</span>${r.label}`;
      else if (r.type === 'audio') {
        d.append(r.label);
        const g = document.createElement('input');
        g.type = 'number'; g.className = 'gain'; g.step = '0.1'; g.min = '0'; g.title = 'gain';
        g.value = r.clip.gain ?? 1;
        g.onchange = () => this.tl.setAudioGain(r.clip, Math.max(0, +g.value || 0));
        d.appendChild(g);
        const lip = document.createElement('button');       // M5: lip-sync from this audio
        lip.className = 'lip'; lip.textContent = '🗣';
        lip.title = 'lip-sync: rhubarb this audio → viseme keys on a character';
        lip.onclick = () => this._lipSync(r.clip, lip);
        d.appendChild(lip);
      } else d.textContent = r.label;
      this.$names.appendChild(d);
    });
    // size lanes to content so no row (esp. Cameras) is clipped as rows grow.
    // ponytail: grow-to-content; add a max-height+scroll only if a scene ever
    // has so many entities the panel dominates the viewport.
    const hpx = RULER_H + this.rows.length * ROW_H;
    this.$names.style.height = hpx + 'px';
    this.lanesEl.style.height = hpx + 'px';
    this.draw();
  }

  // ---- geometry ----
  _dims() {
    const w = this.canvas.clientWidth, h = this.canvas.clientHeight;
    const dpr = window.devicePixelRatio || 1;
    if (this.canvas.width !== w * dpr || this.canvas.height !== h * dpr) {
      this.canvas.width = w * dpr; this.canvas.height = h * dpr;
    }
    return { w, h, dpr, pps: (w / (this.tl.duration || 1)) * this._zoom };
  }
  _x2t(x) { const { pps } = this._dims(); return Math.max(0, Math.min(this.tl.duration, this._panT + x / pps)); }
  _t2x(t) { const { pps } = this._dims(); return (t - this._panT) * pps; }
  // UX (session-5 nit): plain wheel is NOT captured — the page scrolls as users
  // expect. Cmd/Ctrl+wheel (incl. trackpad pinch → ctrlKey) zooms around the
  // cursor; horizontal wheel pans when zoomed in.
  _wheel(e) {
    const zoomG = e.ctrlKey || e.metaKey;
    const panG = this._zoom > 1 && Math.abs(e.deltaX) > Math.abs(e.deltaY);
    if (!zoomG && !panG) return;
    e.preventDefault();
    const { x } = this._local(e);
    const { w, pps } = this._dims();
    if (zoomG) {
      const tAt = this._panT + x / pps;                      // time under the cursor
      this._zoom = Math.max(1, Math.min(64, this._zoom * Math.pow(1.0015, -e.deltaY)));
      this._panT = tAt - x / ((w / (this.tl.duration || 1)) * this._zoom);   // keep it under the cursor
    } else {
      this._panT += e.deltaX / pps;
    }
    const view = (this.tl.duration || 1) / this._zoom;       // visible seconds
    this._panT = Math.max(0, Math.min(this.tl.duration - view, this._panT));
    this.draw();
  }
  _rowAtY(y) { const i = Math.floor((y - RULER_H) / ROW_H); return (i >= 0 && i < this.rows.length) ? i : -1; }

  // ---- draw ----
  draw() {
    if (!this.rows) this.rows = this._rows();
    const { w, h, dpr } = this._dims();
    const c = this.canvas.getContext('2d');
    c.setTransform(dpr, 0, 0, dpr, 0, 0);
    c.clearRect(0, 0, w, h);
    this._hits = [];

    // ruler
    c.fillStyle = '#12161c'; c.fillRect(0, 0, w, RULER_H);
    c.fillStyle = '#565f6b'; c.font = '10px ui-monospace';
    const dur = this.tl.duration || 1;
    const stepSec = dur <= 5 ? 0.5 : dur <= 20 ? 1 : 5;
    for (let t = 0; t <= dur + 1e-6; t += stepSec) {
      const x = this._t2x(t);
      c.strokeStyle = '#1b2027'; c.beginPath(); c.moveTo(x, 0); c.lineTo(x, h); c.stroke();
      c.fillText(t.toFixed(stepSec < 1 ? 1 : 0) + 's', x + 2, 12);
    }

    // lanes
    this.rows.forEach((r, i) => {
      const y = RULER_H + i * ROW_H;
      c.fillStyle = i % 2 ? '#161a20' : '#13171d';
      c.fillRect(0, y, w, ROW_H);
      c.strokeStyle = '#1b2027'; c.beginPath(); c.moveTo(0, y + ROW_H); c.lineTo(w, y + ROW_H); c.stroke();
      if (r.type === 'transform') this._drawKeys(c, r, y);
      else if (r.type === 'params') this._drawParams(c, r, y);
      else if (r.type === 'morphs') this._drawMorphs(c, r, y);
      else if (r.type === 'clip') this._drawClips(c, r, y);
      else if (r.type === 'cameras') this._drawCuts(c, y);
      else if (r.type === 'audio') this._drawAudio(c, r, y);
    });

    // box-select overlay
    const d = this._drag;
    if (d && d.kind === 'box' && d.moved) {
      c.fillStyle = 'rgba(122,162,247,0.15)'; c.strokeStyle = '#7aa2f7';
      const x = Math.min(d.x0, d.x), y = Math.min(d.y0, d.y);
      c.fillRect(x, y, Math.abs(d.x - d.x0), Math.abs(d.y - d.y0));
      c.strokeRect(x + 0.5, y + 0.5, Math.abs(d.x - d.x0), Math.abs(d.y - d.y0));
    }

    // playhead
    const px = this._t2x(this.tl.time);
    c.strokeStyle = '#f7768e'; c.lineWidth = 1.5;
    c.beginPath(); c.moveTo(px, 0); c.lineTo(px, h); c.stroke(); c.lineWidth = 1;
    c.fillStyle = '#f7768e'; c.beginPath(); c.moveTo(px - 4, 0); c.lineTo(px + 4, 0); c.lineTo(px, 6); c.fill();

    this.$clock.textContent = this.tl.time.toFixed(2) + 's';
    this.$play.textContent = this.tl.playing ? '❚❚' : '▶';
  }

  _entity(id) { return this.stage.getEntity(id); }          // stage: live transform/existence
  _te(id) { return this.tl.scene.entities.find((e) => e.id === id); }  // timeline: authoritative tracks
  _selected(k) { return this._selKeys.some((s) => s.key === k); }

  _diamond(c, x, cy, r, fill, sel) {
    c.fillStyle = fill;
    c.beginPath(); c.moveTo(x, cy - r); c.lineTo(x + r, cy); c.lineTo(x, cy + r); c.lineTo(x - r, cy); c.closePath(); c.fill();
    if (sel) { c.strokeStyle = '#fff'; c.lineWidth = 1.5; c.stroke(); c.lineWidth = 1; }
  }
  _drawKeys(c, r, y) {
    const cy = y + ROW_H / 2;
    const keys = (this._te(r.id)?.tracks?.transform) || [];
    for (const k of keys) {
      const x = this._t2x(k.t);
      this._diamond(c, x, cy, KEY_R, '#7aa2f7', this._selected(k));
      this._hits.push({ kind: 'key', id: r.id, track: 'transform', key: k, x, y: cy });
    }
  }
  _paramColor(name) { let h = 0; for (const ch of name) h = (h * 31 + ch.charCodeAt(0)) % 360; return `hsl(${h},55%,62%)`; }
  _drawParams(c, r, y) {
    const cy = y + ROW_H / 2;
    const keys = (this._te(r.id)?.tracks?.params) || [];
    for (const k of keys) {
      const x = this._t2x(k.t);
      this._diamond(c, x, cy, 4, this._paramColor(k.key), this._selected(k));
      this._hits.push({ kind: 'key', id: r.id, track: 'params', key: k, x, y: cy });
    }
  }
  _drawClips(c, r, y) {
    const blocks = (this._te(r.id)?.tracks?.clips) || [];
    for (const b of blocks) {
      const span = (b.out - b.in) || 0.0001, end = b.start + span * (b.loop || 1);
      const x0 = this._t2x(b.start), x1 = this._t2x(end), bw = Math.max(2, x1 - x0);
      c.fillStyle = '#3d5a80'; c.fillRect(x0, y + 5, bw, ROW_H - 10);
      c.strokeStyle = '#98c1d9'; c.strokeRect(x0 + 0.5, y + 5.5, bw - 1, ROW_H - 11);
      if (b.fade > 0) { // fade-out wedge at the tail
        const fx = this._t2x(end - b.fade);
        c.fillStyle = 'rgba(231,175,104,0.35)'; c.fillRect(fx, y + 5, x1 - fx, ROW_H - 10);
      }
      c.fillStyle = '#e0e6ed'; c.font = '10px ui-monospace';
      c.save(); c.beginPath(); c.rect(x0, y, x1 - x0, ROW_H); c.clip();
      c.fillText((b.path || '').split('/').pop(), x0 + 4, y + ROW_H / 2 + 3); c.restore();
      this._hits.push({ kind: 'block', id: r.id, block: b, x0, x1, y });
      this._hits.push({ kind: 'edge', id: r.id, block: b, side: 'out', x: x1, y });
    }
  }
  _drawCuts(c, y) {
    const cy = y + ROW_H / 2;
    for (const cut of this.tl.cameraCuts) {
      const x = this._t2x(cut.t);
      c.fillStyle = '#e0af68'; c.fillRect(x - 1, y + 4, 2, ROW_H - 8);
      c.beginPath(); c.arc(x, cy, 4, 0, Math.PI * 2); c.fill();
      c.fillStyle = '#161a20'; c.font = '9px ui-monospace'; c.fillText(cut.camera || '?', x + 6, cy + 3);
      this._hits.push({ kind: 'cut', cut, x, y: cy });
    }
  }
  _drawMorphs(c, r, y) {
    const cy = y + ROW_H / 2;
    const keys = (this._te(r.id)?.tracks?.morphs) || [];
    for (const k of keys) {
      const x = this._t2x(k.t);
      this._diamond(c, x, cy, 4, this._paramColor(k.key), this._selected(k));
      this._hits.push({ kind: 'key', id: r.id, track: 'morphs', key: k, x, y: cy });
    }
  }
  _drawAudio(c, r, y) {
    const clip = r.clip;
    const srcDur = this._audioDur(clip.path);
    const inT = clip.in || 0;                          // trim within the source (like clip blocks)
    const outT = clip.out ?? srcDur;
    const len = outT != null ? Math.max(0.05, outT - inT) : null;
    const x0 = this._t2x(clip.start);
    const x1 = len != null ? this._t2x(clip.start + len) : x0 + 60;   // fallback width until decoded
    const bw = Math.max(3, x1 - x0);
    c.fillStyle = '#2e7d5b'; c.fillRect(x0, y + 5, bw, ROW_H - 10);
    c.strokeStyle = '#57c99a'; c.strokeRect(x0 + 0.5, y + 5.5, bw - 1, ROW_H - 11);
    c.fillStyle = '#dff5ea'; c.font = '10px ui-monospace';
    c.save(); c.beginPath(); c.rect(x0, y, bw, ROW_H); c.clip();
    const trimmed = clip.in != null || clip.out != null;
    c.fillText((trimmed ? '✂ ' : '') + (clip.path || '').split('/').pop() + (srcDur == null ? ' …' : ''), x0 + 4, y + ROW_H / 2 + 3); c.restore();
    this._hits.push({ kind: 'audioblock', clip, x0, x1, y });
    if (len != null) {                                  // drag an edge = trim (head / tail)
      this._hits.push({ kind: 'aedge', clip, side: 'out', x: x1, y });
      this._hits.push({ kind: 'aedge', clip, side: 'in', x: x0, y });
    }
  }

  // ---- interaction ----
  _local(e) { const r = this.canvas.getBoundingClientRect(); return { x: e.clientX - r.left, y: e.clientY - r.top }; }
  _snap(t, e) {
    if ((e && e.altKey) || !this._snapOn) return t;
    const step = this._snapStep === 'frame' ? 1 / this.tl.fps : (+this._snapStep || 1 / this.tl.fps);
    return Math.round(t / step) * step;
  }
  _hitAt(x, y) {
    for (const h of this._hits) {
      if (h.kind === 'key' || h.kind === 'cut') { if (Math.abs(h.x - x) < 7 && Math.abs(h.y - y) < 9) return h; }
      else if (h.kind === 'edge' || h.kind === 'aedge') { if (Math.abs(h.x - x) < 5 && y > h.y && y < h.y + ROW_H) return h; }
    }
    for (const h of this._hits) if ((h.kind === 'block' || h.kind === 'audioblock') && x >= h.x0 && x <= h.x1 && y > h.y && y < h.y + ROW_H) return h;
    return null;
  }
  _seek(t) { this.tl.seek(t); if (this.tl.playing) this._audioStart(); }   // user seek: reschedule audio
  _keysInRect(x0, y0, x1, y1) {
    const ax = Math.min(x0, x1), bx = Math.max(x0, x1), ay = Math.min(y0, y1), by = Math.max(y0, y1);
    const out = [];
    for (const h of this._hits) if (h.kind === 'key' && h.x >= ax && h.x <= bx && h.y >= ay && h.y <= by) out.push({ id: h.id, track: h.track, key: h.key });
    return out;
  }

  _down(e) {
    const { x, y } = this._local(e);
    if (y < RULER_H) { this._drag = { kind: 'seek' }; this._seek(this._x2t(x)); return; }
    const h = this._hitAt(x, y);
    if (!h) { this._drag = { kind: 'box', x0: x, y0: y, x, y, moved: false }; return; }  // empty → box/seek
    if (h.kind === 'key') {
      if (this._selected(h.key) && this._selKeys.length > 1) {
        this._drag = { kind: 'multikey', grabT: this._x2t(x), orig: this._selKeys.map((s) => ({ ...s, t0: s.key.t })) };
      } else { this._selKeys = []; this._drag = { kind: 'key', h }; }
    } else if (h.kind === 'edge') this._drag = { kind: 'trim', h };
    else if (h.kind === 'aedge') this._drag = { kind: 'atrim', h };
    else if (h.kind === 'block') this._drag = { kind: 'block', h, grabT: this._x2t(x) - h.block.start };
    else if (h.kind === 'audioblock') this._drag = { kind: 'audio', h, grabT: this._x2t(x) - h.clip.start };
    else if (h.kind === 'cut') this._drag = { kind: 'cut', h };
  }
  _move(e) {
    if (!this._drag) return;
    const { x, y } = this._local(e);
    const t = this._x2t(x), d = this._drag;
    if (d.kind === 'seek') this._seek(t);
    else if (d.kind === 'key') { this.tl.moveKey(d.h.id, d.h.track, d.h.key, this._snap(t, e)); this.draw(); }
    else if (d.kind === 'multikey') { for (const s of d.orig) this.tl.moveKey(s.id, s.track, s.key, this._snap(s.t0 + (t - d.grabT), e)); this.draw(); }
    else if (d.kind === 'cut') { d.h.cut.t = this._snap(t, e); this.tl.cameraCuts.sort((a, b) => a.t - b.t); this.tl._activeCam = undefined; this.draw(); }
    else if (d.kind === 'block') { this.tl.moveClipBlock(d.h.id, d.h.block, Math.max(0, this._snap(t - d.grabT, e))); this.draw(); }
    else if (d.kind === 'audio') { this.tl.moveAudio(d.h.clip, this._snap(t - d.grabT, e)); this.draw(); }
    else if (d.kind === 'trim') { const b = d.h.block; this.tl.trimClipBlock(d.h.id, b, { out: Math.max(b.in + 0.05, b.in + (t - b.start)) }); this.draw(); }
    else if (d.kind === 'atrim') {
      const cl = d.h.clip, srcDur = this._audioDur(cl.path);
      if (d.h.side === 'in') this.tl.trimAudioIn(cl, this._snap(t, e), srcDur);   // head trim: in + start together
      else {
        let out = (cl.in || 0) + (t - cl.start);
        if (srcDur != null) out = Math.min(out, srcDur);
        this.tl.trimAudio(cl, { out });
      }
      this.draw();
    }
    else if (d.kind === 'box') { d.x = x; d.y = y; d.moved = Math.abs(x - d.x0) > 4 || Math.abs(y - d.y0) > 4; this.draw(); }
  }
  _up() {
    const d = this._drag; this._drag = null;
    if (!d) return;
    if (d.kind === 'box') {
      if (!d.moved) this._seek(this._x2t(d.x0));         // click on empty = seek
      else { this._selKeys = this._keysInRect(d.x0, d.y0, d.x, d.y); this.draw(); }
    }
  }

  _dbl(e) {
    const { x, y } = this._local(e);
    const i = this._rowAtY(y); if (i < 0) return;
    const r = this.rows[i];
    const t = this._snap(this._x2t(x), e);
    if (r.type === 'transform') {
      const cur = this.stage.entityTransform(r.id);
      this.tl.addKey(r.id, 'transform', { t, pos: cur.pos, rot: cur.rot, scale: cur.scale, ease: 'inout' });
      this.draw();
    } else if (r.type === 'params') {
      // capture every keyable param at its current value (mirrors transform capture)
      const params = (this._entity(r.id)?.params) || {};
      for (const [key, value] of Object.entries(params)) {
        if (key === 'type' || typeof value === 'boolean') continue;   // non-keyable descriptors
        this.tl.addKey(r.id, 'params', { t, key, value, ease: 'inout' });
      }
      this.draw();
    } else if (r.type === 'cameras') {
      const cams = this.stage.entities().filter((en) => en.kind === 'camera');
      const cam = this.tl._activeCam || (cams[0] && cams[0].id);
      if (cam) { this.tl.addCut(t, cam); this.tl.seek(this.tl.time); this.draw(); }
    }
  }
  _ctx(e) {
    e.preventDefault();
    const { x, y } = this._local(e);
    const h = this._hitAt(x, y);
    if (h && h.kind === 'key') { this.tl.deleteKey(h.id, h.track, h.key); this._selKeys = this._selKeys.filter((s) => s.key !== h.key); this.draw(); }
    else if (h && h.kind === 'cut') { const i = this.tl.cameraCuts.indexOf(h.cut); if (i >= 0) this.tl.cameraCuts.splice(i, 1); this.tl._activeCam = undefined; this.draw(); }
    else if (h && h.kind === 'audioblock') { this.tl.removeAudio(h.clip); this._syncRows(); }
  }
  _key(e) {
    if (e.target && (/INPUT|TEXTAREA|SELECT/.test(e.target.tagName) || e.target.isContentEditable)) return;
    if (e.key === '?') { e.preventDefault(); this._toggleHelp(); }   // never hijacked while typing
    else if (e.key === 'Escape') this._helpClose();
    else if (e.code === 'Space') { e.preventDefault(); this._toggle(); }
    else if (e.key === 'Home') this._seek(0);
    else if (e.key === 'End') this._seek(this.tl.duration);
    else if ((e.ctrlKey || e.metaKey) && e.key === 'z') { e.preventDefault(); this.tl.undo(); this.draw(); }
    else if ((e.key === 'Delete' || e.key === 'Backspace') && this._selKeys.length) {
      e.preventDefault();
      for (const s of this._selKeys) this.tl.deleteKey(s.id, s.track, s.key);
      this._selKeys = []; this.draw();
    }
  }
  _toggle() {
    if (this.tl.playing) { this.tl.pause(); this._audioStop(); }
    else { this.tl.play(); this._audioStart(); }
    this._wasPlaying = this.tl.playing;
    this.draw();
  }

  // ---- Web Audio (draft playback synced to the master clock). step()/render
  // NEVER touch this — the server muxes from scene.audio deterministically. ----
  _ensureCtx() {
    if (!this._audioCtx) { const C = window.AudioContext || window.webkitAudioContext; if (C) this._audioCtx = new C(); }
    return this._audioCtx;
  }
  _audioDur(path) { const b = this._audioBuf.get(path); return b ? b.duration : null; }
  async _decode(path) {
    if (this._audioBuf.has(path)) return this._audioBuf.get(path);
    const ctx = this._ensureCtx(); if (!ctx) return null;
    try {
      const res = await fetch('assets/file?path=' + encodeURIComponent(path));
      if (!res.ok) throw new Error(res.status);
      const buf = await ctx.decodeAudioData(await res.arrayBuffer());
      this._audioBuf.set(path, buf);
      this.draw();                       // width now known
      return buf;
    } catch { return null; }             // keep the block at fallback width
  }
  _decodeAll() { for (const clip of (this.tl.scene.audio || [])) this._decode(clip.path); }
  _audioStart() {
    const ctx = this._ensureCtx(); if (!ctx) return;
    if (ctx.state === 'suspended') ctx.resume();
    this._audioStop();
    const now = ctx.currentTime, t = this.tl.time;
    for (const clip of (this.tl.scene.audio || [])) {
      const buf = this._audioBuf.get(clip.path); if (!buf) continue;
      const inT = Math.min(clip.in || 0, buf.duration);          // trim within source
      const len = Math.min(clip.out ?? buf.duration, buf.duration) - inT;
      const offset = Math.max(0, t - clip.start);    // seconds into the (trimmed) block at playhead
      if (len <= 0 || offset >= len) continue;       // already finished
      const src = ctx.createBufferSource(); src.buffer = buf;
      const g = ctx.createGain(); g.gain.value = clip.gain ?? 1;
      src.connect(g).connect(ctx.destination);
      const when = now + Math.max(0, clip.start - t);
      src.start(when, inT + offset, len - offset);
      this._audioSrcs.push(src);
    }
  }
  _audioStop() { for (const s of this._audioSrcs) { try { s.stop(); } catch { /* already stopped */ } } this._audioSrcs = []; }

  async _pickAudio() {
    let list = [];
    try { const r = await fetch('assets/tree'); if (r.ok) list = (await r.json()).audio || []; } catch { /* offline */ }
    const menu = document.createElement('div'); menu.className = 'tl-menu';
    if (!list.length) menu.innerHTML = '<div class="empty">no audio in /assets/tree</div>';
    for (const it of list) {
      const path = it.path || it;
      const item = document.createElement('div'); item.className = 'item';
      item.textContent = (it.name || path).split('/').pop();
      item.onclick = async () => {
        this.tl.addAudio({ path, start: this.tl.time, gain: 1 });
        menu.remove();
        await this._decode(path);
        this._syncRows();
      };
      menu.appendChild(item);
    }
    document.body.appendChild(menu);
    const rect = this.$audioBtn.getBoundingClientRect();
    menu.style.left = rect.left + 'px'; menu.style.top = (rect.bottom + 2) + 'px';
    const close = (ev) => { if (!menu.contains(ev.target)) { menu.remove(); document.removeEventListener('mousedown', close); } };
    setTimeout(() => document.addEventListener('mousedown', close), 0);
  }

  // ---- M7-B: new from template (Lane C's read-only /templates) ----
  // All URLs stay RELATIVE — the app is served under /scenegod/ in prod.
  async _pickTemplate() {
    let list = [];
    try { const r = await fetch('templates'); if (r.ok) list = await r.json(); } catch { /* offline */ }
    const menu = document.createElement('div'); menu.className = 'tl-menu tmpl';
    if (!Array.isArray(list) || !list.length) menu.innerHTML = '<div class="empty">no starter templates on the server</div>';
    for (const t of (list || [])) {
      const item = document.createElement('div'); item.className = 'item';
      if (t.thumb) {
        const img = document.createElement('img');
        img.src = 'assets/file?path=' + encodeURIComponent(t.thumb);
        img.onerror = () => img.remove();            // thumb missing → text-only row
        item.appendChild(img);
      }
      const txt = document.createElement('div');
      const ti = document.createElement('div'); ti.className = 't'; ti.textContent = t.title || t.name;
      txt.appendChild(ti);
      if (t.description) { const d = document.createElement('div'); d.className = 'd'; d.textContent = t.description; txt.appendChild(d); }
      item.appendChild(txt);
      item.onclick = () => { menu.remove(); this.newFromTemplate(t.name); };
      menu.appendChild(item);
    }
    document.body.appendChild(menu);
    const rect = this.$tmplBtn.getBoundingClientRect();
    menu.style.top = (rect.bottom + 2) + 'px';
    menu.style.left = Math.max(4, Math.min(rect.left, window.innerWidth - menu.offsetWidth - 6)) + 'px';
    const close = (ev) => { if (!menu.contains(ev.target)) { menu.remove(); document.removeEventListener('mousedown', close); } };
    setTimeout(() => document.addEventListener('mousedown', close), 0);
  }

  // Applies exactly like load(): stage.applyState → tl.load → preload (all three
  // inside tl.applyScene, which also strips the presentation-only `template` key).
  async newFromTemplate(name) {
    if (this.tl.hasContent() && !confirm('Replace the current scene with this template? Unsaved work is lost.')) return;
    let json;
    try {
      const res = await fetch('templates/' + encodeURIComponent(name));
      if (!res.ok) throw new Error(res.status);
      json = await res.json();
    } catch (e) { this._toast('template "' + name + '" failed to load: ' + ((e && e.message) || e)); return; }
    try { await this.tl.applyScene(json); }
    catch (e) { this._toast('template failed to apply: ' + ((e && e.message) || e)); return; }
    this._decodeAll();
    this.draw();
  }

  // ---- M7-B: ? shortcuts overlay. Documents what the code ACTUALLY binds
  // (stage.js gizmo keys + dock drops + everything in _key/_down/_dbl/_ctx/
  // _wheel below). Toggle with ?, close with Escape or a click outside. ----
  _toggleHelp() {
    if (this._help) { this._helpClose(); return; }
    const S = (h, rows) => `<section><h4>${h}</h4><dl>` +
      rows.map(([k, v]) => `<dt>${k}</dt><dd>${v}</dd>`).join('') + '</dl></section>';
    const el = document.createElement('div'); el.className = 'tl-help';
    el.innerHTML = `<button class="close" title="close">✕</button>
      <h3>SCENEGOD shortcuts</h3><div class="hint">? toggles this panel · Escape closes it</div><div class="cols">` +
      S('STAGE', [
        ['drag / right-drag / wheel', 'orbit · pan · dolly the director cam'],
        ['click', 'select an object'],
        ['W / E / R', 'gizmo: move · rotate · scale (on the selection)'],
        ['drag a dock card in', 'place a character, prop or backdrop'],
        ['drag an animation onto a character', 'retarget + drop a clip block at the playhead'],
        ['drop files on the page', 'local glb/fbx/image/video (upload — not saved)'],
      ]) +
      S('TIMELINE', [
        ['Space', 'play / pause'],
        ['Home / End', 'jump to start / end'],
        ['click or drag the ruler', 'scrub'],
        ['double-click a transform lane', 'key the object where it stands now'],
        ['double-click a params lane', 'key its current params (fov, intensity, colour…)'],
        ['double-click the Cameras row', 'cut to the active camera'],
        ['drag a key', 'move it — snaps to the increment, Alt = free'],
        ['drag empty lane space', 'box-select keys; drag one of them to move them all'],
        ['Delete / Backspace', 'delete the selected keys'],
        ['right-click', 'delete a key, a cut, or an audio block'],
        ['drag a clip / audio block', 'move it; drag an edge to trim (audio trims either end)'],
        ['Cmd/Ctrl + wheel', 'zoom the time axis 1–64× around the cursor'],
        ['two-finger sideways', 'pan when zoomed in (plain wheel scrolls the page)'],
        ['Cmd/Ctrl + Z', 'undo — one director preset = one undo'],
      ]) +
      S('SCENE BAR', [
        ['New…', 'start from a starter template (asks before clobbering)'],
        ['Save / Load', 'scenes by name (falls back to localStorage offline)'],
        ['dur / snap', 'scene length · snap increment for drags'],
        ['🎵 / 🗣', 'add audio at the playhead · lip-sync that clip onto a character'],
      ]) + '</div>';
    el.querySelector('.close').onclick = () => this._helpClose();
    document.body.appendChild(el);
    this._help = el;
    // the ? button closes via _toggleHelp — don't let click-outside close first,
    // or the button would just reopen the panel on every click.
    this._helpAway = (ev) => { if (!el.contains(ev.target) && ev.target !== this.$helpBtn) this._helpClose(); };
    setTimeout(() => document.addEventListener('mousedown', this._helpAway), 0);
  }
  _helpClose() {
    if (!this._help) return;
    document.removeEventListener('mousedown', this._helpAway);
    this._help.remove(); this._help = null;
  }

  // ---- M5: lip-sync from audio (🗣 on an audio row) ----
  // GET /rhubarb?path=… → importRhubarb onto a viseme-bearing character.
  // >1 candidate → picker menu; 503 → toast the install hint from `detail`.
  async _lipSync(clip, anchorEl) {
    const vt = (id) => (this.stage.visemeTargets && this.stage.visemeTargets(id)) || [];
    const chars = this.stage.entities().filter((en) => en.kind === 'character' && vt(en.id).length > 0);
    if (!chars.length) { this._toast('no character with viseme morph targets in the scene'); return; }
    const id = chars.length === 1 ? chars[0].id
      : await this._choose(chars.map((c) => ({ label: c.label || c.id, value: c.id })), anchorEl);
    if (!id) return;
    let res;
    try { res = await fetch('rhubarb?path=' + encodeURIComponent(clip.path)); }
    catch { this._toast('server unreachable — /rhubarb needs Lane C running'); return; }
    if (!res.ok) {
      let msg = 'rhubarb failed: ' + res.status;
      try { const j = await res.json(); if (j.detail) msg = j.detail; } catch { /* non-json body */ }
      this._toast(msg); return;                      // 503 carries the rhubarb install hint
    }
    const json = await res.json();
    this.tl.importRhubarb(id, json, clip.start || 0);   // grouped: one undo reverts the import
    this._toast(`🗣 ${(json.mouthCues || []).length} cues → viseme keys on ${id}`);
    this.tl.seek(this.tl.time);
    this._syncRows();                                // viseme lane may be new
  }
  _choose(items, anchorEl) {                         // small promise-menu (resolves value | null)
    return new Promise((resolve) => {
      const menu = document.createElement('div'); menu.className = 'tl-menu';
      for (const it of items) {
        const el = document.createElement('div'); el.className = 'item'; el.textContent = it.label;
        el.onclick = () => { menu.remove(); resolve(it.value); };
        menu.appendChild(el);
      }
      document.body.appendChild(menu);
      const rect = anchorEl.getBoundingClientRect();
      menu.style.left = rect.left + 'px'; menu.style.top = (rect.bottom + 2) + 'px';
      const close = (ev) => { if (!menu.contains(ev.target)) { menu.remove(); document.removeEventListener('mousedown', close); resolve(null); } };
      setTimeout(() => document.addEventListener('mousedown', close), 0);
    });
  }
  _toast(msg) {
    const d = document.createElement('div'); d.className = 'tl-toast'; d.textContent = msg;
    document.body.appendChild(d);
    setTimeout(() => d.remove(), 4000);
  }

  // ---- persistence (Lane C endpoints; localStorage fallback) ----
  async save() {
    const name = (this.$name.value || 'untitled').trim();
    this.tl.scene.name = name;
    const json = this.tl.toJSON();
    try {
      const res = await fetch(`scenes/${encodeURIComponent(name)}`, {
        method: 'POST', headers: { 'content-type': 'application/json' }, body: JSON.stringify(json),
      });
      if (!res.ok) throw new Error(res.status);
    } catch {
      localStorage.setItem('scenegod:scene:' + name, JSON.stringify(json)); // fallback until Lane C reachable
    }
  }
  async load(name) {
    name = (name || '').trim(); if (!name) return;
    let json = null;
    try { const res = await fetch(`scenes/${encodeURIComponent(name)}`); if (res.ok) json = await res.json(); } catch { /* fall through */ }
    if (!json) { const raw = localStorage.getItem('scenegod:scene:' + name); if (raw) json = JSON.parse(raw); }
    if (!json) return;
    await this.tl.applyScene(json);     // stage.applyState → tl.load (onLoad → rows+bar) → preload
    this._decodeAll();                  // decode audio for lane widths + playback
    this.draw();
  }
}

export default TimelineUI;