// stagestub.js — dev-only fake Stage implementing the PLAN §4.2 API with
// plain objects, so Lane B's timeline can be built + tested headless before
// Lane A's real Stage lands. DELETED at SYNC 1 (one-line swap in the page).
// ponytail: no three.js, no DOM — runs under plain node for timeline_test.mjs.

const clone = (x) => (x == null ? x : JSON.parse(JSON.stringify(x)));

class StubAction {
  constructor(clip) {
    this._clip = clip;
    this.time = 0;
    this.weight = 0;
    this.enabled = false;
    this.paused = false;
  }
  play() { this._playing = true; return this; }
  reset() { this.time = 0; return this; }
}

// M6 seam: fake HTMLVideoElement for video backdrops/screens. Records every
// currentTime assignment so tests can assert "seek only when drift >50ms".
class StubVideo {
  constructor(duration) { this.duration = duration; this.paused = true; this.seeks = []; this._t = 0; }
  get currentTime() { return this._t; }
  set currentTime(v) { this._t = v; this.seeks.push(v); }
  play() { this.paused = false; return Promise.resolve(); }   // real video.play() → Promise
  pause() { this.paused = true; }
}

class StubMixer {
  constructor(id, stage) { this.id = id; this.stage = stage; this._actions = new Map(); }
  clipAction(clip) {
    if (!this._actions.has(clip)) this._actions.set(clip, new StubAction(clip));
    return this._actions.get(clip);
  }
  update(_dt) {
    // record every audibly-active action so tests can assert clip local time
    for (const a of this._actions.values()) {
      if (a.enabled && a.weight > 0) {
        this.stage.applied.push({ type: 'clip', id: this.id, clip: a._clip.name, time: a.time, weight: a.weight });
      }
    }
  }
}

export class StageStub {
  constructor(viewportEl) {
    this.viewportEl = viewportEl || null;
    this._entities = new Map();
    this._mixers = new Map();
    this._videos = new Map();
    this._clipCache = new Map();
    this._changeCbs = [];
    this._selectCbs = [];
    this._active = null;
    this._selected = null;
    this.applied = [];              // timeline effects land here for assertions
  }

  async addEntity(desc) {
    const e = clone(desc);
    if (!e.transform) e.transform = { pos: [0, 0, 0], rot: [0, 0, 0], scale: 1 };
    if (!e.params) e.params = {};
    this._entities.set(e.id, e);
    // M6: video backdrops/screens get a StubVideo (kept OUT of the entity
    // object so captureState stays clean). videoDuration is a stub-only knob.
    if (e.kind === 'screen' || (e.kind === 'backdrop' &&
        ((e.params && e.params.mode === 'video') || /\.mp4$/i.test((e.params && e.params.image) || '')))) {
      this._videos.set(e.id, new StubVideo((e.params && e.params.videoDuration) || 5));
    }
    this._fireChange(e);
    return e;
  }
  removeEntity(id) {
    const e = this._entities.get(id);
    this._entities.delete(id); this._mixers.delete(id); this._videos.delete(id);
    this._fireChange(e || { id });   // fire WITH the removed entity; getEntity(id) now null (real Stage contract)
  }
  getEntity(id) { return this._entities.get(id) || null; }
  entities() { return [...this._entities.values()]; }

  select(id) { this._selected = id; this._selectCbs.forEach((cb) => cb(id)); }
  onSelect(cb) { this._selectCbs.push(cb); }
  onChange(cb) { this._changeCbs.push(cb); }
  _fireChange(e) { this._changeCbs.forEach((cb) => cb(e)); }

  entityTransform(id) {
    const e = this._entities.get(id);
    return e ? clone(e.transform) : { pos: [0, 0, 0], rot: [0, 0, 0], scale: 1 };
  }
  setTransform(id, t) {
    const e = this._entities.get(id);
    if (e) e.transform = clone(t);
    this.applied.push({ type: 'transform', id, ...clone(t) });
    console.debug('stub.setTransform', id, t);
  }
  setParam(id, key, value) {
    const e = this._entities.get(id);
    if (e) { e.params = e.params || {}; e.params[key] = value; }
    this.applied.push({ type: 'param', id, key, value });
    console.debug('stub.setParam', id, key, value);
  }

  async prepareClip(id, path, clipIndex) {
    const k = `${path}#${clipIndex}`;                 // CACHED per §4.2
    if (!this._clipCache.has(k)) this._clipCache.set(k, { name: k, duration: 2.4 });
    return this._clipCache.get(k);
  }
  entityMixer(id) {
    if (!this._mixers.has(id)) this._mixers.set(id, new StubMixer(id, this));
    return this._mixers.get(id);
  }

  setActiveCamera(id) { this._active = id; this.applied.push({ type: 'camera', id }); console.debug('stub.setActiveCamera', id); }
  renderActiveCamera(_canvas) { /* noop in stub */ }

  // M4-B viseme seam (real Stage: Lane A). Entities may carry a `visemes` array.
  setMorph(id, name, weight) { this.applied.push({ type: 'morph', id, name, weight }); console.debug('stub.setMorph', id, name, weight); }
  visemeTargets(id) { const e = this._entities.get(id); return (e && e.visemes) || []; }

  // M6 seam (real Stage: Lane A): the HTMLVideoElement behind a video
  // backdrop/screen, or null (image backdrop, other kinds, not loaded yet).
  entityVideo(id) { return this._videos.get(id) || null; }

  captureState() { return this.entities().map(clone); }
  async applyState(scene) {
    this._entities.clear(); this._mixers.clear(); this._videos.clear();
    for (const e of (scene.entities || [])) await this.addEntity(e);
  }
}

export default StageStub;