// timeline_test.mjs — Lane B M1 self-check. Runs under plain `node`, no deps.
//   node scenegod/web/timeline_test.mjs
import assert from 'node:assert/strict';
import { StageStub } from './stagestub.js';
import { Timeline } from './timeline.js';

const near = (a, b, eps = 1e-6) => Math.abs(a - b) <= eps;

const scene = {
  version: 1, name: 'test', fps: 30, duration: 3,
  entities: [
    {
      id: 'e1', kind: 'character', label: 'lady',
      source: { type: 'assets', path: 'characters/lady.glb' },
      params: {}, transform: { pos: [0, 0, 0], rot: [0, 0, 0], scale: 1 },
      tracks: {
        transform: [
          { t: 0, pos: [0, 0, 0], rot: [0, 0, 0], scale: 1, ease: 'linear' },
          { t: 2, pos: [10, 0, 0], rot: [0, 0, 0], scale: 1, ease: 'linear' },
        ],
        clips: [
          { path: 'animations/walk.fbx', clipIndex: 0, start: 1.0, in: 0.0, out: 2.4, loop: 1, fade: 0 },
        ],
      },
    },
    {
      id: 'e2', kind: 'light', label: 'sun',
      params: { type: 'key', color: '#000000', intensity: 0 },
      transform: { pos: [0, 5, 0], rot: [0, 0, 0], scale: 1 },
      tracks: {
        params: [
          { t: 0, key: 'intensity', value: 0, ease: 'step' },
          { t: 2, key: 'intensity', value: 10, ease: 'step' },
        ],
      },
    },
    { id: 'cam1', kind: 'camera', params: { fov: 45 }, transform: { pos: [0, 1, 5], rot: [0, 0, 0], scale: 1 }, tracks: {} },
    { id: 'cam2', kind: 'camera', params: { fov: 60 }, transform: { pos: [5, 1, 5], rot: [0, 0, 0], scale: 1 }, tracks: {} },
  ],
  cameraCuts: [{ t: 0, camera: 'cam1' }, { t: 1.5, camera: 'cam2' }],
  audio: [],
};

const stage = new StageStub();
await stage.applyState(scene);
const tl = new Timeline(stage);
tl.load(scene);
await tl.preload();

const last = (pred) => { for (let i = stage.applied.length - 1; i >= 0; i--) if (pred(stage.applied[i])) return stage.applied[i]; return null; };

// step through 90 frames (3s @ 30fps)
for (let f = 0; f <= 90; f++) {
  stage.applied.length = 0;
  tl.step(f);

  if (f === 30) {                                    // t=1.0 → midpoint of a 2s linear move
    const tr = last((a) => a.type === 'transform' && a.id === 'e1');
    assert.ok(tr && near(tr.pos[0], 5, 1e-4), `midpoint x should be ~5, got ${tr && tr.pos[0]}`);
  }
  if (f === 15) {                                    // t=0.5 → ease:step holds start (0)
    const p = last((a) => a.type === 'param' && a.id === 'e2' && a.key === 'intensity');
    assert.ok(p && near(p.value, 0), `step-ease should hold 0, got ${p && p.value}`);
  }
  if (f === 45) {                                    // t=1.5 → clip active, local = 0.5 into walk
    const c = last((a) => a.type === 'clip' && a.id === 'e1');
    assert.ok(c && near(c.time, 0.5, 1e-6), `clip local time should be 0.5, got ${c && c.time}`);
    const cam = last((a) => a.type === 'camera');    // camera flips to cam2 at t>=1.5
    // cut fires only on change; check stage state instead
    assert.equal(stage._active, 'cam2', `active cam should be cam2 at t=1.5, is ${stage._active}`);
  }
  if (f === 20) {                                    // t=0.667 → before the 1.5s cut, still cam1
    assert.equal(stage._active, 'cam1', `active cam should be cam1 before cut, is ${stage._active}`);
  }
  if (f === 0) {                                     // clip not started at t=0
    const c = last((a) => a.type === 'clip' && a.id === 'e1');
    assert.equal(c, null, 'clip should be inactive at t=0');
  }
}

// clip sample frames: at t=1.0 (start) local=0, at t=2.4 local≈1.4
stage.applied.length = 0; tl.step(30); // t=1.0
let c = last((a) => a.type === 'clip' && a.id === 'e1');
assert.ok(c && near(c.time, 0, 1e-6), `clip local at start should be 0, got ${c && c.time}`);
stage.applied.length = 0; tl.step(72); // t=2.4
c = last((a) => a.type === 'clip' && a.id === 'e1');
assert.ok(c && near(c.time, 1.4, 1e-6), `clip local at 2.4 should be 1.4, got ${c && c.time}`);

// toJSON deep-equals a re-loaded copy (lossless round-trip)
const out = tl.toJSON();
const tl2 = new Timeline(new StageStub());
tl2.load(out);
assert.deepEqual(tl2.toJSON(), out, 'round-trip must be lossless');

// unknown entity fields preserved (Lane A owns them)
const withExtra = structuredClone(scene);
withExtra.entities[0].laneAOnly = { gizmo: 'move', foo: [1, 2, 3] };
const tl3 = new Timeline(new StageStub());
tl3.load(withExtra);
assert.deepEqual(tl3.toJSON().entities[0].laneAOnly, { gizmo: 'move', foo: [1, 2, 3] }, 'unknown fields must survive');

// ---- M2: onLoad fires ----
let loadFired = 0;
const tlL = new Timeline(new StageStub());
tlL.onLoad(() => loadFired++);
tlL.load(scene);
assert.equal(loadFired, 1, 'onLoad must fire once per load()');

// ---- M2: addClipDrop sets out = clip duration, drops block at playhead ----
const dropStage = new StageStub();
await dropStage.addEntity({ id: 'c1', kind: 'character', label: 'c', tracks: {} });
const tlD = new Timeline(dropStage);
tlD.load({ version: 1, fps: 30, duration: 10, entities: [{ id: 'c1', kind: 'character', tracks: {} }], cameraCuts: [] });
tlD.seek(2);
await tlD.addClipDrop({ id: 'c1', path: 'animations/run.fbx', clipIndex: 0 });
const blk = tlD.scene.entities[0].tracks.clips[0];
assert.ok(blk && near(blk.start, 2) && near(blk.out, 2.4), `clipdrop block start=2 out=2.4, got ${blk && blk.start}/${blk && blk.out}`);

// ---- M2: crossfade — two abutting blocks fade through ~0.5 at the boundary ----
const xStage = new StageStub();
await xStage.addEntity({ id: 'c2', kind: 'character', tracks: {} });
const tlX = new Timeline(xStage);
tlX.load({
  version: 1, fps: 30, duration: 10, cameraCuts: [],
  entities: [{ id: 'c2', kind: 'character', tracks: { clips: [
    { path: 'a.fbx', clipIndex: 0, start: 0, in: 0, out: 1.0, loop: 1, fade: 0.4 },
    { path: 'b.fbx', clipIndex: 0, start: 1.0, in: 0, out: 1.0, loop: 1, fade: 0 },
  ] } }],
});
await tlX.preload();
xStage.applied.length = 0;
tlX.step(24);                                     // t=0.8 → mid of block-A's [0.6,1.0] fade
const lastIn = (arr, pred) => { for (let i = arr.length - 1; i >= 0; i--) if (pred(arr[i])) return arr[i]; return null; };
const wa = lastIn(xStage.applied, (a) => a.type === 'clip' && a.clip === 'a.fbx#0');
const wb = lastIn(xStage.applied, (a) => a.type === 'clip' && a.clip === 'b.fbx#0');
assert.ok(wa && near(wa.weight, 0.5, 1e-6), `A fade-out weight ~0.5, got ${wa && wa.weight}`);
assert.ok(wb && near(wb.weight, 0.5, 1e-6), `B fade-in weight ~0.5, got ${wb && wb.weight}`);
assert.ok(near(wa.weight + wb.weight, 1, 1e-6), 'crossfade weights sum to 1');

console.log('OK — timeline_test.mjs: all assertions passed');