// PROCITY Lane C — optional GLB-upgrade layer. Reads Lane E's web/assets/manifest.json and swaps a
// primitive fitting for a detailed depot GLB where one exists ("reserve the detailed GLB hero props
// for where the camera gets close" — RESEARCH). Strictly ADDITIVE and OFF by default:
//   • the whole lane runs 100% on primitives with no manifest and no network (LANE_C acceptance);
//   • enable per build with opts.useGLB (interiors.js), or globally via preloadManifest().
//
// Pattern (house law): promise-cached loader, PLACEHOLDER-PERSISTS — the primitive shows immediately
// and stays until the GLB resolves; if the depot is unreachable the primitive stays forever (never a
// crash, never a blank). The GLB is placed at real-metre scale (glb_law), yaw-corrected per kind, and
// clamped to the primitive's reserved footprint, so occupancy/paths already computed by layout.js stay valid.

import { loadGLB } from '../core/loaders.js';
import { clone as skeletonClone } from 'three/addons/utils/SkeletonUtils.js';

// my fitting kind → manifest.fittings id (only kinds with a depot GLB; others stay primitive).
// NOTE: `counter` is intentionally NOT mapped — the counter GLB (procity_fit_counter_01.glb) is a real
// 4.0 m-long × 1.1 m asset that squashes to ~0.6 m when fit to the ~2.2 m interior counter slot and has
// no till modelled; the primitive counter (correct height + till + keeper stand) reads better. Reported
// to Lane E (see C-progress.md / LANE_C_GLB_VALIDATION.md). Re-map here once a ~2 m counter asset lands.
const KIND_TO_GLB = {
  crate: 'record_crate', recordBin: 'record_crate',   // record_crate GLB currently fails to load → fail-soft to primitive (reported)
  metalShelf: 'wire_shelf', wallShelf: 'wire_shelf',
  clothesRack: 'clothes_rack',
  bookshelf: 'bookshelf',
  cubeShelf: 'cube_shelf_wide',
  trestleTable: 'work_table',
};

// Per-kind facing correction (radians, about +Y). The GLBs follow glb_law (metres, +Y up, base at origin)
// but carry NO automatic facing (manifest.conventions.facing: "Lane B/C rotate directional props"). The
// z-major assets (bookshelf/cube/work_table are modelled wide along Z) need a quarter-turn so their width
// runs along the fitting's X, matching the primitive the layout placed. Tuned by on-screen validation.
const KIND_TO_YAW = {
  bookshelf: Math.PI / 2,
  cubeShelf: Math.PI / 2,
  trestleTable: Math.PI / 2,
};

let _manifestP = null;
// Fetch + cache the manifest. Returns null (not throw) if absent/unreachable → primitives everywhere.
export function preloadManifest(url = 'assets/manifest.json') {
  return (_manifestP ||= fetch(url).then(r => (r.ok ? r.json() : null)).catch(() => null));
}
export function manifestReady() { return _manifestP && typeof _manifestP.then === 'function' ? _manifestP : Promise.resolve(null); }

// Upgrade one placed fitting in-place, if the manifest maps its kind. No-op when disabled/unavailable.
// `manifest` is the resolved object (or null). ctx is the room build context (for the _disposed guard).
// Returns a promise that settles when the swap is done (or immediately when there is nothing to do), so
// callers can await a room's GLB upgrades (buildInterior exposes this as room.glbReady).
// Resolution: production uses `depot:<file>` (loaders.js → depot CDN / local-depot). A manifest may set
// `localBase` (e.g. "assets/_local_glb/") to load straight from a served local dir — used for offline
// GLB validation before the depot is reachable.
export function upgradeFitting(ctx, fitting, kind, manifest) {
  if (!manifest || !manifest.fittings) return Promise.resolve();
  const id = KIND_TO_GLB[kind];
  const entry = id && manifest.fittings[id];
  if (!entry || !entry.file) return Promise.resolve();

  const ref = manifest.localBase ? `${manifest.localBase}${entry.file}` : `depot:${entry.file}`;
  return loadGLB(ref).then(gltf => {
    if (!gltf || ctx._disposed || !fitting.group.parent) return;   // room rebuilt / disposed mid-flight
    const THREE = ctx.THREE;
    const inst = skeletonClone(gltf.scene);                        // clone-safe even if skinned
    // Facing: rotate the directional prop to match the primitive the layout placed (before measuring).
    inst.rotation.y = KIND_TO_YAW[kind] || 0;
    // Scale: GLBs are authored in metres (glb_law), so keep REAL-WORLD scale — only shrink if the prop
    // would overflow the footprint the occupancy grid reserved (never inflate a small prop to fill a slot).
    const bb = new THREE.Box3().setFromObject(inst);
    const size = new THREE.Vector3(); bb.getSize(size);
    const want = fitting.footprint;
    const glbW = Math.max(size.x, size.z) || 1;
    const s = Math.min(1, Math.max(want.w, want.d) / glbW);
    inst.scale.setScalar(s);
    inst.position.y -= bb.min.y * s;                               // plant on the floor (glb_law minY≈0)
    // hide the primitive FRAME (the first frameCount children) but keep procedural stock — which was
    // added after the frame — visible on top of the detailed GLB shelf/counter.
    const frameCount = fitting.frameCount ?? fitting.group.children.length;
    for (let i = 0; i < frameCount && i < fitting.group.children.length; i++) fitting.group.children[i].visible = false;
    inst.userData = { glbUpgrade: true, kind };
    fitting.group.add(inst);
  });
}

// Upgrade every placed fitting in a room. Called from buildInterior when GLB mode is on.
// Returns a promise resolving once all in-room fittings' GLB swaps have settled.
export function upgradeRoom(ctx, placed, manifest) {
  if (!manifest) return Promise.resolve();
  return Promise.all(placed.filter(p => !p.removed).map(p => upgradeFitting(ctx, p.fitting, p.kind, manifest)));
}