// PROCITY Lane C — build context: the seed + disposal backbone every interior module shares.
//
// Two hard constraints this file exists to satisfy (CITY_SPEC + LANE_C acceptance):
//   1. DETERMINISM. All randomness in an interior derives from `shop.seed`. We hand out
//      INDEPENDENT sub-streams keyed by a salt string, so adding a fitting in one subsystem
//      never shifts the wallpaper pick in another. Math.random() is banned in generation.
//   2. LEAK-FREE DISPOSAL. The 50-room soak must return renderer.info.memory to baseline.
//      Every geometry / material / CanvasTexture we mint per room is tracked and freed in
//      dispose(). Globally-cached FILE textures (loaders.loadTex) are shared across rooms by
//      design and are NOT disposed here — that's a bounded cache, not a leak.

import { mulberry32, xmur3 } from '../core/prng.js';
import * as THREE_NS from 'three';

// Deterministic 32-bit hash of a salt string → xor'd into the seed for an independent stream.
const hash = (s) => xmur3(s)();

// One shared TextureLoader for per-surface tiled loads (each surface needs its own repeat).
const _texLoader = new THREE_NS.TextureLoader();

export class Ctx {
  constructor(THREE, seed) {
    this.THREE = THREE;
    this.seed = seed >>> 0;
    this._geometries = new Set();   // per-room BufferGeometry — dispose all
    this._materials = new Set();    // per-room Material — dispose all
    this._canvasTex = new Set();    // per-room CanvasTexture + tiled file textures — dispose all
    this._streams = new Map();      // salt → mulberry32 fn (memoized so a salt is stable)
    this._geoCache = new Map();     // dims-key → shared geometry (stock items reuse; disposed once)
    this._disposed = false;
  }

  // An independent, memoized seeded stream for a subsystem. stream('wallpaper') always returns
  // the same sequence for a given seed, regardless of what other subsystems do.
  stream(salt) {
    let s = this._streams.get(salt);
    if (!s) { s = mulberry32((this.seed ^ hash(salt)) >>> 0); this._streams.set(salt, s); }
    return s;
  }

  // A one-shot seeded value 0..1 (fresh stream, not advancing anyone else's).
  rand(salt) { return mulberry32((this.seed ^ hash(salt)) >>> 0)(); }

  // ---- tracked resource factories -------------------------------------------------

  geom(g) { this._geometries.add(g); return g; }

  // Shared geometry caches — the same box/plane/cyl dims are reused across the many stock items in a
  // room (a book barn has hundreds of identically-sized spines). Cuts allocation + build time hugely;
  // each cached geometry is tracked once and disposed once. Dims rounded to 2mm to key the cache.
  boxGeo(w, h, d) {
    const k = `b${Math.round(w * 500)},${Math.round(h * 500)},${Math.round(d * 500)}`;
    let g = this._geoCache.get(k);
    if (!g) { g = this.geom(new this.THREE.BoxGeometry(w, h, d)); this._geoCache.set(k, g); }
    return g;
  }
  planeGeo(w, h) {
    const k = `p${Math.round(w * 500)},${Math.round(h * 500)}`;
    let g = this._geoCache.get(k);
    if (!g) { g = this.geom(new this.THREE.PlaneGeometry(w, h)); this._geoCache.set(k, g); }
    return g;
  }
  cylGeo(r, h, seg) {
    const k = `c${Math.round(r * 500)},${Math.round(h * 500)},${seg}`;
    let g = this._geoCache.get(k);
    if (!g) { g = this.geom(new this.THREE.CylinderGeometry(r, r, h, seg)); this._geoCache.set(k, g); }
    return g;
  }

  // MeshStandardMaterial with sane 90s-matte defaults; colour accepts hex/number/THREE.Color.
  mat(color = 0xcccccc, roughness = 0.9, opts = {}) {
    const m = new this.THREE.MeshStandardMaterial({
      color: new this.THREE.Color(color), roughness, metalness: 0, ...opts,
    });
    this._materials.add(m);
    return m;
  }

  // Cheap box helper — the workhorse. Geometry shared via cache; material tracked for disposal.
  box(w, h, d, material, x = 0, y = 0, z = 0, parent = null) {
    const me = new this.THREE.Mesh(this.boxGeo(w, h, d), material);
    me.position.set(x, y, z);
    if (parent) parent.add(me);
    return me;
  }

  plane(w, h, material, parent = null) {
    const me = new this.THREE.Mesh(this.planeGeo(w, h), material);
    if (parent) parent.add(me);
    return me;
  }

  // Cylinder helper (rails, uprights, spinner posts). rz rotates for horizontal rails.
  cyl(r, h, material, x = 0, y = 0, z = 0, parent = null, rz = 0, seg = 12) {
    const me = new this.THREE.Mesh(this.cylGeo(r, h, seg), material);
    me.position.set(x, y, z);
    me.rotation.z = rz;
    if (parent) parent.add(me);
    return me;
  }

  // Per-room CanvasTexture (tracked → disposed). Use for signs and stock sleeves.
  canvasTexture(canvas) {
    const t = new this.THREE.CanvasTexture(canvas);
    t.colorSpace = this.THREE.SRGBColorSpace;
    t.anisotropy = 4;
    this._canvasTex.add(t);
    return t;
  }

  // Skin a material with a tiled file texture, thriftgod-style: the map is assigned ONLY inside the
  // load callback (so nothing renders a mapless-but-marked texture → no "no image data" warnings,
  // and the flat-colour fallback shows until the file resolves). Each tiled surface gets its OWN
  // texture (per-wall/floor repeat differs). The texture is TRACKED immediately for disposal; if the
  // room is disposed before the load finishes, the callback no-ops (guarded by _disposed).
  skin(material, url, { repeat = null, tint = 0xcccccc } = {}) {
    const t = _texLoader.load(url, () => {
      if (this._disposed) return;
      material.map = t; material.color.set(tint); material.needsUpdate = true;
    }, undefined, () => { /* missing asset → fallback colour stays */ });
    t.colorSpace = this.THREE.SRGBColorSpace;
    t.anisotropy = 4;
    if (repeat) { t.wrapS = t.wrapT = this.THREE.RepeatWrapping; t.repeat.set(repeat[0], repeat[1]); }
    this._canvasTex.add(t);                // per-room texture → freed in disposeAll()
    return material;
  }

  disposeAll() {
    this._disposed = true;                 // late texture-load callbacks will no-op after this
    for (const g of this._geometries) g.dispose();
    for (const m of this._materials) m.dispose();
    for (const t of this._canvasTex) t.dispose();
    this._geometries.clear();
    this._materials.clear();
    this._canvasTex.clear();
    this._streams.clear();
    this._geoCache.clear();
  }

  // Snapshot for the leak assertion / debugging.
  counts() {
    return {
      geometries: this._geometries.size,
      materials: this._materials.size,
      canvasTextures: this._canvasTex.size,
    };
  }
}

// Seeded helpers that take an explicit stream fn (so callers stay deterministic).
export const pick = (r, arr) => arr[(r() * arr.length) | 0];
export const irange = (r, lo, hi) => lo + ((r() * (hi - lo + 1)) | 0);
export const frange = (r, lo, hi) => lo + r() * (hi - lo);
export const chance = (r, p) => r() < p;
export function shuffle(r, arr) {
  for (let i = arr.length - 1; i > 0; i--) {
    const j = (r() * (i + 1)) | 0;
    [arr[i], arr[j]] = [arr[j], arr[i]];
  }
  return arr;
}
// Weighted pick: items = [{...,weight}]; returns the item.
export function weighted(r, items) {
  const total = items.reduce((s, it) => s + (it.weight || 1), 0);
  let t = r() * total;
  for (const it of items) { t -= (it.weight || 1); if (t <= 0) return it; }
  return items[items.length - 1];
}