/**
 * SHADES — the yard. Lane A owns this file.
 *
 * M0 is deliberately graybox: every mesh here is a stand-in with the right
 * dimensions and the right NAME, so Lane E's real GLBs drop into the same slots
 * without anyone re-deriving positions. What is NOT placeholder, and what other
 * lanes should build against, is the layout: anchor positions, ground heights,
 * the garden rect and the sun direction.
 *
 * Geometry conventions: meters, +Y up, origin at yard centre on the ground.
 * North (-Z) is the house edge. The yard is 30 (x) by 20 (z).
 */

import * as THREE from '../vendor/three.module.js';
import { YARD, createStubWind } from './contracts.js';

/**
 * Ground height in meters at a world XZ. Pure and cheap — this is called by the
 * player every frame and by every piece of debris, so it stays closed-form
 * rather than sampling a texture. Gentle by design (about ±0.3 m): enough that
 * water has somewhere to go and the yard doesn't read as a table, not so much
 * that it fights the rigging puzzle.
 *
 * @param {number} x
 * @param {number} z
 * @returns {number}
 */
export function heightAt(x, z) {
  return (
    0.18 * Math.sin(x * 0.21 + 1.3) * Math.cos(z * 0.27 - 0.4) +
    0.09 * Math.sin(x * 0.53 - 2.1) * Math.sin(z * 0.41 + 0.8) -
    0.06 * Math.cos(x * 0.11)
  );
}

const GARDEN_BED = { x: 1, z: 2, w: 6, d: 4 };

// Sun: mid-afternoon, high and off the north-west shoulder. Elevation 55°.
// Stored as the direction from the GROUND toward the SUN (see contracts.js).
const SUN_ELEV = (55 * Math.PI) / 180;
const SUN_AZIM = (-125 * Math.PI) / 180;
const SUN_DIR = new THREE.Vector3(
  Math.cos(SUN_ELEV) * Math.sin(SUN_AZIM),
  Math.sin(SUN_ELEV),
  Math.cos(SUN_ELEV) * Math.cos(SUN_AZIM),
).normalize();

const COLORS = {
  sky: 0x9fc4dd,
  grass: 0x4a7c3f,
  soil: 0x6b4a2f,
  plant: 0x7fce6a,
  house: 0x8a8f96,
  trim: 0x6e737a,
  bark: 0x5a3d24,
  leaf: 0x2f6b28,
  steel: 0x9aa4ad,
  timber: 0x7a6a4f,
};
// (kept explicit rather than clever — Lane E will replace these with materials
// baked into the GLBs, at which point this table shrinks to nothing.)

/**
 * Build the yard.
 *
 * @param {THREE.Scene} scene
 * @param {object} [opts]
 * @param {import('./contracts.js').Wind} [opts.wind]
 *   Wind is injected because tree anchors sway with it, and sway is dynamic
 *   load — the whole reason a tree anchor is scarier than a post. Defaults to
 *   the calm stub so world.js is usable headless before Lane C lands.
 * @returns {import('./contracts.js').World}
 */
export function createWorld(scene, opts = {}) {
  const wind = opts.wind ?? createStubWind({ calm: true });

  const root = new THREE.Group();
  root.name = 'yard';
  scene.add(root);

  /** @type {THREE.Object3D[]} */
  const solids = [];
  /** @type {import('./contracts.js').Anchor[]} */
  const anchors = [];
  /** @type {{group: THREE.Object3D, phase: number, base: THREE.Euler}[]} */
  const canopies = [];

  // --- sky & light -------------------------------------------------------
  // Calm-day only. Lane C's skyfx.js takes over the sky and this becomes the
  // "before" state the storm darkens away from.
  scene.background = new THREE.Color(COLORS.sky);
  scene.fog = new THREE.Fog(COLORS.sky, 34, 95);

  // Sky fill carries more here than it would in most scenes. The sun sits in
  // the NORTH (this is an Australian yard — "southerly change", gum trees), and
  // the house is the yard's north edge, so the wall the player spends the whole
  // game looking at is permanently backlit. That's correct, and it's also how
  // a real south-facing rear wall looks — but the fascia line carries three of
  // the seven anchors, so it has to stay readable in shadow rather than going
  // to a void. Sky bounce is what does that in the real yard too.
  const hemi = new THREE.HemisphereLight(0xbfd8ea, COLORS.grass, 1.8);
  scene.add(hemi);

  const sun = new THREE.DirectionalLight(0xfff2dc, 2.0);
  sun.position.copy(SUN_DIR).multiplyScalar(40);
  sun.target.position.set(0, 0, 0);
  sun.castShadow = true;
  sun.shadow.mapSize.set(2048, 2048);
  // Frame the yard tightly — a loose shadow frustum is why sail shadows go
  // soft and blocky, and the sail's shadow IS the product here.
  const sc = sun.shadow.camera;
  sc.left = -19; sc.right = 19; sc.top = 15; sc.bottom = -15;
  sc.near = 1; sc.far = 90;
  sun.shadow.bias = -0.0006;
  sun.shadow.normalBias = 0.02;
  scene.add(sun);
  scene.add(sun.target);

  // --- terrain -----------------------------------------------------------
  const groundGeo = new THREE.PlaneGeometry(YARD.width, YARD.depth, 60, 40);
  groundGeo.rotateX(-Math.PI / 2);
  const gpos = groundGeo.attributes.position;
  for (let i = 0; i < gpos.count; i++) {
    gpos.setY(i, heightAt(gpos.getX(i), gpos.getZ(i)));
  }
  gpos.needsUpdate = true;
  groundGeo.computeVertexNormals();
  const ground = new THREE.Mesh(
    groundGeo,
    new THREE.MeshStandardMaterial({ color: COLORS.grass, roughness: 0.95 }),
  );
  ground.name = 'ground';
  ground.receiveShadow = true;
  root.add(ground);
  // Deliberately NOT in `solids`: the ground is answered by heightAt(), which
  // is exact and free. Raycasting it would be 4800 triangles a frame to learn
  // something we already know in closed form.

  // --- house (north edge) ------------------------------------------------
  // Rear wall sits exactly on z = -10 so the fascia anchors have a round
  // number to live on. Lane E's house_yardside.glb replaces this group and
  // should keep fascia_anchor_* at these positions.
  const house = new THREE.Group();
  house.name = 'house_yardside';
  const wall = new THREE.Mesh(
    new THREE.BoxGeometry(16, 3.0, 6),
    new THREE.MeshStandardMaterial({ color: COLORS.house, roughness: 0.85 }),
  );
  wall.position.set(0, 1.5, -13);
  wall.castShadow = true;
  wall.receiveShadow = true;
  house.add(wall);

  const roof = new THREE.Mesh(
    new THREE.BoxGeometry(16.8, 0.22, 6.8),
    new THREE.MeshStandardMaterial({ color: COLORS.trim, roughness: 0.7 }),
  );
  roof.position.set(0, 3.1, -13);
  roof.castShadow = true;
  house.add(roof);

  // The fascia line — the lie the player will be tempted by (DESIGN.md).
  const fascia = new THREE.Mesh(
    new THREE.BoxGeometry(16, 0.24, 0.12),
    new THREE.MeshStandardMaterial({ color: COLORS.trim, roughness: 0.6 }),
  );
  fascia.position.set(0, 2.72, -9.98);
  house.add(fascia);

  root.add(house);
  solids.push(wall, roof);

  for (const [i, x] of [-5, 0, 5].entries()) {
    anchors.push(makeStaticAnchor(`h${i + 1}`, 'house', new THREE.Vector3(x, 2.6, -9.9)));
  }

  // --- trees -------------------------------------------------------------
  // Two, on opposite shoulders, mirroring the prototype's tree placement.
  // Canopies are separate named nodes so they can be swayed independently —
  // Lane E's tree_gum_01.glb must keep `trunk` / `canopy_*` / `branch_anchor_*`.
  const treeSpecs = [
    { id: 't1', x: -9, z: 2, phase: 0.7, trunkH: 4.2, anchorY: 3.4 },
    { id: 't2', x: 8, z: -2, phase: 2.9, trunkH: 3.8, anchorY: 3.1 },
  ];
  for (const spec of treeSpecs) {
    const y0 = heightAt(spec.x, spec.z);
    const tree = new THREE.Group();
    tree.name = `tree_${spec.id}`;
    tree.position.set(spec.x, y0, spec.z);

    const trunk = new THREE.Mesh(
      new THREE.CylinderGeometry(0.18, 0.28, spec.trunkH, 8),
      new THREE.MeshStandardMaterial({ color: COLORS.bark, roughness: 1 }),
    );
    trunk.name = 'trunk';
    trunk.position.y = spec.trunkH / 2;
    trunk.castShadow = true;
    tree.add(trunk);
    solids.push(trunk);

    const canopy = new THREE.Group();
    canopy.name = 'canopy';
    canopy.position.y = spec.trunkH;
    const blobMat = new THREE.MeshStandardMaterial({ color: COLORS.leaf, roughness: 1 });
    for (const [j, b] of [
      { x: 0, y: 0.7, z: 0, r: 2.1 },
      { x: 1.1, y: 0.1, z: 0.5, r: 1.4 },
      { x: -0.9, y: 0.3, z: -0.6, r: 1.5 },
    ].entries()) {
      const blob = new THREE.Mesh(new THREE.SphereGeometry(b.r, 12, 8), blobMat);
      blob.name = `canopy_${j}`;
      blob.position.set(b.x, b.y, b.z);
      blob.castShadow = true;
      canopy.add(blob);
    }
    tree.add(canopy);
    canopies.push({ group: canopy, phase: spec.phase, base: canopy.rotation.clone() });

    root.add(tree);

    // The anchor is at a branch fork, not the canopy centre.
    anchors.push(makeSwayAnchor(
      spec.id,
      new THREE.Vector3(spec.x, y0 + spec.anchorY, spec.z),
      spec.phase,
      wind,
    ));
  }

  // --- posts -------------------------------------------------------------
  // Raked away from the yard centre, because that is the correct practice and
  // the shape should teach it before any text does (DESIGN.md: "rake the post
  // away from the load").
  const postSpecs = [
    { id: 'p1', x: -6, z: 7, h: 4.0 },
    { id: 'p2', x: 5, z: 7.5, h: 4.0 },
  ];
  const RAKE = (8 * Math.PI) / 180;
  for (const spec of postSpecs) {
    const y0 = heightAt(spec.x, spec.z);
    // Lean away from the centre of the yard, in the XZ plane.
    const away = new THREE.Vector2(spec.x, spec.z).normalize();
    const top = new THREE.Vector3(
      spec.x + Math.sin(RAKE) * spec.h * away.x,
      y0 + Math.cos(RAKE) * spec.h,
      spec.z + Math.sin(RAKE) * spec.h * away.y,
    );

    const post = new THREE.Mesh(
      new THREE.CylinderGeometry(0.06, 0.08, spec.h, 8),
      new THREE.MeshStandardMaterial({ color: COLORS.steel, roughness: 0.5, metalness: 0.6 }),
    );
    post.name = `sail_post_${spec.id}`;
    post.position.set((spec.x + top.x) / 2, (y0 + top.y) / 2, (spec.z + top.z) / 2);
    post.quaternion.setFromUnitVectors(
      new THREE.Vector3(0, 1, 0),
      top.clone().sub(new THREE.Vector3(spec.x, y0, spec.z)).normalize(),
    );
    post.castShadow = true;
    root.add(post);
    solids.push(post);

    const footing = new THREE.Mesh(
      new THREE.CylinderGeometry(0.22, 0.26, 0.18, 10),
      new THREE.MeshStandardMaterial({ color: 0x9c9c96, roughness: 0.95 }),
    );
    footing.position.set(spec.x, y0 + 0.06, spec.z);
    footing.receiveShadow = true;
    root.add(footing);

    anchors.push(makeStaticAnchor(spec.id, 'post', top));
  }

  // --- garden bed (the thing you are protecting) -------------------------
  const bed = new THREE.Group();
  bed.name = 'garden_bed';
  const bedY = heightAt(GARDEN_BED.x, GARDEN_BED.z);
  bed.position.set(GARDEN_BED.x, bedY, GARDEN_BED.z);

  const soil = new THREE.Mesh(
    new THREE.BoxGeometry(GARDEN_BED.w, 0.3, GARDEN_BED.d),
    new THREE.MeshStandardMaterial({ color: COLORS.soil, roughness: 1 }),
  );
  soil.position.y = 0.15;
  soil.receiveShadow = true;
  bed.add(soil);

  const plantMat = new THREE.MeshStandardMaterial({ color: COLORS.plant, roughness: 0.9 });
  for (let i = 0; i < 6; i++) {
    for (let j = 0; j < 4; j++) {
      const plant = new THREE.Mesh(new THREE.SphereGeometry(0.28, 8, 6), plantMat);
      plant.position.set(
        (-0.5 + (i + 0.5) / 6) * GARDEN_BED.w,
        0.42,
        (-0.5 + (j + 0.5) / 4) * GARDEN_BED.d,
      );
      plant.castShadow = true;
      plant.receiveShadow = true;
      bed.add(plant);
    }
  }
  root.add(bed);

  // --- boundary fence ----------------------------------------------------
  // East, south and west only: the house is the north boundary.
  const fence = new THREE.Group();
  fence.name = 'fence';
  const railMat = new THREE.MeshStandardMaterial({ color: 0x7a6a4f, roughness: 1 });
  const hx = YARD.width / 2, hz = YARD.depth / 2;
  const runs = [
    { from: [-hx, hz], to: [hx, hz] },     // south
    { from: [-hx, -hz], to: [-hx, hz] },   // west
    { from: [hx, -hz], to: [hx, hz] },     // east
  ];
  for (const run of runs) {
    const [x0, z0] = run.from, [x1, z1] = run.to;
    const len = Math.hypot(x1 - x0, z1 - z0);
    const n = Math.round(len / 2.5);
    for (let i = 0; i <= n; i++) {
      const f = i / n;
      const x = x0 + (x1 - x0) * f, z = z0 + (z1 - z0) * f;
      const p = new THREE.Mesh(new THREE.BoxGeometry(0.1, 1.6, 0.1), railMat);
      p.position.set(x, heightAt(x, z) + 0.8, z);
      p.castShadow = true;
      fence.add(p);
    }
    for (const ry of [0.6, 1.35]) {
      const rail = new THREE.Mesh(new THREE.BoxGeometry(len, 0.12, 0.04), railMat);
      rail.position.set((x0 + x1) / 2, heightAt((x0 + x1) / 2, (z0 + z1) / 2) + ry, (z0 + z1) / 2);
      rail.rotation.y = Math.atan2(-(z1 - z0), x1 - x0);
      rail.castShadow = true;
      fence.add(rail);
    }
  }
  root.add(fence);
  solids.push(fence);

  // --- the world object --------------------------------------------------
  return {
    anchors,
    heightAt,
    gardenBed: GARDEN_BED,
    sunDir: SUN_DIR.clone(),
    solids,
    root,
    sun,

    /** @param {string} id */
    anchor(id) {
      return anchors.find((a) => a.id === id) ?? null;
    },

    update(dt, t) {
      // Canopies lean with the wind they actually stand in — this is the tell
      // the player reads a gust front from, a beat before it reaches the sail.
      for (const c of canopies) {
        const w = wind.sample(c.group.getWorldPosition(_worldPos), t);
        const speed = w.length();
        const lean = Math.min(0.22, speed * 0.007);
        const flutter = 0.55 + 0.45 * Math.sin(t * 2.3 + c.phase);
        c.group.rotation.z = c.base.z - Math.cos(Math.atan2(w.z, w.x)) * lean * flutter;
        c.group.rotation.x = c.base.x + Math.sin(Math.atan2(w.z, w.x)) * lean * flutter;
      }
    },
  };
}

const _worldPos = new THREE.Vector3();

/** @returns {import('./contracts.js').Anchor} */
function makeStaticAnchor(id, type, pos) {
  const p = pos.clone();
  return { id, type, pos: p, sway: () => p };
}

/**
 * A tree anchor. Wanders with the wind it stands in, which is exactly why it is
 * the dangerous choice: the sway is dynamic load the rig has to eat, and a
 * drum-tight rig on a swaying tree snaps turnbuckles (DESIGN.md).
 *
 * @returns {import('./contracts.js').Anchor}
 */
function makeSwayAnchor(id, pos, phase, wind) {
  const p = pos.clone();
  const scratch = new THREE.Vector3();   // per-anchor, so two anchors never alias
  return {
    id,
    type: 'tree',
    pos: p,
    sway(t) {
      const speed = wind.sample(p, t).length();
      const amp = Math.min(0.35, speed * 0.012);
      const s = Math.sin(t * 1.9 + phase);
      return scratch.set(
        p.x + s * amp,
        p.y - Math.abs(s) * amp * 0.25,
        p.z + Math.cos(t * 1.3 + phase) * amp * 0.5,
      );
    },
  };
}