'use strict';
// SHADES — Lane C — weather: the wind field everyone samples.
//
// Implements the contracts.js wind surface (PLAN3D §4):
//   wind.sample(pos, t) -> Vector3        m/s, includes gusts & local effects
//   wind.gustTelegraph(t) -> {eta, dir, power} | null
//
// All the maths lives in weather.core.js (pure, no imports). This file is just
// the THREE adapter + storm loading, so the sim stays node-testable and the
// determinism rule can't be broken by accident.

import * as THREE from '../vendor/three.module.js';
import { createWindField, validateStorm, GUST } from './weather.core.js';

export { GUST, validateStorm };

// Resolved against this module, not the server root: server.py serves the repo
// root (so the 2D prototype stays reachable), but the demo bench serves web/.
// import.meta.url is right under both, and under whatever Lane A does next.
const STORM_DIR = new URL('../data/storms', import.meta.url).href;

/** Fetch + validate a storm def. Throws loud on bad data — storms are content. */
export async function loadStorm(name, dir = STORM_DIR) {
  const url = `${dir}/${name}.json`;
  const res = await fetch(url);
  if (!res.ok) throw new Error(`weather: cannot load ${url} (${res.status})`);
  const def = await res.json();
  const { ok, errors } = validateStorm(def, name);
  if (!ok) throw new Error(`weather: ${url} is invalid:\n  ${errors.join('\n  ')}`);
  return def;
}

/**
 * @param {object} def   parsed storm JSON
 * @param {object} [opts] {seed} — same seed + same def = same storm, every run
 * @returns the `wind` object from contracts.js
 */
export function createWind(def, opts = {}) {
  const field = createWindField(def, opts);
  const scratch = { x: 0, y: 0, z: 0 };

  const wind = {
    /**
     * Wind velocity at a world position, m/s.
     * @param {THREE.Vector3} pos
     * @param {number} t              storm time, seconds
     * @param {THREE.Vector3} [out]   pass one to avoid allocating — sail.js
     *                                samples per-face per-frame, so this matters
     */
    sample(pos, t, out) {
      const v = out || new THREE.Vector3();
      field.vecAt(pos.x, pos.z, t, scratch);
      return v.set(scratch.x, scratch.y, scratch.z);
    },

    /** Scalar speed — for HUD, rain, grass. Cheaper than sample(); no allocation. */
    speedAt(pos, t) {
      return field.speedAt(pos.x, pos.z, t);
    },

    /** {eta, dir, power} while a gust is inbound but hasn't risen yet, else null. */
    gustTelegraph(t) {
      return field.telegraph(t);
    },

    /**
     * Register wind shadows (trees, house). Lane A: call after the yard is built.
     * Until then there are simply no shadows — nothing breaks.
     * @param {Array<{x,z,radius,strength,length}>} list
     */
    setShelters(list) { field.setShelters(list); return wind; },

    /** Convenience: take shadows straight off world.anchors' tree entries. */
    setSheltersFromTrees(trees, o = {}) {
      return wind.setShelters(trees.map((tr) => ({
        x: tr.pos ? tr.pos.x : tr.x,
        z: tr.pos ? tr.pos.z : tr.z,
        radius: o.radius ?? tr.radius ?? 3,
        strength: o.strength ?? 0.45,
        length: o.length ?? 14,
      })));
    },

    /** Storm events fired in (a,b] — poll with (t-dt, t). Deterministic. */
    eventsBetween(a, b) { return field.eventsBetween(a, b); },

    /** 0..1 rain intensity. */
    rainAt(t) { return field.rainAt(t); },

    /** Direction (radians, XZ plane from +X toward +Z) ignoring local effects. */
    dirAt(t) { return field.dirAt(t); },

    get duration() { return field.duration; },
    get gusts() { return field.gusts; },
    get def() { return field.def; },
    get seed() { return field.seed; },
    core: field,
  };

  return wind;
}