/**
 * SHADES — boot, game loop, phase machine. Lane A owns this file.
 *
 * This is the assembly point: every other lane's module is proven in isolation,
 * and this file is where they become one game. Two rules make that possible and
 * are worth not breaking:
 *
 *  - **Nothing auto-runs on import.** index.html calls boot(). That keeps
 *    createGame() importable from selftest.html, which must never construct a
 *    WebGLRenderer.
 *  - **The loop is a fixed-dt accumulator.** Sim modules only ever see FIXED_DT,
 *    never a real frame delta. That is the whole reason selftest can fast-forward
 *    a 90 s storm in milliseconds and get the numbers the player got.
 */

import * as THREE from '../vendor/three.module.js';
import { FIXED_DT, PHASES, STORM_LEN, HARDWARE, Emitter } from './contracts.js';
import { createWorld } from './world.js';
import { createCameraRig } from './camera.js';
import { loadStorm, createWind } from './weather.js';
import { SailRig, createSailView } from './sail.js';
import { createPlayer } from './player.js';
import { Interact, wireYardActions } from './interact.js';
import { createDebris } from './debris.js';
import { createSkyFx } from './skyfx.js';

/** Which storm each phase runs under (SPRINT2 §Lane A.1). */
const CALM_STORM = 'storm_01_gentle';
const WILD_STORM = 'storm_02_wildnight';

// ---------------------------------------------------------------------------
// Phase machine
// ---------------------------------------------------------------------------

/**
 * forecast → prep → storm → aftermath → forecast.
 * @returns {import('./contracts.js').Game}
 */
export function createGame() {
  const emitter = new Emitter();
  let phase = 'forecast';
  let phaseT = 0;

  return {
    get phase() { return phase; },
    /** Seconds since this phase began. The storm clock. */
    get phaseT() { return phaseT; },

    on(type, fn) { return emitter.on(type, fn); },

    /** @param {'forecast'|'prep'|'storm'|'aftermath'} next */
    setPhase(next) {
      if (!PHASES.includes(next)) throw new Error(`unknown phase '${next}'`);
      if (next === phase) return;
      const from = phase;
      phase = next;
      phaseT = 0;
      emitter.emit('phaseChange', { from, to: next });
    },

    /** Advance to the next phase in loop order. */
    advance() {
      this.setPhase(PHASES[(PHASES.indexOf(phase) + 1) % PHASES.length]);
    },

    tick(dt) {
      phaseT += dt;
      // The storm is on a timer; every other phase waits for the player.
      if (phase === 'storm' && phaseT >= STORM_LEN) this.setPhase('aftermath');
    },
  };
}

// ---------------------------------------------------------------------------
// Wind router
// ---------------------------------------------------------------------------

/**
 * One wind object whose identity never changes, delegating to whichever storm
 * is currently running.
 *
 * Every consumer binds to wind exactly once, at construction — the yard closes
 * over it for tree sway, createPlayer takes it in opts, createDebris reads its
 * event stream. So swapping storm_01 for storm_02 at the phase change has to be
 * a re-point, not a re-wire, or half the game would still be sampling the calm
 * day while the other half is in a gale.
 *
 * Shelters are applied to every storm rather than just the active one: they
 * describe the yard's trees, which don't stop existing when the weather turns.
 *
 * @param {object[]} all  every wind this session can switch between
 */
function createWindRouter(all) {
  let active = all[0];

  const router = {
    /** The wind currently in force. Assign through use(). */
    get active() { return active; },
    use(w) { active = w; return router; },

    sample: (pos, t, out) => active.sample(pos, t, out),
    speedAt: (pos, t) => active.speedAt(pos, t),
    gustTelegraph: (t) => active.gustTelegraph(t),
    eventsBetween: (a, b) => active.eventsBetween(a, b),
    rainAt: (t) => active.rainAt(t),
    dirAt: (t) => active.dirAt(t),

    setShelters(list) {
      for (const w of all) w.setShelters(list);
      return router;
    },
    setSheltersFromTrees(trees, o = {}) {
      return router.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,
      })));
    },

    get duration() { return active.duration; },
    get gusts() { return active.gusts; },
    get def() { return active.def; },
    get seed() { return active.seed; },
    get core() { return active.core; },
  };
  return router;
}

// ---------------------------------------------------------------------------
// Debris models
// ---------------------------------------------------------------------------

/**
 * Lane E's crates and tubs, keyed by the names storm JSON spawns and debris.js
 * has radii for. A browser can't glob a directory, so the list is explicit —
 * and it should stay matched to MODEL_SPEC in debris.js (Lane C's ask: tell them
 * rather than fighting the radii).
 *
 * Missing files are not fatal: debris.js falls back to a graybox box per piece,
 * which is exactly the degrade-quietly behaviour Lane C designed for.
 */
const DEBRIS_MODELS = ['BlueCrate_v2', 'BlackTub_v2', 'WhiteTub_v2', 'WoodenBin_v2'];

async function loadDebrisModels() {
  const { GLTFLoader } = await import('../vendor/addons/loaders/GLTFLoader.js');
  const loader = new GLTFLoader();
  const out = {};
  await Promise.all(DEBRIS_MODELS.map(async (name) => {
    try {
      const gltf = await loader.loadAsync(`./models/debris/${name}.glb`);
      gltf.scene.traverse((o) => { if (o.isMesh) { o.castShadow = true; o.receiveShadow = true; } });
      out[name] = gltf.scene;
    } catch (err) {
      console.warn(`[main] debris model ${name} unavailable, using graybox:`, err.message);
    }
  }));
  return out;
}

// ---------------------------------------------------------------------------
// Boot
// ---------------------------------------------------------------------------

/**
 * @param {object} [opts]
 * @param {HTMLCanvasElement} [opts.canvas]
 */
export async function boot(opts = {}) {
  const canvas = opts.canvas ?? document.getElementById('c');

  const renderer = new THREE.WebGLRenderer({ canvas, antialias: true });
  renderer.setPixelRatio(Math.min(devicePixelRatio, 2));
  renderer.shadowMap.enabled = true;
  renderer.shadowMap.type = THREE.PCFSoftShadowMap;
  renderer.toneMapping = THREE.ACESFilmicToneMapping;
  renderer.toneMappingExposure = 1.0;

  const scene = new THREE.Scene();

  // --- 1. weather ---------------------------------------------------------
  // Both storms load up front: the forecast card needs to read storm_02's shape
  // before the player has agreed to face it.
  const [calmDef, wildDef] = await Promise.all([loadStorm(CALM_STORM), loadStorm(WILD_STORM)]);
  const calmWind = createWind(calmDef);
  const wildWind = createWind(wildDef);
  const wind = createWindRouter([calmWind, wildWind]);

  // --- world & camera -----------------------------------------------------
  const world = createWorld(scene, { wind });
  const cameraRig = createCameraRig(canvas);
  cameraRig.setSolids(world.solids);
  cameraRig.setGround(world.heightAt);

  // Lane C: trees don't shelter anything until they're told where they are.
  wind.setSheltersFromTrees(world.anchors.filter((a) => a.type === 'tree'));

  // --- 2. player ----------------------------------------------------------
  const interact = new Interact();
  const player = await createPlayer(scene, world, cameraRig, { wind, interact });

  // --- 3. sail ------------------------------------------------------------
  const rig = new SailRig({ anchors: world.anchors });
  let sailView = null;

  /**
   * Attach the cloth across 4 anchors and (re)build its view.
   *
   * The order here is load-bearing. createSailView reads rig.pos and rig.tris,
   * which don't exist until attach() allocates them in _build() — build the view
   * first and it throws on an undefined array. A re-rig can also change the grid,
   * so the view has to be rebuilt rather than reused. Both facts make this the
   * single door that boot and Lane B's picking adapter should come through.
   *
   * Re-wiring interact each time is deliberate: its targets close over corner
   * objects and attach() makes a fresh corners array, so stale closures would
   * point at corners the sim no longer steps. The ids are stable, so this
   * replaces the old targets rather than stacking duplicates.
   */
  async function rigSail(anchorIds, hwChoices, tension = 1.0) {
    rig.attach(anchorIds, hwChoices, tension);
    if (sailView) {
      scene.remove(sailView);
      sailView.traverse((o) => { o.geometry?.dispose(); o.material?.dispose(); });
    }
    sailView = await createSailView(rig);
    scene.add(sailView);
    wireYardActions(interact, { sailRig: rig, world });
    return sailView;
  }

  // Until Lane B's prep-phase picking adapter lands (SPRINT2 §B.3), rig a
  // default quad so the yard has a live sail and Lane D has something to
  // repair. Deliberately the prototype's AUTO loadout — one dodgy carabiner
  // corner. It also spans most of the yard, which is the 70–192 m² problem
  // decision 2 fixes in step 6, not a fault in the cloth.
  await rigSail(['h1', 'h3', 'p2', 'p1'], [HARDWARE[2], HARDWARE[1], HARDWARE[1], HARDWARE[0]]);

  const game = createGame();

  // --- clocks -------------------------------------------------------------
  // Two of them, and the distinction matters. `simT` is wall-clock seconds since
  // boot. `windT` is STORM time — storm JSON is authored with t=0 at the storm's
  // first gust, so it's phase time during the storm, and off-storm it wraps the
  // calm day around its own duration so the breeze keeps breathing however long
  // you spend rigging. Every sim module samples windT; nothing samples simT.
  let simT = 0;
  let windT = 0;
  let acc = 0;

  function windTime() {
    if (game.phase === 'storm') return game.phaseT;
    return simT % Math.max(1, calmWind.duration);
  }

  // --- 4. sky, audio, debris ---------------------------------------------
  const events = [];
  const pushEvent = (text) => {
    events.push({ t: game.phaseT, text });
    if (events.length > 4) events.shift();
  };

  const debris = createDebris({
    wind,
    scene,
    heightAt: world.heightAt,
    // knockdown(t, dirX, dirZ) — the first arg is the sim clock, NOT the impact
    // magnitude. Passing `impact` here would jam ~40 into the state machine's
    // start time and the player would never get up. The piece's own velocity is
    // the direction, so you fall the way the crate was travelling.
    onHitPlayer: (piece) => player.sim.knockdown(windT, piece.vx, piece.vz),
    onEvent: pushEvent,
  });
  debris.setModels(await loadDebrisModels());

  // skyfx reads the storm's `sky` block at construction (darkness, cloud scroll,
  // night), so it is rebuilt when the storm changes rather than re-pointed like
  // wind. dispose() hands world.sun/world.hemi back exactly as they were, which
  // is what makes that safe to do mid-session.
  let sky = null;
  let audioUnlocked = false;
  function makeSky() {
    if (sky) sky.dispose();
    sky = createSkyFx({
      scene,
      camera: cameraRig.object,
      wind,
      sun: world.sun,
      hemi: world.hemi,
      onEvent: pushEvent,
    });
    if (audioUnlocked) sky.unlockAudio();
    return sky;
  }
  makeSky();

  // Browsers won't start an AudioContext without a gesture. Without this the
  // storm is silent, and half of DESIGN.md's threat model is audible.
  const unlock = () => {
    if (audioUnlocked) return;
    audioUnlocked = true;
    sky?.unlockAudio();
    removeEventListener('pointerdown', unlock);
    removeEventListener('keydown', unlock);
  };
  addEventListener('pointerdown', unlock);
  addEventListener('keydown', unlock);

  // --- dev overlay (temporary — hud.js replaces it in step 7) -------------
  const hud = document.getElementById('dev');
  const banner = document.getElementById('banner');
  addEventListener('keydown', (e) => {
    if (e.key === 'Enter') game.advance();
  });

  // --- phases -------------------------------------------------------------
  game.on('phaseChange', ({ to }) => {
    wind.use(to === 'storm' ? wildWind : calmWind);
    makeSky();
    events.length = 0;
    if (banner) {
      banner.textContent = to.toUpperCase();
      banner.style.opacity = '1';
      setTimeout(() => { banner.style.opacity = '0'; }, 1400);
    }
  });

  // --- resize -------------------------------------------------------------
  function resize() {
    const w = canvas.clientWidth || innerWidth;
    const h = canvas.clientHeight || innerHeight;
    renderer.setSize(w, h, false);
    cameraRig.resize(w, h);
  }
  addEventListener('resize', resize);
  resize();

  // --- loop ---------------------------------------------------------------
  const clock = new THREE.Clock();
  let frames = 0, fpsT = 0, fps = 0;

  function step(dt) {
    game.tick(dt);
    simT += dt;
    windT = windTime();
    world.update(dt, windT);
    player.update(dt, windT);
    rig.step(dt, wind, windT);
    debris.step(dt, windT, { player: player.sim, sail: rig });
    sky?.step(dt, windT, { sail: rig });
  }

  function frame() {
    // Clamped so a background tab or a breakpoint doesn't make the sim try to
    // catch up over thousands of steps and lock the page.
    const raw = Math.min(0.25, clock.getDelta());
    acc += raw;
    let guard = 0;
    while (acc >= FIXED_DT && guard++ < 60) {
      step(FIXED_DT);
      acc -= FIXED_DT;
    }

    cameraRig.update(raw, player.pos);
    sailView?.update();
    renderer.render(scene, cameraRig.object);

    frames++; fpsT += raw;
    if (fpsT >= 0.5) { fps = frames / fpsT; frames = 0; fpsT = 0; }
    if (hud) {
      const wt = windT;
      const speed = wind.speedAt(player.pos, wt);
      const tel = wind.gustTelegraph(wt);
      const worst = rig.corners.reduce((m, c) => Math.max(m, c.load || 0), 0);
      hud.textContent =
        `${fps.toFixed(0)} fps | ${game.phase} ${game.phaseT.toFixed(1)}s | ` +
        `wind ${speed.toFixed(1)} m/s${tel ? ` | GUST in ${tel.eta.toFixed(1)}s` : ''} | ` +
        `worst corner ${worst.toFixed(1)} | debris ${debris.pieces.length}` +
        `${events.length ? ` | ${events[events.length - 1].text}` : ''}`;
    }
    requestAnimationFrame(frame);
  }
  requestAnimationFrame(frame);

  // Handy for poking at the world from the console, and for the selftest-free
  // hand checks the sprint's acceptance actually turns on.
  const api = {
    renderer, scene, world, cameraRig, player, game, wind, rig, rigSail,
    get sailView() { return sailView; },
    debris, interact, events,
    get sky() { return sky; },
    get simT() { return simT; },
    windTime,
    calmWind, wildWind,

    /**
     * Drive the sim by hand at fixed dt, and draw on demand. rAF is throttled to
     * a standstill in a hidden tab, so these are the only honest way to
     * fast-forward a storm or capture one from a headless browser — which is
     * exactly what this sprint's "90 s storm_02 run captured" acceptance needs.
     * Same code path the rAF loop uses; no test-only branch to drift.
     */
    step,
    render() {
      sailView?.update();
      renderer.render(scene, cameraRig.object);
    },
  };
  globalThis.SHADES = api;
  return api;
}