import baseCss from './style.css?inline';
import embedCss from './embed.css?inline';
import SolverWorker from './sim/worker.ts?worker&inline';
import { CONFIGS, type AnyConfig } from './instruments/configs';
import { BeadScene } from './ui/scene3d';
import { RATES, Timeline } from './ui/timeline';
import { encodeWav } from './ui/wav';
import { fmtNum } from './ui/plot';
import { CPU_RATE, parseSettings, runCost, simOptions } from './ui/settings';
import { runInWorker, type Running } from './sim/run';
import { checkPasscode, getPasscode, loadFrames, loadLight, probeFrames, probeResult, resultKey, setPasscode, storeResult, type Backend, type LightResult } from './sim/cache';
import type { Built, SimParams } from './ui/instrumentPage';
import type { SimResult } from './sim/types';

// <toy-instrument-sim settings="…" exaggeration="5" name="…">: one simulation of a toy
// instrument, for embedding in other pages (blog posts).
//
// - settings: a link from "Copy link to these settings" (or just its #/<instrument>?… part).
// - exaggeration: how much the motion is magnified in the replay (default 5). It only
//   affects the drawing, so it is not part of the cache key.
// - name: file name of the downloaded .wav (default toy-instrument).
//
// The reader sees the 3D model with "Play sound" and "Play motion" buttons; each downloads
// what it needs from the shared cache on first press (the small light entry for the sound,
// the frames for the motion, played in slow motion). When the cache has no result, the
// widget offers to run the simulation in the browser; with the cache passcode set, the run
// is stored under the same key, so the next reader gets it from the cache.
//
// The key hashes what this bundle's model code builds from the settings, so a page that
// keeps this exact bundle (jeremy.magland.org freezes each upload) always asks for, and
// fills, the same entry, however the app changes later.

interface Found {
  key: string;
  stored?: Date;
  framesBytes: number | null;
}

class ToyInstrumentSim extends HTMLElement {
  private root!: ShadowRoot;
  private running: Running | null = null;
  private abort = new AbortController();
  private audioUrl: string | null = null;
  private cleanup: (() => void)[] = [];
  private p!: SimParams;
  private built!: Built;
  private scene!: BeadScene;
  private timeline = new Timeline();
  private found: Found | null = null;
  private light: Promise<LightResult> | null = null;
  private exaggeration = 5;

  connectedCallback() {
    if (this.shadowRoot) return;
    this.root = this.attachShadow({ mode: 'open' });
    this.root.innerHTML = `
      <style>${baseCss}${embedCss}</style>
      <div class="tis">
        <div data-r="scene"></div>
        <div class="players">
        <div class="player">
          <button class="btn play" data-r="sound-btn" hidden>▶ Play sound</button>
          <div class="audio-row" data-r="audio-row" hidden><audio controls data-r="audio"></audio><a class="btn-small" data-r="download">Download .wav</a></div>
        </div>
        <div class="player">
          <button class="btn play" data-r="motion-btn" hidden>▶ Play motion</button>
          <div class="viewer-bar" data-r="motion-bar" hidden>
            <button class="btn-small" data-r="m-play">Play</button>
            <input type="range" min="0" max="0" value="0" data-r="m-slider" aria-label="time">
            <span class="mono" data-r="m-label"></span>
            <label class="inline">speed <select data-r="m-rate">${RATES.map(([v, l]) => `<option value="${v}">${l}</option>`).join('')}</select></label>
          </div>
        </div>
        </div>
        <p class="status" data-r="status">Looking for a stored result…</p>
        <div class="actions">
          <button class="btn" data-r="run" hidden></button>
          <button class="btn-small" data-r="cancel" hidden>Cancel</button>
        </div>
        <progress data-r="progress" max="1" value="0" hidden></progress>
        <p class="error" data-r="error" hidden></p>
        <details class="cache-ctl">
          <summary data-r="cache-state"></summary>
          <p class="note">Results come from a shared cache. With its passcode, simulations run here are stored there, for everyone who opens this page.</p>
          <div class="cache-form"><input type="password" data-r="cache-pass" placeholder="Passcode" autocomplete="off"><button class="btn-small" data-r="cache-save">Save</button><button class="btn-small" data-r="cache-forget">Forget</button></div>
          <p class="note" data-r="cache-msg"></p>
        </details>
      </div>`;
    this.mountPasscode();
    this.mountMotionBar();
    this.start().catch((e) => this.fail(`Something went wrong: ${(e as Error).message}`));
  }

  disconnectedCallback() {
    this.running?.cancel();
    this.abort.abort();
    this.timeline.pause();
    for (const f of this.cleanup) f();
    this.cleanup = [];
  }

  private q<T extends HTMLElement>(r: string): T {
    return this.root.querySelector(`[data-r="${r}"]`) as T;
  }

  private status(text: string) {
    this.q('status').textContent = text;
  }

  private fail(text: string) {
    const box = this.q('error');
    box.textContent = text;
    box.hidden = false;
  }

  private async start() {
    const spec = this.getAttribute('settings') ?? '';
    const hash = spec.includes('#') ? spec.slice(spec.indexOf('#') + 1) : spec;
    const [route, query = ''] = hash.split('?');
    const id = route.replace(/^\//, '');
    const cfg: AnyConfig | undefined = CONFIGS[id];
    if (!cfg) {
      this.status('');
      return this.fail(`Unknown instrument "${id}" in the settings attribute.`);
    }
    const settings = parseSettings(cfg, query);
    this.p = settings.params;
    const built = cfg.setup(this.p).built;
    if (!built) {
      this.status('');
      return this.fail('These settings do not give a valid instrument.');
    }
    this.built = built;

    const ex = Number(this.getAttribute('exaggeration') ?? 5);
    if (ex > 0) this.exaggeration = ex;
    this.scene = new BeadScene(this.q('scene'), this.timeline, { simple: true, exaggeration: this.exaggeration });
    this.scene.showSetup(built.scene);
    this.followTheme();

    const wanted: Backend = (settings.gpu ?? cfg.webgpuDefault !== false) ? 'gpu' : 'cpu';
    const opt = simOptions(this.p, built);
    const order: Backend[] = wanted === 'gpu' ? ['gpu', 'cpu'] : ['cpu', 'gpu'];

    // the result for the settings' backend, or else for the other one (HEAD requests only)
    let unreachable = false;
    for (const backend of order) {
      const key = await resultKey(id, built.sys, built.exc, opt, backend);
      try {
        const hit = await probeResult(key, this.abort.signal);
        if (hit) {
          this.found = { key, stored: hit.stored, framesBytes: await probeFrames(key, this.abort.signal) };
          break;
        }
      } catch {
        unreachable = true;
      }
    }
    if (this.found) return this.offerPlayback();

    // nothing stored: offer to run it here
    const gpu = wanted === 'gpu' && 'gpu' in navigator;
    const cpuSeconds = runCost(this.p, built).work / CPU_RATE;
    this.status(
      `${unreachable ? 'The shared cache could not be reached' : 'No stored result for these settings yet'}. ` +
        `You can run the simulation in this browser: roughly ${duration(cpuSeconds)} on a desktop CPU` +
        (gpu ? ', usually much less with WebGPU.' : wanted === 'gpu' ? ' (this browser has no WebGPU, so it runs on the CPU).' : '.'),
    );
    const runBtn = this.q<HTMLButtonElement>('run');
    runBtn.textContent = `Run simulation${gpu ? ' (WebGPU)' : ''}`;
    runBtn.hidden = false;
    runBtn.addEventListener('click', () => this.run(id, gpu));
  }

  // A stored result: buttons that download the sound and the motion when first pressed.
  private offerPlayback() {
    const f = this.found!;
    this.status(f.stored ? `Computed on ${f.stored.toISOString().slice(0, 10)}.` : '');
    const soundBtn = this.q<HTMLButtonElement>('sound-btn');
    soundBtn.hidden = false;
    soundBtn.addEventListener('click', async () => {
      soundBtn.disabled = true;
      soundBtn.textContent = 'Loading…';
      try {
        const light = await this.loadLight();
        soundBtn.hidden = true;
        this.setAudio(light.audio, light.fs);
        this.q<HTMLAudioElement>('audio').play().catch(() => {});
      } catch (e) {
        soundBtn.disabled = false;
        soundBtn.textContent = '▶ Play sound';
        this.fail(`Could not load the sound: ${(e as Error).message}`);
      }
    });
    if (f.framesBytes === null) return;
    const motionBtn = this.q<HTMLButtonElement>('motion-btn');
    const label = `▶ Play motion (${fmtNum(Math.round(f.framesBytes / 1e5) / 10)} MB)`;
    motionBtn.textContent = label;
    motionBtn.hidden = false;
    motionBtn.addEventListener('click', async () => {
      motionBtn.disabled = true;
      motionBtn.textContent = 'Loading…';
      try {
        const light = await this.loadLight();
        const frames = await loadFrames(f.key, (x) => (motionBtn.textContent = `Loading… ${Math.round(x * 100)}%`), this.abort.signal);
        if (!frames) throw new Error('it is no longer in the cache');
        motionBtn.hidden = true;
        this.showMotion({ ...light, frames });
        this.timeline.play();
      } catch (e) {
        if (this.abort.signal.aborted) return;
        motionBtn.disabled = false;
        motionBtn.textContent = label;
        this.fail(`Could not load the motion: ${(e as Error).message}`);
      }
    });
  }

  // the light entry (audio, frame times, mallet path), downloaded once
  private loadLight(): Promise<LightResult> {
    this.light ??= loadLight(this.found!.key, this.abort.signal).then((hit) => {
      if (!hit) throw new Error('it is no longer in the cache');
      return hit.light;
    });
    this.light.catch(() => (this.light = null));
    return this.light;
  }

  private async run(id: string, gpu: boolean) {
    const { p, built } = this;
    const runBtn = this.q<HTMLButtonElement>('run');
    const cancelBtn = this.q<HTMLButtonElement>('cancel');
    const progress = this.q<HTMLProgressElement>('progress');
    const opt = simOptions(p, built);
    runBtn.disabled = true;
    cancelBtn.hidden = progress.hidden = false;
    progress.value = 0;
    this.q('error').hidden = true;
    this.status('Simulating…');
    const running = runInWorker(
      () => new SolverWorker(),
      built.sys,
      built.exc,
      opt,
      gpu,
      (x) => (progress.value = x),
      (r) => this.status(`Simulating… ${fmtNum(r.audio.length / r.fs)} s of ${fmtNum(p.duration)} s done.`),
    );
    this.running = running;
    cancelBtn.onclick = () => running.cancel();
    try {
      const r = await running.promise;
      runBtn.hidden = true;
      this.setAudio(r.audio, r.fs);
      this.showMotion(r);
      const ran = `Simulated in this browser with ${r.backend ?? 'CPU'}${r.fallback ? ` (WebGPU failed: ${r.fallback})` : ''} in ${duration(r.wallSeconds)}.`;
      if (!getPasscode()) return this.status(`${ran} Not stored: this browser has no cache passcode.`);
      this.status(`${ran} Storing in the shared cache…`);
      // a WebGPU run that fell back to the CPU is stored as a CPU result
      const backend: Backend = r.backend?.startsWith('WebGPU') ? 'gpu' : 'cpu';
      const key = await resultKey(id, built.sys, built.exc, opt, backend);
      try {
        await storeResult(key, r, { instrument: id, backend: r.backend, wallSeconds: r.wallSeconds, from: location.href });
        this.status(`${ran} Stored in the shared cache.`);
      } catch (e) {
        this.status(`${ran} Not stored in the shared cache: ${(e as Error).message}`);
      }
    } catch (e) {
      runBtn.disabled = false;
      if ((e as Error).message === 'cancelled') this.status('The run was cancelled.');
      else this.fail(`The simulation failed: ${(e as Error).message}`);
    } finally {
      this.running = null;
      cancelBtn.hidden = progress.hidden = true;
    }
  }

  private showMotion(r: SimResult) {
    this.timeline.setTimes(r.frameTimes);
    this.scene.showReplay({ ...this.built.scene, frames: r.frames, malletPos: r.malletPos });
    this.q('motion-bar').hidden = false;
    this.q('motion-bar').parentElement!.classList.add('wide');
  }

  // Play/pause, time slider, time label and speed for the replay.
  private mountMotionBar() {
    const tl = this.timeline;
    const play = this.q<HTMLButtonElement>('m-play');
    const slider = this.q<HTMLInputElement>('m-slider');
    const label = this.q('m-label');
    const rate = this.q<HTMLSelectElement>('m-rate');
    play.addEventListener('click', () => tl.toggle());
    slider.addEventListener('input', () => tl.seek(Number(slider.value)));
    rate.addEventListener('change', () => tl.setRate(Number(rate.value)));
    const sync = () => {
      play.textContent = tl.playing ? 'Pause' : 'Play';
      slider.max = String(tl.times.length - 1);
      slider.value = String(tl.frame);
      label.textContent = `t = ${(tl.times[tl.frame] * 1000).toFixed(1)} ms, motion drawn ×${fmtNum(this.exaggeration)}`;
      rate.value = String(tl.rate);
    };
    tl.onChange(sync);
    sync();
  }

  private setAudio(audio: Float32Array, fs: number) {
    if (this.audioUrl) URL.revokeObjectURL(this.audioUrl);
    this.audioUrl = URL.createObjectURL(encodeWav(audio, fs));
    this.q<HTMLAudioElement>('audio').src = this.audioUrl;
    const a = this.q<HTMLAnchorElement>('download');
    a.href = this.audioUrl;
    a.download = `${this.getAttribute('name') ?? 'toy-instrument'}.wav`;
    a.title = `16-bit mono, ${fs} Hz, normalized so the peak is −1 dBFS`;
    this.q('sound-btn').hidden = true;
    this.q('audio-row').hidden = false;
    this.q('audio-row').parentElement!.classList.add('wide');
  }

  // Dark or light series colors from the host page's color-scheme, and a redraw when the
  // page switches theme (jeremy.magland.org sets data-theme on <html>).
  private followTheme() {
    const box = this.root.querySelector('.tis')!;
    const media = window.matchMedia('(prefers-color-scheme: dark)');
    const apply = () => {
      const scheme = getComputedStyle(this).colorScheme;
      const dark = scheme.includes('dark') && (!scheme.includes('light') || media.matches);
      box.classList.toggle('dark', dark);
      this.scene.restyle();
    };
    apply();
    const obs = new MutationObserver(apply);
    obs.observe(document.documentElement, { attributes: true, attributeFilter: ['data-theme', 'class', 'style'] });
    media.addEventListener('change', apply);
    this.cleanup.push(() => obs.disconnect(), () => media.removeEventListener('change', apply));
  }

  private mountPasscode() {
    const input = this.q<HTMLInputElement>('cache-pass');
    const msg = this.q('cache-msg');
    const show = () => (this.q('cache-state').textContent = getPasscode() ? 'Shared cache: runs here are stored' : 'Shared cache');
    show();
    this.q('cache-save').addEventListener('click', async () => {
      const pass = input.value.trim();
      if (!pass) return;
      msg.textContent = 'Checking…';
      try {
        const { valid, reason } = await checkPasscode(pass);
        if (!valid) {
          msg.textContent = `Not saved: ${reason ?? 'invalid passcode'}.`;
          return;
        }
        setPasscode(pass);
        input.value = '';
        msg.textContent = 'Saved in this browser.';
      } catch (e) {
        msg.textContent = `Could not check the passcode: ${(e as Error).message}`;
      }
      show();
    });
    this.q('cache-forget').addEventListener('click', () => {
      setPasscode(null);
      msg.textContent = 'Passcode removed from this browser.';
      show();
    });
  }
}

function duration(s: number): string {
  if (s < 90) return `${fmtNum(Math.max(1, Math.round(s)))} s`;
  if (s < 5400) return `${fmtNum(Math.round(s / 60))} min`;
  return `${fmtNum(Math.round((s / 3600) * 10) / 10)} h`;
}

if (!customElements.get('toy-instrument-sim')) customElements.define('toy-instrument-sim', ToyInstrumentSim);