// Your own hardware: a run on one of the person's own quantum providers (a
// device, an account, a simulator), in the desktop app only.
//
// A provider needs the person's credential, and a browser tab must not hold
// one, so in the browser the "Your hardware" switch only says where such a
// run goes: the desktop app, or the command line (`wai-quantum run
// --provider NAME`). In the desktop app the app holds the credential (in the
// operating system's keychain) and the page never sees it: the page lists
// the providers, asks for the provider's estimate first, and when the run is
// not free asks the person in a dialog before it is submitted. The answer is
// a job like every other, its counts measured on the device and sealed.
import { el } from './dom.js';
import { t as tr } from './i18n.js';

export const NOTE = tr('hardware.note');

// Whether a plan (the dry run's answer) needs the person's confirmation: any
// run not stated free, an unknown cost included.
export const needsConfirmation = (plan) => plan?.free !== true;

// The estimate in words.
export function costText(plan) {
  const e = plan?.estimate || {};
  if (e.unknown) return tr('hardware.cost_unknown', { why: e.unknown });
  if (e.free === true) return tr('hardware.free');
  const unit = e.unit ? tr('hardware.billed_by', { unit: e.unit }) : '';
  const secs = e.seconds !== undefined ? tr('hardware.about_seconds', { seconds: e.seconds }) : '';
  return `${e.amount} ${e.currency}${unit}${secs}`;
}

// What the dialog says before a run that is not free.
export function confirmText(plan) {
  const p = plan?.provider || {};
  const c = plan?.plan?.compile || {};
  return [
    tr('hardware.confirm_run', { name: p.name, device: p.device, provenance: p.provenance }),
    tr('hardware.confirm_cost', { cost: costText(plan) }),
    tr('hardware.confirm_compiled', { gates: c.native_gates, basis: c.basis, swaps: c.swaps, shots: plan?.plan?.shots }),
    tr('hardware.confirm_spend'),
  ];
}

// A run on a provider, through the desktop app's commands.
//
// The app writes the job down before it sends it, so a job in a provider's
// queue outlives the window. The run waits here while the person watches,
// asking after it by its id, less often the longer it waits (a device's queue
// can take hours). Cancel cancels it at the provider; "Wait in the
// background" leaves it there and frees the Studio. Jobs left waiting, from
// this window or an earlier one, are followed in the background, and each
// one's result goes to the history when it finishes.
export class HardwareEngine {
  constructor(invoke, ask, { first = 2000, most = 60000 } = {}) {
    this.invoke = invoke;
    this.ask = ask;
    this.first = first;
    this.most = most;
    this.provider = null;
    this.where = 'your hardware';
    this.current = null; // the id of the job the run waits for
    this.stop = null; // 'cancel' or 'later', when the person has said
    this.wake = null;
    this.watched = new Set();
    this.onFinished = null; // (job) => …, for a job followed in the background
    this.onEnded = null;
  }
  // A command's answer; one that failed throws. A job that ended (failed or
  // cancelled) is an answer, with its `status` and why, not a failure.
  async call(cmd, args) {
    const v = JSON.parse(await this.invoke(cmd, args));
    if (v && v.error && !v.plan && !v.status) throw new Error(v.error);
    return v;
  }
  async providers() { return (await this.call('providers_list', {})).providers || []; }
  select(name) { this.provider = name; this.where = name ? `your provider ${name}` : 'your hardware'; }
  estimate(request) { return this.call('provider_estimate', { name: this.provider, request: JSON.stringify({ ...request, provider: this.provider }) }); }
  // The estimate first; the person's yes before anything that is not free.
  async run(request, onProgress) {
    if (!this.provider) throw new Error(tr('hardware.choose_provider'));
    const req = { qasm: request.qasm, shots: request.shots, seed: request.seed, provider: this.provider };
    const plan = await this.estimate(req);
    let confirm = false;
    if (needsConfirmation(plan)) {
      if (!(await this.ask(plan))) throw new Error('cancelled');
      confirm = true;
    }
    this.stop = null;
    const v = await this.call('run_on_provider', { name: this.provider, request: JSON.stringify(req), confirmCost: confirm });
    if (v.error) throw new Error(v.error);
    return this.follow(v, onProgress);
  }
  // A job until it ends, or until the person cancels it or leaves it waiting.
  async follow(job, onProgress) {
    this.current = job.id;
    let wait = this.first;
    let asked = 0;
    let failed = null;
    try {
      while (job.status === 'running') {
        onProgress?.(job, asked, failed);
        if (!this.stop) await this.nap(wait);
        if (this.stop === 'later') {
          this.watch(job.id);
          const e = new Error(tr('hardware.left_waiting', { id: job.id, provider: job.request?.provider }));
          e.later = true;
          throw e;
        }
        const cancel = this.stop === 'cancel';
        try {
          job = await this.call('provider_job', { id: job.id, cancel });
          failed = null;
        } catch (e) {
          // Nothing about the job changed, and asking again is safe. A
          // cancel that did not reach the provider says so, and the job,
          // still waiting, is followed in the background.
          if (cancel) { this.watch(job.id); throw e; }
          failed = e.message;
        }
        asked += 1;
        wait = Math.min(this.most, wait * 1.5);
      }
    } finally { this.current = null; this.stop = null; }
    if (job.status === 'done') return job;
    throw new Error(job.status === 'cancelled' ? 'cancelled' : job.error || `the job ${job.status}`);
  }
  nap(ms) { return new Promise((r) => { const t = setTimeout(r, ms); this.wake = () => { clearTimeout(t); r(); }; }); }
  // What the status line says while a job waits.
  progressText(job, asked, failed) {
    const s = tr('hardware.waiting', { id: job.id, provider: job.request?.provider, asked });
    return failed ? `${s} ${tr('hardware.ask_failed', { why: failed })}` : s;
  }
  // Cancel the job at the provider; a job that finished first gives its result.
  cancel() { this.stop = 'cancel'; this.wake?.(); }
  // Leave the job at the provider and follow it in the background.
  later() { this.stop = 'later'; this.wake?.(); }
  // The jobs recorded on the person's providers, as each last stood.
  async jobs() { return (await this.call('provider_jobs', {})).jobs || []; }
  askAfter(id, cancel = false) { return this.call('provider_job', { id, cancel }); }
  // Every job still waiting, from an earlier window too, followed in the background.
  async resume() {
    for (const j of await this.jobs().catch(() => [])) if (j.status === 'running') this.watch(j.id);
  }
  // A job followed in the background until it ends: its result to
  // onFinished, or why it ended to onEnded. Asking spends nothing.
  watch(id) {
    if (this.watched.has(id)) return;
    this.watched.add(id);
    (async () => {
      let wait = this.first;
      for (;;) {
        await new Promise((r) => setTimeout(r, wait));
        wait = Math.min(this.most, wait * 1.5);
        let job;
        try { job = await this.call('provider_job', { id, cancel: false }); } catch (e) { continue; }
        if (job.status === 'running') continue;
        this.watched.delete(id);
        if (job.status === 'done') this.onFinished?.(job); else this.onEnded?.(job);
        return;
      }
    })();
  }
  methods() { return Promise.resolve({ methods: [] }); }
}

// A dialog that asks before a run that is not free: resolves true on "Run".
export function askDialog(host) {
  return (plan) => new Promise((resolve) => {
    const yes = el('button', { class: 'qs-btn qs-primary', type: 'button', id: 'qs-hw-yes', text: tr('hardware.run_it') });
    const no = el('button', { class: 'qs-btn', type: 'button', id: 'qs-hw-no', text: tr('hardware.cancel') });
    const d = el('dialog', { class: 'qs-dialog', id: 'qs-hw-confirm', 'aria-labelledby': 'qs-hw-confirm-title' },
      el('h2', { id: 'qs-hw-confirm-title', text: tr('hardware.not_free_title') }),
      ...confirmText(plan).map((t) => el('p', { text: t })),
      el('div', { class: 'qs-row' }, no, yes));
    const end = (v) => { d.close(); d.remove(); resolve(v); };
    yes.addEventListener('click', () => end(true));
    no.addEventListener('click', () => end(false));
    d.addEventListener('cancel', (e) => { e.preventDefault(); end(false); });
    host.append(d);
    d.showModal();
    no.focus();
  });
}

// A job in the list, in words: where it stands and when it was sent.
export function jobLine(j, when = (ms) => new Date(ms).toLocaleString()) {
  const key = `hardware.state_${j.status}`;
  const state = tr(key) === key ? j.status : tr(key);
  return tr('hardware.job_line', { id: j.id, provider: j.provider, shots: j.shots, state, when: when(j.submitted_ms) });
}

// The jobs sent to the person's providers from this computer: each one's
// state as last recorded, a finished one shown in the Studio, and Cancel for
// one still waiting. Opening the list asks no provider.
export function jobsDialog(host, { engine, show, say }) {
  const list = el('ul', { class: 'qs-hw-jobs', id: 'qs-hw-jobs-list' });
  const close = el('button', { class: 'qs-btn', type: 'button', text: tr('hardware.close') });
  const d = el('dialog', { class: 'qs-dialog', id: 'qs-hw-jobs', 'aria-labelledby': 'qs-hw-jobs-title' },
    el('h2', { id: 'qs-hw-jobs-title', text: tr('hardware.jobs') }), list, el('div', { class: 'qs-row' }, close));
  const fill = async () => {
    let jobs = [];
    try { jobs = await engine.jobs(); } catch (e) { say(e.message); }
    list.replaceChildren(...(jobs.length ? jobs.map((j) => {
      const act = [];
      if (j.status === 'done') act.push(el('button', { class: 'qs-btn', type: 'button', text: tr('hardware.show'), onclick: async () => { try { show(await engine.askAfter(j.id)); end(); } catch (e) { say(e.message); } } }));
      if (j.status === 'running') act.push(el('button', { class: 'qs-btn', type: 'button', text: tr('hardware.cancel_job'), onclick: async () => {
        try {
          const v = await engine.askAfter(j.id, true);
          if (v.status === 'done') { show(v); end(); return; }
          say(tr('hardware.ended', { id: j.id, provider: j.provider, why: v.error || v.status }));
          fill();
        } catch (e) { say(e.message); }
      } }));
      return el('li', {}, el('span', { text: jobLine(j) }), j.error ? el('span', { class: 'qs-note', text: ' ' + j.error }) : null, ...act);
    }) : [el('li', { class: 'qs-note', text: tr('hardware.jobs_empty') })]));
  };
  const end = () => { d.close(); d.remove(); };
  close.addEventListener('click', end);
  d.addEventListener('cancel', (e) => { e.preventDefault(); end(); });
  host.append(d);
  d.showModal();
  close.focus();
  return fill();
}

// The switch's segment and, on the desktop, the provider picker and the
// list of jobs sent. `onPick` is told when the person picks this place to
// run; `jobs` opens the list.
export function hardwareSegment({ desktop, engine, onPick, say, jobs }) {
  const seg = el('button', { class: 'qs-seg', type: 'button', 'aria-pressed': 'false', 'data-where': 'hardware', id: 'qs-where-hardware', text: tr('hardware.segment'), title: desktop ? tr('hardware.segment_title') : NOTE });
  const select = el('select', { class: 'qs-select', id: 'qs-provider', 'aria-label': tr('hardware.provider_label') });
  const jobsBtn = el('button', { class: 'qs-btn', type: 'button', id: 'qs-hw-jobs-open', text: tr('hardware.jobs'), title: tr('hardware.jobs_title') });
  const picker = el('span', { class: 'qs-hw', hidden: true }, select, jobsBtn);
  seg.addEventListener('click', async () => {
    if (!desktop) { say(NOTE); return; }
    try {
      const list = await engine.providers();
      if (!list.length) { say(tr('hardware.no_providers')); return; }
      select.replaceChildren(...list.map((p) => el('option', { value: p.name, text: `${p.name} (${p.kind})` })));
      picker.hidden = false;
      engine.select(select.value);
      onPick();
    } catch (e) { say(e.message); }
  });
  select.addEventListener('change', () => engine.select(select.value));
  jobsBtn.addEventListener('click', () => jobs?.());
  return { seg, picker };
}