// The Result widget: a job's result as the engine gave it. Its counts as bars, the
// most frequent first (or their sampled frequencies: each count over the shots),
// its expectation values with the bound or standard error the method gives, its
// amplitudes, the method and the accuracy class it names, and the receipt's check
// made by the engine in Python. The model's `frequencies` and `top` choose what
// the bars show.

const SVG = 'http://www.w3.org/2000/svg';
const BAR = '#7aa0ff';

function el(tag, attrs = {}, ...kids) {
  const e = document.createElement(tag);
  for (const [k, v] of Object.entries(attrs)) {
    if (k === 'text') e.textContent = v;
    else if (v != null) e.setAttribute(k, String(v));
  }
  for (const k of kids) if (k != null) e.append(k);
  return e;
}

function svgEl(tag, attrs = {}, text) {
  const e = document.createElementNS(SVG, tag);
  for (const [k, v] of Object.entries(attrs)) e.setAttribute(k, String(v));
  if (text != null) e.textContent = text;
  return e;
}

const num = (x) => (typeof x === 'number' ? (Number.isInteger(x) ? String(x) : String(Number(x.toPrecision(6)))) : String(x));

function badge(ok) {
  return el('span', { class: `wq-badge ${ok ? 'wq-good' : 'wq-bad'}`, text: ok ? 'verified' : 'INVALID' });
}

function histogram(counts, shots, top, frequencies) {
  const rows = Object.entries(counts).slice(0, top);
  if (!rows.length) return null;
  const labelW = Math.max(7.5 * Math.max(...rows.map(([k]) => k.length)) + 12, 40);
  const barW = 260, rowH = 18;
  const peak = Math.max(...rows.map(([, v]) => v)) || 1;
  const W = labelW + barW + 70, H = rowH * rows.length + 4;
  const s = svgEl('svg', { width: W, height: H, viewBox: `0 0 ${W} ${H}`, class: 'wq-histogram', role: 'img', 'aria-label': `Counts of ${rows.length} outcomes` });
  rows.forEach(([k, v], i) => {
    const y = 2 + i * rowH;
    const w = Math.max((barW * v) / peak, 1);
    s.append(svgEl('text', { x: labelW - 6, y: y + 9, 'text-anchor': 'end', 'dominant-baseline': 'central', class: 'wq-mono' }, k));
    const r = svgEl('rect', { x: labelW, y: y + 2, width: w.toFixed(1), height: rowH - 4, rx: 2, fill: BAR });
    r.append(svgEl('title', {}, `${k}: ${v} of ${shots}`));
    s.append(r);
    s.append(svgEl('text', { x: (labelW + w + 6).toFixed(1), y: y + 9, 'dominant-baseline': 'central', class: 'wq-small' }, frequencies && shots ? (v / shots).toFixed(4) : String(v)));
  });
  return s;
}

function table(head, rows) {
  const t = el('table', { class: 'wq-table' }, el('tr', {}, ...head.map((h) => el('th', { text: h }))));
  for (const r of rows) t.append(el('tr', {}, ...r.map((c) => el('td', { class: 'wq-mono', text: c }))));
  return t;
}

function render({ model, el: host }) {
  const root = el('div', { class: 'wq wq-result-widget' });
  host.append(root);

  function draw() {
    const d = model.get('data') || {};
    const top = Math.max(1, model.get('top') || 16);
    const frequencies = !!model.get('frequencies');
    const head = el('div', {}, el('b', { text: d.method || '?' }), ' · accuracy ', el('b', { text: d.accuracy || '?' }));
    if (d.accuracy_note) head.append(' ', el('span', { class: 'wq-muted', text: `(${d.accuracy_note})` }));
    const parts = [head];
    if (d.why) parts.push(el('div', { class: 'wq-muted', text: d.why }));
    const counts = d.counts || {};
    const n = Object.keys(counts).length;
    if (n) {
      const toggle = el('input', { type: 'checkbox' });
      toggle.checked = frequencies;
      toggle.addEventListener('change', () => { model.set('frequencies', toggle.checked); model.save_changes(); });
      const topBox = el('input', { type: 'number', min: 1, max: Math.max(n, 1), value: Math.min(top, n), class: 'wq-num' });
      topBox.addEventListener('change', () => { model.set('top', Math.max(1, Number(topBox.value) || 1)); model.save_changes(); });
      parts.push(el('div', { class: 'wq-bar' },
        el('span', { text: `${d.shots} shots, ${d.distinct_outcomes ?? n} distinct outcomes; showing` }), topBox,
        el('label', { class: 'wq-check' }, toggle, el('span', { text: 'as sampled frequencies' }))));
      parts.push(histogram(counts, d.shots, top, frequencies));
      const rest = Object.values(counts).slice(top).reduce((a, b) => a + b, 0) + (d.omitted_shots || 0);
      if (rest) parts.push(el('div', { class: 'wq-muted', text: `${rest} more shots fell on outcomes not drawn` }));
    }
    const exps = d.expectations || [];
    if (exps.length) {
      parts.push(table(['observable', 'value', 'error'], exps.map((e) => [
        e.observable, num(e.value),
        e.bound != null ? `± ${num(e.bound)} (bound)` : e.stderr != null ? `± ${num(e.stderr)} (std. error)` : '',
      ])));
    }
    const amps = d.amplitudes || [];
    if (amps.length) parts.push(table(['basis state', 're', 'im', '|a|²'], amps.map((a) => [a.bits, num(a.re), num(a.im), num(a.re * a.re + a.im * a.im)])));
    if (d.receipt) {
      const r = d.receipt;
      const line = el('div', { class: 'wq-line' }, 'receipt ', badge(r.valid === true), ' signed by ', el('span', { class: 'wq-mono', title: r.signer || '', text: r.signer || r.key || '?' }));
      if (r.demo) line.append(' ', el('span', { class: 'wq-muted', text: '(the published demo key: it shows the result is unaltered, not who signed it)' }));
      parts.push(line);
    }
    root.replaceChildren(...parts.filter(Boolean));
  }

  draw();
  for (const ev of ['change:data', 'change:frequencies', 'change:top']) model.on(ev, draw);
  return () => { for (const ev of ['change:data', 'change:frequencies', 'change:top']) model.off(ev, draw); };
}

export default { render };