/* The panel. Every control acts immediately and reconciles with what the
   speakers report a moment later, because a remote that waits for a
   network round trip before it looks like it did anything feels broken. */

const STEP = Number(document.documentElement.dataset.step) || 2;
const POLL_MS = 5000;

const el = (sel, root = document) => root.querySelector(sel);
const els = (sel, root = document) => Array.from(root.querySelectorAll(sel));

const ui = {
  foot: el('[data-role="foot"]'),
  toast: el('[data-role="toast"]'),
  refresh: el('[data-role="refresh"]'),
  splitAll: el('[data-role="split-all"]'),
  avrStatus: el('[data-role="avr-status"]'),
  inputButton: el('[data-role="input-button"]'),
  inputName: el('[data-role="input-name"]'),
  sheet: el('[data-role="sheet"]'),
  options: el('[data-role="options"]'),
};

const rooms = {};
let inputs = [];
let currentInput = null;

/* --- transport -------------------------------------------------------- */
async function api(path, body) {
  const options = body === undefined
    ? {}
    : { method: 'POST', headers: { 'Content-Type': 'application/json' }, body: JSON.stringify(body) };
  const response = await fetch(path, options);
  let data = {};
  try { data = await response.json(); } catch (_) { /* empty or not JSON */ }
  if (!response.ok) throw new Error(data.error || `${response.status} ${response.statusText}`);
  return data;
}

let toastTimer;
function toast(message) {
  ui.toast.textContent = message;
  ui.toast.hidden = false;
  clearTimeout(toastTimer);
  toastTimer = setTimeout(() => { ui.toast.hidden = true; }, 4000);
}

/* --- rooms ------------------------------------------------------------ */
els('.room').forEach((node) => {
  const key = node.dataset.room;
  const room = {
    key,
    node,
    level: el('[data-role="level"]', node),
    bar: el('[data-role="bar"]', node),
    toggle: el('[data-role="group"]', node),
    toggleLabel: el('[data-role="group-label"]', node),
    steps: els('.step', node),
    volume: null,
    grouped: false,
    available: false,
    pending: 0,     // taps not yet sent
    inflight: false,
    busy: false,    // a grouping change is in flight
  };
  rooms[key] = room;

  room.steps.forEach((button) => {
    const direction = Number(button.dataset.delta);
    holdable(button, () => nudge(key, direction));
  });

  room.toggle.addEventListener('click', () => setGrouped(key, !room.grouped));
});

function paintRoom(room) {
  const known = room.volume !== null && room.volume !== undefined;
  room.level.textContent = known ? room.volume : '—';
  room.bar.style.width = `${known ? room.volume : 0}%`;
  room.node.classList.toggle('offline', !room.available);
  room.steps.forEach((button) => { button.disabled = !room.available; });
  room.toggle.disabled = !room.available;
  room.toggle.classList.toggle('busy', room.busy);
  room.toggle.setAttribute('aria-pressed', String(room.grouped));
  room.toggleLabel.textContent = room.grouped ? 'Grouped with AVR' : 'Separate';
}

/* Press and hold to keep moving, accelerating as you hold. */
function holdable(node, action) {
  let timer = null;
  let delay = 420;

  const stop = () => { clearTimeout(timer); timer = null; delay = 420; };
  const tick = () => {
    action();
    delay = Math.max(130, delay * 0.72);
    timer = setTimeout(tick, delay);
  };

  node.addEventListener('pointerdown', (event) => {
    if (event.button > 0 || node.disabled) return;
    event.preventDefault();   // also suppresses the click that would double-fire
    action();
    timer = setTimeout(tick, delay);
  });
  ['pointerup', 'pointercancel', 'pointerleave'].forEach((type) => node.addEventListener(type, stop));
}

function nudge(key, direction) {
  const room = rooms[key];
  if (!room.available) return;
  room.volume = Math.max(0, Math.min(100, (room.volume ?? 0) + direction * STEP));
  room.pending += direction * STEP;
  paintRoom(room);
  flushVolume(key);
}

/* A burst of taps collapses into one call, so holding + does not queue up
   thirty requests the speakers then have to chew through. */
async function flushVolume(key) {
  const room = rooms[key];
  if (room.inflight || !room.pending) return;
  const delta = room.pending;
  room.pending = 0;
  room.inflight = true;
  try {
    const data = await api('/api/volume', { target: key, delta });
    if (!room.pending) {
      room.volume = data.level;
      paintRoom(room);
    }
  } catch (error) {
    toast(error.message);
    refresh();
  } finally {
    room.inflight = false;
    if (room.pending) flushVolume(key);
  }
}

async function setGrouped(key, joined) {
  const room = rooms[key];
  if (room.busy || !room.available) return;
  room.busy = true;
  room.grouped = joined;      // show the new state while the speakers catch up
  paintRoom(room);
  try {
    const data = await api('/api/group', { target: key, joined });
    applyJoined(data.joined || []);
  } catch (error) {
    toast(error.message);
  } finally {
    room.busy = false;
    refresh();
  }
}

function applyJoined(joined) {
  Object.values(rooms).forEach((room) => {
    room.grouped = joined.includes(room.key);
    paintRoom(room);
  });
}

ui.splitAll.addEventListener('click', async () => {
  try {
    applyJoined([]);
    const data = await api('/api/group/none');
    applyJoined(data.joined || []);
  } catch (error) {
    toast(error.message);
  } finally {
    refresh();
  }
});

/* --- the input picker -------------------------------------------------- */
ui.inputButton.addEventListener('click', openSheet);
el('[data-role="scrim"]').addEventListener('click', closeSheet);
el('[data-role="sheet-close"]').addEventListener('click', closeSheet);

function sheetOpen() { return !ui.sheet.hidden; }

function openSheet() {
  if (!inputs.length) {
    toast('No inputs reported by the AVR yet');
    return;
  }
  ui.options.innerHTML = '';
  inputs.forEach((source) => {
    const option = document.createElement('button');
    option.className = 'option';
    option.setAttribute('aria-current', String(currentInput && currentInput.code === source.code));
    option.innerHTML = '<span></span><span class="code"></span>';
    option.firstChild.textContent = source.name;
    option.lastChild.textContent = source.code;
    option.addEventListener('click', () => chooseInput(source));
    ui.options.appendChild(option);
  });
  ui.sheet.hidden = false;
}

function closeSheet() { ui.sheet.hidden = true; }

async function chooseInput(source) {
  closeSheet();
  currentInput = source;
  ui.inputName.textContent = source.name;
  try {
    const data = await api('/api/avr/input', { code: source.code });
    currentInput = data;
    ui.inputName.textContent = data.name;
  } catch (error) {
    toast(error.message);
    refresh();
  }
}

/* --- state ------------------------------------------------------------- */
function render(state) {
  (state.rooms || []).forEach((incoming) => {
    const room = rooms[incoming.key];
    if (!room) return;
    room.available = incoming.available;
    room.grouped = incoming.grouped;
    // Do not stomp on a volume the user is in the middle of changing.
    if (!room.pending && !room.inflight) room.volume = incoming.volume;
    paintRoom(room);
  });

  const avr = state.avr || {};
  inputs = avr.inputs || [];
  currentInput = avr.input || null;
  ui.inputName.textContent = currentInput ? currentInput.name : '—';
  ui.avrStatus.textContent = avr.connected ? 'ready' : 'offline';
  ui.avrStatus.classList.toggle('on', Boolean(avr.connected));

  const problems = state.errors || [];
  ui.foot.textContent = problems.length ? problems[0] : (state.demo ? 'demo mode — no real speakers' : '');
  ui.foot.classList.toggle('bad', problems.length > 0);
}

let refreshing = false;
async function refresh() {
  if (refreshing) return;
  refreshing = true;
  try {
    render(await api('/api/state'));
  } catch (error) {
    ui.foot.textContent = error.message;
    ui.foot.classList.add('bad');
  } finally {
    refreshing = false;
  }
}

function busy() {
  return sheetOpen() || Object.values(rooms).some((r) => r.pending || r.inflight || r.busy);
}

ui.refresh.addEventListener('click', () => {
  ui.refresh.classList.add('spin');
  setTimeout(() => ui.refresh.classList.remove('spin'), 700);
  refresh();
});

setInterval(() => {
  if (document.visibilityState === 'visible' && !busy()) refresh();
}, POLL_MS);

document.addEventListener('visibilitychange', () => {
  if (document.visibilityState === 'visible') refresh();
});

Object.values(rooms).forEach(paintRoom);
refresh();