const state = {
  token: null,
  kcId: null,
  whoami: null,
  socket: null,
  activeChannelId: null,
  pickedUsers: new Set(),
  pickedGuests: new Set(),
};

const $ = (id) => document.getElementById(id);

function decodeJwtPayload(token) {
  try {
    const [, payload] = token.split('.');
    return JSON.parse(atob(payload.replace(/-/g, '+').replace(/_/g, '/')));
  } catch {
    return null;
  }
}

function setStatus(el, message, kind) {
  el.textContent = message;
  el.classList.remove('status-ok', 'status-error');
  if (kind === 'ok') el.classList.add('status-ok');
  if (kind === 'error') el.classList.add('status-error');
}

function setConnBadge(online) {
  const badge = $('conn-badge');
  if (!badge) return;
  badge.textContent = online ? 'angemeldet' : 'nicht angemeldet';
  badge.classList.toggle('badge-online', online);
  badge.classList.toggle('badge-muted', !online);
}

function clearList(listEl, emptyMessage) {
  listEl.innerHTML = '';
  if (emptyMessage) {
    const li = document.createElement('li');
    li.className = 'list-empty';
    li.textContent = emptyMessage;
    listEl.appendChild(li);
  }
}

async function apiFetch(path, options = {}) {
  const headers = Object.assign({}, options.headers);
  if (state.token) headers.Authorization = `Bearer ${state.token}`;
  if (options.body && !headers['Content-Type']) headers['Content-Type'] = 'application/json';
  return fetch(`/api${path}`, Object.assign({}, options, { headers }));
}

/// --- Tabs (Gast / Team-Login) ---
document.querySelectorAll('.tab-btn').forEach((btn) => {
  btn.addEventListener('click', () => {
    document.querySelectorAll('.tab-btn').forEach((b) => b.classList.remove('active'));
    document.querySelectorAll('.tab-panel').forEach((p) => (p.hidden = true));
    btn.classList.add('active');
    const panel = document.querySelector(`[data-panel="${btn.dataset.tab}"]`);
    if (panel) panel.hidden = false;
  });
});

/// --- Login: Gast/Konfi ---
$('guest-form').addEventListener('submit', async (event) => {
  event.preventDefault();
  const inviteCode = $('invite-code').value;
  const firstName = $('first-name').value;
  const lastName = $('last-name').value;

  setStatus($('login-status'), 'Wird geprüft…');

  let res;
  try {
    res = await apiFetch('/auth/guest', {
      method: 'POST',
      body: JSON.stringify({ inviteCode, firstName, lastName }),
    });
  } catch (err) {
    setStatus($('login-status'), 'Netzwerkfehler. Bitte erneut versuchen.', 'error');
    return;
  }

  if (!res.ok) {
    setStatus($('login-status'), `Fehler: ${res.status}`, 'error');
    return;
  }

  const { accessToken } = await res.json();
  await onLoggedIn(accessToken);
});

/// --- Login: Team (Gemeinde-Name + Passwort) ---
$('team-form').addEventListener('submit', async (event) => {
  event.preventDefault();
  const gemeindeName = $('team-gemeinde').value;
  const password = $('team-password').value;

  setStatus($('login-status'), 'Wird geprüft…');

  let res;
  try {
    res = await apiFetch('/auth/team-login', {
      method: 'POST',
      body: JSON.stringify({ gemeindeName, password }),
    });
  } catch (err) {
    setStatus($('login-status'), 'Netzwerkfehler. Bitte erneut versuchen.', 'error');
    return;
  }

  if (!res.ok) {
    setStatus($('login-status'), `Fehler: ${res.status}`, 'error');
    return;
  }

  const { accessToken } = await res.json();
  await onLoggedIn(accessToken);
});

async function onLoggedIn(accessToken) {
  state.token = accessToken;
  const claims = decodeJwtPayload(accessToken);
  state.kcId = claims?.kcId ?? null;

  // Fetch identity/role from the API so the UI can show role-appropriate
  // sections (Gruppenchat creation is LT/Verantwortliche/r only).
  let me = null;
  try {
    const res = await apiFetch('/auth/me');
    if (res.ok) me = await res.json();
  } catch {
    // best-effort
  }
  state.whoami = me;

  setStatus($('login-status'), 'Angemeldet.', 'ok');
  setConnBadge(true);
  $('login-section').hidden = true;
  $('app-section').hidden = false;
  renderWhoAmI();
}

function renderWhoAmI() {
  const card = $('whoami-card');
  const text = $('whoami-text');
  const gruppenCard = $('gruppen-card');
  const manageCard = $('manage-card');

  if (!state.whoami) {
    card.hidden = true;
    gruppenCard.hidden = true;
    manageCard.hidden = true;
    return;
  }

  card.hidden = false;
  if (state.whoami.kind === 'guest') {
    text.textContent = `Konfi/Gast (KC ${state.whoami.kcId})`;
    gruppenCard.hidden = true;
    manageCard.hidden = true;
  } else {
    const roles = (state.whoami.memberships || []).map((m) => m.role).join(', ') || 'keine Rolle';
    text.textContent = `${state.whoami.email} — ${roles}`;
    const canManageGruppen =
      state.whoami.isLeitungsteam ||
      (state.whoami.memberships || []).some((m) => m.role === 'GEMEINDE_VERANTWORTLICHER');
    gruppenCard.hidden = !canManageGruppen;
    manageCard.hidden = !canManageGruppen;
    if (state.kcId) $('gruppe-kcid').value = state.kcId;
  }
}

$('logout-btn').addEventListener('click', () => {
  if (state.socket) state.socket.close();
  state.token = null;
  state.kcId = null;
  state.whoami = null;
  state.activeChannelId = null;
  setConnBadge(false);
  $('app-section').hidden = true;
  $('login-section').hidden = false;
  setStatus($('login-status'), '');
});

/// --- Gruppenchat: Kandidaten laden + auswählen ---
$('load-candidates').addEventListener('click', async () => {
  const kcId = $('gruppe-kcid').value.trim();
  if (!kcId) {
    setStatus($('gruppe-status'), 'Bitte KC-ID angeben.', 'error');
    return;
  }

  let res;
  try {
    res = await apiFetch(`/chat/${kcId}/gruppen/participant-candidates`);
  } catch {
    setStatus($('gruppe-status'), 'Netzwerkfehler beim Laden.', 'error');
    return;
  }
  if (!res.ok) {
    setStatus($('gruppe-status'), `Fehler: ${res.status}`, 'error');
    return;
  }

  const { users, guests } = await res.json();
  state.pickedUsers = new Set();
  state.pickedGuests = new Set();
  renderCandidateList($('candidate-users'), users, 'userId', (u) => `${u.firstName} ${u.lastName} (${u.role})`, state.pickedUsers);
  renderCandidateList($('candidate-guests'), guests, 'guestId', (g) => `${g.firstName} ${g.lastName}`, state.pickedGuests);
  setStatus($('gruppe-status'), `${users.length} Team-Mitglieder, ${guests.length} Konfis geladen.`, 'ok');
});

function renderCandidateList(listEl, items, idKey, labelFn, pickedSet) {
  clearList(listEl);
  if (!items.length) {
    clearList(listEl, 'Keine Kandidaten gefunden.');
    return;
  }
  listEl.innerHTML = '';
  for (const item of items) {
    const id = item[idKey];
    const li = document.createElement('li');
    const checkbox = document.createElement('input');
    checkbox.type = 'checkbox';
    checkbox.addEventListener('change', () => {
      if (checkbox.checked) pickedSet.add(id);
      else pickedSet.delete(id);
      li.classList.toggle('picked', checkbox.checked);
    });
    const label = document.createElement('span');
    label.textContent = labelFn(item);
    li.appendChild(checkbox);
    li.appendChild(label);
    li.addEventListener('click', (e) => {
      if (e.target === checkbox) return;
      checkbox.checked = !checkbox.checked;
      checkbox.dispatchEvent(new Event('change'));
    });
    listEl.appendChild(li);
  }
}

$('create-gruppe').addEventListener('click', async () => {
  const kcId = $('gruppe-kcid').value.trim();
  const name = $('gruppe-name').value.trim();
  if (!kcId) {
    setStatus($('gruppe-status'), 'Bitte KC-ID angeben.', 'error');
    return;
  }

  setStatus($('gruppe-status'), 'Wird erstellt…');

  let res;
  try {
    res = await apiFetch(`/chat/${kcId}/gruppen`, {
      method: 'POST',
      body: JSON.stringify({
        type: 'GRUPPE',
        name,
        participantUserIds: [...state.pickedUsers],
        participantGuestIds: [...state.pickedGuests],
      }),
    });
  } catch {
    setStatus($('gruppe-status'), 'Netzwerkfehler.', 'error');
    return;
  }

  if (!res.ok) {
    setStatus($('gruppe-status'), `Fehler: ${res.status}`, 'error');
    return;
  }

  const channel = await res.json();
  setStatus($('gruppe-status'), `Erstellt: ${channel.id}`, 'ok');
  $('manage-channel-id').value = channel.id;
  $('channel-id').value = channel.id;
});

/// --- Teilnehmerverwaltung ---
$('add-participant').addEventListener('click', () => manageParticipant('add'));
$('remove-participant').addEventListener('click', () => manageParticipant('remove'));

async function manageParticipant(action) {
  const channelId = $('manage-channel-id').value.trim();
  const userId = $('manage-user-id').value.trim();
  const guestId = $('manage-guest-id').value.trim();
  if (!channelId || (!userId && !guestId)) {
    setStatus($('manage-status'), 'Channel-ID und User- oder Gast-ID angeben.', 'error');
    return;
  }

  setStatus($('manage-status'), 'Wird gesendet…');
  const method = action === 'add' ? 'POST' : 'DELETE';

  let res;
  try {
    res = await apiFetch(`/chat/gruppen/${channelId}/participants`, {
      method,
      body: JSON.stringify({ userId: userId || undefined, guestId: guestId || undefined }),
    });
  } catch {
    setStatus($('manage-status'), 'Netzwerkfehler.', 'error');
    return;
  }

  if (!res.ok) {
    setStatus($('manage-status'), `Fehler: ${res.status}`, 'error');
    return;
  }
  setStatus($('manage-status'), action === 'add' ? 'Hinzugefügt.' : 'Entfernt.', 'ok');
}

/// --- Workshop-Wahl ---
$('submit-wahl').addEventListener('click', async () => {
  const wahlId = $('wahl-id').value;
  const prioritaeten = $('prioritaeten')
    .value.split(',')
    .map((s) => s.trim())
    .filter(Boolean);

  if (!wahlId || prioritaeten.length === 0) {
    setStatus($('wahl-status'), 'Bitte Wahl-ID und mindestens eine Priorität angeben.', 'error');
    return;
  }

  setStatus($('wahl-status'), 'Wird gesendet…');

  let res;
  try {
    res = await apiFetch(`/wahl/${wahlId}/teilnehmer`, {
      method: 'POST',
      body: JSON.stringify({ prioritaeten }),
    });
  } catch (err) {
    setStatus($('wahl-status'), 'Netzwerkfehler. Bitte erneut versuchen.', 'error');
    return;
  }

  if (res.ok) {
    setStatus($('wahl-status'), 'Gespeichert.', 'ok');
  } else {
    setStatus($('wahl-status'), `Fehler: ${res.status}`, 'error');
  }
});

/// --- Dateien ---
$('load-files').addEventListener('click', async () => {
  if (!state.kcId) return;

  let res;
  try {
    res = await apiFetch(`/files/${state.kcId}`);
  } catch (err) {
    clearList($('file-list'), 'Fehler beim Laden der Dateien.');
    return;
  }

  const files = res.ok ? await res.json() : [];
  const list = $('file-list');

  if (!files.length) {
    clearList(list, 'Keine Dateien verfügbar.');
    return;
  }

  list.innerHTML = '';
  for (const file of files) {
    const li = document.createElement('li');
    li.textContent = file.filename;
    list.appendChild(li);
  }
});

/// --- Chat: eigene Channels auflisten ---
$('load-channels').addEventListener('click', async () => {
  if (!state.kcId) {
    setStatus($('login-status'), '');
    return;
  }

  let res;
  try {
    res = await apiFetch(`/chat/${state.kcId}/channels`);
  } catch {
    clearList($('channel-list'), 'Fehler beim Laden der Chats.');
    return;
  }

  const channels = res.ok ? await res.json() : [];
  const list = $('channel-list');
  if (!channels.length) {
    clearList(list, 'Keine Chats verfügbar.');
    return;
  }

  list.innerHTML = '';
  for (const channel of channels) {
    const li = document.createElement('li');
    const label = document.createElement('span');
    label.textContent = channel.name || channel.type;
    const chip = document.createElement('span');
    chip.className = 'chip';
    chip.textContent = channel.type;
    li.appendChild(label);
    li.appendChild(chip);
    li.addEventListener('click', () => {
      $('channel-id').value = channel.id;
      joinChannel(channel.id);
    });
    list.appendChild(li);
  }
});

/// --- Chat: beitreten + live mitlesen/schreiben ---
$('join-channel').addEventListener('click', () => {
  const channelId = $('channel-id').value;
  if (!channelId || !state.token) return;
  joinChannel(channelId);
});

function joinChannel(channelId) {
  if (state.socket) state.socket.close();
  state.activeChannelId = channelId;

  const protocol = location.protocol === 'https:' ? 'wss' : 'ws';
  const socket = new WebSocket(`${protocol}://${location.host}/chat?token=${state.token}`);
  state.socket = socket;

  const chatLog = $('chat-log');
  clearList(chatLog, 'Verbindung wird hergestellt…');

  socket.addEventListener('open', () => {
    socket.send(JSON.stringify({ event: 'chat:join', data: { channelId } }));
    clearList(chatLog, 'Verbunden. Warte auf Nachrichten…');
  });

  socket.addEventListener('message', (event) => {
    const { event: name, data } = JSON.parse(event.data);

    if (name === 'chat:participants-changed') {
      if (data.channelId === state.activeChannelId) {
        setStatus($('manage-status'), 'Teilnehmerliste wurde aktualisiert.', 'ok');
      }
      return;
    }

    if (name !== 'chat:message') return;

    const emptyPlaceholder = chatLog.querySelector('.list-empty');
    if (emptyPlaceholder) emptyPlaceholder.remove();

    const li = document.createElement('li');
    const body = document.createElement('span');
    body.className = 'chat-body';
    body.textContent = data.body;
    li.appendChild(body);
    chatLog.appendChild(li);
    chatLog.scrollTop = chatLog.scrollHeight;
  });

  socket.addEventListener('close', () => {
    setConnBadge(!!state.token);
  });
}

$('send-message').addEventListener('click', () => {
  const input = $('chat-message');
  const body = input.value.trim();
  if (!body || !state.socket || !state.activeChannelId) return;
  state.socket.send(
    JSON.stringify({ event: 'chat:send', data: { channelId: state.activeChannelId, body } }),
  );
  input.value = '';
});

$('chat-message').addEventListener('keydown', (e) => {
  if (e.key === 'Enter') $('send-message').click();
});