/**
 * Overview page — summary stats, quick-action cards, and virtualized connection lists.
 * Uses the OvList class for infinite-scroll, searchable tables of connections and servers.
 * Depends on: core/utils.js ($, escapeHtml), ui/state-tag.js (stateTag),
 *             ui/modal.js (openModal), ui/toast.js (copyToClipboard, showToast),
 *             pages/ssh.js (openAddSshModal), pages/rdp.js (openAddRdpModal),
 *             core/state.js (sshConnections, rdpConnections), data/install-commands.js (getInstallCommand, detectPlatform, INSTALL_SCRIPT_BASE_URL)
 */

const OV_PAGE = 20; // rows per page

/**
 * Virtualized, searchable, infinite-scroll list for the Overview page.
 * Renders rows in pages of OV_PAGE, loading more when the sentinel element scrolls into view.
 */
class OvList {
  constructor({ bodyId, sentinelId, searchId, subtitleId, rowFn, emptyMsg, cols }) {
    this.body       = $(bodyId);
    this.sentinel   = $(sentinelId);
    this.searchEl   = $(searchId);
    this.subtitleEl = $(subtitleId);
    this.scrollArea = this.body?.closest('.ov-scroll-area') || null;
    this.rowFn      = rowFn;
    this.emptyMsg   = emptyMsg;
    this.cols       = cols;
    this.data       = [];
    this.filtered   = [];
    this.rendered   = 0;
    this._debounce  = null;
    this._observer  = null;
    this._initObserver();
    this._initSearch();
  }

  _initObserver() {
    if (!this.sentinel) return;
    this._observer = new IntersectionObserver(entries => {
      if (entries[0].isIntersecting) this._appendPage();
    }, { threshold: 0 });
    this._observer.observe(this.sentinel);
  }

  _initSearch() {
    if (!this.searchEl) return;
    this.searchEl.addEventListener('input', () => {
      clearTimeout(this._debounce);
      this._debounce = setTimeout(() => this._applyFilter(), 180);
    });
  }

  setData(data, subtitleText) {
    this.data = data;
    if (this.subtitleEl) this.subtitleEl.textContent = subtitleText;
    this._applyFilter();
  }

  _applyFilter() {
    const q = (this.searchEl?.value || '').trim().toLowerCase();
    this.filtered = q
      ? this.data.filter(item => JSON.stringify(item).toLowerCase().includes(q))
      : this.data.slice();
    this._reset();
  }

  _reset() {
    if (!this.body) return;
    this.rendered = 0;
    this.body.innerHTML = '';
    if (this.filtered.length === 0) {
      this.body.innerHTML = `<tr><td colspan="${this.cols}" class="empty">${this.emptyMsg}</td></tr>`;
      this.scrollArea?.classList.add('ov-empty');
      return;
    }
    this.scrollArea?.classList.remove('ov-empty');
    this._appendPage();
  }

  _appendPage() {
    if (!this.body || this.rendered >= this.filtered.length) return;
    const next = this.filtered.slice(this.rendered, this.rendered + OV_PAGE);
    this.body.insertAdjacentHTML('beforeend', next.map(this.rowFn).join(''));
    this.rendered += next.length;
  }
}

// Instances — created once, reused on every updateDashboard call
let _ovVhost   = null;
let _ovServers = null;
let _ovSvc     = null;
let _ovSsh     = null;
let _ovRdp     = null;

/** Current platform for onboarding card (win32 | macos | linux). Set by detectPlatform or switcher. */
let _onboardingPlatform = null;

/**
 * Update the onboarding card command and label for the given platform.
 * @param {'macos'|'linux'|'win32'} platform
 */
function _updateOnboardingCommand(platform) {
  if (typeof getInstallCommand === 'undefined' || typeof INSTALL_SCRIPT_BASE_URL === 'undefined') return;
  const { label, command } = getInstallCommand(INSTALL_SCRIPT_BASE_URL, platform);
  const labelEl = $('onboardingPlatformLabel');
  const cmdEl = $('onboardingCommand');
  if (labelEl) labelEl.textContent = label;
  if (cmdEl) cmdEl.textContent = command;
}

/**
 * Create and wire up the OvList instances for virtual hosts and server tunnels.
 * Called once during dashboard initialisation.
 */
function initOvLists() {
  _ovVhost = new OvList({
    bodyId: 'recentConnections', sentinelId: 'ovVhostSentinel',
    searchId: 'ovVhostSearch', subtitleId: 'ovVhostSubtitle',
    cols: 3, emptyMsg: 'No virtual hosts',
    rowFn: v => {
      const h = v.hostname || v.id || '';
      return `<tr>
        <td style="font-size:12px;"><span class="mono-chip">${escapeHtml(h)}</span></td>
        <td>${stateTag(v.state)}</td>
        <td><a href="https://${escapeHtml(h)}" target="_blank" rel="noopener"
              class="btn btn-ghost btn-sm" style="padding:3px 8px;">
          <svg viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2"
               style="width:11px;height:11px;">
            <path d="M18 13v6a2 2 0 0 1-2 2H5a2 2 0 0 1-2-2V8a2 2 0 0 1 2-2h6"/>
            <polyline points="15,3 21,3 21,9"/><line x1="10" y1="14" x2="21" y2="3"/>
          </svg>Open</a></td>
      </tr>`;
    }
  });

  _ovServers = new OvList({
    bodyId: 'ovServersBody', sentinelId: 'ovServersSentinel',
    searchId: 'ovServersSearch', subtitleId: 'ovServersSubtitle',
    cols: 3, emptyMsg: 'No server tunnels',
    rowFn: s => {
      const key = s.url || s.hsUrl || '';
      const short = key.length > 22 ? key.slice(0, 9) + '…' + key.slice(-7) : key;
      const display = s.label ? escapeHtml(s.label) : `<span class="mono" style="font-size:11px;color:var(--text3);">${escapeHtml(String(s.port || '—'))}</span>`;
      return `<tr>
        <td style="font-size:12px;">${display}</td>
        <td>${stateTag(s.state)}</td>
        <td class="mono" style="font-size:11px;color:var(--text3);"
            title="${escapeHtml(key)}">${escapeHtml(short)}</td>
      </tr>`;
    }
  });

  _ovSvc = new OvList({
    bodyId: 'ovSvcBody', sentinelId: 'ovSvcSentinel',
    searchId: 'ovSvcSearch', subtitleId: 'ovSvcSubtitle',
    cols: 3, emptyMsg: 'No service tunnels',
    rowFn: t => `<tr>
      <td style="font-size:12px;">${escapeHtml(t.label || '—')}</td>
      <td class="mono" style="font-size:12px;">${escapeHtml(String(t.localPort || '—'))}</td>
      <td>${stateTag(t.state)}</td>
    </tr>`
  });

  _ovSsh = new OvList({
    bodyId: 'ovSshBody', sentinelId: 'ovSshSentinel',
    searchId: 'ovSshSearch', subtitleId: 'ovSshSubtitle',
    cols: 2, emptyMsg: 'No SSH connections',
    rowFn: c => `<tr>
      <td style="font-size:12px;">${escapeHtml(c.label || c.hsUrl || '—')}</td>
      <td class="mono" style="font-size:12px;color:var(--text3);">${escapeHtml(c.username || '—')}</td>
    </tr>`
  });

  _ovRdp = new OvList({
    bodyId: 'ovRdpBody', sentinelId: 'ovRdpSentinel',
    searchId: 'ovRdpSearch', subtitleId: 'ovRdpSubtitle',
    cols: 2, emptyMsg: 'No remote desktops',
    rowFn: c => `<tr>
      <td style="font-size:12px;">${escapeHtml(c.label || '—')}</td>
      <td><span class="badge badge-neutral" style="font-size:10px;padding:2px 6px;">
        ${escapeHtml((c.type || 'vnc').toUpperCase())}</span></td>
    </tr>`
  });

  // Quick action buttons
  $('qaAddVhost')  ?.addEventListener('click', () => openModal('modal-addVhost'));
  $('qaAddServer')?.addEventListener('click', () => {
    const editIdEl = $('serverEditId');
    if (editIdEl) editIdEl.value = '';
    const labelEl = $('startServerLabel');
    if (labelEl) labelEl.value = '';
    const portEl = $('startServerPort');
    if (portEl) portEl.value = '3000';
    const hostEl = $('startServerHost');
    if (hostEl) hostEl.value = '127.0.0.1';
    const secureEl = $('startServerSecure');
    if (secureEl) secureEl.checked = true;
    const tcpEl = $('startServerProtocolTcp');
    if (tcpEl) tcpEl.checked = true;
    const titleEl = $('modal-startServer-title');
    if (titleEl) titleEl.textContent = 'Start Server Tunnel';
    const submitEl = $('startServerSubmit');
    if (submitEl) submitEl.textContent = 'Start Server';
    openModal('modal-startServer');
  });
  $('qaAddSvc')    ?.addEventListener('click', () => openModal('modal-addServiceTunnel'));
  $('qaAddSsh')    ?.addEventListener('click', () => openAddSshModal(null));
  $('qaAddRdp')    ?.addEventListener('click', () => openAddRdpModal(null));
  $('qaInstallCA') ?.addEventListener('click', () => openModal('modal-installCA'));

  // Onboarding card (native host not found): Copy, Check again, platform switcher
  const copyBtn = $('onboardingCopyBtn');
  if (copyBtn) {
    copyBtn.addEventListener('click', () => {
      const cmdEl = $('onboardingCommand');
      if (cmdEl && typeof copyToClipboard === 'function') copyToClipboard(cmdEl.textContent, copyBtn);
    });
  }
  const checkAgainBtn = $('onboardingCheckAgainBtn');
  if (checkAgainBtn) {
    checkAgainBtn.addEventListener('click', async () => {
      if (typeof refresh !== 'function') return;
      const state = await refresh();
      if (state?.hostConnected) {
        if (typeof showToast === 'function') showToast('Native host connected', 'success');
      } else {
        if (typeof showToast === 'function') showToast('Still disconnected. Install the native host using the command above.', 'default');
      }
    });
  }
  const switchMacLinux = $('onboardingSwitchMacLinux');
  if (switchMacLinux) {
    switchMacLinux.addEventListener('click', () => {
      _onboardingPlatform = 'macos';
      _updateOnboardingCommand('macos');
    });
  }
  const switchWin = $('onboardingSwitchWin');
  if (switchWin) {
    switchWin.addEventListener('click', () => {
      _onboardingPlatform = 'win32';
      _updateOnboardingCommand('win32');
    });
  }
}

/**
 * Render the Overview page with the latest extension state.
 * Updates summary stat cards, quick-action buttons, and the connection/server lists.
 * @param {object} state - Full extension state from `fetchState()`.
 */
function updateDashboard(state) {
  currentState = state;
  const servers        = state.servers        || [];
  const virtualHosts   = state.virtualHosts   || [];
  const serviceTunnels = state.serviceTunnels || [];

  const dot = $('sidebarDot');
  const statusText = $('sidebarStatus');
  if (state.hostConnected) {
    dot?.classList.add('connected');
    dot?.classList.remove('disconnected');
    if (statusText) statusText.textContent = 'Connected';
  } else {
    dot?.classList.remove('connected');
    dot?.classList.add('disconnected');
    if (statusText) statusText.textContent = 'Disconnected';
  }

  const setText = (id, val) => { const el = $(id); if (el) el.textContent = val; };

  setText('dashConnections',    virtualHosts.length);
  setText('dashSwarms',         servers.length);
  setText('dashServiceTunnels', serviceTunnels.length);
  setText('dashSsh',            sshConnections.length);
  setText('dashRdp',            rdpConnections.length);
  setText('dashUptime',         state.caInstalled ? 'Trusted' : 'Not trusted');

  const caIcon = $('caStatIcon');
  if (caIcon) {
    caIcon.style.background = state.caInstalled ? 'var(--green-dim)' : 'var(--red-dim)';
    caIcon.style.color      = state.caInstalled ? 'var(--green)'     : 'var(--red)';
  }

  const ovHostDot = $('ovHostDot');
  if (ovHostDot) {
    ovHostDot.classList.toggle('connected',    !!state.hostConnected);
    ovHostDot.classList.toggle('disconnected', !state.hostConnected);
  }
  setText('ovHostLabel',    state.hostConnected ? 'Connected' : 'Disconnected');
  const ovCaDot = $('ovCaDot');
  if (ovCaDot) {
    ovCaDot.style.background = state.caInstalled ? 'var(--green)' : 'var(--red)';
    ovCaDot.style.boxShadow  = state.caInstalled ? '0 0 5px var(--green)' : 'none';
  }
  setText('ovCaLabel',      state.caInstalled ? 'Installed & trusted' : 'Not installed');
  setText('ovProxyLabel',   state.proxyPort        != null ? `port ${state.proxyPort}`        : '—');
  setText('ovConnectLabel', state.connectProxyPort != null ? `port ${state.connectProxyPort}` : '—');
  if (state.trafficStats) {
    const { bytesIn, bytesOut, requests } = state.trafficStats;
    const fmt = (n) => n >= 1048576 ? (n / 1048576).toFixed(1) + ' MB' : n >= 1024 ? (n / 1024).toFixed(1) + ' KB' : n + ' B';
    setText('ovTrafficLabel', `↑ ${fmt(bytesIn)} ↓ ${fmt(bytesOut)} (${requests} req)`);
  }

  const lu = $('overviewLastUpdated');
  if (lu) lu.textContent = 'Updated ' + new Date().toLocaleTimeString();

  // Onboarding card: show when native host is disconnected
  const onboardingEl = $('onboardingNativeHost');
  if (onboardingEl) {
    if (!state.hostConnected) {
      onboardingEl.style.display = 'block';
      if (_onboardingPlatform == null && typeof detectPlatform === 'function') _onboardingPlatform = detectPlatform();
      _updateOnboardingCommand(_onboardingPlatform || 'linux');
    } else {
      onboardingEl.style.display = 'none';
      _onboardingPlatform = null;
    }
  }

  setText('swarmCount',         servers.length);
  setText('connCount',          virtualHosts.length);
  setText('serviceTunnelCount', serviceTunnels.length);
  setText('sshCount',           sshConnections.length);
  setText('rdpCount',           rdpConnections.length);
  setText('tabCount',           state.caInstalled ? 'CA ✓' : 'CA');

  if (!_ovVhost) initOvLists();

  const sub = (n, unit, readyArr) => {
    if (n === 0) return `No ${unit}s`;
    const r = readyArr.filter(x => x.state === 'ready').length;
    return `${n} ${unit}${n !== 1 ? 's' : ''} — ${r} ready`;
  };

  _ovVhost  .setData(virtualHosts,   sub(virtualHosts.length,   'host',    virtualHosts));
  _ovServers.setData(servers,        sub(servers.length,        'tunnel',  servers));
  _ovSvc    .setData(serviceTunnels, sub(serviceTunnels.length, 'tunnel',  serviceTunnels));
  _ovSsh    .setData(sshConnections, sshConnections.length === 0
    ? 'No SSH connections' : `${sshConnections.length} saved`);
  _ovRdp    .setData(rdpConnections, rdpConnections.length === 0
    ? 'No remote desktops' : `${rdpConnections.length} saved`);
}