/**
 * Main Application - Data Visualization Display Wall
 */
(function () {
  'use strict';

  // ---- Config ----
  const REFRESH_INTERVAL = 5000; // 5 seconds
  const NETWORK_HISTORY_INTERVAL = 60000; // 1 minute

  // ---- DOM Elements ----
  const dom = {
    clock: document.getElementById('clock'), // May be null if removed from UI
    serverCountText: document.getElementById('serverCountText'),
    sourceCount: document.getElementById('sourceCount'),
    totalServers: document.getElementById('totalServers'),
    cpuPercent: document.getElementById('cpuPercent'),
    cpuDetail: document.getElementById('cpuDetail'),
    memPercent: document.getElementById('memPercent'),
    memDetail: document.getElementById('memDetail'),
    diskPercent: document.getElementById('diskPercent'),
    diskDetail: document.getElementById('diskDetail'),
    totalBandwidth: document.getElementById('totalBandwidth'),
    bandwidthDetail: document.getElementById('bandwidthDetail'),
    traffic24hRx: document.getElementById('traffic24hRx'),
    traffic24hTx: document.getElementById('traffic24hTx'),
    traffic24hTotal: document.getElementById('traffic24hTotal'),
    trafficP95: document.getElementById('trafficP95'),
    networkCanvas: document.getElementById('networkCanvas'),
    serverTableBody: document.getElementById('serverTableBody'),
    btnSettings: document.getElementById('btnSettings'),
    settingsModal: document.getElementById('settingsModal'),
    modalClose: document.getElementById('modalClose'),
    sourceName: document.getElementById('sourceName'),
    sourceUrl: document.getElementById('sourceUrl'),
    sourceDesc: document.getElementById('sourceDesc'),
    btnTest: document.getElementById('btnTest'),
    btnAdd: document.getElementById('btnAdd'),
    formMessage: document.getElementById('formMessage'),
    sourceItems: document.getElementById('sourceItems'),
    // Site Settings
    modalTabs: document.querySelectorAll('.modal-tab'),
    tabContents: document.querySelectorAll('.tab-content'),
    pageNameInput: document.getElementById('pageNameInput'),
    siteTitleInput: document.getElementById('siteTitleInput'),
    logoUrlInput: document.getElementById('logoUrlInput'),
    btnSaveSiteSettings: document.getElementById('btnSaveSiteSettings'),
    siteSettingsMessage: document.getElementById('siteSettingsMessage'),
    logoText: document.getElementById('logoText'),
    logoIconContainer: document.getElementById('logoIconContainer'),
    defaultThemeInput: document.getElementById('defaultThemeInput'),
    // Auth & Theme elements
    themeToggle: document.getElementById('themeToggle'),
    sunIcon: document.querySelector('.sun-icon'),
    moonIcon: document.querySelector('.moon-icon'),
    userSection: document.getElementById('userSection'),
    btnLogin: document.getElementById('btnLogin'),
    loginModal: document.getElementById('loginModalOverlay'),
    closeLoginModal: document.getElementById('closeLoginModal'),
    loginForm: document.getElementById('loginForm'),
    loginError: document.getElementById('loginError'),
    footerTime: document.getElementById('footerTime'),
    legendP95: document.getElementById('legendP95'),
    // Server Details Modal
    serverDetailModal: document.getElementById('serverDetailModal'),
    serverDetailClose: document.getElementById('serverDetailClose'),
    serverDetailTitle: document.getElementById('serverDetailTitle'),
    detailMetricsList: document.getElementById('detailMetricsList'),
    detailLoading: document.getElementById('detailLoading'),
    detailCpuCores: document.getElementById('detailCpuCores'),
    detailMemTotal: document.getElementById('detailMemTotal'),
    detailUptime: document.getElementById('detailUptime'),
    detailContainer: document.getElementById('detailContainer'),
    sourceFilter: document.getElementById('sourceFilter')
  };

  // ---- State ----
  let previousMetrics = null;
  let networkChart = null;
  let user = null; // Currently logged in user
  let currentServerDetail = { instance: null, job: null, source: null, charts: {} };
  let allServersData = [];
  let currentSourceFilter = 'all';

  // ---- Initialize ----
  function init() {
    // Resource Gauges Time
    updateGaugesTime();
    setInterval(updateGaugesTime, 1000);

    // Initial theme check (localStorage handled after site settings load to ensure priority)

    // Network chart
    networkChart = new AreaChart(dom.networkCanvas);

    // Event listeners
    dom.btnSettings.addEventListener('click', openSettings);
    dom.modalClose.addEventListener('click', closeSettings);
    dom.settingsModal.addEventListener('click', (e) => {
      if (e.target === dom.settingsModal) closeSettings();
    });
    dom.btnTest.addEventListener('click', testConnection);
    dom.btnAdd.addEventListener('click', addSource);

    // Auth & Theme listeners
    dom.themeToggle.addEventListener('change', toggleTheme);
    dom.btnLogin.addEventListener('click', openLoginModal);
    dom.closeLoginModal.addEventListener('click', closeLoginModal);
    dom.loginForm.addEventListener('submit', handleLogin);
    dom.loginModal.addEventListener('click', (e) => {
      if (e.target === dom.loginModal) closeLoginModal();
    });

    // Tab switching
    dom.modalTabs.forEach(tab => {
      tab.addEventListener('click', () => {
        const targetTab = tab.getAttribute('data-tab');
        switchTab(targetTab);
      });
    });

    // Site settings
    dom.btnSaveSiteSettings.addEventListener('click', saveSiteSettings);

    // Keyboard shortcut
    document.addEventListener('keydown', (e) => {
      if (e.key === 'Escape') {
        closeSettings();
        closeLoginModal();
        closeServerDetail();
      }
    });

    // Server detail modal listeners
    dom.serverDetailClose.addEventListener('click', closeServerDetail);
    dom.serverDetailModal.addEventListener('click', (e) => {
      if (e.target === dom.serverDetailModal) closeServerDetail();
    });

    // Server table row click delegator
    dom.serverTableBody.addEventListener('click', (e) => {
      const row = e.target.closest('tr');
      if (row && !row.classList.contains('empty-row')) {
        const instance = row.getAttribute('data-instance');
        const job = row.getAttribute('data-job');
        const source = row.getAttribute('data-source');
        if (instance && job && source) {
          openServerDetail(instance, job, source);
        }
      }
    });

    // P95 Toggle
    if (dom.legendP95) {
      dom.legendP95.addEventListener('click', () => {
        networkChart.showP95 = !networkChart.showP95;
        dom.legendP95.classList.toggle('disabled', !networkChart.showP95);
        networkChart.draw();
      });
    }
    
    // Source filter listener
    if (dom.sourceFilter) {
      dom.sourceFilter.addEventListener('change', () => {
        currentSourceFilter = dom.sourceFilter.value;
        renderFilteredServers();
      });
    }

    // Check auth status
    checkAuthStatus();

    // Start data fetching
    fetchMetrics();
    fetchNetworkHistory();

    // Site settings
    if (window.SITE_SETTINGS) {
      applySiteSettings(window.SITE_SETTINGS);
      // Actual theme class already applied in head, just update icons and inputs
      const savedTheme = localStorage.getItem('theme');
      const currentTheme = savedTheme || window.SITE_SETTINGS.default_theme || 'dark';
      updateThemeIcons(currentTheme);

      // Still populate inputs
      dom.pageNameInput.value = window.SITE_SETTINGS.page_name || '';
      dom.siteTitleInput.value = window.SITE_SETTINGS.title || '';
      dom.logoUrlInput.value = window.SITE_SETTINGS.logo_url || '';
      dom.defaultThemeInput.value = window.SITE_SETTINGS.default_theme || 'dark';
    }

    loadSiteSettings();

    setInterval(fetchMetrics, REFRESH_INTERVAL);
    setInterval(fetchNetworkHistory, NETWORK_HISTORY_INTERVAL);
  }

  // ---- Theme Switching ----
  function toggleTheme() {
    const theme = dom.themeToggle.checked ? 'light' : 'dark';
    document.documentElement.classList.toggle('light-theme', theme === 'light');
    localStorage.setItem('theme', theme);
    updateThemeIcons(theme);
  }

  function applyTheme(theme) {
    let actualTheme = theme;
    if (theme === 'auto') {
      actualTheme = window.matchMedia('(prefers-color-scheme: light)').matches ? 'light' : 'dark';
    }

    const isLight = actualTheme === 'light';
    dom.themeToggle.checked = isLight;
    document.documentElement.classList.toggle('light-theme', isLight);
    updateThemeIcons(actualTheme);
  }

  function updateThemeIcons(theme) {
    // Icons are in the slider, we adjust their opacity to show which one is active
    if (theme === 'light') {
      dom.sunIcon.style.opacity = '0.3';
      dom.moonIcon.style.opacity = '1';
    } else {
      dom.sunIcon.style.opacity = '1';
      dom.moonIcon.style.opacity = '0.3';
    }
  }

  // ---- Auth Logic ----
  async function checkAuthStatus() {
    try {
      const resp = await fetch('/api/auth/status');
      const data = await resp.json();
      if (data.authenticated) {
        updateUserUI(data.username);
      } else {
        updateUserUI(null);
      }
    } catch (err) {
      updateUserUI(null);
    }
  }

  function updateUserUI(username) {
    if (username) {
      user = username;
      dom.btnSettings.style.display = 'flex';
      dom.userSection.innerHTML = `
        <div class="user-info">
          <span class="username">${escapeHtml(username)}</span>
          <button class="btn btn-logout" id="btnLogout">退出</button>
        </div>
      `;
      document.getElementById('btnLogout').addEventListener('click', handleLogout);
    } else {
      user = null;
      dom.btnSettings.style.display = 'none';
      dom.userSection.innerHTML = `<button class="btn btn-login" id="btnLogin">登录</button>`;
      document.getElementById('btnLogin').addEventListener('click', openLoginModal);
    }
  }

  function openLoginModal() {
    dom.loginModal.classList.add('active');
    dom.loginError.style.display = 'none';
  }

  function closeLoginModal() {
    dom.loginModal.classList.remove('active');
    dom.loginForm.reset();
  }

  async function handleLogin(e) {
    e.preventDefault();
    const username = document.getElementById('username').value;
    const password = document.getElementById('password').value;

    try {
      const resp = await fetch('/api/auth/login', {
        method: 'POST',
        headers: { 'Content-Type': 'application/json' },
        body: JSON.stringify({ username, password })
      });
      const data = await resp.json();
      if (resp.ok) {
        updateUserUI(data.username);
        closeLoginModal();
      } else {
        dom.loginError.textContent = data.error || '登录失败';
        dom.loginError.style.display = 'block';
      }
    } catch (err) {
      dom.loginError.textContent = '服务器错误';
      dom.loginError.style.display = 'block';
    }
  }

  async function handleLogout() {
    try {
      await fetch('/api/auth/logout', { method: 'POST' });
      updateUserUI(null);
    } catch (err) {
      console.error('Logout failed:', err);
    }
  }

  // ---- Clock ----
  function updateClock() {
    if (dom.clock) {
      dom.clock.textContent = formatClock();
    }
  }

  function updateGaugesTime() {
    const clockStr = formatClock();
    if (dom.footerTime) {
      dom.footerTime.textContent = clockStr;
    }
  }

  // ---- Fetch Metrics ----
  async function fetchMetrics() {
    try {
      const response = await fetch('/api/metrics/overview');
      const data = await response.json();
      allServersData = data.servers || [];
      updateDashboard(data);
    } catch (err) {
      console.error('Error fetching metrics:', err);
    }
  }

  // ---- Update Dashboard ----
  function updateDashboard(data) {
    // Server count
    dom.totalServers.textContent = data.totalServers;
    dom.serverCountText.textContent = `${data.activeServers} / ${data.totalServers} 在线`;

    // CPU
    const cpuPct = data.cpu.percent;
    dom.cpuPercent.textContent = formatPercent(cpuPct);
    dom.cpuDetail.textContent = `${data.cpu.used.toFixed(1)} / ${data.cpu.total.toFixed(0)} 核心`;

    // Memory
    const memPct = data.memory.percent;
    dom.memPercent.textContent = formatPercent(memPct);
    dom.memDetail.textContent = `${formatBytes(data.memory.used)} / ${formatBytes(data.memory.total)}`;

    // Disk
    const diskPct = data.disk.percent;
    dom.diskPercent.textContent = formatPercent(diskPct);
    dom.diskDetail.textContent = `${formatBytes(data.disk.used)} / ${formatBytes(data.disk.total)}`;

    // Bandwidth
    dom.totalBandwidth.textContent = formatBandwidth(data.network.total || 0);
    dom.bandwidthDetail.textContent = `↓ ${formatBandwidth(data.network.rx)} ↑ ${formatBandwidth(data.network.tx)}`;

    // 24h traffic
    dom.traffic24hRx.textContent = formatBytes(data.traffic24h.rx);
    dom.traffic24hTx.textContent = formatBytes(data.traffic24h.tx);
    dom.traffic24hTotal.textContent = formatBytes(data.traffic24h.total || (data.traffic24h.rx + data.traffic24h.tx));

    // Update server table
    renderFilteredServers();

    // Flash animation
    if (previousMetrics) {
      [dom.cpuPercent, dom.memPercent, dom.diskPercent, dom.totalBandwidth].forEach(el => {
        el.classList.remove('value-update');
        void el.offsetWidth; // Force reflow
        el.classList.add('value-update');
      });
    }

    previousMetrics = data;
  }

  function renderFilteredServers() {
    let filtered = allServersData;
    if (currentSourceFilter !== 'all') {
      filtered = allServersData.filter(s => s.source === currentSourceFilter);
    }
    updateServerTable(filtered);
  }

  // ---- Server Table ----
  function updateServerTable(servers) {
    if (!servers || servers.length === 0) {
      dom.serverTableBody.innerHTML = `
        <tr class="empty-row">
          <td colspan="8">暂无数据 - 请先配置 Prometheus 数据源</td>
        </tr>
      `;
      return;
    }

    // Sort servers: online first, then by cpu usage
    servers.sort((a, b) => {
      if (a.up !== b.up) return b.up ? 1 : -1;
      return b.cpuPercent - a.cpuPercent;
    });

    dom.serverTableBody.innerHTML = servers.map(server => {
      const memPct = server.memTotal > 0 ? (server.memUsed / server.memTotal * 100) : 0;
      const diskPct = server.diskTotal > 0 ? (server.diskUsed / server.diskTotal * 100) : 0;

      return `
        <tr data-instance="${escapeHtml(server.instance)}" data-job="${escapeHtml(server.job)}" data-source="${escapeHtml(server.source)}" style="cursor: pointer;">
          <td>
            <span class="status-dot ${server.up ? 'status-dot-online' : 'status-dot-offline'}"></span>
          </td>
          <td>
            <div style="color: var(--text-primary); font-weight: 600; font-family: var(--font-sans);">${escapeHtml(server.job)}</div>
          </td>
          <td>${escapeHtml(server.source)}</td>
          <td>
            <div class="usage-bar">
              <div class="usage-bar-track">
                <div class="usage-bar-fill usage-bar-fill-cpu" style="width: ${Math.min(server.cpuPercent, 100)}%"></div>
              </div>
              <span>${formatPercent(server.cpuPercent)}</span>
            </div>
          </td>
          <td>
            <div class="usage-bar">
              <div class="usage-bar-track">
                <div class="usage-bar-fill usage-bar-fill-mem" style="width: ${Math.min(memPct, 100)}%"></div>
              </div>
              <span>${formatPercent(memPct)}</span>
            </div>
          </td>
          <td>
            <div class="usage-bar">
              <div class="usage-bar-track">
                <div class="usage-bar-fill usage-bar-fill-disk" style="width: ${Math.min(diskPct, 100)}%"></div>
              </div>
              <span>${formatPercent(diskPct)}</span>
            </div>
          </td>
          <td>${formatBandwidth(server.netRx)}</td>
          <td>${formatBandwidth(server.netTx)}</td>
        </tr>
      `;
    }).join('');
  }

  // ---- Server Detail ----
  async function openServerDetail(instance, job, source) {
    currentServerDetail = { instance, job, source, charts: {} };
    dom.serverDetailTitle.textContent = `${job}`;
    dom.serverDetailModal.classList.add('active');

    // Show loading
    dom.detailContainer.style.opacity = '0.3';
    dom.detailLoading.style.display = 'block';
    dom.detailMetricsList.innerHTML = '';

    try {
      const url = `/api/metrics/server-details?instance=${encodeURIComponent(instance)}&job=${encodeURIComponent(job)}&source=${encodeURIComponent(source)}`;
      const response = await fetch(url);
      if (!response.ok) throw new Error('Fetch failed');
      const data = await response.json();

      renderServerDetail(data);
    } catch (err) {
      console.error('Error fetching server details:', err);
    } finally {
      dom.detailContainer.style.opacity = '1';
      dom.detailLoading.style.display = 'none';
    }
  }

  function closeServerDetail() {
    dom.serverDetailModal.classList.remove('active');
    // Destroy charts
    Object.values(currentServerDetail.charts).forEach(chart => {
      if (chart && chart.destroy) chart.destroy();
    });
    currentServerDetail = { instance: null, job: null, source: null, charts: {} };
  }

  function renderServerDetail(data) {
    dom.detailCpuCores.textContent = data.cpuCores + ' 核心';
    dom.detailMemTotal.textContent = formatBytes(data.memTotal);

    // Uptime formatting
    const uptimeSec = data.uptime;
    const days = Math.floor(uptimeSec / 86400);
    const hours = Math.floor((uptimeSec % 86400) / 3600);
    const mins = Math.floor((uptimeSec % 3600) / 60);
    dom.detailUptime.textContent = `${days}天 ${hours}小时 ${mins}分`;

    // Define metrics to show
    const cpuValueHtml = `
        <div style="display: flex; flex-direction: column; align-items: flex-end; gap: 2px;">
            <span style="font-weight: 700;">${formatPercent(data.cpuBusy)}</span>
            <div style="font-size: 0.65rem; color: var(--text-secondary); display: flex; gap: 6px; font-weight: normal;">
                <span>Sys: ${data.cpuSystem.toFixed(1)}%</span>
                <span>User: ${data.cpuUser.toFixed(1)}%</span>
                <span>Wait: ${data.cpuIowait.toFixed(1)}%</span>
            </div>
        </div>
    `;

    const metrics = [
        { key: 'cpuBusy', label: 'CPU 使用率 (Busy Breakdown)', value: cpuValueHtml },
        { key: 'sysLoad', label: '系统负载 (Load)', value: data.sysLoad.toFixed(1) + '%' },
        { key: 'memUsedPct', label: '内存使用率 (RAM)', value: formatPercent(data.memUsedPct) },
        { key: 'swapUsedPct', label: 'SWAP 使用率', value: formatPercent(data.swapUsedPct) },
        { key: 'rootFsUsedPct', label: '根分区使用率 (/)', value: formatPercent(data.rootFsUsedPct) },
        { key: 'netRx', label: '网络接收速率 (RX)', value: formatBandwidth(data.netRx) },
        { key: 'netTx', label: '网络发送速率 (TX)', value: formatBandwidth(data.netTx) },
        { key: 'sockstatTcp', label: 'TCP 链接数 (Sockstat)', value: data.sockstatTcp.toFixed(0) },
        { key: 'sockstatTcpMem', label: 'TCP 内存占用', value: formatBytes(data.sockstatTcpMem) }
    ];

    dom.detailMetricsList.innerHTML = metrics.map(m => `
        <div class="metric-item" id="metric-${m.key}">
            <div class="metric-item-header" onclick="toggleMetricExpand('${m.key}')">
                <div class="metric-label-group">
                    <span class="metric-label">${m.label}</span>
                    <span class="metric-value">${m.value}</span>
                </div>
                <svg class="chevron-icon" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2">
                    <polyline points="6 9 12 15 18 9"></polyline>
                </svg>
            </div>
            <div class="metric-item-content">
                <div class="chart-controls">
                    <div class="time-range-group">
                        <div class="time-range-selector">
                            <button class="time-range-btn active" onclick="loadMetricHistory('${m.key}', '1h', event)">1h</button>
                            <button class="time-range-btn" onclick="loadMetricHistory('${m.key}', '6h', event)">6h</button>
                            <button class="time-range-btn" onclick="loadMetricHistory('${m.key}', '12h', event)">12h</button>
                            <button class="time-range-btn" onclick="loadMetricHistory('${m.key}', '24h', event)">24h</button>
                        </div>
                        <div class="custom-range-selector">
                            <input type="text" class="custom-range-input" id="custom-range-${m.key}" placeholder="相对范围 (如: 2h)" onkeydown="if(event.key==='Enter') loadCustomMetricHistory('${m.key}', event)">
                        </div>
                        <div class="absolute-range-selector">
                            <input type="datetime-local" class="time-input" id="start-time-${m.key}">
                            <span style="color: var(--text-secondary); font-size: 0.7rem;">至</span>
                            <input type="datetime-local" class="time-input" id="end-time-${m.key}">
                            <button class="btn-custom-go" onclick="loadCustomMetricHistory('${m.key}', event)">查询</button>
                        </div>
                    </div>
                </div>
                <div class="detail-chart-wrapper" style="${m.key === 'cpuBusy' ? 'height: 260px;' : ''}">
                    <canvas id="chart-${m.key}"></canvas>
                </div>
            </div>
        </div>
    `).join('');
  }

  window.toggleMetricExpand = async function (metricKey) {
    const el = document.getElementById(`metric-${metricKey}`);
    const wasActive = el.classList.contains('active');

    // Close all others
    document.querySelectorAll('.metric-item').forEach(item => item.classList.remove('active'));

    if (!wasActive) {
      el.classList.add('active');
      // Initial load
      loadMetricHistory(metricKey, '1h');
    }
  };

  window.loadMetricHistory = async function (metricKey, range, event, start = null, end = null) {
    if (event) {
      event.stopPropagation();
      const group = event.target.closest('.time-range-group');
      if (group) {
        group.querySelectorAll('.time-range-btn').forEach(btn => btn.classList.remove('active'));
        if (event.target.classList.contains('time-range-btn')) {
          event.target.classList.add('active');
        }
      }
    }

    const canvas = document.getElementById(`chart-${metricKey}`);
    if (!canvas) return;

    let chart = currentServerDetail.charts[metricKey];
    if (!chart) {
      let unit = '';
      if (metricKey.includes('Pct') || metricKey === 'cpuBusy') unit = '%';
      if (metricKey.startsWith('net')) unit = 'B/s';
      if (metricKey === 'sockstatTcpMem') unit = 'B';
      
      chart = new MetricChart(canvas, unit);
      currentServerDetail.charts[metricKey] = chart;
    }

    try {
      const { instance, job, source } = currentServerDetail;
      let url = `/api/metrics/server-history?instance=${encodeURIComponent(instance)}&job=${encodeURIComponent(job)}&source=${encodeURIComponent(source)}&metric=${metricKey}`;

      if (start && end) {
        url += `&start=${encodeURIComponent(start)}&end=${encodeURIComponent(end)}`;
      } else {
        url += `&range=${range}`;
      }

      const res = await fetch(url);
      if (!res.ok) throw new Error('Query failed');
      const data = await res.json();
      chart.setData(data);
    } catch (err) {
      console.error(`Error loading history for ${metricKey}:`, err);
    }
  };

  window.loadCustomMetricHistory = async function (metricKey, event) {
    if (event) event.stopPropagation();

    const rangeInput = document.getElementById(`custom-range-${metricKey}`);
    const startInput = document.getElementById(`start-time-${metricKey}`);
    const endInput = document.getElementById(`end-time-${metricKey}`);

    const range = (rangeInput.value || '').trim().toLowerCase();
    const startTime = startInput.value;
    const endTime = endInput.value;

    if (startTime && endTime) {
      // Absolute range
      loadMetricHistory(metricKey, null, event, startTime, endTime);
    } else if (range) {
      // Relative range
      if (!/^\d+[smhd]$/.test(range)) {
        alert('格式不正确，请使用如: 2h, 30m, 1d 等格式');
        return;
      }
      loadMetricHistory(metricKey, range, event);
    } else {
      alert('请输入相对范围或选择具体时间范围');
    }
  };

  // ---- Network History ----
  async function fetchNetworkHistory() {
    try {
      const response = await fetch('/api/metrics/network-history');
      const data = await response.json();
      networkChart.setData(data);
      if (dom.trafficP95 && networkChart.p95) {
        dom.trafficP95.textContent = formatBandwidth(networkChart.p95);
      }
    } catch (err) {
      console.error('Error fetching network history:', err);
    }
  }

  // ---- Settings Modal ----
  function openSettings() {
    dom.settingsModal.classList.add('active');
    loadSources();
  }

  function closeSettings() {
    dom.settingsModal.classList.remove('active');
    hideMessage();
    hideSiteMessage();
  }

  // ---- Tab Switching ----
  function switchTab(tabId) {
    dom.modalTabs.forEach(tab => {
      tab.classList.toggle('active', tab.getAttribute('data-tab') === tabId);
    });
    dom.tabContents.forEach(content => {
      content.classList.toggle('active', content.id === `tab-${tabId}`);
    });
  }

  // ---- Site Settings ----
  async function loadSiteSettings() {
    try {
      const response = await fetch('/api/settings');
      const settings = await response.json();

      window.SITE_SETTINGS = settings; // Cache it globally

      // Update inputs
      dom.pageNameInput.value = settings.page_name || '';
      dom.siteTitleInput.value = settings.title || '';
      dom.logoUrlInput.value = settings.logo_url || '';
      dom.defaultThemeInput.value = settings.default_theme || 'dark';

      // Apply to UI
      applySiteSettings(settings);

      // Handle Theme Priority: localStorage > Site Default
      const savedTheme = localStorage.getItem('theme');
      const themeToApply = savedTheme || settings.default_theme || 'dark';
      applyTheme(themeToApply);

      // Listen for system theme changes if set to auto
      window.matchMedia('(prefers-color-scheme: light)').addEventListener('change', () => {
        const currentSavedTheme = localStorage.getItem('theme');
        const defaultTheme = window.SITE_SETTINGS ? window.SITE_SETTINGS.default_theme : 'dark';
        const activeTheme = currentSavedTheme || defaultTheme;
        if (activeTheme === 'auto') {
          applyTheme('auto');
        }
      });
    } catch (err) {
      console.error('Error loading site settings:', err);
    }
  }

  function applySiteSettings(settings) {
    if (settings.page_name) {
      document.title = settings.page_name;
    }
    if (settings.title) {
      dom.logoText.textContent = settings.title;
    }

    // Logo Icon
    if (settings.logo_url) {
      dom.logoIconContainer.innerHTML = `<img src="${escapeHtml(settings.logo_url)}" alt="Logo" class="logo-icon-img">`;
    } else {
      // Restore default SVG
      dom.logoIconContainer.innerHTML = `
        <svg class="logo-icon" id="logoSvg" viewBox="0 0 32 32" fill="none">
          <rect x="2" y="2" width="28" height="28" rx="8" stroke="url(#logoGrad)" stroke-width="2.5"/>
          <path d="M8 22 L12 14 L16 18 L20 10 L24 16" stroke="url(#logoGrad)" stroke-width="2" stroke-linecap="round" stroke-linejoin="round" fill="none"/>
          <circle cx="12" cy="14" r="2" fill="url(#logoGrad)"/>
          <circle cx="20" cy="10" r="2" fill="url(#logoGrad)"/>
          <defs>
            <linearGradient id="logoGrad" x1="0" y1="0" x2="32" y2="32">
              <stop offset="0%" stop-color="#6366f1"/>
              <stop offset="100%" stop-color="#06b6d4"/>
            </linearGradient>
          </defs>
        </svg>
      `;
    }
  }

  async function saveSiteSettings() {
    if (!user) {
      showSiteMessage('请先登录后操作', 'error');
      openLoginModal();
      return;
    }

    const settings = {
      page_name: dom.pageNameInput.value.trim(),
      title: dom.siteTitleInput.value.trim(),
      logo_url: dom.logoUrlInput.value.trim(),
      default_theme: dom.defaultThemeInput.value
    };

    dom.btnSaveSiteSettings.disabled = true;
    dom.btnSaveSiteSettings.textContent = '保存中...';

    try {
      const response = await fetch('/api/settings', {
        method: 'POST',
        headers: { 'Content-Type': 'application/json' },
        body: JSON.stringify(settings)
      });

      if (response.ok) {
        showSiteMessage('设置保存成功', 'success');
        applySiteSettings(settings);
      } else {
        const err = await response.json();
        showSiteMessage(`保存失败: ${err.error}`, 'error');
        if (response.status === 401) openLoginModal();
      }
    } catch (err) {
      showSiteMessage(`保存失败: ${err.message}`, 'error');
    } finally {
      dom.btnSaveSiteSettings.disabled = false;
      dom.btnSaveSiteSettings.textContent = '保存设置';
    }
  }

  function showSiteMessage(text, type) {
    dom.siteSettingsMessage.textContent = text;
    dom.siteSettingsMessage.className = `form-message ${type}`;
    setTimeout(hideSiteMessage, 5000);
  }

  function hideSiteMessage() {
    dom.siteSettingsMessage.className = 'form-message';
  }

  function updateSourceFilterOptions(sources) {
    if (!dom.sourceFilter) return;
    const current = dom.sourceFilter.value;
    let html = '<option value="all">所有数据源</option>';
    sources.forEach(source => {
      html += `<option value="${escapeHtml(source.name)}">${escapeHtml(source.name)}</option>`;
    });
    dom.sourceFilter.innerHTML = html;
    if (sources.some(s => s.name === current)) {
      dom.sourceFilter.value = current;
    } else {
      dom.sourceFilter.value = 'all';
      currentSourceFilter = 'all';
    }
  }

  async function loadSources() {
    try {
      const response = await fetch('/api/sources');
      const sources = await response.json();
      dom.sourceCount.textContent = `${sources.length} 个数据源`;
      updateSourceFilterOptions(sources);
      renderSources(sources);
    } catch (err) {
      console.error('Error loading sources:', err);
    }
  }

  function renderSources(sources) {
    if (sources.length === 0) {
      dom.sourceItems.innerHTML = '<div class="source-empty">暂无数据源</div>';
      return;
    }

    dom.sourceItems.innerHTML = sources.map(source => `
      <div class="source-item" data-id="${source.id}">
        <div class="source-item-info">
          <div class="source-item-name">
            ${escapeHtml(source.name)}
            <span class="source-status ${source.status === 'online' ? 'source-status-online' : 'source-status-offline'}">
              ${source.status === 'online' ? '在线' : '离线'}
            </span>
          </div>
          <div class="source-item-url">${escapeHtml(source.url)}</div>
          ${source.description ? `<div class="source-item-desc">${escapeHtml(source.description)}</div>` : ''}
        </div>
        <div class="source-item-actions">
          <button class="btn btn-delete" onclick="deleteSource(${source.id})">删除</button>
        </div>
      </div>
    `).join('');
  }

  // ---- Test Connection ----
  async function testConnection() {
    const url = dom.sourceUrl.value.trim();
    if (!url) {
      showMessage('请输入 Prometheus URL', 'error');
      return;
    }

    dom.btnTest.textContent = '测试中...';
    dom.btnTest.disabled = true;

    try {
      const response = await fetch('/api/sources/test', {
        method: 'POST',
        headers: { 'Content-Type': 'application/json' },
        body: JSON.stringify({ url })
      });
      const data = await response.json();
      if (data.status === 'ok') {
        showMessage(`连接成功！Prometheus 版本: ${data.version}`, 'success');
      } else {
        if (response.status === 401) {
          showMessage('请先登录', 'error');
          openLoginModal();
        } else {
          showMessage(`连接失败: ${data.message || data.error}`, 'error');
        }
      }
    } catch (err) {
      showMessage(`连接失败: ${err.message}`, 'error');
    } finally {
      dom.btnTest.textContent = '测试连接';
      dom.btnTest.disabled = false;
    }
  }

  // ---- Add Source ----
  async function addSource() {
    if (!user) {
      showMessage('请先登录后操作', 'error');
      openLoginModal();
      return;
    }

    const name = dom.sourceName.value.trim();
    const url = dom.sourceUrl.value.trim();
    const description = dom.sourceDesc.value.trim();

    if (!name || !url) {
      showMessage('请填写名称和URL', 'error');
      return;
    }

    dom.btnAdd.textContent = '添加中...';
    dom.btnAdd.disabled = true;

    try {
      const response = await fetch('/api/sources', {
        method: 'POST',
        headers: { 'Content-Type': 'application/json' },
        body: JSON.stringify({ name, url, description })
      });

      if (response.ok) {
        showMessage('数据源添加成功', 'success');
        dom.sourceName.value = '';
        dom.sourceUrl.value = '';
        dom.sourceDesc.value = '';
        loadSources();
        fetchMetrics();
        fetchNetworkHistory();
      } else {
        const err = await response.json();
        showMessage(`添加失败: ${err.error}`, 'error');
        if (response.status === 401) openLoginModal();
      }
    } catch (err) {
      showMessage(`添加失败: ${err.message}`, 'error');
    } finally {
      dom.btnAdd.textContent = '添加';
      dom.btnAdd.disabled = false;
    }
  }

  // ---- Delete Source ----
  window.deleteSource = async function (id) {
    if (!user) {
      showMessage('请先登录后操作', 'error');
      openLoginModal();
      return;
    }
    if (!confirm('确定要删除这个数据源吗？')) return;

    try {
      const response = await fetch(`/api/sources/${id}`, { method: 'DELETE' });
      if (response.ok) {
        loadSources();
        fetchMetrics();
        fetchNetworkHistory();
      } else {
        if (response.status === 401) openLoginModal();
      }
    } catch (err) {
      console.error('Error deleting source:', err);
    }
  };

  // ---- Messages ----
  function showMessage(text, type) {
    dom.formMessage.textContent = text;
    dom.formMessage.className = `form-message ${type}`;
    setTimeout(hideMessage, 5000);
  }

  function hideMessage() {
    dom.formMessage.className = 'form-message';
  }

  // ---- Escape HTML ----
  function escapeHtml(text) {
    const div = document.createElement('div');
    div.textContent = text || '';
    return div.innerHTML;
  }

  // ---- Load source count on page load ----
  async function loadSourceCount() {
    try {
      const response = await fetch('/api/sources');
      const sources = await response.json();
      const sourcesArray = Array.isArray(sources) ? sources : [];
      dom.sourceCount.textContent = `${sourcesArray.length} 个数据源`;
      updateSourceFilterOptions(sourcesArray);
    } catch (err) {
      // ignore
    }
  }

  // ---- Start ----
  loadSourceCount();
  init();
})();