const { WebSocket } = require('ws');

function normalizeClientName(value) {
  return String(value || '').trim();
}

function enrichScreensWithConnections(screens, connectionsBySlug, onboardingNameBySlug) {
  return (screens || []).map(function (screen) {
    const connectionState = connectionsBySlug[screen.slug] || { count: 0, connections: [] };
    return Object.assign({}, screen, {
      client_name: onboardingNameBySlug[screen.slug] || null,
      player_connection_count: connectionState.count || 0,
      player_connections: Array.isArray(connectionState.connections) ? connectionState.connections : []
    });
  });
}

function buildClientRows(screens, connectionsBySlug, onboardingNameBySlug, onboardingNameByDeviceId, playerPublicBaseUrl, formatDashboardDate) {
  return (screens || []).flatMap(function (screen) {
    const connectionState = connectionsBySlug[screen.slug] || { count: 0, connections: [] };
    return (connectionState.connections || []).map(function (connection) {
      const deviceId = String(connection.deviceId || '').trim();
      return Object.assign({}, connection, {
        screen_slug: screen.slug,
        screen_name: screen.name,
        client_name: (deviceId && onboardingNameByDeviceId && onboardingNameByDeviceId[deviceId]) || connection.clientName || onboardingNameBySlug[screen.slug] || String(connection.clientId || '').trim() || null,
        playlist_name: screen.playlist_name || null,
        connectedAtLabel: formatDashboardDate(connection.connectedAt),
        lastSeenAtLabel: formatDashboardDate(connection.lastSeenAt),
        player_url: `${playerPublicBaseUrl}/screen/${encodeURIComponent(screen.slug)}`
      });
    });
  });
}

function createDashboardStateService(options) {
  const pool = options && options.pool;
  const common = options && options.common;
  const playerSnapshotCache = options && options.playerSnapshotCache;
  const playerSnapshotSockets = options && options.playerSnapshotSockets;
  const ensurePlayerSnapshotSubscription = options && options.ensurePlayerSnapshotSubscription;
  const playerPublicBaseUrl = String(options && options.playerPublicBaseUrl || '').replace(/\/$/, '');
  const formatDashboardDate = options && options.formatDashboardDate;

  if (!pool || !common || !playerSnapshotCache || !playerSnapshotSockets || typeof ensurePlayerSnapshotSubscription !== 'function' || typeof formatDashboardDate !== 'function') {
    throw new Error('createDashboardStateService requires the dashboard dependencies.');
  }

  async function buildDashboardState() {
    const data = await common.fetchAdminData(pool);
    const screensData = data.screens || [];
    screensData.forEach(function (screen) {
      ensurePlayerSnapshotSubscription(screen.slug);
    });

    const [onboardingRows] = await pool.query(
      `SELECT s.slug, pod.device_id, pod.client_name
       FROM player_onboarding_devices pod
       JOIN screens s ON s.id = pod.screen_id
       WHERE pod.client_name IS NOT NULL
         AND TRIM(pod.client_name) <> ''`
    );
    const onboardingNameBySlug = {};
    const onboardingNameByDeviceId = {};
    onboardingRows.forEach(function (row) {
      const clientName = normalizeClientName(row.client_name);
      const slug = normalizeClientName(row.slug);
      const deviceId = normalizeClientName(row.device_id);
      if (slug) {
        onboardingNameBySlug[slug] = clientName;
      }
      if (deviceId) {
        onboardingNameByDeviceId[deviceId] = clientName;
      }
    });

    const connectionsBySlug = {};
    screensData.forEach(function (screen) {
      const cached = playerSnapshotCache.get(String(screen.slug || '').trim());
      if (cached && Array.isArray(cached.connections)) {
        connectionsBySlug[screen.slug] = cached;
      }
    });

    const screens = enrichScreensWithConnections(data.screens || [], connectionsBySlug, onboardingNameBySlug).map(function (screen) {
      return Object.assign({}, screen, {
        player_url: `${playerPublicBaseUrl}/screen/${encodeURIComponent(screen.slug)}`
      });
    });
    const clients = buildClientRows(screens, connectionsBySlug, onboardingNameBySlug, onboardingNameByDeviceId, playerPublicBaseUrl, formatDashboardDate);
    const playerServiceConnected = Array.from(playerSnapshotSockets.values()).some(function (socket) {
      return socket && socket.readyState === WebSocket.OPEN;
    });

    return {
      playlists: data.playlists || [],
      screens: screens,
      clients: clients,
      slides: data.slides || [],
      playerServiceConnected: playerServiceConnected,
      connectedClientsCount: screens.reduce(function (total, screen) {
        return total + Number(screen.player_connection_count || 0);
      }, 0)
    };
  }

  return {
    buildDashboardState: buildDashboardState
  };
}

module.exports = { createDashboardStateService };