const crypto = require('crypto');
const { WebSocketServer, WebSocket } = require('ws');
const { isClientNameAvailable } = require('../data/client-name-check');
const { verifyPageAuthToken, verifyRequestAuth } = require('../request-auth');

function createPlayerRuntime(options) {
  const pool = options && options.pool ? options.pool : null;
  const normalizeDeviceId = typeof options.normalizeDeviceId === 'function'
    ? options.normalizeDeviceId
    : function (value) {
      return String(value || '').trim().replace(/[^a-zA-Z0-9_-]/g, '').slice(0, 128);
    };
  const connectionsBySlug = new Map();
  const dashboardListenersBySlug = new Map();
  const wss = new WebSocketServer({ noServer: true });

  function normalizeClientIp(value) {
    const ip = String(value || '').trim();
    if (!ip) {
      return null;
    }

    if (ip.toLowerCase().startsWith('::ffff:')) {
      return ip.slice(7).trim() || null;
    }

    return ip;
  }

  function getConnectionBucket(slug) {
    const key = String(slug || '').trim();
    if (!key) {
      return null;
    }
    if (!connectionsBySlug.has(key)) {
      connectionsBySlug.set(key, new Map());
    }
    return connectionsBySlug.get(key);
  }

  function removeConnection(slug, connectionId) {
    const bucket = connectionsBySlug.get(String(slug || '').trim());
    if (!bucket) {
      return;
    }
    bucket.delete(connectionId);
    if (!bucket.size) {
      connectionsBySlug.delete(String(slug || '').trim());
    }
  }

  function getDashboardListenerBucket(slug) {
    const key = String(slug || '').trim();
    if (!key) {
      return null;
    }
    if (!dashboardListenersBySlug.has(key)) {
      dashboardListenersBySlug.set(key, new Set());
    }
    return dashboardListenersBySlug.get(key);
  }

  function removeDashboardListener(slug, socket) {
    const key = String(slug || '').trim();
    const bucket = dashboardListenersBySlug.get(key);
    if (!bucket) {
      return;
    }
    bucket.delete(socket);
    if (!bucket.size) {
      dashboardListenersBySlug.delete(key);
    }
  }

  function buildClientLabel(connection) {
    const clientName = String(connection.clientName || '').trim();
    const clientId = String(connection.clientId || '').trim();
    const userAgent = String(connection.userAgent || '').trim();
    const clientIp = String(connection.clientIp || '').trim();
    const viewport = connection.viewport && typeof connection.viewport === 'object'
      ? connection.viewport
      : null;
    const labelParts = [];

    if (userAgent) {
      labelParts.push(userAgent.length > 72 ? `${userAgent.slice(0, 72)}...` : userAgent);
    }

    if (clientName) {
      labelParts.push(clientName);
    } else if (clientId) {
      labelParts.push(`id ${clientId.slice(-6)}`);
    }

    if (clientIp) {
      labelParts.push(clientIp);
    }

    if (viewport && Number.isFinite(Number(viewport.width)) && Number.isFinite(Number(viewport.height))) {
      labelParts.push(`${Number(viewport.width)}x${Number(viewport.height)}`);
    }

    if (!labelParts.length) {
      return connection.remoteAddress || 'connected client';
    }

    return labelParts.join(' • ');
  }

  function snapshotConnections(slug) {
    const bucket = connectionsBySlug.get(String(slug || '').trim());
    if (!bucket) {
      return [];
    }

    return Array.from(bucket.values()).map(function (connection) {
      return {
        id: connection.id,
        clientId: connection.clientId || null,
        clientName: connection.clientName || null,
        deviceId: connection.deviceId || null,
        label: connection.label,
        userAgent: connection.userAgent || null,
        viewport: connection.viewport || null,
        page: connection.page || null,
        currentSlide: connection.currentSlide || null,
        paused: Boolean(connection.paused),
        blackout: Boolean(connection.blackout),
        currentSlideId: connection.currentSlide && connection.currentSlide.id ? connection.currentSlide.id : null,
        currentSlideTitle: connection.currentSlide && connection.currentSlide.title ? connection.currentSlide.title : null,
        clientIp: connection.clientIp || null,
        remoteAddress: connection.remoteAddress || null,
        connectedAt: connection.connectedAt ? connection.connectedAt.toISOString() : null,
        lastSeenAt: connection.lastSeenAt ? connection.lastSeenAt.toISOString() : null
      };
    });
  }

  function snapshotAllConnections() {
    const allConnections = [];
    for (const bucket of connectionsBySlug.values()) {
      if (!bucket || typeof bucket.values !== 'function') {
        continue;
      }
      for (const connection of bucket.values()) {
        allConnections.push({
          clientId: connection.clientId || null,
          clientName: connection.clientName || null,
          deviceId: connection.deviceId || null
        });
      }
    }
    return allConnections;
  }

  async function isClientNameAvailableOnScreen(poolArg, clientName, excludeDeviceId) {
    return isClientNameAvailable(poolArg || pool, clientName, excludeDeviceId, snapshotAllConnections());
  }

  function broadcastConnectionSnapshot(slug) {
    const key = String(slug || '').trim();
    const bucket = dashboardListenersBySlug.get(key);
    if (!bucket || !bucket.size) {
      return;
    }

    const payload = JSON.stringify({
      type: 'snapshot',
      slug: key,
      connections: snapshotConnections(slug),
      sentAt: new Date().toISOString()
    });

    bucket.forEach(function (socket) {
      if (socket.readyState === WebSocket.OPEN) {
        socket.send(payload);
      }
    });
  }

  async function sendCommandToConnection(slug, connectionId, commandOrPayload) {
    const bucket = connectionsBySlug.get(String(slug || '').trim());
    if (!bucket || !bucket.size) {
      return 0;
    }

    const target = bucket.get(String(connectionId || '').trim());
    if (!target || target.socket.readyState !== WebSocket.OPEN) {
      return 0;
    }

    const payload = typeof commandOrPayload === 'object' && commandOrPayload !== null
      ? Object.assign({}, commandOrPayload)
      : { command: commandOrPayload };
    payload.type = 'command';
    payload.targetConnectionId = target.id;
    payload.sentAt = new Date().toISOString();

    target.socket.send(JSON.stringify(payload));
    return 1;
  }

  async function broadcastCommand(slug, commandOrPayload) {
    const bucket = connectionsBySlug.get(String(slug || '').trim());
    if (!bucket || !bucket.size) {
      return 0;
    }

    let sent = 0;
    bucket.forEach(function (connection) {
      if (connection.socket.readyState !== WebSocket.OPEN) {
        return;
      }
      const payload = typeof commandOrPayload === 'object' && commandOrPayload !== null
        ? Object.assign({}, commandOrPayload)
        : { command: commandOrPayload };
      payload.type = 'command';
      payload.sentAt = new Date().toISOString();

      connection.socket.send(JSON.stringify(payload));
      sent += 1;
    });

    return sent;
  }

  function handleUpgrade(request, socket, head) {
    let pathname = '';
    try {
      pathname = new URL(request.url, 'http://localhost').pathname;
    } catch (_error) {
      socket.destroy();
      return;
    }

    const dashboardMatch = pathname.match(/^\/ws\/screens\/([^/]+)\/events$/);
    const playerMatch = pathname.match(/^\/ws\/screens\/([^/]+)$/);
    if (!dashboardMatch && !playerMatch) {
      socket.destroy();
      return;
    }

    if (dashboardMatch) {
      if (!verifyRequestAuth(request)) {
        socket.destroy();
        return;
      }
    }

    if (playerMatch) {
      const authToken = String(new URL(request.url, 'http://localhost').searchParams.get('auth') || '').trim();
      const payload = verifyPageAuthToken(authToken);
      if (!payload || String(payload.scope || '').trim() !== 'player') {
        socket.destroy();
        return;
      }
    }

    const slug = decodeURIComponent((dashboardMatch || playerMatch)[1]);
    wss.handleUpgrade(request, socket, head, function (ws) {
      wss.emit('connection', ws, request, slug, dashboardMatch ? 'dashboard' : 'player');
    });
  }

  wss.on('connection', function (socket, request, slug, role) {
    if (role === 'dashboard') {
      const listenerBucket = getDashboardListenerBucket(slug);
      if (!listenerBucket) {
        socket.close();
        return;
      }

      listenerBucket.add(socket);
      socket.send(JSON.stringify({
        type: 'snapshot',
        slug: String(slug || '').trim(),
        connections: snapshotConnections(slug),
        sentAt: new Date().toISOString()
      }));

      socket.on('close', function () {
        removeDashboardListener(slug, socket);
      });

      socket.on('error', function () {
        removeDashboardListener(slug, socket);
      });
      return;
    }

    const remoteAddress = request.socket && request.socket.remoteAddress ? request.socket.remoteAddress : null;
    const forwardedFor = normalizeClientIp(String(request.headers['x-forwarded-for'] || '').split(',')[0]);
    const normalizedRemoteAddress = normalizeClientIp(remoteAddress);
    const connectionId = crypto.randomUUID();
    const connection = {
      id: connectionId,
      slug: slug,
      socket: socket,
      clientId: null,
      clientName: null,
      deviceId: null,
      userAgent: null,
      viewport: null,
      page: null,
      paused: false,
      blackout: false,
      clientIp: forwardedFor || normalizedRemoteAddress,
      remoteAddress: normalizedRemoteAddress,
      label: forwardedFor || normalizedRemoteAddress || 'connected client',
      connectedAt: new Date(),
      lastSeenAt: new Date()
    };
    const bucket = getConnectionBucket(slug);

    if (!bucket) {
      socket.close();
      return;
    }

    bucket.set(connectionId, connection);

    socket.on('message', function (rawMessage) {
      connection.lastSeenAt = new Date();
      let payload = null;
      try {
        payload = JSON.parse(String(rawMessage || ''));
      } catch (_error) {
        return;
      }

      if (!payload || (payload.type !== 'hello' && payload.type !== 'state')) {
        return;
      }

      connection.clientId = payload.clientId ? String(payload.clientId).trim() : connection.clientId;
      connection.clientName = payload.clientName ? String(payload.clientName).trim() : connection.clientName;
      connection.deviceId = payload.deviceId ? normalizeDeviceId(payload.deviceId) || connection.deviceId : connection.deviceId;
      if (!connection.clientName && connection.clientId) {
        connection.clientName = connection.clientId;
      }
      connection.userAgent = payload.userAgent ? String(payload.userAgent).trim() : connection.userAgent;
      connection.viewport = payload.viewport && typeof payload.viewport === 'object' ? payload.viewport : connection.viewport;
      connection.page = payload.page ? String(payload.page).trim() : connection.page;
      connection.paused = Boolean(payload.paused);
      connection.blackout = Boolean(payload.blackout);
      connection.clientIp = payload.clientIp ? normalizeClientIp(payload.clientIp) || connection.clientIp : connection.clientIp;
      connection.currentSlide = payload.currentSlide && typeof payload.currentSlide === 'object' ? {
        id: payload.currentSlide.id || null,
        title: payload.currentSlide.title || '',
        kind: payload.currentSlide.kind || '',
        playlistSignature: payload.currentSlide.playlistSignature || ''
      } : connection.currentSlide;
      connection.label = buildClientLabel(connection);
      connection.lastSeenAt = new Date();
      broadcastConnectionSnapshot(slug);
    });

    socket.on('close', function () {
      removeConnection(slug, connectionId);
      broadcastConnectionSnapshot(slug);
    });

    socket.on('error', function () {
      removeConnection(slug, connectionId);
      broadcastConnectionSnapshot(slug);
    });
  });

  function installWebsocket(server) {
    server.on('upgrade', handleUpgrade);
  }

  return {
    installWebsocket: installWebsocket,
    snapshotConnections: snapshotConnections,
    snapshotAllConnections: snapshotAllConnections,
    isClientNameAvailableOnScreen: isClientNameAvailableOnScreen,
    sendCommandToConnection: sendCommandToConnection,
    broadcastCommand: broadcastCommand
  };
}

module.exports = {
  createPlayerRuntime: createPlayerRuntime
};