// ─────────────────────────────────────────────────────────────
// WebRTC Helper — Manages peer connections for video/audio
// ─────────────────────────────────────────────────────────────

export const ICE_SERVERS: RTCConfiguration = {
  iceServers: [
    { urls: 'stun:stun.l.google.com:19302' },
    { urls: 'stun:stun1.l.google.com:19302' },
    { urls: 'stun:stun2.l.google.com:19302' },
    { urls: 'stun:stun3.l.google.com:19302' },
  ],
};

/**
 * Create an RTCPeerConnection with the configured ICE servers
 */
export function createPeerConnection(): RTCPeerConnection {
  return new RTCPeerConnection(ICE_SERVERS);
}

/**
 * Get user media with fallback handling
 */
export async function getUserMedia(
  video: boolean = true,
  audio: boolean = true
): Promise<MediaStream> {
  try {
    return await navigator.mediaDevices.getUserMedia({ video, audio });
  } catch (error: any) {
    // Try audio-only if video fails
    if (video) {
      console.warn('Video access failed, trying audio only');
      return await navigator.mediaDevices.getUserMedia({ video: false, audio });
    }
    throw error;
  }
}

/**
 * Get display media for screen sharing
 */
export async function getDisplayMedia(): Promise<MediaStream> {
  return await navigator.mediaDevices.getDisplayMedia({
    video: { cursor: 'always' } as any,
    audio: true,
  });
}

/**
 * Check if WebRTC is supported
 */
export function isWebRTCSupported(): boolean {
  return !!(
    window.RTCPeerConnection &&
    navigator.mediaDevices &&
    navigator.mediaDevices.getUserMedia
  );
}

/**
 * Estimate connection quality based on RTCPeerConnection stats
 */
export async function getConnectionQuality(
  pc: RTCPeerConnection
): Promise<'excellent' | 'good' | 'poor' | 'disconnected'> {
  if (pc.connectionState === 'disconnected' || pc.connectionState === 'failed') {
    return 'disconnected';
  }

  try {
    const stats = await pc.getStats();
    let roundTripTime = 0;
    let packetsLost = 0;

    stats.forEach((report) => {
      if (report.type === 'candidate-pair' && report.currentRoundTripTime) {
        roundTripTime = report.currentRoundTripTime * 1000; // ms
      }
      if (report.type === 'inbound-rtp' && report.packetsLost) {
        packetsLost = report.packetsLost;
      }
    });

    if (roundTripTime < 100 && packetsLost < 5) return 'excellent';
    if (roundTripTime < 300 && packetsLost < 20) return 'good';
    return 'poor';
  } catch {
    return 'good'; // Default if stats unavailable
  }
}