import { NextResponse } from 'next/server';
import { getAdminAuth, getAdminDb } from '@/lib/firebase/admin';
import { FieldValue } from 'firebase-admin/firestore';

/**
 * Store GitHub connection for authenticated user
 * Encrypts and stores the access token securely
 */
export async function POST(request: Request) {
  try {
    const authHeader = request.headers.get('Authorization');
    if (!authHeader?.startsWith('Bearer ')) {
      return NextResponse.json({ error: 'Unauthorized' }, { status: 401 });
    }

    const idToken = authHeader.split('Bearer ')[1];
    const adminAuth = getAdminAuth();
    const adminDb = getAdminDb();

    let userId: string;
    try {
      const decodedToken = await adminAuth.verifyIdToken(idToken);
      userId = decodedToken.uid;
    } catch (error) {
      return NextResponse.json({ error: 'Invalid token' }, { status: 401 });
    }

    const { accessToken, githubUser } = await request.json();

    if (!accessToken || !githubUser) {
      return NextResponse.json(
        { error: 'Missing required fields' },
        { status: 400 }
      );
    }

    // TODO: Encrypt the access token before storing
    // For now, we'll store it directly (should use crypto.subtle or a library)
    const encryptedToken = accessToken; // PLACEHOLDER

    // Store GitHub connection
    const connectionRef = adminDb.collection('githubConnections').doc(userId);
    await connectionRef.set({
      userId,
      githubUserId: githubUser.id,
      githubUsername: githubUser.login,
      githubName: githubUser.name,
      githubEmail: githubUser.email,
      githubAvatarUrl: githubUser.avatar_url,
      accessToken: encryptedToken,
      connectedAt: FieldValue.serverTimestamp(),
      lastSyncedAt: null,
    });

    return NextResponse.json({
      success: true,
      githubUsername: githubUser.login,
    });
  } catch (error) {
    console.error('[GitHub Connect] Error:', error);
    return NextResponse.json(
      { error: 'Failed to store GitHub connection' },
      { status: 500 }
    );
  }
}

/**
 * Get GitHub connection status for authenticated user
 */
export async function GET(request: Request) {
  try {
    const authHeader = request.headers.get('Authorization');
    if (!authHeader?.startsWith('Bearer ')) {
      return NextResponse.json({ error: 'Unauthorized' }, { status: 401 });
    }

    const idToken = authHeader.split('Bearer ')[1];
    const adminAuth = getAdminAuth();
    const adminDb = getAdminDb();

    let userId: string;
    try {
      const decodedToken = await adminAuth.verifyIdToken(idToken);
      userId = decodedToken.uid;
    } catch (error) {
      return NextResponse.json({ error: 'Invalid token' }, { status: 401 });
    }

    const connectionDoc = await adminDb
      .collection('githubConnections')
      .doc(userId)
      .get();

    if (!connectionDoc.exists) {
      return NextResponse.json({ connected: false });
    }

    const data = connectionDoc.data()!;
    
    return NextResponse.json({
      connected: true,
      githubUsername: data.githubUsername,
      githubName: data.githubName,
      githubAvatarUrl: data.githubAvatarUrl,
      connectedAt: data.connectedAt,
      lastSyncedAt: data.lastSyncedAt,
    });
  } catch (error) {
    console.error('[GitHub Connect] Error:', error);
    return NextResponse.json(
      { error: 'Failed to fetch GitHub connection' },
      { status: 500 }
    );
  }
}

/**
 * Disconnect GitHub account
 */
export async function DELETE(request: Request) {
  try {
    const authHeader = request.headers.get('Authorization');
    if (!authHeader?.startsWith('Bearer ')) {
      return NextResponse.json({ error: 'Unauthorized' }, { status: 401 });
    }

    const idToken = authHeader.split('Bearer ')[1];
    const adminAuth = getAdminAuth();
    const adminDb = getAdminDb();

    let userId: string;
    try {
      const decodedToken = await adminAuth.verifyIdToken(idToken);
      userId = decodedToken.uid;
    } catch (error) {
      return NextResponse.json({ error: 'Invalid token' }, { status: 401 });
    }

    await adminDb.collection('githubConnections').doc(userId).delete();

    return NextResponse.json({ success: true });
  } catch (error) {
    console.error('[GitHub Disconnect] Error:', error);
    return NextResponse.json(
      { error: 'Failed to disconnect GitHub' },
      { status: 500 }
    );
  }
}