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

/**
 * Fetch file content from GitHub
 * GET /api/github/file-content?owner=X&repo=Y&path=Z
 */
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 url = new URL(request.url);
    const owner = url.searchParams.get('owner');
    const repo = url.searchParams.get('repo');
    const path = url.searchParams.get('path');
    const branch = url.searchParams.get('branch') || 'main';

    if (!owner || !repo || !path) {
      return NextResponse.json(
        { error: 'Missing owner, repo, or path' },
        { status: 400 }
      );
    }

    // Get GitHub connection
    const connectionDoc = await adminDb
      .collection('githubConnections')
      .doc(userId)
      .get();

    if (!connectionDoc.exists) {
      return NextResponse.json(
        { error: 'GitHub not connected' },
        { status: 404 }
      );
    }

    const connection = connectionDoc.data()!;
    const accessToken = connection.accessToken; // TODO: Decrypt

    // Fetch file content from GitHub API
    const response = await fetch(
      `https://api.github.com/repos/${owner}/${repo}/contents/${encodeURIComponent(path)}?ref=${branch}`,
      {
        headers: {
          Authorization: `Bearer ${accessToken}`,
          Accept: 'application/vnd.github.v3+json',
        },
      }
    );

    if (!response.ok) {
      if (response.status === 404) {
        return NextResponse.json({ error: 'File not found' }, { status: 404 });
      }
      const error = await response.json();
      throw new Error(`GitHub API error: ${error.message || response.statusText}`);
    }

    const data = await response.json();

    // GitHub returns base64-encoded content
    const content = Buffer.from(data.content, 'base64').toString('utf-8');

    return NextResponse.json({
      path: data.path,
      name: data.name,
      size: data.size,
      sha: data.sha,
      content,
      encoding: 'utf-8',
    });
  } catch (error) {
    console.error('[GitHub File Content] Error:', error);
    return NextResponse.json(
      {
        error: 'Failed to fetch file content',
        details: error instanceof Error ? error.message : String(error),
      },
      { status: 500 }
    );
  }
}