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

/**
 * Fetch repository file tree from GitHub
 * GET /api/github/repo-tree?owner=X&repo=Y
 */
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 branch = url.searchParams.get('branch') || 'main';

    if (!owner || !repo) {
      return NextResponse.json({ error: 'Missing owner or repo' }, { 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 repository tree from GitHub API (recursive)
    const response = await fetch(
      `https://api.github.com/repos/${owner}/${repo}/git/trees/${branch}?recursive=1`,
      {
        headers: {
          Authorization: `Bearer ${accessToken}`,
          Accept: 'application/vnd.github.v3+json',
        },
      }
    );

    if (!response.ok) {
      const error = await response.json();
      throw new Error(`GitHub API error: ${error.message || response.statusText}`);
    }

    const data = await response.json();

    // Filter to only include files (not directories)
    // and exclude common non-code files
    const excludePatterns = [
      /node_modules\//,
      /\.git\//,
      /dist\//,
      /build\//,
      /\.next\//,
      /coverage\//,
      /\.cache\//,
      /\.env/,
      /package-lock\.json$/,
      /yarn\.lock$/,
      /pnpm-lock\.yaml$/,
      /\.png$/,
      /\.jpg$/,
      /\.jpeg$/,
      /\.gif$/,
      /\.svg$/,
      /\.ico$/,
      /\.woff$/,
      /\.woff2$/,
      /\.ttf$/,
      /\.eot$/,
      /\.min\.js$/,
      /\.min\.css$/,
      /\.map$/,
    ];

    // Include common code file extensions
    const includePatterns = [
      /\.(ts|tsx|js|jsx|py|java|go|rs|cpp|c|h|cs|rb|php|swift|kt)$/,
      /\.(json|yaml|yml|toml|xml)$/,
      /\.(md|txt)$/,
      /\.(sql|graphql|proto)$/,
      /\.(css|scss|sass|less)$/,
      /\.(html|htm)$/,
      /Dockerfile$/,
      /Makefile$/,
      /README$/,
    ];

    const files = data.tree
      .filter((item: any) => item.type === 'blob')
      .filter((item: any) => {
        // Exclude patterns
        if (excludePatterns.some(pattern => pattern.test(item.path))) {
          return false;
        }
        // Include patterns
        return includePatterns.some(pattern => pattern.test(item.path));
      })
      .map((item: any) => ({
        path: item.path,
        sha: item.sha,
        size: item.size,
        url: item.url,
      }));

    console.log(`[GitHub Tree] Found ${files.length} code files in ${owner}/${repo}`);

    return NextResponse.json({
      owner,
      repo,
      branch,
      totalFiles: files.length,
      files,
    });
  } catch (error) {
    console.error('[GitHub Tree] Error:', error);
    return NextResponse.json(
      {
        error: 'Failed to fetch repository tree',
        details: error instanceof Error ? error.message : String(error),
      },
      { status: 500 }
    );
  }
}