// /api/thumbnails/[...path]/route.ts
// This endpoint serves thumbnails from the thumbnails directory

import { NextResponse } from 'next/server';
import * as fs from 'fs';
import * as path from 'path';
import { getViewer } from '@/lib/video-access';

// Path to thumbnails directory (should match UPLOADS_DIR/thumbnails)
const THUMBNAILS_DIR = path.join(process.env.UPLOADS_DIR || '/uploads', 'thumbnails');

export async function GET(
  request: Request,
  context: { params: Promise<{ path?: string[] }> }
) {
  try {
    const params = await context.params;
    const pathSegments = params?.path || [];

    if (pathSegments.length === 0) {
      return NextResponse.json(
        { error: 'Invalid thumbnail request' },
        { status: 400 }
      );
    }

    // Thumbnails show course content, so they need a signed-in user.
    if (!(await getViewer())) {
      return NextResponse.json({ error: 'Unauthorized' }, { status: 401 });
    }

    // Construct the file path and validate it
    const requestedPath = path.join(THUMBNAILS_DIR, ...pathSegments);
    
    // Security: prevent directory traversal attacks
    if (!requestedPath.startsWith(THUMBNAILS_DIR + path.sep)) {
      return NextResponse.json(
        { error: 'Invalid request' },
        { status: 403 }
      );
    }

    // Check if file exists
    if (!fs.existsSync(requestedPath)) {
      console.log(`[Thumbnails] File not found: ${requestedPath}`);
      return NextResponse.json(
        { error: 'Not found' },
        { status: 404 }
      );
    }

    // Read the file
    const fileContent = await fs.promises.readFile(requestedPath);

    // Determine content type based on file extension
    let contentType = 'application/octet-stream';
    
    if (requestedPath.endsWith('.jpg') || requestedPath.endsWith('.jpeg')) {
      contentType = 'image/jpeg';
    } else if (requestedPath.endsWith('.png')) {
      contentType = 'image/png';
    } else if (requestedPath.endsWith('.webp')) {
      contentType = 'image/webp';
    } else if (requestedPath.endsWith('.gif')) {
      contentType = 'image/gif';
    }

    // Return the file with appropriate headers
    return new NextResponse(fileContent, {
      status: 200,
      headers: {
        'Content-Type': contentType,
        'Cache-Control': 'private, max-age=31536000, immutable', // Cache for 1 year (thumbnails don't change)
      },
    });
  } catch (error) {
    console.error('[Thumbnails] Error serving thumbnail file:', error);
    return NextResponse.json(
      { error: 'Internal server error' },
      { status: 500 }
    );
  }
}

// HEAD request support for thumbnail validation
export async function HEAD(
  request: Request,
  context: { params: Promise<{ path?: string[] }> }
) {
  try {
    const params = await context.params;
    const pathSegments = params?.path || [];

    if (pathSegments.length === 0) {
      return new NextResponse(null, { status: 400 });
    }

    if (!(await getViewer())) return new NextResponse(null, { status: 401 });

    const requestedPath = path.join(THUMBNAILS_DIR, ...pathSegments);
    
    // Security: prevent directory traversal attacks
    if (!requestedPath.startsWith(THUMBNAILS_DIR + path.sep)) {
      return new NextResponse(null, { status: 403 });
    }

    // Check if file exists
    if (!fs.existsSync(requestedPath)) {
      return new NextResponse(null, { status: 404 });
    }

    // Return headers only
    return new NextResponse(null, {
      status: 200,
      headers: {
        'Content-Type': 'image/jpeg', // Default for HEAD requests
        'Cache-Control': 'private, max-age=31536000, immutable',
      },
    });
  } catch (error) {
    console.error('[Thumbnails] Error in HEAD request:', error);
    return new NextResponse(null, { status: 500 });
  }
}