/**
 * Pulpie WebUI - Cloudflare Worker Edge Handler
 *
 * Serves static assets and provides a high-performance, CORS-enabled
 * edge proxy endpoint (/api/proxy) for fetching external documentation/web pages.
 */

const CORS_HEADERS = {
  'Access-Control-Allow-Origin': '*',
  'Access-Control-Allow-Methods': 'GET, HEAD, OPTIONS',
  'Access-Control-Allow-Headers': '*',
  'Access-Control-Max-Age': '86400',
};

const BROWSER_HEADERS = {
  'User-Agent':
    'Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/124.0.0.0 Safari/537.36',
  'Accept':
    'text/html,application/xhtml+xml,application/xml;q=0.9,image/avif,image/webp,*/*;q=0.8',
  'Accept-Language': 'en-US,en;q=0.9',
  'Sec-Ch-Ua': '"Not-A.Brand";v="99", "Chromium";v="124"',
  'Sec-Ch-Ua-Mobile': '?0',
  'Sec-Ch-Ua-Platform': '"Linux"',
};

async function handleProxy(request) {
  if (request.method === 'OPTIONS') {
    return new Response(null, { status: 204, headers: CORS_HEADERS });
  }

  const url = new URL(request.url);
  const targetUrl = url.searchParams.get('url');

  if (!targetUrl) {
    return new Response(JSON.stringify({ error: "Missing 'url' query parameter." }), {
      status: 400,
      headers: { ...CORS_HEADERS, 'Content-Type': 'application/json' },
    });
  }

  let parsedTarget;
  try {
    parsedTarget = new URL(targetUrl);
    if (!['http:', 'https:'].includes(parsedTarget.protocol)) {
      throw new Error('Invalid protocol');
    }
  } catch {
    return new Response(
      JSON.stringify({ error: "Invalid target URL. Must start with http:// or https://." }),
      { status: 400, headers: { ...CORS_HEADERS, 'Content-Type': 'application/json' } }
    );
  }

  try {
    const controller = new AbortController();
    const timeout = setTimeout(() => controller.abort(), 15000);

    const upstreamResponse = await fetch(parsedTarget.toString(), {
      signal: controller.signal,
      headers: BROWSER_HEADERS,
      redirect: 'follow',
    });
    clearTimeout(timeout);

    const body = await upstreamResponse.text();
    const contentType =
      upstreamResponse.headers.get('content-type') || 'text/html; charset=utf-8';

    return new Response(body, {
      status: 200,
      headers: {
        ...CORS_HEADERS,
        'Content-Type': contentType,
        'X-Final-Url': upstreamResponse.url || parsedTarget.toString(),
      },
    });
  } catch (err) {
    return new Response(
      JSON.stringify({ error: `Failed to fetch target URL: ${err.message}` }),
      { status: 502, headers: { ...CORS_HEADERS, 'Content-Type': 'application/json' } }
    );
  }
}

export default {
  async fetch(request, env) {
    const url = new URL(request.url);

    if (url.pathname === '/api/proxy') {
      return handleProxy(request);
    }

    if (env.ASSETS) {
      return env.ASSETS.fetch(request);
    }

    return new Response('Not Found', { status: 404 });
  },
};