import process from 'node:process';
import { Buffer } from 'buffer';
import { FetchMode, ServerSetting } from './src/types/types';
import { Connect } from 'vite';
import httpProxy from 'http-proxy';
import { exec } from 'child_process';
import { brotliDecompressSync, gunzipSync, zstdDecompressSync } from 'zlib';

const proxy = httpProxy.createProxyServer({});

const settings: ServerSetting = {
  CLIENT_HOST: 'http://localhost:3000',
  fetchMode: FetchMode.PROXY,
  disAllowedRequestHeaders: [
    'sec-ch-ua',
    'sec-ch-ua-mobile',
    'sec-ch-ua-platform',
    'sec-fetch-site',
    'origin',
    'sec-fetch-site',
    'sec-fetch-dest',
    'pragma',
  ],
  disAllowResponseHeaders: ['link', 'set-cookie', 'set-cookie2'],
  useUserAgent: true,
};

const proxySettingMiddleware: Connect.NextHandleFunction = (req, res) => {
  if (req.method === 'GET') {
    res.statusCode = 200;
    res.setHeader('Content-Type', 'application/json');
    res.write(JSON.stringify(settings));
    res.end();
    return;
  }

  let str = '';
  req.on('data', chunk => {
    str += chunk;
  });
  req.on('end', () => {
    try {
      const newSettings = JSON.parse(str);
      for (const key in newSettings) {
        // @ts-ignore
        settings[key] = newSettings[key];
      }
      res.statusCode = 200;
      res.setHeader('Content-Type', 'application/json');
      res.write(JSON.stringify(settings));
    } catch {
      res.statusCode = 400;
    } finally {
      res.end();
    }
  });
};

const proxyHandlerMiddle: Connect.NextHandleFunction = (req, res) => {
  const rawUrl = 'https:' + req.url;
  if (req.headers['access-control-request-method']) {
    res.setHeader(
      'access-control-allow-methods',
      req.headers['access-control-request-method'],
    );
    delete req.headers['access-control-request-method'];
  }
  if (req.headers['access-control-request-headers']) {
    res.setHeader(
      'access-control-allow-headers',
      req.headers['access-control-request-headers'],
    );
    delete req.headers['access-control-request-headers'];
  }
  res.setHeader('Access-Control-Allow-Origin', settings.CLIENT_HOST);
  res.setHeader('Access-Control-Allow-Credentials', 'true');
  req.headers.referer = rawUrl;

  if (req.method === 'OPTIONS') {
    res.statusCode = 200;
    res.end();
  } else {
    try {
      const _url = new URL(rawUrl);
      for (const _header in req.headers) {
        if (
          req.headers[_header]?.includes('localhost') ||
          settings.disAllowedRequestHeaders.includes(_header)
        ) {
          delete req.headers[_header];
        }
      }
      req.headers['sec-fetch-mode'] = 'cors';
      if (settings.cookies) req.headers['cookie'] = settings.cookies;
      if (!settings.useUserAgent) delete req.headers['user-agent'];
      req.headers.host = _url.host;
      req.url = _url.toString();
      proxyRequest(req, res);
    } catch (err) {
      console.log('\x1b[31m', '----------ERRROR----------');
      console.error(err);
      console.log('\x1b[31m', '----------ERRROR----------');
      if (!res.closed) {
        res.statusCode = 500;
        res.end();
      }
    }
  }
};

const proxyRequest: Connect.SimpleHandleFunction = (req, res) => {
  const _url = new URL(req.url || '');
  console.log('\x1b[36m', '----------------');
  console.log(
    `Making proxy request - at ${new Date().toLocaleTimeString()}
  url: ${_url.href}
  headers:`,
  );
  Object.entries(req.headers).forEach(([name, value]) => {
    console.log('\t', '\x1b[32m', name + ':', '\x1b[37m', value);
  });
  console.log('\x1b[36m', '----------------');

  if (settings.fetchMode === FetchMode.CURL) {
    let curl = `curl -L '${_url.href}'`;
    if (settings.useUserAgent)
      curl += ` -H 'User-Agent: ${req.headers['user-agent']}'`;
    if (settings.cookies) curl += ` -H 'Cookie: ${settings.cookies}'`;
    if (req.headers.origin2) curl += ` -H 'Origin: ${req.headers.origin2}'`;

    const isWindows = process.platform === 'win32';
    const options = isWindows
      ? {
          shell:
            process.env.BASH_LOCATION ||
            process.env.ProgramFiles + '\\git\\usr\\bin\\bash.exe',
        }
      : {};

    exec(curl, options, (error, stdout) => {
      if (error) {
        res.statusCode = 500;
        res.write(`exec error: ${error}`);
        res.end();
        return;
      }
      res.statusCode = 200;
      res.write(stdout);
      res.end();
    });
  } else if (settings.fetchMode === FetchMode.NODE_FETCH) {
    const headers = new Headers();
    if (settings.useUserAgent)
      headers.append('user-agent', req.headers['user-agent'] as string);
    if (settings.cookies) headers.append('cookie', settings.cookies);
    if (req.headers.origin2)
      headers.append('origin', req.headers.origin2 as string);

    fetch(_url.href, { headers })
      .then(async res2 => {
        res.statusCode = res2.status;
        res2.headers.forEach((val, key) => {
          if (
            !settings.disAllowResponseHeaders.includes(key) &&
            key !== 'content-encoding' &&
            key !== 'content-length'
          ) {
            res.setHeader(key, val);
          }
        });
        res.write(await res2.text());
        res.end();
      })
      .catch(err => {
        console.error(err);
        res.statusCode = 500;
        res.end();
      });
  } else if (settings.fetchMode === FetchMode.PROXY) {
    proxy.web(
      req,
      res,
      { target: _url.origin, selfHandleResponse: true, followRedirects: true },
      err => {
        console.error('Proxy target error:', err);
        res.statusCode = 500;
        res.end();
      },
    );
  }
};

proxy.on('proxyRes', function (proxyRes, req, res) {
  const statusCode = proxyRes.statusCode || 200;

  // Redirect handling
  if ([301, 302, 303, 307, 308].includes(statusCode)) {
    const location = proxyRes.headers['location'];
    if (location) {
      try {
        const _url = new URL(req.url || '');
        const redirectUrl = new URL(location, _url.href);
        req.url = redirectUrl.toString();

        // Prevent infinite loops
        const reqWithRedirect = req as Connect.IncomingMessage & {
          _redirectCount?: number;
        };
        const redirectCount = reqWithRedirect._redirectCount || 0;
        if (redirectCount >= 5) {
          res.statusCode = 508;
          res.end('Too many redirects');
          return;
        }
        reqWithRedirect._redirectCount = redirectCount + 1;

        // Update method for 301/302/303 to GET as per spec
        if ([301, 302, 303].includes(statusCode)) {
          req.method = 'GET';
          req.headers['content-length'] = '0';
          delete req.headers['content-type'];
        }

        req.removeAllListeners();
        proxyRequest(req, res);
        return;
      } catch (err) {
        console.error('Redirect parsing error:', err);
      }
    }
  }

  res.statusCode = statusCode;

  // Propagate headers but filter restricted ones
  Object.keys(proxyRes.headers).forEach(key => {
    if (
      !settings.disAllowResponseHeaders.includes(key) &&
      key !== 'content-encoding' &&
      key !== 'content-length'
    ) {
      res.setHeader(key, proxyRes.headers[key] as string);
    }
  });

  if (statusCode === 304) {
    res.end();
    return;
  }

  const contentEncoding = proxyRes.headers['content-encoding'] || '';
  const chunks: Buffer[] = [];
  proxyRes.on('data', chunk => chunks.push(Buffer.from(chunk)));
  proxyRes.on('end', () => {
    try {
      const compressedBuffer = Buffer.concat(chunks);
      if (compressedBuffer.length > 0) {
        let decompressedBuffer: Buffer;
        if (contentEncoding.includes('br')) {
          decompressedBuffer = brotliDecompressSync(compressedBuffer);
        } else if (contentEncoding.includes('gzip')) {
          decompressedBuffer = gunzipSync(compressedBuffer);
        } else if (contentEncoding.includes('zstd')) {
          decompressedBuffer = zstdDecompressSync(compressedBuffer);
        } else {
          decompressedBuffer = compressedBuffer;
        }
        res.write(decompressedBuffer);
      }
      res.end();
    } catch (err) {
      console.error('Decompression error:', err);
      res.statusCode = 500;
      res.end('Decompression error');
    }
  });
});

export { proxyHandlerMiddle, proxySettingMiddleware };