<?php
// By: Colime – PHP reverse proxy, tuned for Google

// Root page
if ($_SERVER['REQUEST_URI'] === '/' || $_SERVER['REQUEST_URI'] === '') {
    header('Content-Type: text/html; charset=utf-8');
    echo '<p>about:blank</p>';
    exit;
}

// CORS preflight
if ($_SERVER['REQUEST_METHOD'] === 'OPTIONS') {
    http_response_code(204);
    header('Access-Control-Allow-Origin: *');
    header('Access-Control-Allow-Methods: GET, POST, PUT, DELETE, PATCH, OPTIONS');
    header('Access-Control-Allow-Headers: *');
    header('Access-Control-Max-Age: 86400');
    exit;
}

// Build target URL from path + query string
$target = substr($_SERVER['REQUEST_URI'], 1);          // strip leading /
$query  = $_SERVER['QUERY_STRING'];
if ($query !== '') {
    $target .= '?' . $query;
}
if (!preg_match('#^https?://#i', $target)) {
    $target = 'http://' . $target;
}

$parts = parse_url($target);
if (!$parts || !isset($parts['host'])) {
    http_response_code(400);
    echo 'Invalid target URL provided.';
    exit;
}

// Collect and clean request headers
$requestHeaders = getallheaders();
$forwardHeaders = [];

// Hop-by-hop headers that should NOT be forwarded (both request and response)
$hopByHop = [
    'connection', 'keep-alive', 'proxy-authenticate',
    'proxy-authorization', 'te', 'trailer', 'transfer-encoding',
    'upgrade'
];

foreach ($requestHeaders as $name => $value) {
    $lower = strtolower($name);
    // Drop Cloudflare headers, real IP, and original Host
    if (strpos($lower, 'cf-') === 0 || $lower === 'x-real-ip' || $lower === 'host') {
        continue;
    }
    // Don't forward hop-by-hop request headers
    if (in_array($lower, $hopByHop)) {
        continue;
    }
    // Accept-Encoding is handled by cURL automatically; do not forward it
    if ($lower === 'accept-encoding') {
        continue;
    }
    $forwardHeaders[] = "$name: $value";
}

// Set the target host
$forwardHeaders[] = 'Host: ' . $parts['host'];

// Fallback User-Agent (only if client didn't send one)
$hasUserAgent = false;
foreach ($forwardHeaders as $h) {
    if (stripos($h, 'User-Agent:') === 0) {
        $hasUserAgent = true;
        break;
    }
}
if (!$hasUserAgent) {
    $forwardHeaders[] = 'User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/125.0.0.0 Safari/537.36';
}

// cURL request
$ch = curl_init($target);
curl_setopt_array($ch, [
    CURLOPT_CUSTOMREQUEST  => $_SERVER['REQUEST_METHOD'],
    CURLOPT_HTTPHEADER     => $forwardHeaders,
    CURLOPT_RETURNTRANSFER => true,
    CURLOPT_FOLLOWLOCATION => true,
    CURLOPT_HEADER         => true,       // include headers in output
    CURLOPT_TIMEOUT        => 30,
    CURLOPT_ENCODING       => '',         // accept any compression, decompress automatically
    CURLOPT_SSL_VERIFYPEER => true,       // keep enabled (HF has CA certs)
]);

// Forward request body (if any)
$body = file_get_contents('php://input');
if ($body !== '' && $body !== false) {
    curl_setopt($ch, CURLOPT_POSTFIELDS, $body);
}

$response = curl_exec($ch);
$error    = curl_error($ch);
$info     = curl_getinfo($ch);
curl_close($ch);

if ($error) {
    http_response_code(502);
    echo 'Upstream server fetch failed. Please check the URL and network.';
    exit;
}

// Split headers and body
$headerSize      = $info['header_size'];
$responseHeaders = substr($response, 0, $headerSize);
$responseBody    = substr($response, $headerSize);

// Parse incoming response headers
$headersArr = explode("\r\n", $responseHeaders);
$statusCode = 200;
$outHeaders = []; // name -> value pairs (duplicates allowed, but we'll filter some)

foreach ($headersArr as $line) {
    // Status line
    if (stripos($line, 'HTTP/') === 0) {
        preg_match('/\d{3}/', $line, $m);
        $statusCode = (int)($m[0] ?? 200);
        continue;
    }
    if (trim($line) === '') {
        continue;
    }

    $colon = strpos($line, ':');
    if ($colon !== false) {
        $name  = substr($line, 0, $colon);
        $value = trim(substr($line, $colon + 1));
        $lower = strtolower($name);

        // Remove security headers that block iframes
        if ($lower === 'content-security-policy' || $lower === 'x-frame-options') {
            continue;
        }
        // Remove hop-by-hop response headers
        if (in_array($lower, $hopByHop)) {
            continue;
        }
        // cURL already decompressed the body – remove Content-Encoding
        if ($lower === 'content-encoding') {
            continue;
        }

        $outHeaders[] = [$name, $value];
    }
}

// --- Send final response ---
http_response_code($statusCode);

// Always add CORS and no-cache headers
header('Access-Control-Allow-Origin: *');
header('Access-Control-Allow-Methods: *');
header('Access-Control-Allow-Headers: *');
header('Cache-Control: no-store, no-cache, must-revalidate, proxy-revalidate');
header('Pragma: no-cache');
header('Expires: 0');

// Forward upstream headers (except those we filtered out)
foreach ($outHeaders as $h) {
    header($h[0] . ': ' . $h[1]);
}

echo $responseBody;