<?php
/**
 * Caterium same-origin /api and api.caterium.ru -> Supabase HTTP proxy.
 * Forwards only REST/Auth/Storage/Edge Functions HTTP traffic.
 * Browser updates use authenticated HTTP polling; this is not a WebSocket proxy.
 * Upstream host is a fixed constant - never derived from request input (no open-proxy risk).
 */

const UPSTREAM = 'https://usfjwhztqoopzzfmfbis.supabase.co';

const ALLOWED_PREFIXES = ['/rest/v1/', '/auth/v1/', '/storage/v1/', '/functions/v1/'];

// The same source is deployed to the dedicated API host and app /api/index.php.
// Never accept another Host or derive the upstream host from browser input.
$requestHost = strtolower(explode(':', $_SERVER['HTTP_HOST'] ?? '')[0]);
$path = parse_url($_SERVER['REQUEST_URI'] ?? '/', PHP_URL_PATH) ?: '/';
$query = parse_url($_SERVER['REQUEST_URI'] ?? '/', PHP_URL_QUERY);
if ($requestHost === 'app.caterium.ru' && $path === '/api/index.php' && is_string($_GET['__caterium_path'] ?? null)) {
    $path = $_GET['__caterium_path'];
    $query = implode('&', array_filter(explode('&', $query ?? ''), static function ($part) {
        return urldecode(explode('=', $part, 2)[0]) !== '__caterium_path';
    }));
} elseif ($requestHost !== 'api.caterium.ru') {
    http_response_code(404);
    exit;
}

const ALLOWED_ORIGINS = [
    'https://app.caterium.ru',
    'https://caterium.ru',
    'https://www.caterium.ru',
];

const FORWARD_REQUEST_HEADERS = [
    'authorization', 'apikey', 'content-type', 'prefer', 'range',
    'x-client-info', 'x-supabase-api-version', 'accept-profile', 'content-profile', 'x-upsert', 'cache-control',
];

const STRIP_RESPONSE_HEADERS = [
    'transfer-encoding', 'connection', 'content-encoding', 'content-length', 'cache-control', 'expires', 'pragma', 'set-cookie',
];

function send_cors_headers(): void
{
    $origin = $_SERVER['HTTP_ORIGIN'] ?? '';
    if (in_array($origin, ALLOWED_ORIGINS, true)) {
        header('Access-Control-Allow-Origin: ' . $origin);
        header('Vary: Origin');
    }
    header('Access-Control-Allow-Methods: GET, POST, PATCH, PUT, DELETE, OPTIONS');
    header('Access-Control-Allow-Headers: ' . implode(', ', FORWARD_REQUEST_HEADERS));
    header('Access-Control-Max-Age: 86400');
}

function request_headers(): array
{
    if (function_exists('getallheaders')) {
        $raw = getallheaders();
        if (is_array($raw)) {
            return $raw;
        }
    }
    // Fallback for environments without getallheaders().
    $out = [];
    foreach ($_SERVER as $key => $value) {
        if (strpos($key, 'HTTP_') === 0) {
            $name = str_replace(' ', '-', ucwords(strtolower(str_replace('_', ' ', substr($key, 5)))));
            $out[$name] = $value;
        }
    }
    if (isset($_SERVER['CONTENT_TYPE'])) {
        $out['Content-Type'] = $_SERVER['CONTENT_TYPE'];
    }
    return $out;
}

send_cors_headers();
header('Cache-Control: private, no-store');
header('X-Content-Type-Options: nosniff');

if (($_SERVER['REQUEST_METHOD'] ?? '') === 'OPTIONS') {
    http_response_code(204);
    exit;
}

$allowed = false;
foreach (ALLOWED_PREFIXES as $prefix) {
    if (strpos($path, $prefix) === 0) {
        $allowed = true;
        break;
    }
}

if (!$allowed || strpos(rawurldecode($path), '..') !== false || preg_match('/[\\\\?#\x00-\x20]/', $path)) {
    http_response_code(404);
    header('Content-Type: application/json');
    echo json_encode(['error' => 'not_found', 'message' => 'Path not proxied.']);
    exit;
}

$upstreamUrl = UPSTREAM . $path . ($query !== null && $query !== '' ? '?' . $query : '');

$incoming = request_headers();
$incomingLower = [];
foreach ($incoming as $name => $value) {
    $incomingLower[strtolower($name)] = $value;
}

$forwardHeaders = [];
foreach (FORWARD_REQUEST_HEADERS as $name) {
    if (isset($incomingLower[$name]) && $incomingLower[$name] !== '') {
        $forwardHeaders[] = $name . ': ' . $incomingLower[$name];
    }
}

$method = $_SERVER['REQUEST_METHOD'] ?? 'GET';
$body = ($method === 'GET' || $method === 'HEAD') ? null : file_get_contents('php://input');

$ch = curl_init($upstreamUrl);
curl_setopt_array($ch, [
    CURLOPT_CUSTOMREQUEST => $method,
    CURLOPT_HTTPHEADER => $forwardHeaders,
    CURLOPT_RETURNTRANSFER => true,
    CURLOPT_HEADER => true,
    CURLOPT_FOLLOWLOCATION => false,
    CURLOPT_CONNECTTIMEOUT => 10,
    CURLOPT_TIMEOUT => 30,
    CURLOPT_SSL_VERIFYPEER => true,
    CURLOPT_SSL_VERIFYHOST => 2,
    CURLOPT_NOBODY => $method === 'HEAD',
]);

if ($body !== null && $body !== '') {
    curl_setopt($ch, CURLOPT_POSTFIELDS, $body);
}

$response = curl_exec($ch);

if ($response === false) {
    http_response_code(502);
    header('Content-Type: application/json');
    echo json_encode(['error' => 'upstream_unreachable']);
    curl_close($ch);
    exit;
}

$headerSize = curl_getinfo($ch, CURLINFO_HEADER_SIZE);
$statusCode = curl_getinfo($ch, CURLINFO_HTTP_CODE);
$rawHeaders = substr($response, 0, $headerSize);
$respBody = substr($response, $headerSize);
curl_close($ch);

http_response_code($statusCode);

$responseContentType = '';
foreach (preg_split('/\r\n/', $rawHeaders) as $line) {
    if ($line === '' || stripos($line, 'HTTP/') === 0) {
        continue;
    }
    $colon = strpos($line, ':');
    if ($colon === false) {
        continue;
    }
    $headerName = strtolower(trim(substr($line, 0, $colon)));
    if ($headerName === 'content-type') {
        $responseContentType = trim(substr($line, $colon + 1));
    }
    if (in_array($headerName, STRIP_RESPONSE_HEADERS, true) || strpos($headerName, 'access-control-') === 0) {
        continue;
    }
    // Backend HTTP endpoints do not require external redirects. Keep any
    // upstream redirect on the dedicated API host, including signed downloads.
    if ($headerName === 'location') $line = str_replace(UPSTREAM, 'https://api.caterium.ru', $line);
    header($line, false);
}

// Supabase returns absolute upstream URLs inside some JSON bodies (e.g. Storage
// createSignedUrl). Rewrite those to our public host so the browser's follow-up
// request (an <img src>, a download link, ...) is proxied too, not sent to
// *.supabase.co directly. Only touch text/JSON bodies - never binary payloads.
if (stripos($responseContentType, 'application/json') !== false || stripos($responseContentType, 'text/') !== false) {
    $respBody = str_replace(UPSTREAM, 'https://api.caterium.ru', $respBody);
}

echo $respBody;