<?php
// this is the source for the script that RemoteV2 interacts with

define('SRV_REQ_SEC', 'secret key goes here');
define('SRV_REQ_LIFE', 60);
define('SRV_DIR_FMT', '/srv/minecraft/%s');

function base64url_encode(string $input): string {
    return rtrim(strtr(base64_encode($input), '+/', '-_'), '=');
}

function base64url_decode(string $input): string {
    return base64_decode(str_pad(strtr($input, '-_', '+/'), strlen($input) % 4, '=', STR_PAD_RIGHT));
}

function rcon_open(int $port) {
    $conn = fsockopen('localhost', $port, $code, $message, 2);
    return $conn;
}

function rcon_close($conn) {
    if(is_resource($conn))
        fclose($conn);
}

function rcon_recv($conn): array {
    if(!is_resource($conn))
        return ['error' => ':rcon:conn'];

    extract(unpack('Vlength', fread($conn, 4)));
    if($length < 10)
        return ['error' => ':rcon:length'];

    extract(unpack('VreqId/Vopcode', fread($conn, 8)));
    $body = substr(fread($conn, $length - 8), 0, -2);

    return compact('reqId', 'opcode', 'body');
}

function rcon_send($conn, int $opcode, string $text): int {
    if(!is_resource($conn))
        return -1;
    $length = 10 + strlen($text);
    $reqId = random_int(1, 0x7FFFFFFF);
    fwrite($conn, pack('VVV', $length, $reqId, $opcode) . $text . "\0\0");
    return $reqId;
}

function rcon_send_large($conn, int $opcode, string $text): array {
    if(!is_resource($conn))
        return ['error' => ':rcon:conn'];

    $reqId = rcon_send($conn, $opcode, $text);
    if($reqId < 1) return ['error' => ':rcon:request'];

    $trailer = rcon_send($conn, 2, 'time query gametime');
    if($trailer < 1) return ['error' => ':rcon:trailer'];

    $opcode = 0;
    $body = '';

    for(;;) {
        $resp = rcon_recv($conn);
        if(!empty($resp['error']))
            return $resp;

        if($resp['reqId'] === $trailer) break;
        if($resp['reqId'] !== $reqId)   continue;

        if($resp['opcode'] !== 0)
            return ['error' => ':rcon:opcode'];

        $body .= $resp['body'];
    }

    return compact('reqId', 'trailer', 'opcode', 'body');
}

function rcon_open_props(array $props) {
    if(empty($props['rcon.port']))
        die('{"error":":conf:rcon-port"}');
    if(empty($props['rcon.password']))
        die('{"error":":conf:rcon-passwd"}');

    return rcon_open($props['rcon.port']);
}

function rcon_auth_props($conn, array $props): void {
    if(empty($props['rcon.password']))
        die('{"error":":conf:rcon-passwd"}');

    rcon_send($conn, 3, $props['rcon.password']);
    $resp = rcon_recv($conn);
    if(!empty($resp['error']))
        die(json_encode(['error' => $resp['error']]));
}

function rcon_get_whitelist($conn): array {
    $resp = rcon_send_large($conn, 2, 'whitelist list');
    if(!empty($resp['error'])) return $resp;

    $halfs = explode(':', $resp['body'], 2);
    if(empty($halfs[1])) return [];

    $names = explode(',', $halfs[1]);
    foreach($names as &$name)
        $name = trim($name);

    return array_values(array_filter($names));
}

function rcon_add_whitelist($conn, array $userNames): array {
    $results = [];

    foreach($userNames as $name) {
        rcon_send($conn, 2, 'whitelist add ' . $name); // todo: sanitise username
        $resp = rcon_recv($conn);

        $results[$name] = [
            'success' => str_starts_with($resp['body'], 'Added '),
            'message' => $resp['body'],
        ];
    }

    rcon_send($conn, 2, 'whitelist reload');
    rcon_recv($conn); // discard reload message

    return compact('results');
}

function rcon_remove_whitelist($conn, array $userNames): array {
    $results = [];

    foreach($userNames as $name) {
        rcon_send($conn, 2, 'whitelist remove ' . $name); // todo: sanitise username
        $resp = rcon_recv($conn);

        $results[$name] = [
            'success' => str_starts_with($resp['body'], 'Removed '),
            'message' => $resp['body'],
        ];
    }

    rcon_send($conn, 2, 'whitelist reload');
    rcon_recv($conn); // discard reload message

    return compact('results');
}

function read_server_props(string $serverPath, string $fileName = 'server.properties'): array {
    $props = [];

    $path = realpath($serverPath . '/' . $fileName);
    if(is_file($path)) {
        $lines = file($path, FILE_IGNORE_NEW_LINES | FILE_SKIP_EMPTY_LINES);
        foreach($lines as $line) {
            if(empty($line) || str_starts_with($line, '#'))
                continue;

            $parts = explode('=', $line, 2);
            if(count($parts) == 2) {
                $value = $parts[1];
                if($value === 'false' || $value === 'true')
                    $value = $value === 'true';
                elseif(ctype_digit($value))
                    $value = (int)$value;
                elseif(is_numeric($value))
                    $value = (float)$value;

                $props[$parts[0]] = $value;
            }
        }
    }

    return $props;
}

function create_request_hash(int $time = -1, ?array $params = null, ?string $method = null, ?string $path = null): string {
    if($time < 0)
        $time = time();
    if($params === null)
        $params = $_REQUEST ?? [];
    if($method === null)
        $method = $GLOBALS['reqMethod'] ?? '';
    if($path === null)
        $path = $GLOBALS['reqPath'] ?? '';

    ksort($params);
    $compare = [];

    $stringify = null; // use() gets sad if it's not defined yet
    $stringify = function(array $arr, string $prefix = '') use(&$compare, &$stringify) {
        foreach($arr as $name => $value) {
            if(is_array($value))
                $stringify($value, $name . ';');
            else
                $compare[] = "{$name}:{$value}";
        }
    };

    $stringify($params);
    $input = "{$time}%{$method} {$path}%" . implode('#', $compare);

    return hash_hmac('sha256', $input, SRV_REQ_SEC, true);
}

function verify_request_hash(): bool {
    $realTime = time();
    $lifeTimeHalf = (int)ceil(SRV_REQ_LIFE / 2);

    $userHash = base64url_decode((string)filter_input(INPUT_SERVER, 'HTTP_X_MINCE_SIGNATURE'));
    $userTime = (int)filter_input(INPUT_SERVER, 'HTTP_X_MINCE_TIMESTAMP', FILTER_SANITIZE_NUMBER_INT);
    if(strlen($userHash) !== 32 || $userTime < ($realTime - $lifeTimeHalf) || $userTime > ($realTime + $lifeTimeHalf))
        return false;

    return hash_equals(create_request_hash($userTime), $userHash);
}

function get_server_path(string $serverId): string {
    if(empty($serverId) || !ctype_alnum($serverId))
        die('{"error":":req:id"}');

    $path = sprintf(SRV_DIR_FMT, $serverId);
    if(!is_dir($path))
        die('{"error":":req:server"}');

    return $path;
}

$reqMethod = (string)filter_input(INPUT_SERVER, 'REQUEST_METHOD');
$reqPath = '/' . trim(parse_url((string)filter_input(INPUT_SERVER, 'REQUEST_URI'), PHP_URL_PATH), '/');

header('Content-Type: application/json; charset=utf-8');

if(!verify_request_hash())
    die('{"error":":request:verification"}');

if($reqMethod === 'GET' && $reqPath === '/') {
    $dirs = glob(__DIR__ . '/../*');
    $servers = [];

    foreach($dirs as $dir)
        if(is_file($dir . '/server.properties') && !is_file($dir . '/.dead'))
            $servers[] = basename($dir);

    echo json_encode(compact('servers'));
    return;
}

if($reqMethod === 'GET' && $reqPath === '/whitelist') {
    $sPath = get_server_path((string)filter_input(INPUT_GET, 'server'));
    $sProps = read_server_props($sPath);
    $rcon = rcon_open_props($sProps);

    try {
        rcon_auth_props($rcon, $sProps);
        echo json_encode(['list' => rcon_get_whitelist($rcon)]);
    } finally {
        rcon_close($rcon);
    }
    return;
}

if($reqMethod === 'POST' && $reqPath === '/whitelist') {
    $wNames = json_decode((string)filter_input(INPUT_POST, 'names'));
    $sPath = get_server_path((string)filter_input(INPUT_POST, 'server'));
    $sProps = read_server_props($sPath);
    $rcon = rcon_open_props($sProps);

    try {
        rcon_auth_props($rcon, $sProps);
        echo json_encode(rcon_add_whitelist($rcon, $wNames));
    } finally {
        rcon_close($rcon);
    }
    return;
}

if($reqMethod === 'DELETE' && $reqPath === '/whitelist') {
    $wNames = json_decode((string)filter_input(INPUT_GET, 'names'));
    $sPath = get_server_path((string)filter_input(INPUT_GET, 'server'));
    $sProps = read_server_props($sPath);
    $rcon = rcon_open_props($sProps);

    try {
        rcon_auth_props($rcon, $sProps);
        echo json_encode(rcon_remove_whitelist($rcon, $wNames));
    } finally {
        rcon_close($rcon);
    }
    return;
}

echo '{"error":":request:notfound"}';