<?php

namespace App\Network\Clients\Hsgq;

use RuntimeException;

class HsgqTelnetClient implements HsgqCliClient
{
    /** @var resource|null */
    private $socket;

    public function __construct(private readonly string $host, private readonly int $port = 23, private readonly int $timeout = 10) {}

    public function connect(string $username, string $password): void
    {
        $errorNumber = 0;
        $errorMessage = '';
        $this->socket = @stream_socket_client("tcp://{$this->host}:{$this->port}", $errorNumber, $errorMessage, $this->timeout);
        if (! is_resource($this->socket)) {
            throw new RuntimeException('TELNET_UNREACHABLE: koneksi Telnet HSGQ port 23 gagal.');
        }

        stream_set_timeout($this->socket, $this->timeout);
        $this->readUntil('/(?:login|username|user\s*name)\s*:\s*$/i');
        $this->write($username);
        $this->readUntil('/password\s*:\s*$/i');
        $this->write($password);
        $output = $this->readPrompt();
        if (! preg_match('/[>#]\s*$/', trim($output))) {
            throw new RuntimeException('AUTHENTICATION_FAILED: login Telnet HSGQ ditolak.');
        }
    }

    public function command(string $command): string
    {
        $this->write($command);
        $output = $this->readPrompt();
        $isHelpCommand = in_array(trim($command), ['?', 'help', 'list'], true);
        if (! $isHelpCommand && preg_match('/(?:Error|Invalid|Failed|failure|unknown command|Command incomplete|There is no matched command)/i', $output)) {
            preg_match('/^(?!.*user\s+(?:add|password)).*(?:Error|Invalid|Failed|failure|unknown command|Command incomplete|There is no matched command).*$/mi', $output, $detail);
            throw new RuntimeException('COMMAND_REJECTED: '.str($detail[0] ?? 'HSGQ menolak perintah CLI Telnet.')->trim()->limit(180));
        }

        return $output;
    }

    public function enterEnable(string $password): void
    {
        $this->write('enable');
        $output = $this->readUntil('/(?:Password\s*:|#\s*$)/i');
        if (preg_match('/Password\s*:/i', $output)) {
            $this->write($password);
            $output = $this->readPrompt();
        }
        if (! str_ends_with(trim($output), '#')) {
            throw new RuntimeException('ENABLE_FAILED: gagal masuk privileged mode Telnet HSGQ.');
        }
    }

    public function disconnect(): void
    {
        if (is_resource($this->socket)) {
            fclose($this->socket);
        }
        $this->socket = null;
    }

    private function write(string $value): void
    {
        if (! is_resource($this->socket) || fwrite($this->socket, $value."\r\n") === false) {
            throw new RuntimeException('CONNECTION_CLOSED: sesi Telnet HSGQ terputus.');
        }
    }

    private function readPrompt(): string
    {
        return $this->readUntil('/(?:\([^\r\n]+\))?[#>]\s*$/');
    }

    private function readUntil(string $pattern): string
    {
        if (! is_resource($this->socket)) {
            throw new RuntimeException('CONNECTION_CLOSED: sesi Telnet HSGQ belum tersambung.');
        }

        $output = '';
        $startedAt = microtime(true);
        while (microtime(true) - $startedAt < $this->timeout) {
            $chunk = fread($this->socket, 4096);
            if ($chunk === false || ($chunk === '' && feof($this->socket))) {
                throw new RuntimeException('CONNECTION_CLOSED: sesi Telnet HSGQ ditutup perangkat.');
            }
            if ($chunk !== '') {
                $output .= $this->stripNegotiation($chunk);
                if (preg_match($pattern, $output)) {
                    return $output;
                }
            }
            $metadata = stream_get_meta_data($this->socket);
            if ($metadata['timed_out']) {
                break;
            }
        }

        throw new RuntimeException('CONNECTION_TIMEOUT: prompt Telnet HSGQ tidak diterima.');
    }

    private function stripNegotiation(string $data): string
    {
        $clean = '';
        $length = strlen($data);
        for ($index = 0; $index < $length; $index++) {
            if (ord($data[$index]) !== 255) {
                $clean .= $data[$index];

                continue;
            }
            if ($index + 2 >= $length) {
                break;
            }
            $command = ord($data[++$index]);
            $option = ord($data[++$index]);
            if (in_array($command, [251, 252], true)) {
                fwrite($this->socket, pack('CCC', 255, 254, $option));
            } elseif (in_array($command, [253, 254], true)) {
                fwrite($this->socket, pack('CCC', 255, 252, $option));
            }
        }

        return str_replace("\0", '', $clean);
    }
}