<?php

declare(strict_types=1);

namespace KTXM\ProviderImap\Client\Transport;

use KTXM\ProviderImap\Client\ConnectionConfig;
use KTXM\ProviderImap\Client\ImapException;
use Psr\Log\LoggerInterface;

final class SocketConnection implements ConnectionInterface
{
    /** @var resource|null */
    private $stream = null;

    public function __construct(
        private readonly ConnectionConfig $config,
        private readonly ?LoggerInterface $logger = null,
    ) {}

    public function connect(ConnectionConfig $config): void
    {
        if ($this->isConnected()) {
            return;
        }

        $context = stream_context_create($config->streamContextOptions());
        $errorCode = 0;
        $errorMessage = '';

        $stream = @stream_socket_client(
            $config->endpoint(),
            $errorCode,
            $errorMessage,
            $config->timeout(),
            STREAM_CLIENT_CONNECT,
            $context,
        );

        if (!is_resource($stream)) {
            $this->logger?->error('IMAP socket connection failed', [
                'endpoint' => $config->endpoint(),
                'code' => $errorCode,
                'message' => $errorMessage ?: 'unknown error',
            ]);

            throw new ImapException(sprintf(
                'Unable to connect to %s (%d: %s)',
                $config->endpoint(),
                $errorCode,
                $errorMessage ?: 'unknown error',
            ));
        }

        stream_set_timeout($stream, (int) $config->timeout());
        $this->stream = $stream;

        $this->logger?->info('IMAP socket connected to {endpoint} (timeout={timeout})', [
            'endpoint' => $config->endpoint(),
            'timeout' => $config->timeout(),
        ]);
    }

    public function disconnect(): void
    {
        if (!is_resource($this->stream)) {
            return;
        }

        fclose($this->stream);
        $this->stream = null;

        $this->logger?->info('IMAP socket disconnected');
    }

    public function isConnected(): bool
    {
        return is_resource($this->stream);
    }

    public function write(string $payload): void
    {
        $stream = $this->stream();
        $written = fwrite($stream, $payload);

        if ($written === false || $written !== strlen($payload)) {
            $this->logger?->error('IMAP socket write failed (bytes={bytes})', [
                'bytes' => strlen($payload),
            ]);

            throw new ImapException('Failed to write complete payload to IMAP socket.');
        }
    }

    public function readLine(): string
    {
        $stream = $this->stream();
        $line = fgets($stream);

        if ($line === false) {
            $this->logger?->error('IMAP socket read failed');
            throw new ImapException('Failed to read line from IMAP socket.');
        }

        return $line;
    }

    public function readBytes(int $length): string
    {
        if ($length < 0) {
            throw new ImapException('IMAP socket cannot read a negative number of bytes.');
        }

        if ($length === 0) {
            return '';
        }

        $stream = $this->stream();
        $buffer = '';

        while (strlen($buffer) < $length) {
            $chunk = fread($stream, $length - strlen($buffer));

            if ($chunk === false || $chunk === '') {
                $this->logger?->error('IMAP socket literal read failed (bytes={bytes})', [
                    'bytes' => $length,
                ]);

                throw new ImapException('Failed to read literal payload from IMAP socket.');
            }

            $buffer .= $chunk;
        }

        return $buffer;
    }

    public function upgradeToTls(): void
    {
        $stream = $this->stream();
        $result = stream_socket_enable_crypto($stream, true, STREAM_CRYPTO_METHOD_TLS_CLIENT);

        if ($result !== true) {
            $this->logger?->error('IMAP TLS upgrade failed');
            throw new ImapException('Failed to enable TLS on IMAP socket.');
        }

        $this->logger?->info('IMAP socket upgraded to TLS');
    }

    /**
     * @return resource
     */
    private function stream()
    {
        if (!is_resource($this->stream)) {
            throw new ImapException('IMAP socket is not connected.');
        }

        return $this->stream;
    }
}