<?php

declare(strict_types=1);

namespace KTXM\ProviderImap\Client;

use KTXM\ProviderImap\Client\Command\CapabilityCommand;
use KTXM\ProviderImap\Client\Command\CommandInterface;
use KTXM\ProviderImap\Client\FetchTarget;
use KTXM\ProviderImap\Client\Command\LoginCommand;
use KTXM\ProviderImap\Client\Command\StartTlsCommand;
use KTXM\ProviderImap\Client\Protocol\CommandExecutor;
use KTXM\ProviderImap\Client\Protocol\ProtocolReader;
use KTXM\ProviderImap\Client\Protocol\ProtocolWriter;
use KTXM\ProviderImap\Client\Protocol\TagGenerator;
use KTXM\ProviderImap\Client\Transport\ConnectionFactoryInterface;
use KTXM\ProviderImap\Client\Transport\SocketConnectionFactory;
use Psr\Log\LoggerInterface;

final class Client implements ClientInterface
{
    private ?SessionContext $session = null;
    private ?CommandExecutor $executor = null;

    public function __construct(
        private readonly ConnectionFactoryInterface $connectionFactory = new SocketConnectionFactory(),
        private readonly ?LoggerInterface $logger = null,
    ) {}

    public function connect(ConnectionConfig $config): void
    {
        $connection = $this->connectionFactory->create($config, $this->logger);
        $connection->connect($config);

        $reader = new ProtocolReader($connection, $this->logger);
        $writer = new ProtocolWriter($connection, $this->logger);
        $session = new SessionContext($config, $connection);
        $greeting = $reader->readGreeting();

        $session->setGreeting($greeting);
        $session->setState(match ($greeting->status()) {
            'OK' => SessionState::NotAuthenticated,
            'PREAUTH' => SessionState::Authenticated,
            'BYE' => SessionState::Logout,
            default => throw new ImapException('Unexpected IMAP greeting status: ' . $greeting->status()),
        });

        if ($session->state() === SessionState::Logout) {
            throw new ImapException('IMAP server rejected the connection: ' . $greeting->text());
        }

        $this->session = $session;
        $this->executor = new CommandExecutor($reader, $writer, new TagGenerator(), $this->logger);

        $this->perform(new CapabilityCommand());

        if ($config->security() === ConnectionSecurity::StartTls) {
            $this->perform(new StartTlsCommand());
            $this->perform(new CapabilityCommand());
        }

        if ($config->hasCredentials()) {
            $this->perform(new LoginCommand(
                $config->username() ?? '',
                $config->password() ?? '',
            ));
            $this->perform(new CapabilityCommand());
        }
    }

    public function capabilities(): array
    {
        return $this->session()->capabilities();
    }

    public function hasCapability(string $capability): bool
    {
        return $this->session()->hasCapability($capability);
    }

    public function perform(CommandInterface $command): mixed
    {
        if ($this->session === null || $this->executor === null) {
            throw new ImapException('IMAP client is not connected.');
        }

        return $this->executor->perform($command, $this->session);
    }

    public function download(FetchTarget $target, string $section, int $chunkSize = 8192): \Generator
    {
        if ($this->session === null || $this->executor === null) {
            throw new ImapException('IMAP client is not connected.');
        }

        return $this->executor->download($target, $section, $chunkSize, $this->session);
    }

    public function session(): SessionContext
    {
        if ($this->session === null) {
            throw new ImapException('IMAP client is not connected.');
        }

        return $this->session;
    }
}