<?php

declare(strict_types=1);

/**
 * SPDX-FileCopyrightText: Sebastian Krupinski <krupinski01@gmail.com>
 * SPDX-License-Identifier: AGPL-3.0-or-later
 */

namespace KTXM\ProviderImap\Smtp;

use KTXM\ProviderImap\Smtp\Protocol\Response\Response;

/**
 * Parsed EHLO capabilities.
 *
 * The first line of an EHLO reply is the server greeting/domain; every
 * subsequent line is a capability keyword optionally followed by parameters
 * (e.g. "AUTH PLAIN LOGIN", "SIZE 35882577").
 */
final class SmtpCapabilities
{
    /**
     * @param array<string,list<string>> $keywords capability keyword => parameters
     */
    private function __construct(
        private readonly array $keywords,
    ) {}

    public static function fromEhlo(Response $reply): self
    {
        $keywords = [];
        $lines = $reply->lines();

        // Skip the first line (greeting/domain); the rest are capabilities.
        foreach (array_slice($lines, 1) as $line) {
            $parts = preg_split('/\s+/', trim($line)) ?: [];
            $keyword = strtoupper((string) array_shift($parts));
            if ($keyword === '') {
                continue;
            }
            $keywords[$keyword] = array_map('strtoupper', $parts);
        }

        return new self($keywords);
    }

    public function has(string $keyword): bool
    {
        return isset($this->keywords[strtoupper($keyword)]);
    }

    public function supportsStartTls(): bool
    {
        return $this->has('STARTTLS');
    }

    /**
     * @return list<string> Advertised AUTH mechanisms (uppercased).
     */
    public function authMechanisms(): array
    {
        return $this->keywords['AUTH'] ?? [];
    }

    public function maxSize(): ?int
    {
        $size = $this->keywords['SIZE'][0] ?? null;

        return $size !== null && ctype_digit($size) ? (int) $size : null;
    }
}