<?php
declare(strict_types=1);

final class MessageClassifier
{
    /** @param array<string,string> $headers */
    public static function shouldSuppress(array $headers, string $sender): bool
    {
        $sender = strtolower(trim($sender));
        if ($sender === '' || str_starts_with($sender, 'mailer-daemon') || str_starts_with($sender, 'postmaster')) {
            return true;
        }
        $normalized = [];
        foreach ($headers as $key => $value) {
            $normalized[strtolower(trim($key))] = strtolower(trim($value));
        }
        if (($normalized['auto-submitted'] ?? 'no') !== 'no') {
            return true;
        }
        if (in_array($normalized['precedence'] ?? '', ['bulk', 'list', 'junk'], true)) {
            return true;
        }
        if (($normalized['list-id'] ?? '') !== '') {
            return true;
        }
        if (str_contains($normalized['content-type'] ?? '', 'delivery-status')) {
            return true;
        }
        return false;
    }
}