<?php

namespace App\Services;

use App\Models\Ticket;
use App\Models\User;
use App\Support\Imap\InboundEmail;
use App\Support\Settings;

/**
 * Pure decision logic for the IMAP fetcher — no IMAP connection, no
 * side effects, so it's fully Pest-testable against hand-built
 * InboundEmail instances. ImapMailboxFetcher does all the I/O and calls
 * into this for every decision.
 */
class ImapMessageClassifier
{
    /**
     * RFC 3834 (Auto-Submitted) + common vendor headers, plus EN/PL subject
     * phrasing for autoresponders/bounces that don't set those headers at
     * all — the two layers catch most real-world autoresponders/mailer-daemons.
     */
    private const AUTO_REPLY_SUBJECT_PATTERNS = [
        '/\bout of office\b/i',
        '/\bautomatic reply\b/i',
        '/\bautomatyczna odpowiedz\b/iu',
        '/\bautoresponder\b/i',
        '/\bundeliverable\b/i',
        '/\bundelivered\b/i',
        '/\bmail delivery failed\b/i',
        '/\bdelivery status notification\b/i',
        '/\bnieobecnosc\b.*\bbiurze\b/iu',
    ];

    /**
     * Returns a human-readable rejection reason, or null if the message
     * should be processed as a genuine ticket/reply.
     *
     * @param  string[]  $extraBlocklist  additional blocked sender local-parts/addresses (per-mailbox)
     */
    public function rejectionReason(InboundEmail $email, array $extraBlocklist = []): ?string
    {
        $autoSubmitted = strtolower((string) $email->header('auto-submitted'));
        if ($autoSubmitted !== '' && $autoSubmitted !== 'no') {
            return "Auto-Submitted: {$autoSubmitted}";
        }

        if ($email->header('x-autoreply') !== null || $email->header('x-autorespond') !== null) {
            return 'X-Autoreply/X-Autorespond header present';
        }

        $precedence = strtolower((string) $email->header('precedence'));
        if (in_array($precedence, ['bulk', 'junk', 'list'], true)) {
            return "Precedence: {$precedence}";
        }

        $senderLocalPart = strtolower(explode('@', $email->fromEmail)[0] ?? '');
        $blocked = array_map('strtolower', $extraBlocklist);
        if ($senderLocalPart !== '' && in_array($senderLocalPart, $blocked, true)) {
            return "Blocked sender: {$email->fromEmail}";
        }
        if (in_array(strtolower($email->fromEmail), $blocked, true)) {
            return "Blocked sender: {$email->fromEmail}";
        }

        foreach (self::AUTO_REPLY_SUBJECT_PATTERNS as $pattern) {
            if (preg_match($pattern, $email->subject) === 1) {
                return "Subject matched auto-reply pattern ({$pattern})";
            }
        }

        return null;
    }

    /**
     * Same gate Landing::submit() applies to web/guest ticket creation
     * (Settings::bool('restrict_tickets_to_ldap')) — must apply identically
     * to mail-originated tickets/replies, or the restriction has a hole.
     */
    public function isSenderAllowed(string $email): bool
    {
        if (! Settings::bool('restrict_tickets_to_ldap')) {
            return true;
        }

        return User::query()->where('email', $email)->exists()
            || app(LdapUserProvisioner::class)->existsInLdap($email);
    }

    /**
     * Existing local user, or an LDAP-provisioned one if enabled — mirrors
     * TicketService::create()'s own guest-resolution branch. Returns null
     * for a genuine, unprovisionable guest.
     */
    public function resolveSender(string $email): ?User
    {
        if ($user = User::query()->where('email', $email)->first()) {
            return $user;
        }

        if (Settings::bool('ldap_auto_provision_guests')) {
            return app(LdapUserProvisioner::class)->findOrCreateByEmail($email);
        }

        return null;
    }

    /**
     * Strips common reply/forward prefixes, then tries every digit run of
     * length >= 4 (longest first) against Ticket::resolveRouteBinding() —
     * covers both the plain sequential number and the obfuscated checksum,
     * since both are plain digit strings and every outbound notification
     * subject already carries one (see database/seeders/DatabaseSeeder.php).
     * Prefix-aware matching was considered and rejected: {numer} email
     * templates hardcode their own literal '#', independent of the
     * admin-configurable ticket_number_prefix setting, and templates are
     * themselves admin-editable.
     */
    public function matchTicket(string $subject): ?Ticket
    {
        $cleaned = preg_replace('/^\s*(re|odp|fwd|fw|aw)\s*:\s*/i', '', $subject) ?? $subject;
        $cleaned = preg_replace('/^\s*(re|odp|fwd|fw|aw)\s*:\s*/i', '', $cleaned) ?? $cleaned;

        preg_match_all('/\d{4,}/', $cleaned, $matches);
        $tokens = $matches[0] ?? [];
        usort($tokens, fn ($a, $b) => strlen($b) <=> strlen($a));

        foreach ($tokens as $token) {
            $ticket = (new Ticket)->resolveRouteBinding($token);
            if ($ticket) {
                return $ticket;
            }
        }

        return null;
    }
}