<?php
namespace SendMails;

defined('ABSPATH') || exit;

/**
 * Warnungen per Mail an den Admin der Website, bevor Kunden etwas merken: Kontingent bei 80 und 100 %,
 * Bounce- oder Beschwerdequote nahe der Sperrgrenze, gesperrtes Konto, Mails, die in der Warteschlange
 * haengen oder aufgegeben wurden, angehaltene Quellen (Bremse) und eine nicht verifizierte Absenderdomain.
 * Jede Warnung kommt hoechstens einmal je Abstand (Kontingent einmal je Monat und Stufe). Dazu montags
 * ein kurzer Wochenbericht. Laeuft mit jedem Abgleich (alle 15 Minuten) und sofort, wenn die Bremse greift.
 */
final class Waechter
{
    public const GEMELDET = 'sendmails_warnungen';
    public const WOCHE = 'sendmails_wochenbericht';
    private const WARTESCHLANGE_S = 30 * MINUTE_IN_SECONDS;

    public static function empfaenger(): string
    {
        $an = sanitize_email((string) Einstellungen::wert('warn_email'));
        return is_email($an) ? $an : (string) get_option('admin_email');
    }

    public static function pruefen(): void
    {
        self::bremseAufraeumen();
        if (!Einstellungen::versandAktiv() && Einstellungen::apiSchluessel() === '') {
            return;
        }
        if (Einstellungen::wert('warnungen')) {
            foreach (self::warnungen() as [$schluessel, $abstand, $betreff, $text]) {
                self::melden($schluessel, $abstand, $betreff, $text);
            }
        }
        if (Einstellungen::wert('wochenbericht')) {
            self::wochenbericht();
        }
    }

    /** @return array<int, array{0: string, 1: int, 2: string, 3: string}> Schluessel, Abstand in Sekunden, Betreff, Text */
    public static function warnungen(): array
    {
        $w = [];
        $portal = 'https://portal.send-mails.de/#/kunde/konto';
        $wahl = Admin\Seite::einstellungenUrl() . '#kontingent';
        foreach (Bremse::angehalten() as $b) {
            $name = Protokoll::name($b['quelle']);
            $w[] = ['bremse:' . $b['quelle'], 6 * HOUR_IN_SECONDS,
                /* translators: %s: plugin or theme name */
                sprintf(__('send-mails.de: emails from %s held', 'purehost-send-mails'), $name),
                sprintf(
                    /* translators: 1: plugin name, 2: emails in the last hour, 3: usual maximum, 4: held emails, 5: link */
                    __("%1\$s sent %2\$d emails within one hour, usually at most %3\$d. This often means that bots are abusing a form. To protect your domain and your quota, the plugin holds further emails from this source.\n\n%4\$d emails are waiting for your decision: send them, discard them or trust this source from now on.\n\n%5\$s", 'purehost-send-mails'),
                    $name, (int) ($b['stunde'] ?? 0), (int) ($b['grenze'] ?? 0), (int) $b['mails'], Admin\Seite::url()
                )];
        }
        $k = Einstellungen::apiSchluessel() !== '' ? Api::kontingentGespeichert() : null;
        if ($k && $k['ok']) {
            $d = $k['daten'];
            if (($d['status'] ?? 'aktiv') !== 'aktiv' || !empty($d['missbrauch_gesperrt'])) {
                $w[] = ['konto_gesperrt', DAY_IN_SECONDS, __('send-mails.de: your account is suspended', 'purehost-send-mails'),
                    /* translators: %s: link */
                    sprintf(__("send-mails.de does not accept emails from this website at the moment because the account is suspended. Details are in the customer portal:\n\n%s", 'purehost-send-mails'), $portal)];
            }
            $p = (int) ($d['prozent'] ?? 0);
            $verhalten = (string) ($d['verhalten_wirksam'] ?? 'sperren');
            $folge = match ($verhalten) {
                'drosseln'      => __('When the quota is used up, emails continue at a reduced pace and the overage is charged up to your cost cap.', 'purehost-send-mails'),
                'nachberechnen' => __('When the quota is used up, emails continue normally and the overage is charged up to your cost cap.', 'purehost-send-mails'),
                default         => __('When the quota is used up, send-mails.de accepts no more emails until the end of the month.', 'purehost-send-mails'),
            };
            $monat = substr((string) ($d['monat'] ?? gmdate('Y-m')), 0, 7);
            if ($p >= 100) {
                $w[] = ['kontingent100:' . $monat, 40 * DAY_IN_SECONDS, __('send-mails.de: monthly quota used up', 'purehost-send-mails'),
                    /* translators: 1: used, 2: quota, 3: consequence, 4: link */
                    sprintf(__("This month %1\$s of %2\$s emails have been sent. %3\$s\n\nYou can choose what happens when the quota is used up in the plugin settings:\n\n%4\$s", 'purehost-send-mails'),
                        number_format_i18n((int) ($d['verbraucht'] ?? 0)), number_format_i18n((int) ($d['mails_pro_monat'] ?? 0)), $folge, $wahl)];
            } elseif ($p >= 80) {
                /* translators: %d: percent */
                $w[] = ['kontingent80:' . $monat, 40 * DAY_IN_SECONDS, sprintf(__('send-mails.de: %d %% of the monthly quota used', 'purehost-send-mails'), $p),
                    /* translators: 1: used, 2: quota, 3: consequence, 4: link */
                    sprintf(__("This month %1\$s of %2\$s emails have been sent. %3\$s\n\nYou can choose what happens when the quota is used up in the plugin settings:\n\n%4\$s", 'purehost-send-mails'),
                        number_format_i18n((int) ($d['verbraucht'] ?? 0)), number_format_i18n((int) ($d['mails_pro_monat'] ?? 0)), $folge, $wahl)];
            }
        }
        $st = Einstellungen::apiSchluessel() !== '' ? Api::statistik(false, '7t') : null;
        $q = $st && $st['ok'] ? (array) ($st['daten']['quoten'] ?? []) : [];
        $sperrliste = Admin\Statistik::url() . '#sperrliste';
        foreach (['bounce' => __('bounce rate', 'purehost-send-mails'), 'beschwerde' => __('complaint rate', 'purehost-send-mails')] as $feld => $name) {
            if (!empty($q[$feld . '_warnung']) && !empty($q['gewertet'])) {
                $w[] = ['quote_' . $feld, DAY_IN_SECONDS,
                    /* translators: %s: bounce rate or complaint rate */
                    sprintf(__('send-mails.de: %s close to the limit', 'purehost-send-mails'), $name),
                    sprintf(
                        /* translators: 1: bounce rate or complaint rate, 2: days, 3: current value, 4: limit, 5: link */
                        __("The %1\$s of the last %2\$d days is %3\$s, the limit is %4\$s. Above the limit, send-mails.de suspends sending to protect all customers. Check where the bounces come from and remove invalid addresses from your lists:\n\n%5\$s", 'purehost-send-mails'),
                        $name, (int) ($q['fenster_tage'] ?? 7), Admin\Ansicht::prozent((float) ($q[$feld] ?? 0)), Admin\Ansicht::prozent((float) ($q[$feld . '_grenze'] ?? 0)), $sperrliste
                    )];
            }
        }
        $wartet = self::aeltesteWartende();
        if ($wartet['anzahl'] > 0 && $wartet['erste'] > 0 && time() - $wartet['erste'] > self::WARTESCHLANGE_S) {
            $w[] = ['warteschlange', 6 * HOUR_IN_SECONDS, __('send-mails.de: emails are waiting in the queue', 'purehost-send-mails'),
                /* translators: 1: count, 2: last error, 3: link */
                sprintf(__("%1\$d emails could not be handed over to send-mails.de for more than 30 minutes. The plugin keeps retrying for up to 24 hours. Last error: %2\$s\n\n%3\$s", 'purehost-send-mails'),
                    $wartet['anzahl'], $wartet['fehler'] !== '' ? $wartet['fehler'] : '–', Admin\Seite::url())];
        }
        $aufgegeben = Warteschlange::anzahl('aufgegeben');
        if ($aufgegeben > 0) {
            $w[] = ['aufgegeben', DAY_IN_SECONDS, __('send-mails.de: emails could not be delivered', 'purehost-send-mails'),
                /* translators: 1: count, 2: link */
                sprintf(__("%1\$d emails could not be delivered even after 24 hours and were given up. Details and the recipients are on the overview page:\n\n%2\$s", 'purehost-send-mails'), $aufgegeben, Admin\Seite::url())];
        }
        $absender = strtolower((string) Einstellungen::wert('absender_email'));
        $verifiziert = Api::bekannteDomains();
        $domain = substr((string) strrchr($absender, '@'), 1);
        if (Einstellungen::versandAktiv() && $domain !== '' && $verifiziert !== null && !in_array($domain, $verifiziert, true)) {
            $w[] = ['domain:' . $domain, DAY_IN_SECONDS,
                /* translators: %s: domain */
                sprintf(__('send-mails.de: sender domain %s is not verified', 'purehost-send-mails'), $domain),
                /* translators: 1: domain, 2: link */
                sprintf(__("The sender domain %1\$s is currently not verified at send-mails.de, for example because a DNS entry was removed. Until it is verified again, emails with this sender are not accepted. Check the DNS entries in the customer portal:\n\n%2\$s", 'purehost-send-mails'), $domain, 'https://portal.send-mails.de/#/kunde/domains')];
        }
        return $w;
    }

    /** @return array{anzahl: int, erste: int, fehler: string} */
    private static function aeltesteWartende(): array
    {
        global $wpdb;
        $z = $wpdb->get_row($wpdb->prepare(
            "SELECT COUNT(*) AS anzahl, MIN(erstellt) AS erste, MAX(letzter_fehler) AS fehler FROM %i WHERE status = 'wartet'",
            Warteschlange::tabelle()
        ), ARRAY_A);
        return ['anzahl' => (int) ($z['anzahl'] ?? 0), 'erste' => !empty($z['erste']) ? (int) strtotime($z['erste'] . ' UTC') : 0, 'fehler' => (string) ($z['fehler'] ?? '')];
    }

    /** Warnung senden, wenn sie in den letzten $abstand Sekunden nicht schon kam. */
    public static function melden(string $schluessel, int $abstand, string $betreff, string $text): bool
    {
        $gemeldet = get_option(self::GEMELDET, []);
        $gemeldet = is_array($gemeldet) ? $gemeldet : [];
        if (time() - (int) ($gemeldet[$schluessel] ?? 0) < $abstand) {
            return false;
        }
        $gemeldet[$schluessel] = time();
        // Alte Schluessel (z. B. Kontingent vergangener Monate) nicht ewig mitschleppen
        $gemeldet = array_filter($gemeldet, static fn($t) => time() - (int) $t < 60 * DAY_IN_SECONDS);
        update_option(self::GEMELDET, $gemeldet, false);
        return self::senden($betreff, $text);
    }

    private static function senden(string $betreff, string $text): bool
    {
        $fuss = "\n\n-- \n" . sprintf(
            /* translators: 1: website address, 2: settings link */
            __("Sent by the send-mails.de plugin on %1\$s. Warnings and weekly report can be turned off in the settings:\n%2\$s", 'purehost-send-mails'),
            home_url(),
            Admin\Seite::einstellungenUrl()
        );
        return (bool) Protokoll::mitQuelle('sendmails', static fn() => wp_mail(self::empfaenger(), $betreff, $text . $fuss));
    }

    /** Montags ab 8 Uhr (Zeitzone der Website) einmal je Woche, nur wenn es in der Woche Mails gab. */
    public static function wochenbericht(bool $erzwingen = false): bool
    {
        $woche = wp_date('o-W');
        if (!$erzwingen && ((int) wp_date('N') !== 1 || (int) wp_date('G') < 8 || get_option(self::WOCHE) === $woche)) {
            return false;
        }
        $z = Protokoll::zahlen(7);
        if (!$erzwingen) {
            update_option(self::WOCHE, $woche, false);
        }
        if ($z['gesamt'] === 0 && !$erzwingen) {
            return false;
        }
        $zeilen = [
            /* translators: %s: count */
            sprintf(__('Emails sent: %s', 'purehost-send-mails'), number_format_i18n($z['gesamt'])),
            /* translators: %s: count */
            sprintf(__('Delivered: %s', 'purehost-send-mails'), number_format_i18n($z['zugestellt'])),
            /* translators: 1: hard bounces, 2: soft bounces */
            sprintf(__('Bounces: %1$s hard, %2$s soft', 'purehost-send-mails'), number_format_i18n($z['bounce_hart']), number_format_i18n($z['bounce_weich'])),
            /* translators: %s: count */
            sprintf(__('Complaints: %s', 'purehost-send-mails'), number_format_i18n($z['beschwerde'])),
            /* translators: %s: count */
            sprintf(__('Rejected or given up: %s', 'purehost-send-mails'), number_format_i18n($z['fehler'])),
        ];
        if ($z['angehalten'] > 0) {
            /* translators: %s: count */
            $zeilen[] = sprintf(__('Held (protection against mass sending): %s', 'purehost-send-mails'), number_format_i18n($z['angehalten']));
        }
        $quellen = '';
        foreach (array_slice($z['quellen'], 0, 5) as $q) {
            $quellen .= '- ' . Protokoll::name((string) $q['quelle']) . ': ' . number_format_i18n((int) $q['mails']) . "\n";
        }
        $k = Einstellungen::apiSchluessel() !== '' ? Api::kontingent() : null;
        $kontingent = '';
        if ($k && $k['ok']) {
            $kontingent = "\n" . sprintf(
                /* translators: 1: used, 2: quota, 3: percent */
                __('Quota this month: %1$s of %2$s emails (%3$d %%)', 'purehost-send-mails'),
                number_format_i18n((int) ($k['daten']['verbraucht'] ?? 0)),
                number_format_i18n((int) ($k['daten']['mails_pro_monat'] ?? 0)),
                (int) ($k['daten']['prozent'] ?? 0)
            ) . "\n";
        }
        $text = sprintf(
            /* translators: %s: website address */
            __('Emails of %s in the last 7 days:', 'purehost-send-mails'),
            home_url()
        ) . "\n\n" . implode("\n", $zeilen) . "\n" . $kontingent
            . ($quellen !== '' ? "\n" . __('Most emails came from:', 'purehost-send-mails') . "\n" . $quellen : '')
            . "\n" . __('Email log:', 'purehost-send-mails') . ' ' . Admin\Mailprotokoll::url() . "\n" . __('Statistics:', 'purehost-send-mails') . ' ' . Admin\Statistik::url();
        return self::senden(__('send-mails.de: weekly report', 'purehost-send-mails'), $text);
    }

    /** Zustand der Bremse ohne angehaltene Mails (verworfen, aufgeraeumt) und abgelaufene Freigaben entfernen. */
    private static function bremseAufraeumen(): void
    {
        Warteschlange::aufraeumen();
        $zustand = Bremse::zustand();
        if (!$zustand) {
            return;
        }
        $angehalten = Bremse::angehalten();
        $neu = array_filter($zustand, static fn($z, $q) => isset($angehalten[$q]) || (int) ($z['frei_bis'] ?? 0) > time(), ARRAY_FILTER_USE_BOTH);
        if ($neu !== $zustand) {
            update_option(Bremse::ZUSTAND, $neu, false);
        }
    }
}