<?php

declare(strict_types=1);

require_once __DIR__ . '/legal.php';
require_once __DIR__ . '/saas-mail.php';
require_once __DIR__ . '/rate-limit.php';
require_once __DIR__ . '/billing.php';

/** @return list<string> */
function app_validate_legal_request(array $input, string $requestType): array
{
    $errors = [];
    $name = trim((string)($input['requester_name'] ?? ''));
    $email = trim((string)($input['requester_email'] ?? ''));
    $reference = trim((string)($input['contract_reference'] ?? ''));
    if (strlen($name) < 2 || strlen($name) > 255) {
        $errors[] = 'Bitte gib deinen vollständigen Namen an.';
    }
    if (!filter_var($email, FILTER_VALIDATE_EMAIL)) {
        $errors[] = 'Bitte gib eine gültige E-Mail-Adresse für die Bestätigung an.';
    }
    if (!preg_match('/^[a-z0-9][a-z0-9-]{1,98}[a-z0-9]$/', strtolower($reference))) {
        $errors[] = 'Bitte gib das Kundenkürzel aus deinem Konto an.';
    }

    if ($requestType === 'cancellation') {
        $kind = (string)($input['cancellation_kind'] ?? '');
        if (!in_array($kind, ['ordinary', 'extraordinary'], true)) {
            $errors[] = 'Bitte wähle die Art der Kündigung.';
        }
        if ($kind === 'extraordinary' && trim((string)($input['request_reason'] ?? '')) === '') {
            $errors[] = 'Bitte nenne bei einer außerordentlichen Kündigung den Kündigungsgrund.';
        }
        $requestedEnd = (string)($input['requested_end'] ?? '');
        if ($requestedEnd !== 'earliest') {
            $date = DateTimeImmutable::createFromFormat('!Y-m-d', $requestedEnd);
            if ($date === false || $date->format('Y-m-d') !== $requestedEnd) {
                $errors[] = 'Bitte wähle „frühestmöglich“ oder ein gültiges Beendigungsdatum.';
            }
        }
    }

    if (strlen((string)($input['request_reason'] ?? '')) > 5000) {
        $errors[] = 'Der Grund ist zu lang (höchstens 5.000 Zeichen).';
    }

    return $errors;
}

function app_update_legal_request(PDO $pdo, string $referenceCode, string $status, array $metadata = []): void
{
    $stmt = $pdo->prepare(
        'UPDATE legal_requests SET status = ?, metadata_json = ?, processed_at = NOW() WHERE reference_code = ?'
    );
    $stmt->execute([
        $status,
        $metadata !== [] ? json_encode($metadata, JSON_UNESCAPED_UNICODE | JSON_UNESCAPED_SLASHES) : null,
        $referenceCode,
    ]);
}

/**
 * Ordentliche Kündigungen eines eindeutig zugeordneten Stripe-Abos werden
 * sofort zum Periodenende vorgemerkt. Alle anderen Erklärungen bleiben als
 * fristwahrender Eingang in der DB und werden manuell bearbeitet.
 *
 * @return array{status: string, effective_end: string, processing_note: string}
 */
function app_process_cancellation_request(PDO $pdo, array $stored, array $input): array
{
    $effectiveEnd = (string)$input['requested_end'] === 'earliest'
        ? 'zum frühestmöglichen Zeitpunkt'
        : (string)$input['requested_end'];
    $manual = [
        'status' => 'received_manual',
        'effective_end' => $effectiveEnd,
        'processing_note' => 'Die Erklärung ist eingegangen und wird anhand der Vertragsdaten bearbeitet.',
    ];

    if ($stored['tenant_id'] === null
        || (string)$input['cancellation_kind'] !== 'ordinary'
        || (string)$input['requested_end'] !== 'earliest'
    ) {
        app_update_legal_request($pdo, (string)$stored['reference_code'], 'received_manual', [
            'cancellation_kind' => (string)$input['cancellation_kind'],
        ]);
        return $manual;
    }

    $billing = billing_fetch_or_init($pdo, (int)$stored['tenant_id']);
    if (empty($billing['stripe_subscription_id'])) {
        if ((string)$billing['plan_code'] === 'free') {
            $pdo->prepare('UPDATE tenants SET termination_requested_at = NOW(), contract_ends_at = NOW() WHERE id = ?')
                ->execute([(int)$stored['tenant_id']]);
            $effectiveEnd = date('d.m.Y, H:i') . ' Uhr';
            app_update_legal_request($pdo, (string)$stored['reference_code'], 'contract_ended', [
                'cancellation_kind' => (string)$input['cancellation_kind'],
                'effective_end' => $effectiveEnd,
            ]);
            return [
                'status' => 'contract_ended',
                'effective_end' => $effectiveEnd,
                'processing_note' => 'Der kostenlose Vertrag ist beendet. Die Anmeldung ist nicht mehr möglich; operative Mandantendaten werden nach 30 Tagen gelöscht.',
            ];
        }
        app_update_legal_request($pdo, (string)$stored['reference_code'], 'received_manual', [
            'cancellation_kind' => (string)$input['cancellation_kind'],
        ]);
        return $manual;
    }

    try {
        $result = stripe_schedule_subscription_cancellation((string)$billing['stripe_subscription_id']);
    } catch (Throwable $e) {
        $result = ['ok' => false, 'current_period_end' => null, 'error' => $e->getMessage()];
    }
    if (!$result['ok']) {
        app_update_legal_request($pdo, (string)$stored['reference_code'], 'received_manual', [
            'cancellation_kind' => (string)$input['cancellation_kind'],
            'stripe_error' => (string)$result['error'],
        ]);
        return $manual;
    }

    billing_update($pdo, (int)$stored['tenant_id'], [
        'subscription_status' => 'canceling',
        'current_period_end' => $result['current_period_end'],
    ]);
    if ($result['current_period_end'] !== null) {
        $pdo->prepare('UPDATE tenants SET termination_requested_at = NOW(), contract_ends_at = ? WHERE id = ?')
            ->execute([$result['current_period_end'], (int)$stored['tenant_id']]);
    }
    $effectiveEnd = $result['current_period_end'] !== null
        ? date('d.m.Y, H:i', strtotime((string)$result['current_period_end'])) . ' Uhr'
        : 'zum Ende der laufenden Abrechnungsperiode';
    app_update_legal_request($pdo, (string)$stored['reference_code'], 'cancellation_scheduled', [
        'cancellation_kind' => (string)$input['cancellation_kind'],
        'effective_end' => $effectiveEnd,
    ]);

    return [
        'status' => 'cancellation_scheduled',
        'effective_end' => $effectiveEnd,
        'processing_note' => 'Das kostenpflichtige Abonnement wurde bei Stripe zum Ende der laufenden Abrechnungsperiode vorgemerkt.',
    ];
}

/**
 * @return array{status: string, effective_end: string, processing_note: string}
 */
function app_process_withdrawal_request(PDO $pdo, array $stored): array
{
    $manual = [
        'status' => 'received_manual',
        'effective_end' => 'mit Eingang des Widerrufs, sofern das Widerrufsrecht besteht',
        'processing_note' => 'Der Widerruf ist eingegangen und wird unverzüglich anhand der Vertragsdaten geprüft.',
    ];
    if ($stored['tenant_id'] === null) {
        app_update_legal_request($pdo, (string)$stored['reference_code'], 'received_manual');
        return $manual;
    }

    $stmt = $pdo->prepare('SELECT customer_type, created_at FROM tenants WHERE id = ?');
    $stmt->execute([(int)$stored['tenant_id']]);
    $tenant = $stmt->fetch();
    if ($tenant === false) {
        app_update_legal_request($pdo, (string)$stored['reference_code'], 'received_manual');
        return $manual;
    }

    $billing = billing_fetch_or_init($pdo, (int)$stored['tenant_id']);
    if ((string)$billing['plan_code'] === 'free') {
        $stmt = $pdo->prepare(
            "SELECT accepted_at, metadata_json FROM legal_acceptances
             WHERE tenant_id = ? AND document_type = 'terms' AND context = 'registration'
             ORDER BY accepted_at ASC LIMIT 1"
        );
        $stmt->execute([(int)$stored['tenant_id']]);
        $contractEvidence = $stmt->fetch();
        $contractStart = $contractEvidence !== false
            ? strtotime((string)$contractEvidence['accepted_at'])
            : strtotime((string)$tenant['created_at']);
    } else {
        $stmt = $pdo->prepare(
            "SELECT accepted_at, metadata_json FROM legal_acceptances
             WHERE tenant_id = ? AND document_type = 'withdrawal_information' AND context = 'paid_order'
             ORDER BY accepted_at DESC LIMIT 1"
        );
        $stmt->execute([(int)$stored['tenant_id']]);
        $contractEvidence = $stmt->fetch();
        $contractStart = $contractEvidence !== false ? strtotime((string)$contractEvidence['accepted_at']) : false;
    }
    $contractMetadata = $contractEvidence !== false
        ? json_decode((string)($contractEvidence['metadata_json'] ?? ''), true)
        : null;
    $contractCustomerType = is_array($contractMetadata)
        ? (string)($contractMetadata['customer_type'] ?? $tenant['customer_type'])
        : (string)$tenant['customer_type'];
    if ($contractCustomerType !== 'consumer') {
        app_update_legal_request($pdo, (string)$stored['reference_code'], 'received_manual', [
            'review_reason' => 'contract_not_recorded_as_consumer',
        ]);
        return $manual;
    }
    if ($contractStart === false || $contractStart < strtotime('-14 days')) {
        app_update_legal_request($pdo, (string)$stored['reference_code'], 'received_manual', [
            'review_reason' => 'automatic_14_day_window_not_proven',
        ]);
        return $manual;
    }

    $stripeError = null;
    if (!empty($billing['stripe_subscription_id'])) {
        try {
            $cancel = stripe_cancel_subscription((string)$billing['stripe_subscription_id']);
            if (!$cancel['ok']) {
                $stripeError = (string)$cancel['error'];
            }
        } catch (Throwable $e) {
            $stripeError = $e->getMessage();
        }
    }

    $pdo->prepare('UPDATE tenants SET termination_requested_at = NOW(), contract_ends_at = NOW() WHERE id = ?')
        ->execute([(int)$stored['tenant_id']]);
    if ($stripeError === null && !empty($billing['stripe_subscription_id'])) {
        billing_update($pdo, (int)$stored['tenant_id'], [
            'plan_code' => 'free',
            'subscription_status' => 'canceled',
        ]);
    }

    $status = $stripeError === null ? 'withdrawal_effective' : 'withdrawal_action_required';
    $effectiveEnd = date('d.m.Y, H:i') . ' Uhr';
    app_update_legal_request($pdo, (string)$stored['reference_code'], $status, [
        'effective_end' => $effectiveEnd,
        'stripe_error' => $stripeError,
        'refund_review_required' => (string)$billing['plan_code'] !== 'free',
    ]);

    return [
        'status' => $status,
        'effective_end' => $effectiveEnd,
        'processing_note' => $stripeError === null
            ? 'Der Vertrag wurde beendet. Eine gegebenenfalls geschuldete Rückzahlung wird unverzüglich über das ursprüngliche Zahlungsmittel bearbeitet.'
            : 'Der Vertrag wurde lokal beendet. Die Beendigung beim Zahlungsdienst und eine gegebenenfalls geschuldete Rückzahlung müssen noch manuell abgeschlossen werden.',
    ];
}

function app_legal_request_confirmation_text(array $input, array $stored, array $processing): string
{
    $isCancellation = (string)$input['request_type'] === 'cancellation';
    $type = $isCancellation ? 'Kündigung' : 'Widerruf';
    $lines = [
        "Eingangsbestätigung {$type} – Kaffeeliste",
        '',
        'Referenz: ' . $stored['reference_code'],
        'Eingang: ' . $stored['received_at'] . ' (Europe/Berlin)',
        'Name: ' . $input['requester_name'],
        'Bestätigungs-E-Mail: ' . $input['requester_email'],
        'Kundenkürzel / Vertragsreferenz: ' . $input['contract_reference'],
    ];
    if ($isCancellation) {
        $lines[] = 'Art: ' . ((string)$input['cancellation_kind'] === 'extraordinary' ? 'außerordentliche Kündigung' : 'ordentliche Kündigung');
        $lines[] = 'Beendigung: ' . $processing['effective_end'];
    }
    if (trim((string)($input['request_reason'] ?? '')) !== '') {
        $lines[] = 'Erklärung / Grund: ' . trim((string)$input['request_reason']);
    }
    $lines[] = '';
    $lines[] = $processing['processing_note'];
    $lines[] = '';
    $lines[] = 'Clemens Creutzburg, CTB-IT';
    $lines[] = 'In den Sieben Stücken 9d, 30655 Hannover';
    $lines[] = app_legal_email();

    return implode("\n", $lines);
}

function app_send_legal_request_confirmations(array $input, array $stored, array $processing): array
{
    $text = app_legal_request_confirmation_text($input, $stored, $processing);
    $downloadUrl = saas_app_url('rechtserklaerung-bestaetigung.php?token=' . urlencode((string)$stored['access_token']) . '&download=1');
    $type = (string)$input['request_type'] === 'cancellation' ? 'Kündigung' : 'Widerruf';
    $customerResult = saas_send_mail(
        (string)$input['requester_email'],
        "Kaffeeliste: Eingang {$type} " . $stored['reference_code'],
        $text . "\n\nBestätigung als Textdatei speichern:\n" . $downloadUrl
    );
    $operatorResult = saas_send_mail(
        app_legal_email(),
        "Kaffeeliste: {$type} eingegangen " . $stored['reference_code'],
        $text . "\n\nInterner Status: " . $processing['status']
    );

    return [
        'customer_ok' => (bool)($customerResult['ok'] ?? false),
        'operator_ok' => (bool)($operatorResult['ok'] ?? false),
    ];
}