<?php

declare(strict_types=1);

require_once __DIR__ . '/app/database.php';
require_once __DIR__ . '/app/billing.php';
require_once __DIR__ . '/app/audit.php';
require_once __DIR__ . '/app/dolibarr.php';

// Kein app_require_csrf()/saas_require_login(): Stripe ruft diesen
// Endpunkt unauthentifiziert von aussen auf. Die Echtheit wird
// ausschliesslich ueber die Signaturpruefung sichergestellt.

if ($_SERVER['REQUEST_METHOD'] !== 'POST') {
    http_response_code(405);
    exit('Nur POST erlaubt.');
}

$payload = file_get_contents('php://input') ?: '';
$signatureHeader = $_SERVER['HTTP_STRIPE_SIGNATURE'] ?? '';

if ($signatureHeader === '' || !stripe_verify_webhook_signature($payload, $signatureHeader, stripe_webhook_secret())) {
    http_response_code(400);
    exit('Ungültige Signatur.');
}

$event = stripe_parse_event($payload);
if ($event === null) {
    http_response_code(400);
    exit('Ungültiges Ereignis.');
}

$pdo = app_db_pdo();
$object = $event['data'];

// Idempotenz: bereits verarbeitete Events (Stripe-Retry bei Timeout) werden
// mit 200 bestaetigt, aber nicht erneut gebucht - verhindert u. a. doppelte
// Dolibarr-Rechnungen bei wiederholtem invoice.paid.
if (billing_webhook_event_seen($pdo, $event['id'], $event['type'])) {
    http_response_code(200);
    echo 'ok (bereits verarbeitet)';
    exit;
}

switch ($event['type']) {
    case 'checkout.session.completed':
        $tenantId = isset($object['metadata']['tenant_id']) ? (int)$object['metadata']['tenant_id'] : null;
        $planCode = (string)($object['metadata']['plan_code'] ?? '');
        $knownPlans = billing_plans();
        if ($tenantId !== null && isset($object['customer'], $object['subscription']) && isset($knownPlans[$planCode])) {
            billing_update($pdo, $tenantId, [
                'plan_code' => $planCode,
                'subscription_status' => 'active',
                'stripe_customer_id' => (string)$object['customer'],
                'stripe_subscription_id' => (string)$object['subscription'],
            ]);
            app_audit_log($pdo, $tenantId, null, 'billing.subscription_started', 'tenant', $tenantId, ['plan_code' => $planCode]);
        }
        break;

    case 'customer.subscription.updated':
        $tenantId = isset($object['metadata']['tenant_id']) ? (int)$object['metadata']['tenant_id'] : null;
        $tenantId ??= billing_find_tenant_id_by_stripe_subscription($pdo, (string)($object['id'] ?? ''));
        if ($tenantId !== null) {
            $status = (string)($object['status'] ?? 'active');
            $periodEnd = isset($object['current_period_end'])
                ? date('Y-m-d H:i:s', (int)$object['current_period_end'])
                : null;
            $updateFields = [
                'subscription_status' => $status,
                'current_period_end' => $periodEnd,
            ];

            // Tarifwechsel aus dem Stripe-Kundenportal lokal nachziehen: der
            // aktuelle Preis steckt am Subscription-Item, per lookup_key wieder
            // auf unseren Plan-Code abbildbar. Nur bei aktiver Subscription und
            // eindeutiger Zuordnung, sonst bleibt der bisherige Plan bestehen.
            $lookupKey = (string)($object['items']['data'][0]['price']['lookup_key'] ?? '');
            $mappedPlan = billing_plan_code_by_lookup_key($lookupKey);
            if ($mappedPlan !== null && in_array($status, ['active', 'trialing', 'past_due'], true)) {
                $updateFields['plan_code'] = $mappedPlan;
            }

            billing_update($pdo, $tenantId, $updateFields);
            app_audit_log($pdo, $tenantId, null, 'billing.subscription_updated', 'tenant', $tenantId, [
                'status' => $status,
                'plan_code' => $updateFields['plan_code'] ?? null,
            ]);
        }
        break;

    case 'customer.subscription.deleted':
        $tenantId = isset($object['metadata']['tenant_id']) ? (int)$object['metadata']['tenant_id'] : null;
        $tenantId ??= billing_find_tenant_id_by_stripe_subscription($pdo, (string)($object['id'] ?? ''));
        if ($tenantId !== null) {
            billing_update($pdo, $tenantId, [
                'plan_code' => 'free',
                'subscription_status' => 'canceled',
            ]);
            app_audit_log($pdo, $tenantId, null, 'billing.subscription_canceled', 'tenant', $tenantId);
        }
        break;

    case 'invoice.payment_failed':
        $tenantId = billing_find_tenant_id_by_stripe_customer($pdo, (string)($object['customer'] ?? ''));
        if ($tenantId !== null) {
            billing_update($pdo, $tenantId, ['subscription_status' => 'past_due']);
            app_audit_log($pdo, $tenantId, null, 'billing.payment_failed', 'tenant', $tenantId);
        }
        break;

    case 'invoice.paid':
        $tenantId = billing_find_tenant_id_by_stripe_customer($pdo, (string)($object['customer'] ?? ''));
        if ($tenantId !== null) {
            $amountPaidCents = (int)($object['amount_paid'] ?? 0);
            app_audit_log($pdo, $tenantId, null, 'billing.invoice_paid', 'tenant', $tenantId, [
                'amount_paid_cents' => $amountPaidCents,
            ]);

            if ($amountPaidCents > 0) {
                $billing = billing_fetch_or_init($pdo, $tenantId);
                try {
                    $sync = dolibarr_sync_invoice_paid($pdo, $tenantId, (string)$billing['plan_code'], $amountPaidCents);
                } catch (Throwable $e) {
                    $sync = ['ok' => false, 'invoice_id' => null, 'ref' => null, 'error' => $e->getMessage()];
                }

                if ($sync['ok']) {
                    app_audit_log($pdo, $tenantId, null, 'billing.dolibarr_invoice_created', 'tenant', $tenantId, [
                        'dolibarr_invoice_id' => $sync['invoice_id'],
                        'dolibarr_ref' => $sync['ref'],
                    ]);
                } else {
                    // Wird bewusst nicht als Fehler an Stripe zurueckgegeben (kein Retry
                    // ausgeloest) - Stripe hat das Geld bereits erfolgreich eingezogen,
                    // das ist unabhaengig vom Dolibarr-Spiegel. Fehler landet im Audit-
                    // Log fuer manuelle Nachbearbeitung.
                    app_audit_log($pdo, $tenantId, null, 'billing.dolibarr_invoice_failed', 'tenant', $tenantId, [
                        'error' => $sync['error'],
                    ]);
                }
            }
        }
        break;

    default:
        // Unbehandelte Ereignistypen werden bewusst ignoriert, aber mit 200
        // bestaetigt, damit Stripe sie nicht wiederholt zustellt.
        break;
}

http_response_code(200);
echo 'ok';