<?php

declare(strict_types=1);

namespace Abovault\Gateway\Stripe;

use Abovault\Dunning\RetryPolicy;
use Abovault\Model\Subscription;

defined('ABSPATH') || exit;

// Data-access on the plugin's own custom tables (internal identifiers only; values are
// prepared). Direct queries + no object cache are inherent to live subscription state.
// phpcs:disable WordPress.DB.DirectDatabaseQuery.DirectQuery, WordPress.DB.DirectDatabaseQuery.NoCaching, WordPress.DB.PreparedSQL.NotPrepared, WordPress.DB.PreparedSQL.InterpolatedNotPrepared, WordPress.DB.DirectDatabaseQuery.SchemaChange, PluginCheck.Security.DirectDB.UnescapedDBParameter, WordPress.NamingConventions.PrefixAllGlobals.NonPrefixedVariableFound

/**
 * Stripe webhook receiver — the source of truth for ASYNCHRONOUS SEPA outcomes.
 *
 * Endpoint: POST /wp-json/abovault/v1/stripe-webhook
 * Verifies the Stripe-Signature header (HMAC-SHA256, timestamp tolerance) against
 * the configured webhook secret, then drives the dunning state machine:
 *
 *   payment_intent.succeeded       → RetryPolicy::resolveSuccess  (advance period)
 *   payment_intent.payment_failed  → RetryPolicy::resolveFailure  (past_due + dunning)
 *   setup_intent.succeeded         → capture PaymentMethod onto the subscription mandate
 */
final class WebhookHandler
{
    private const TOLERANCE = 300; // seconds

    public function register(): void
    {
        add_action('rest_api_init', function (): void {
            register_rest_route('abovault/v1', '/stripe-webhook', [
                'methods'             => 'POST',
                'callback'            => [$this, 'handle'],
                'permission_callback' => '__return_true', // auth = signature verification
            ]);
        });
    }

    public function handle(\WP_REST_Request $request): \WP_REST_Response
    {
        $payload = $request->get_body();
        $sigHeader = (string) $request->get_header('stripe_signature');
        $secret = $this->webhookSecret();

        if ($secret === '' || !$this->verify($payload, $sigHeader, $secret)) {
            return new \WP_REST_Response(['error' => 'invalid-signature'], 400);
        }

        $event = json_decode($payload, true);
        if (!is_array($event) || !isset($event['type'])) {
            return new \WP_REST_Response(['error' => 'bad-payload'], 400);
        }

        $object = $event['data']['object'] ?? [];
        switch ($event['type']) {
            case 'payment_intent.succeeded':
                if ($id = $this->subIdFrom($object)) {
                    RetryPolicy::resolveSuccess($id);
                }
                break;

            case 'payment_intent.payment_failed':
                if ($id = $this->subIdFrom($object)) {
                    $reason = (string) ($object['last_payment_error']['message'] ?? 'sepa-failed');
                    RetryPolicy::resolveFailure($id, $reason);
                }
                break;

            case 'setup_intent.succeeded':
                $this->captureMandate($object);
                break;

            // charge.refunded / charge.dispute.created: TODO(build) — reconciliation.
        }

        return new \WP_REST_Response(['received' => true], 200);
    }

    /** @param array<string,mixed> $object */
    private function subIdFrom(array $object): int
    {
        return (int) ($object['metadata']['abovault_subscription_id'] ?? 0);
    }

    /**
     * setup_intent.succeeded → attach "cus|pm" onto every subscription of the order
     * so renewals can charge. Mandate is per-order (one SetupIntent covers all its subs).
     * @param array<string,mixed> $si
     */
    private function captureMandate(array $si): void
    {
        global $wpdb;
        $orderId  = (int) ($si['metadata']['abovault_order_id'] ?? 0);
        $customer = (string) ($si['customer'] ?? '');
        $pm       = (string) ($si['payment_method'] ?? '');
        if ($orderId <= 0 || $customer === '' || $pm === '') {
            return;
        }
        // Attach the mandate without touching status (a trial must stay trialing).
        $wpdb->query($wpdb->prepare(
            'UPDATE ' . Subscription::table()
            . " SET gateway = 'stripe_sepa', gateway_ref = %s WHERE order_id = %d",
            $customer . '|' . $pm,
            $orderId
        ));
        do_action('abovault_mandate_captured', $orderId, $customer . '|' . $pm);
    }

    /** Constant-time Stripe signature verification. */
    private function verify(string $payload, string $sigHeader, string $secret): bool
    {
        $parts = [];
        foreach (explode(',', $sigHeader) as $kv) {
            [$k, $v] = array_pad(explode('=', $kv, 2), 2, '');
            $parts[$k] = $v;
        }
        $t = $parts['t'] ?? '';
        $v1 = $parts['v1'] ?? '';
        if ($t === '' || $v1 === '') {
            return false;
        }
        if (abs(time() - (int) $t) > self::TOLERANCE) {
            return false;
        }
        $expected = hash_hmac('sha256', $t . '.' . $payload, $secret);
        return hash_equals($expected, $v1);
    }

    private function webhookSecret(): string
    {
        $settings = get_option('woocommerce_abovault_sepa_settings', []);
        return is_array($settings) ? (string) ($settings['webhook_secret'] ?? '') : '';
    }
}