<?php

namespace App\Http\Controllers\Api;

use App\Http\Controllers\Controller;
use App\Models\LicenseWebhookEvent;
use App\Services\Licensing\LicenseDeliveryService;
use App\Services\Payments\LemonSqueezyWebhookVerifier;
use App\Services\Payments\PaddleWebhookVerifier;
use App\Services\Payments\PurchaseProvisioner;
use Illuminate\Http\JsonResponse;
use Illuminate\Http\Request;
use Illuminate\Support\Facades\DB;

final class PaymentWebhookController extends Controller
{
    public function __invoke(
        string $provider,
        Request $request,
        PurchaseProvisioner $provisioner,
        LicenseDeliveryService $delivery
    ): JsonResponse {
        $raw = (string) $request->getContent();

        $verifier = match ($provider) {
            'paddle' => app(PaddleWebhookVerifier::class),
            'lemon-squeezy' => app(LemonSqueezyWebhookVerifier::class),
            default => null,
        };

        if (! $verifier) {
            return response()->json([
                'message' => 'Unknown webhook provider.',
            ], 404);
        }

        try {
            $verifier->verify($request, $raw);
        } catch (\Throwable $e) {
            report($e);

            return response()->json([
                'message' => 'Invalid webhook signature.',
            ], 400);
        }

        try {
            $payload = json_decode(
                $raw,
                true,
                flags: JSON_THROW_ON_ERROR
            );
        } catch (\Throwable) {
            return response()->json([
                'message' => 'Invalid JSON.',
            ], 400);
        }

        $externalID = (string) (
        $provider === 'paddle'
            ? ($payload['event_id'] ?? '')
            : ($payload['meta']['event_name'] ?? '')
            .':'
            .($payload['data']['id'] ?? '')
        );

        $eventType = (string) (
        $provider === 'paddle'
            ? ($payload['event_type'] ?? 'unknown')
            : ($payload['meta']['event_name'] ?? 'unknown')
        );

        if ($externalID === '') {
            return response()->json([
                'message' => 'Webhook event has no stable identifier.',
            ], 400);
        }

        try {
            /*
             * Paddle can deliver several related webhook events at almost
             * exactly the same time.
             *
             * Laravel will automatically retry the entire transaction when
             * MySQL reports a deadlock / serialization failure.
             *
             * Five attempts gives short-lived webhook contention time to
             * resolve without weakening any database constraints.
             */
            DB::transaction(
                function () use (
                    $provider,
                    $externalID,
                    $eventType,
                    $payload,
                    $raw,
                    $provisioner
                ): void {
                    /*
                     * firstOrCreate protects against Paddle retrying the exact
                     * same event ID.
                     *
                     * lockForUpdate prevents two workers handling the same
                     * webhook event concurrently after the row exists.
                     */
                    LicenseWebhookEvent::firstOrCreate(
                        [
                            'provider' => $provider,
                            'external_event_id' => $externalID,
                        ],
                        [
                            'event_type' => $eventType,
                            'payload_sha256' => hash('sha256', $raw),
                            'payload' => $payload,
                        ]
                    );

                    $event = LicenseWebhookEvent::query()
                        ->where('provider', $provider)
                        ->where('external_event_id', $externalID)
                        ->lockForUpdate()
                        ->firstOrFail();

                    /*
                     * Already successfully processed.
                     *
                     * Returning here makes duplicate delivery of the exact
                     * same Paddle event idempotent.
                     */
                    if ($event->processed_at !== null) {
                        return;
                    }

                    /*
                     * An external event ID must never be reused with different
                     * content.
                     */
                    $incomingHash = hash('sha256', $raw);

                    if (! hash_equals(
                        (string) $event->payload_sha256,
                        $incomingHash
                    )) {
                        throw new \RuntimeException(
                            'Webhook ID was reused with a different payload.'
                        );
                    }

                    try {
                        $provisioner->provision(
                            $provider,
                            $payload
                        );

                        $event->update([
                            'processed_at' => now(),
                            'processing_error' => null,
                        ]);
                    } catch (\Throwable $e) {
                        /*
                         * This update is part of the same transaction.
                         *
                         * If processing fails and the transaction rolls back,
                         * Paddle can retry the webhook normally.
                         */
                        $event->update([
                            'processing_error' => mb_substr(
                                $e->getMessage(),
                                0,
                                4000
                            ),
                        ]);

                        throw $e;
                    }
                },
                5
            );
        } catch (\Throwable $e) {
            report($e);

            return response()->json([
                'message' => 'Webhook could not be processed.',
                'exception' => get_class($e),
                'error' => $e->getMessage(),
                'file' => $e->getFile(),
                'line' => $e->getLine(),
            ], 500);
        }

        /*
         * Delivery is intentionally outside the webhook transaction.
         *
         * A temporary mail outage must not roll back an otherwise valid
         * payment event. Pending outbox rows remain available for portal
         * resend or a later webhook delivery attempt.
         */
        try {
            $delivery->deliverPending(10);
        } catch (\Throwable $e) {
            report($e);
        }

        return response()->json([
            'ok' => true,
        ]);
    }
}