<?php
declare(strict_types=1);

function shopify_webhook_order_gid(array $payload, string $topic): ?string
{
    if (!str_starts_with($topic, 'orders/')) {
        return null;
    }

    $graphqlId = trim((string) ($payload['admin_graphql_api_id'] ?? ''));
    if ($graphqlId !== '' && str_starts_with($graphqlId, 'gid://shopify/Order/')) {
        return $graphqlId;
    }

    $numericId = $payload['id'] ?? null;
    if (is_int($numericId) || (is_string($numericId) && ctype_digit($numericId))) {
        return 'gid://shopify/Order/' . (string) $numericId;
    }

    return null;
}

function shopify_webhook_headers(array $server): array
{
    return [
        'hmac' => trim((string) ($server['HTTP_X_SHOPIFY_HMAC_SHA256'] ?? '')),
        'topic' => trim((string) ($server['HTTP_X_SHOPIFY_TOPIC'] ?? '')),
        'webhook_id' => trim((string) ($server['HTTP_X_SHOPIFY_WEBHOOK_ID'] ?? '')),
        'shop_domain' => trim((string) ($server['HTTP_X_SHOPIFY_SHOP_DOMAIN'] ?? '')),
    ];
}

function shopify_webhook_hmac_is_valid(string $rawPayload, string $providedHmac, string $secret): bool
{
    if ($providedHmac === '' || $secret === '') {
        return false;
    }

    $expectedHmac = base64_encode(hash_hmac('sha256', $rawPayload, $secret, true));
    return hash_equals($expectedHmac, $providedHmac);
}

function shopify_webhook_start_run(PDO $pdo, array $headers): int
{
    $stmt = $pdo->prepare(
        'INSERT INTO public.process_runs (process_name, status, scope_json, started_at)
         VALUES (:process_name, \'running\', :scope_json::jsonb, NOW())
         RETURNING id'
    );
    $stmt->execute([
        ':process_name' => 'erp.import-integration.shopify_order_sync',
        ':scope_json' => json_encode([
            'topic' => $headers['topic'],
            'webhook_id' => $headers['webhook_id'],
            'shop_domain' => $headers['shop_domain'],
        ], JSON_THROW_ON_ERROR),
    ]);

    return (int) $stmt->fetchColumn();
}

function shopify_webhook_finish_run(PDO $pdo, int $runId, string $status, array $result, ?string $errorCode = null, ?string $errorMessage = null): void
{
    $stmt = $pdo->prepare(
        'UPDATE public.process_runs
         SET status = :status, result_json = :result_json::jsonb, finished_at = NOW(),
             error_code = :error_code, error_message = :error_message
         WHERE id = :id'
    );
    $stmt->execute([
        ':status' => $status,
        ':result_json' => json_encode($result, JSON_THROW_ON_ERROR),
        ':error_code' => $errorCode,
        ':error_message' => $errorMessage,
        ':id' => $runId,
    ]);
}

function handle_shopify_webhook(PDO $pdo, array $env, string $rawPayload, array $server): array
{
    $headers = shopify_webhook_headers($server);
    $secret = env_value('SHOPIFY_CLIENT_SECRET', $env);

    if (($server['REQUEST_METHOD'] ?? '') !== 'POST') {
        return ['http_status' => 405, 'payload' => ['status' => 'rejected', 'error' => 'method_not_allowed']];
    }

    if ($headers['hmac'] === '' || $headers['topic'] === '' || $headers['webhook_id'] === '' || $headers['shop_domain'] === '') {
        return ['http_status' => 400, 'payload' => ['status' => 'rejected', 'error' => 'required_shopify_header_missing']];
    }

    if (!shopify_webhook_hmac_is_valid($rawPayload, $headers['hmac'], $secret)) {
        return ['http_status' => 401, 'payload' => ['status' => 'rejected', 'error' => 'invalid_shopify_hmac']];
    }

    try {
        $data = json_decode($rawPayload, true, 512, JSON_THROW_ON_ERROR);
    } catch (JsonException) {
        return ['http_status' => 400, 'payload' => ['status' => 'rejected', 'error' => 'invalid_json']];
    }

    if (!is_array($data) || array_is_list($data)) {
        return ['http_status' => 400, 'payload' => ['status' => 'rejected', 'error' => 'json_object_expected']];
    }

    $runId = shopify_webhook_start_run($pdo, $headers);
    $payloadHash = hash('sha256', $rawPayload);
    $orderGid = shopify_webhook_order_gid($data, $headers['topic']);

    try {
        $pdo->beginTransaction();
        $stmt = $pdo->prepare(
            'INSERT INTO public.shopify_webhook_event
                (webhook_id, topic, shop_domain, payload_sha256, payload, shopify_order_gid, status)
             VALUES (:webhook_id, :topic, :shop_domain, :payload_sha256, :payload::jsonb, :shopify_order_gid, \'received\')
             ON CONFLICT (webhook_id) DO NOTHING
             RETURNING id'
        );
        $stmt->execute([
            ':webhook_id' => $headers['webhook_id'],
            ':topic' => $headers['topic'],
            ':shop_domain' => $headers['shop_domain'],
            ':payload_sha256' => $payloadHash,
            ':payload' => $rawPayload,
            ':shopify_order_gid' => $orderGid,
        ]);

        $eventId = $stmt->fetchColumn();
        if ($eventId === false) {
            $duplicateStmt = $pdo->prepare('SELECT id, shopify_order_gid FROM public.shopify_webhook_event WHERE webhook_id = :webhook_id');
            $duplicateStmt->execute([':webhook_id' => $headers['webhook_id']]);
            $duplicate = $duplicateStmt->fetch();
            $pdo->commit();
            shopify_webhook_finish_run($pdo, $runId, 'done', ['status' => 'duplicate', 'technical_event_id' => (int) ($duplicate['id'] ?? 0)]);

            return ['http_status' => 200, 'payload' => [
                'status' => 'duplicate',
                'webhook_id' => $headers['webhook_id'],
                'topic' => $headers['topic'],
                'shop_domain' => $headers['shop_domain'],
                'shopify_order_gid' => $duplicate['shopify_order_gid'] ?? $orderGid,
                'technical_run_id' => $runId,
            ]];
        }

        $pdo->commit();
        shopify_webhook_finish_run($pdo, $runId, 'done', ['status' => 'accepted', 'technical_event_id' => (int) $eventId]);

        return ['http_status' => 200, 'payload' => [
            'status' => 'accepted',
            'webhook_id' => $headers['webhook_id'],
            'topic' => $headers['topic'],
            'shop_domain' => $headers['shop_domain'],
            'shopify_order_gid' => $orderGid,
            'technical_run_id' => $runId,
        ]];
    } catch (Throwable $e) {
        if ($pdo->inTransaction()) {
            $pdo->rollBack();
        }
        shopify_webhook_finish_run($pdo, $runId, 'failed', ['status' => 'failed'], 'shopify_webhook_persistence_failed', $e->getMessage());
        throw $e;
    }
}