Salesforce Payments for Order on Behalf Of

// Script to add a connection between the webstore and the payment gateway for stores using
// Salesforce Payments (SFP) as the payment gateway for SFP does not show in the the Payment 
// Alternate Integration.

String merchantAccountName = 'DemoTest';
String webStoreName = 'B2B Store';

// obtain webstoreid
List<WebStore> webstores = [SELECT Id, Name FROM WebStore WHERE Name = :webStoreName];
System.debug('Webstores: ' + webstores);
if(webstores.isEmpty()){
    System.debug('Error obtaining webstore with name ' + webStoreName);
}
String webStoreId = webstores[0].Id;
System.debug('WebStoreId: ' + webStoreId);

// obtain merchant account 
List<MerchAccPaymentMethodSet> merchAccPaymentMethodSet = [SELECT Id, MerchantAccountId, DeveloperName FROM MerchAccPaymentMethodSet WHERE MerchantAccount.Name = :merchantAccountName];
System.debug('Details: ' + merchAccPaymentMethodSet);
if(merchAccPaymentMethodSet.isEmpty()){
    System.debug('Error obtaining MerchAccPaymentMethodSet with name ' + merchantAccountName);
}
String merchantAccountId = merchAccPaymentMethodSet[0].MerchantAccountId;
System.debug('merchantAccountId: ' + merchantAccountId);

// obtain payment gateway id from the merchant account
List<PaymentGateway> paymentGateways = [SELECT Id, PaymentGatewayName FROM PaymentGateway WHERE MerchantAccountId = :merchantAccountId];
System.debug('paymentGateways: ' + paymentGateways);
if(paymentGateways.isEmpty()){
    System.debug('Error obtaining payment gateway with merchant account id ' + merchantAccountId);
}
String paymentGatewayId = paymentGateways[0].Id;
System.debug('paymentGatewayId: ' + paymentGatewayId);

// If a StoreIntegratedService already exists for Payment on the WebStore then update the Integration field with the paymentGatewayId
List<StoreIntegratedService> storeServices = [SELECT Id FROM StoreIntegratedService WHERE StoreId = :webStoreId AND ServiceProviderType ='Payment' ];
System.debug('storeServices: ' + storeServices);
if(storeServices.isEmpty()){
    StoreIntegratedService storeService = new StoreIntegratedService(
        StoreId = webStoreId,
        Integration = paymentGatewayId,
        ServiceProviderType ='Payment');
    insert storeService;
} else {
    StoreIntegratedService existingStoreService = storeServices[0];
    existingStoreService.Integration = paymentGatewayId;
    update existingStoreService;
}