StoreKit purchases stuck in a loop

Question

I am trying to implement in-app purchases in an app. this is the firs time i am doing this. I think i have the whole thing set up correctly, when i test on the device it seems to work however i get "Purchased" printed on the console a lot, it purchased 500 times (it seemed to be caught in a loop). I checked this by checking Debug -> Store Kit -> Manage transactions it seems to be purchasing in a loop. I can't see where I've gone wrong with the code. This started happening after I added in a button that restores the purchase.

 enum Product: String, CaseIterable {
    case noadspremium = "unlock1"
}

func productsRequest(_ request: SKProductsRequest, didReceive response: SKProductsResponse) {
    if let oProduct = response.products.first {
        print("product is available")
        self.purchase(aproduct: oProduct)
    }
    else {
        print("product not available")
    }
}

func paymentQueue(_ queue: SKPaymentQueue, updatedTransactions transactions: [SKPaymentTransaction]) {
    for transaction in transactions {
        
        switch transaction.transactionState {
        case .purchasing:
            print("customer is in the process of purchase")
        case .purchased:
            SKPaymentQueue.default().finishTransaction(transaction)
            print("purchased")
        case .failed:
            SKPaymentQueue.default().finishTransaction(transaction)
            print("failed")
        case .restored:
            SKPaymentQueue.default().restoreCompletedTransactions()
            print("Restored")
        case .deferred:
            print("deferred")
        default:
            break
        }
        
    }
}


func purchase(aproduct: SKProduct) {
    let payment = SKPayment(product: aproduct)
    SKPaymentQueue.default().add(self)
    SKPaymentQueue.default().add(payment)
}



@IBAction func buyPremium(_ sender: Any) {
    if SKPaymentQueue.canMakePayments(){
        let set: Set<String> = [Product.noadspremium.rawValue]
        
        let productRequest = SKProductsRequest(productIdentifiers: set)
        productRequest.delegate = self
        productRequest.start()
    }
}


@IBAction func restorePressed(_ sender: Any) {
    SKPaymentQueue.default().restoreCompletedTransactions()
}