# Merchant side purchase control

{% hint style="info" %}
Implementation is **OPTIONAL**
{% endhint %}

*Purchase check rules are divided into two groups.* 

* **Product specific** rules will be sent along with product data request. 
* **Store based** rules can be configured in Smarts manager UI. 

### General Flow

* Smarts asks from merchant if the purchase check is needed by sending shopping cart information to merchant.
* Merchant will response with purchase check decision. 
  * Smarts will lock app and shows the purchase check notification to client.
* Merchant send the purchase check result to Smarts.
  * Smarts will unlock the  app
  * Purchase control supervisor is able to make changes from client shopping cart.
  * Purchase control supervisor is able to cancel the shopping process.
* After purchase check client will be directed to payment process.

{% hint style="danger" %}
App lock will **expire after 4 hours** and app will be unlocked.  This might be happen when client will not appear to purchase check or merchant will not send purchase check result back to Smarts.
{% endhint %}

### Configuration

Visit your store configuration page in Smarts manager UI. Switch merchant side purchase control to **ON** position and implement SDK required methods.

### Implementation

You only need to create a new class, implement **`PurchaseControlAdapter`** interface and fill all required methods.  API endpoints for purchase check are created automatically and secured with token. 

It is important to add `@Component` annotation on top of the class. There is no restriction for class name or location in your project. Our SDK will find your implementation based on the interface (DI).

```java
import ee.smarts.common.v1.requests.PurchaseControlCheckRequest;
import ee.smarts.common.v1.responses.PurchaseControlCheckResponse;
import ee.smarts.starter.adapter.PurchaseControlAdapter;
import org.springframework.stereotype.Component;

@Component
public class PurchaseControlAdapterImpl implements PurchaseControlAdapter {
    @Override
    public PurchaseControlCheckResponse check(PurchaseControlCheckRequest request) {
        // implement this method
        return null;
    
} 
}
```

Send purchase check results back to Smarts by calling send method from`PurchaseControlResultSender`

```java
import ee.smarts.common.v1.requests.PurchaseControlCheckRequest;
import ee.smarts.common.v1.responses.PurchaseControlCheckResponse;
import ee.smarts.starter.adapter.PurchaseControlAdapter;
import org.springframework.stereotype.Component;
import lombok.RequiredArgsConstructor;

@Component
@RequiredArgsConstructor
public class PurchaseControlStoreSideSender{

    private final PurchaseControlResultSender resultSender
    
    public void sendResult(PurchaseControlResult result) {
        resultSender.send(result);
    } 
}
```