# SDK API Reference

### PayKKa.useEnv()

Configure the payment environment used by the SDK.

- **Type**

```java
public static void useEnv(PayKKaEnvironment env)
```
- **Details**
This method is used to set the payment environment before initiating a payment. It supports a sandbox environment and multiple production environments. If this method is not called, `PayKKaEnv.SANDBOX` is used by default.
- **Example**

```java
import com.paykka.android.checkout.PayKKa;
import com.paykka.android.checkout.PayKKaEnv;

// Use production environment (Hong Kong)
PayKKa.useEnv(PayKKaEnv.PROD_HK);
```


### PayKKa.goPay()

Initiate the payment process.

- **Type**

```java
public static void goPay(
  Activity context,
  String sessionId,
  PaymentResultCallback onPaymentResultCallback
)

public static void goPay(
  Activity context,
  String sessionId,
  PaymentResultCallback onPaymentResultCallback,
  JSEventCallback onCloseTappedCallback
)
```
- **Details**
  - `context`: The Activity currently initiating the payment.
  - `sessionId`: The payment session ID, retrieved from the server.
  - `onPaymentResultCallback`: Payment result callback.
  - `onCloseTappedCallback` (optional): Callback when the user taps the close button on the payment page.
This method checks if the device supports `PaymentRequest`. If supported, it opens `PayKKaWKWebViewActivity` within the app for payment; otherwise, it redirects to an external browser (Chrome preferred) to complete the payment.
**Note**: When using this method, you must call `PayKKa.onPaymentResult` in the `onActivityResult` of the initiating Activity to ensure the callback is triggered.
- **Example**

```java
PayKKa.goPay(this, "your_session_id", result -> {
    switch (result.getStatus()) {
        case SUCCESS:
            // Payment successful
            break;
        case ERROR:
            // Payment failed
            break;
    }
});

@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
    super.onActivityResult(requestCode, resultCode, data);
    PayKKa.onPaymentResult(requestCode, resultCode, data);
}
```


### PayKKa.registerForActivityResult()

Register a payment result listener in modern Android development (ComponentActivity).

- **Type**

```java
public static PayKKaActivityResultLauncher registerForActivityResult(
  ComponentActivity context,
  PaymentResultCallback onPaymentResultCallback
)
```
- **Details**
This is the recommended integration method, utilizing Android's `ActivityResultLauncher` API. It registers the callback when the Activity is created and returns a `PayKKaActivityResultLauncher` instance.
- **Example**

```java
public class MyActivity extends AppCompatActivity {
    private PayKKaActivityResultLauncher launcher;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        // Must be registered during onCreate or the initialization phase
        launcher = PayKKa.registerForActivityResult(this, result -> {
            // Handle payment result
        });
    }

    private void startPayment() {
        launcher.goPay("your_session_id");
    }
}
```


## Data Types

### PaymentResult

Payment result object.

- **Properties**
  - `getStatus()`: Returns the `PaymentResult.Status` enum.
  - `getResult()`: Returns a `JSONObject` containing detailed payment result data.
  - `getMessage()`: Returns result description information.
- **PaymentResult.Status Enum**
  - `SUCCESS`: Payment successful.
  - `EXPIRED`: Payment expired.
  - `ERROR`: Payment error.
  - `UNKNOWN`: Unknown status.


### JSEvent

JavaScript events from the payment page.

- **Properties**
  - `getType()`: Returns `JSEvent.JSEventType`.
  - `getData()`: Returns the `JSONObject` data carried by the event.
- **JSEvent.JSEventType Enum**
  - `CLOSE_TAPPED`: User tapped the close/back button on the payment page.
  - `UNKNOWN`: Unknown event.


### PayKKaEnv

Predefined payment environments.

- **Enum Values**
  - `SANDBOX`: Sandbox test environment.
  - `PROD_EU`: European production environment.
  - `PROD_HK`: Hong Kong production environment.