feat: add webview cancelled event.

Signed-off-by: Gaurav Goel <[email protected]>

Author: grvgoel81

core/src/main/java/com/web3auth/core/Web3Auth.kt

@@ -521,6 +521,7 @@ class Web3Auth(web3AuthOptions: Web3AuthOptions, context: Context) : WebViewResu
     ): CompletableFuture<SignResponse> {
         signMsgCF = CompletableFuture()
         WebViewActivity.webViewResultCallback = this
+
         val sessionId = sessionManager.getSessionId()
         if (sessionId.isNotBlank()) {
             val sdkUrl = Uri.parse(web3AuthOption.walletSdkUrl)
@@ -681,5 +682,9 @@ class Web3Auth(web3AuthOptions: Web3AuthOptions, context: Context) : WebViewResu
             signMsgCF.complete(signResponse)
         }
     }
+
+    override fun onWebViewCancelled() {
+        signMsgCF.completeExceptionally(Exception("User cancelled the operation."))
+    }
 }
 

core/src/main/java/com/web3auth/core/WebViewActivity.kt

@@ -123,9 +123,11 @@ class WebViewActivity : AppCompatActivity() {
     }
 
     override fun onBackPressed() {
-        when {
-            webView.canGoBack() -> webView.goBack()
-            else -> super.onBackPressed()
+        if (webView.canGoBack()) {
+            webView.goBack()
+        } else {
+            webViewResultCallback?.onWebViewCancelled()
+            super.onBackPressed()
         }
     }
 

core/src/main/java/com/web3auth/core/types/WebViewResultCallback.kt

@@ -2,4 +2,5 @@ package com.web3auth.core.types
 
 interface WebViewResultCallback {
     fun onSignResponseReceived(signResponse: SignResponse?)
+    fun onWebViewCancelled()
 }