add: network connectivity error

lib/src/main/java/com/nextcloud/android/sso/exceptions/NextcloudNetworkException.java

@@ -0,0 +1,20 @@
+/*
+ * Nextcloud Android SingleSignOn Library
+ *
+ * SPDX-FileCopyrightText: 2018-2025 Nextcloud GmbH and Nextcloud contributors
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ */
+package com.nextcloud.android.sso.exceptions;
+
+import androidx.annotation.Nullable;
+import com.nextcloud.android.sso.R;
+
+public class NextcloudNetworkException extends SSOException {
+    public NextcloudNetworkException(@Nullable Throwable cause) {
+        super("Network connection failed. Please check your internet connection and server URL.",
+            R.string.network_error_title,
+            R.string.retry_action,
+            null,
+            cause);
+    }
+}

lib/src/main/java/com/nextcloud/android/sso/exceptions/SSOException.java

@@ -95,13 +95,39 @@ public static SSOException parseNextcloudCustomException(@NonNull Context contex
             case Constants.EXCEPTION_INVALID_REQUEST_URL ->
                 new NextcloudInvalidRequestUrlException(context, exception.getCause());
             case Constants.EXCEPTION_HTTP_REQUEST_FAILED -> {
-                final int statusCode = Integer.parseInt(exception.getCause().getMessage());
-                final var cause = exception.getCause().getCause();
-                yield new NextcloudHttpRequestFailedException(context, statusCode, cause);
+                Throwable rootCause = exception.getCause();
+                if (rootCause != null && rootCause.getMessage() != null) {
+                    int statusCode = Integer.parseInt(rootCause.getMessage());
+                    Throwable cause = (rootCause.getCause() != null) ? rootCause.getCause() : null;
+                    yield new NextcloudHttpRequestFailedException(context, statusCode, cause);
+                } else {
+                    yield new UnknownErrorException(message);
+                }
             }
             case Constants.EXCEPTION_ACCOUNT_ACCESS_DECLINED ->
                 new NextcloudFilesAppAccountPermissionNotGrantedException(context);
-            default -> new UnknownErrorException(exception.getMessage());
+            default -> {
+                if (isNetworkConnectivityError(exception)) {
+                    yield new NextcloudNetworkException(exception);
+                } else {
+                    yield new UnknownErrorException(exception.getMessage());
+                }
+            }
         };
     }
+
+    private static boolean isNetworkConnectivityError(Exception exception) {
+        Throwable current = exception;
+        while (current != null) {
+            if (current instanceof java.net.UnknownHostException ||
+                current instanceof javax.net.ssl.SSLException ||
+                current instanceof java.net.SocketException ||
+                current instanceof java.io.InterruptedIOException ||
+                current instanceof java.net.HttpRetryException) {
+                return true;
+            }
+            current = current.getCause();
+        }
+        return false;
+    }
 }

lib/src/main/res/values/strings.xml

@@ -7,6 +7,9 @@
     -->
     <string name="close">Close</string>
 
+    <string name="network_error_title">Network Error</string>
+    <string name="retry_action">Retry</string>
+
     <string name="unknown_error_title">Unknown error</string>
 
     <string name="no_current_account_selected_exception_title">No account selected</string>