simplify states, add main page widget

android/app/src/main/kotlin/com/yubico/authenticator/MainActivity.kt

@@ -50,6 +50,7 @@ import com.yubico.authenticator.oath.AppLinkMethodChannel
 import com.yubico.authenticator.oath.OathManager
 import com.yubico.authenticator.oath.OathViewModel
 import com.yubico.authenticator.yubikit.NfcActivityDispatcher
+import com.yubico.authenticator.yubikit.NfcActivityListener
 import com.yubico.authenticator.yubikit.NfcActivityState
 import com.yubico.yubikit.android.YubiKitManager
 import com.yubico.yubikit.android.transport.nfc.NfcConfiguration
@@ -85,6 +86,20 @@ class MainActivity : FlutterFragmentActivity() {
 
     private val logger = LoggerFactory.getLogger(MainActivity::class.java)
 
+    private val nfcActivityListener = object : NfcActivityListener {
+
+        var appMethodChannel : AppMethodChannel? = null
+
+        override fun onChange(newState: NfcActivityState) {
+            appMethodChannel?.let {
+                logger.debug("setting nfc activity state to ${newState.name}")
+                it.nfcActivityStateChanged(newState)
+            } ?: {
+                logger.warn("cannot set nfc activity state to ${newState.name} - no method channel")
+            }
+        }
+    }
+
     override fun onCreate(savedInstanceState: Bundle?) {
         super.onCreate(savedInstanceState)
 
@@ -98,7 +113,7 @@ class MainActivity : FlutterFragmentActivity() {
 
         yubikit = YubiKitManager(
             UsbYubiKeyManager(this),
-            NfcYubiKeyManager(this, NfcActivityDispatcher(lifecycleScope))
+            NfcYubiKeyManager(this, NfcActivityDispatcher(nfcActivityListener))
         )
     }
 
@@ -136,7 +151,6 @@ class MainActivity : FlutterFragmentActivity() {
                 this,
                 ::processYubiKey
             )
-            appMethodChannel.nfcActivityStateChanged(NfcActivityState.READY)
             hasNfc = true
         } catch (e: NfcNotAvailable) {
             hasNfc = false
@@ -144,7 +158,6 @@ class MainActivity : FlutterFragmentActivity() {
 
     private fun stopNfcDiscovery() {
         if (hasNfc) {
-            appMethodChannel.nfcActivityStateChanged(NfcActivityState.NOT_ACTIVE)
             yubikit.stopNfcDiscovery(this)
             logger.debug("Stopped nfc discovery")
         }
@@ -313,6 +326,8 @@ class MainActivity : FlutterFragmentActivity() {
         appMethodChannel = AppMethodChannel(messenger)
         appLinkMethodChannel = AppLinkMethodChannel(messenger)
 
+        nfcActivityListener.appMethodChannel = appMethodChannel
+
         flutterStreams = listOf(
             viewModel.deviceInfo.streamTo(this, messenger, "android.devices.deviceInfo"),
             oathViewModel.sessionState.streamTo(this, messenger, "android.oath.sessionState"),
@@ -328,7 +343,8 @@ class MainActivity : FlutterFragmentActivity() {
                     viewModel,
                     oathViewModel,
                     dialogManager,
-                    appPreferences
+                    appPreferences,
+                    nfcActivityListener
                 )
                 else -> null
             }
@@ -337,6 +353,7 @@ class MainActivity : FlutterFragmentActivity() {
     }
 
     override fun cleanUpFlutterEngine(flutterEngine: FlutterEngine) {
+        nfcActivityListener.appMethodChannel = null
         flutterStreams.forEach { it.close() }
         super.cleanUpFlutterEngine(flutterEngine)
     }

android/app/src/main/kotlin/com/yubico/authenticator/oath/OathManager.kt

@@ -42,6 +42,7 @@ import com.yubico.authenticator.oath.keystore.ClearingMemProvider
 import com.yubico.authenticator.oath.keystore.KeyProvider
 import com.yubico.authenticator.oath.keystore.KeyStoreProvider
 import com.yubico.authenticator.oath.keystore.SharedPrefProvider
+import com.yubico.authenticator.yubikit.NfcActivityListener
 import com.yubico.authenticator.yubikit.NfcActivityState
 import com.yubico.authenticator.yubikit.getDeviceInfo
 import com.yubico.authenticator.yubikit.withConnection
@@ -76,6 +77,7 @@ class OathManager(
     private val oathViewModel: OathViewModel,
     private val dialogManager: DialogManager,
     private val appPreferences: AppPreferences,
+    private val nfcActivityListener: NfcActivityListener
 ) : AppContextManager {
     companion object {
         const val NFC_DATA_CLEANUP_DELAY = 30L * 1000 // 30s
@@ -331,20 +333,13 @@ class OathManager(
                 "Successfully read Oath session info (and credentials if unlocked) from connected key"
             )
 
-            (lifecycleOwner as MainActivity).appMethodChannel.nfcActivityStateChanged(
-                NfcActivityState.PROCESSING_FINISHED
-            )
+            nfcActivityListener.onChange(NfcActivityState.PROCESSING_FINISHED)
         } catch (e: Exception) {
             // OATH not enabled/supported, try to get DeviceInfo over other USB interfaces
             logger.error("Failed to connect to CCID", e)
             logger.debug("Set nfc activity state to PROCESSING_INTERRUPTED")
-            (lifecycleOwner as MainActivity).appMethodChannel.nfcActivityStateChanged(
-                NfcActivityState.PROCESSING_INTERRUPTED
-            )
 
-            lifecycleOwner.appMethodChannel.nfcActivityStateChanged(
-                NfcActivityState.TAG_PRESENT
-            )
+            nfcActivityListener.onChange(NfcActivityState.PROCESSING_INTERRUPTED)
 
             if (device.transport == Transport.USB || e is ApplicationNotAvailableException) {
                 val deviceInfo = try {

android/app/src/main/kotlin/com/yubico/authenticator/yubikit/NfcActivityDispatcher.kt

@@ -12,7 +12,11 @@ import kotlinx.coroutines.delay
 import kotlinx.coroutines.launch
 import org.slf4j.LoggerFactory
 
-class NfcActivityDispatcher(private val coroutineScope: CoroutineScope) : NfcDispatcher {
+interface NfcActivityListener {
+    fun onChange(newState: NfcActivityState)
+}
+
+class NfcActivityDispatcher(private val listener: NfcActivityListener) : NfcDispatcher {
 
     private lateinit var adapter: NfcAdapter
     private lateinit var yubikitNfcDispatcher: NfcReaderDispatcher
@@ -32,31 +36,29 @@ class NfcActivityDispatcher(private val coroutineScope: CoroutineScope) : NfcDis
         yubikitNfcDispatcher.enable(
             activity,
             nfcConfiguration,
-            TagInterceptor(activity as MainActivity, coroutineScope, handler)
+            TagInterceptor(listener, handler)
         )
+        listener.onChange(NfcActivityState.READY)
 
     }
 
     override fun disable(activity: Activity) {
+        listener.onChange(NfcActivityState.NOT_ACTIVE)
         yubikitNfcDispatcher.disable(activity)
         logger.info("disabling yubikit NFC activity dispatcher")
     }
 
     class TagInterceptor(
-        private val activity: MainActivity,
-        private val coroutineScope: CoroutineScope,
+        private val listener: NfcActivityListener,
         private val tagHandler: NfcDispatcher.OnTagHandler
     ) : NfcDispatcher.OnTagHandler {
 
         private val logger = LoggerFactory.getLogger(TagInterceptor::class.java)
 
         override fun onTag(tag: Tag) {
-            coroutineScope.launch {
-                activity.appMethodChannel.nfcActivityStateChanged(NfcActivityState.TAG_PRESENT)
-                activity.appMethodChannel.nfcActivityStateChanged(NfcActivityState.PROCESSING_STARTED)
-                logger.info("Calling original onTag")
-                tagHandler.onTag(tag)
-            }
+            listener.onChange(NfcActivityState.PROCESSING_STARTED)
+            logger.debug("forwarding tag")
+            tagHandler.onTag(tag)
         }
 
     }

android/app/src/main/kotlin/com/yubico/authenticator/yubikit/NfcActivityState.kt

@@ -3,8 +3,7 @@ package com.yubico.authenticator.yubikit
 enum class NfcActivityState(val value: Int) {
     NOT_ACTIVE(0),
     READY(1),
-    TAG_PRESENT(2),
-    PROCESSING_STARTED(3),
-    PROCESSING_FINISHED(4),
-    PROCESSING_INTERRUPTED(5)
+    PROCESSING_STARTED(2),
+    PROCESSING_FINISHED(3),
+    PROCESSING_INTERRUPTED(4)
 }

lib/android/state.dart

@@ -78,7 +78,6 @@ class NfcStateNotifier extends StateNotifier<bool> {
 enum NfcActivity {
   notActive,
   ready,
-  tagPresent,
   processingStarted,
   processingFinished,
   processingInterrupted,
@@ -94,10 +93,9 @@ class NfcActivityNotifier extends StateNotifier<NfcActivity> {
     var newState = switch (stateValue) {
       0 => NfcActivity.notActive,
       1 => NfcActivity.ready,
-      2 => NfcActivity.tagPresent,
-      3 => NfcActivity.processingStarted,
-      4 => NfcActivity.processingFinished,
-      5 => NfcActivity.processingInterrupted,
+      2 => NfcActivity.processingStarted,
+      3 => NfcActivity.processingFinished,
+      4 => NfcActivity.processingInterrupted,
       _ => NfcActivity.notActive
     };
 

lib/android/views/nfc/main_page_nfc_activity_widget.dart

@@ -0,0 +1,41 @@
+/*
+ * Copyright (C) 2023 Yubico.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *       http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+import 'package:flutter/material.dart';
+import 'package:yubico_authenticator/android/state.dart';
+import 'package:yubico_authenticator/android/views/nfc/nfc_activity_widget.dart';
+
+class MainPageNfcActivityWidget extends StatelessWidget {
+  final Widget widget;
+  const MainPageNfcActivityWidget(this.widget, {super.key});
+
+  @override
+  Widget build(BuildContext context) {
+    return NfcActivityWidget(
+      width: 128.0,
+      height: 128.0,
+      iconView: (nfcActivityState) {
+        return Opacity(
+          opacity: switch (nfcActivityState) {
+            NfcActivity.processingStarted => 1.0,
+            _ => 0.8
+          },
+          child: widget,
+        );
+      },
+    );
+  }
+}

lib/android/views/nfc/nfc_activity_icon.dart

@@ -27,73 +27,11 @@ class NfcActivityIcon extends StatelessWidget {
 
   @override
   Widget build(BuildContext context) => switch (nfcActivity) {
-        NfcActivity.notActive ||
-        NfcActivity.ready =>
-          const _NfcIconWithOpacity(0.5),
-        NfcActivity.tagPresent => const _NfcIconWithOpacity(0.8),
-        NfcActivity.processingStarted => const _NfcIconProcessing(),
-        NfcActivity.processingFinished => const _NfcIconWithOpacity(0.5),
-        NfcActivity.processingInterrupted => const _NfcIconWithOpacity(0.5),
+        NfcActivity.processingStarted => const _NfcIconWithOpacity(1.0),
+        _ => const _NfcIconWithOpacity(0.8)
       };
 }
 
-class _NfcIconProcessing extends StatefulWidget {
-
-  const _NfcIconProcessing();
-
-  @override
-  State<StatefulWidget> createState() => _NfcIconProcessingState();
-}
-
-class _NfcIconProcessingState extends State<_NfcIconProcessing>
-    with SingleTickerProviderStateMixin {
-  late Animation<double> animation;
-  late AnimationController _controller;
-
-  @override
-  void initState() {
-    super.initState();
-    _controller = AnimationController(
-      duration: const Duration(milliseconds: 100),
-      vsync: this,
-    );
-    animation = CurvedAnimation(parent: _controller, curve: Curves.linear)
-      ..addStatusListener((status) {
-        if (status == AnimationStatus.completed) {
-          _controller.reverse();
-        } else if (status == AnimationStatus.dismissed) {
-          _controller.forward();
-        }
-      });
-    _controller.forward();
-  }
-
-  @override
-  void dispose() {
-    _controller.dispose();
-    super.dispose();
-  }
-
-  @override
-  Widget build(BuildContext context) => _AnimatedNfcIcon(animation: animation);
-}
-
-class _AnimatedNfcIcon extends AnimatedWidget {
-  const _AnimatedNfcIcon({required Animation<double> animation})
-      : super(listenable: animation);
-
-  static final _opacityTween = Tween<double>(begin: 0.0, end: 1.0);
-
-  @override
-  Widget build(BuildContext context) {
-    final animation = listenable as Animation<double>;
-    return Opacity(
-      opacity: _opacityTween.evaluate(animation),
-      child: const _NfcIcon(),
-    );
-  }
-}
-
 class _NfcIconWithOpacity extends StatelessWidget {
   final double opacity;
 

lib/app/views/main_page.dart

@@ -20,6 +20,7 @@ import 'package:flutter_gen/gen_l10n/app_localizations.dart';
 
 import '../../android/app_methods.dart';
 import '../../android/state.dart';
+import '../../android/views/nfc/main_page_nfc_activity_widget.dart';
 import '../../exception/cancellation_exception.dart';
 import '../../core/state.dart';
 import '../../fido/views/fido_screen.dart';
@@ -82,7 +83,7 @@ class MainPage extends ConsumerWidget {
         var hasNfcSupport = ref.watch(androidNfcSupportProvider);
         var isNfcEnabled = ref.watch(androidNfcStateProvider);
         return MessagePage(
-          graphic: noKeyImage,
+          graphic: MainPageNfcActivityWidget(noKeyImage),
           message: hasNfcSupport && isNfcEnabled
               ? l10n.l_insert_or_tap_yk
               : l10n.l_insert_yk,