CWA-164 | added biometric authentication

lib/src/domain/common/biometric_auth.dart

@@ -0,0 +1,24 @@
+import 'package:local_auth/local_auth.dart';
+import 'package:flutter/services.dart';
+import 'package:cake_wallet/generated/i18n.dart';
+
+class BiometricAuth {
+
+  Future<bool> isAuthenticated() async {
+    final LocalAuthentication _localAuth = LocalAuthentication();
+
+    try {
+      return await _localAuth.authenticateWithBiometrics(
+          localizedReason: S.current.biometric_auth_reason,
+          useErrorDialogs: true,
+          stickyAuth: false
+      );
+    } on PlatformException
+    catch(e) {
+      print(e);
+    }
+
+    return false;
+  }
+
+}

lib/src/screens/auth/auth_page.dart

@@ -6,6 +6,8 @@ import 'package:cake_wallet/generated/i18n.dart';
 import 'package:cake_wallet/src/stores/auth/auth_state.dart';
 import 'package:cake_wallet/src/stores/auth/auth_store.dart';
 import 'package:cake_wallet/src/screens/pin_code/pin_code.dart';
+import 'package:cake_wallet/src/stores/settings/settings_store.dart';
+import 'package:cake_wallet/src/domain/common/biometric_auth.dart';
 
 typedef OnAuthenticationFinished = void Function(bool, AuthPageState);
 
@@ -33,6 +35,26 @@ class AuthPageState extends State<AuthPage> {
   @override
   Widget build(BuildContext context) {
     final authStore = Provider.of<AuthStore>(context);
+    final settingsStore = Provider.of<SettingsStore>(context);
+
+    if (settingsStore.allowBiometricalAuthentication) {
+      WidgetsBinding.instance.addPostFrameCallback((_) {
+        final biometricAuth = BiometricAuth();
+        biometricAuth.isAuthenticated().then(
+                (isAuth) {
+              if (isAuth) {
+                authStore.biometricAuth();
+                _key.currentState.showSnackBar(
+                  SnackBar(
+                    content: Text(S.of(context).authenticated),
+                    backgroundColor: Colors.green,
+                  ),
+                );
+              }
+            }
+        );
+      });
+    }
 
     reaction((_) => authStore.state, (AuthState state) {
       if (state is AuthenticatedSuccessfully) {

lib/src/stores/auth/auth_store.dart

@@ -91,4 +91,9 @@ abstract class AuthStoreBase with Store {
 
     return Duration(milliseconds: timeout);
   }
+
+  @action
+  void biometricAuth() {
+    state = AuthenticatedSuccessfully();
+  }
 }