android: split main activity responsibilities

Extract WebViewManager and UsbDeviceManager so MainActivity focuses
on lifecycle wiring. WebView setup, permission handling, and back
button logic move into WebViewManager, while UsbDeviceManager
centralizes USB receiver registration, permissions, and device
selection. This makes the activity easier to read and test.

Author: beerosagos

frontends/android/BitBoxApp/app/src/main/java/ch/shiftcrypto/bitboxapp/MainActivity.java

@@ -1,69 +1,41 @@
 package ch.shiftcrypto.bitboxapp;
 
-import android.Manifest;
-import android.annotation.SuppressLint;
-import android.app.AlertDialog;
-import android.app.PendingIntent;
-import android.content.BroadcastReceiver;
 import android.content.ComponentName;
 import android.content.Context;
 import android.content.Intent;
-import android.content.IntentFilter;
 import android.content.ServiceConnection;
-import android.content.pm.PackageManager;
 import android.content.res.Configuration;
-import android.hardware.usb.UsbDevice;
-import android.hardware.usb.UsbManager;
 import android.net.Uri;
 import android.os.Bundle;
-import android.os.Handler;
 import android.os.IBinder;
-import android.os.Looper;
 import android.view.View;
 import android.view.WindowManager;
-import android.webkit.CookieManager;
 import android.webkit.WebView;
 
 import androidx.activity.OnBackPressedCallback;
-import androidx.activity.result.ActivityResultLauncher;
-import androidx.activity.result.contract.ActivityResultContracts;
 import androidx.annotation.NonNull;
 import androidx.appcompat.app.ActionBar;
 import androidx.appcompat.app.AppCompatActivity;
-import androidx.core.app.ActivityCompat;
 import androidx.core.content.ContextCompat;
 import androidx.lifecycle.ViewModelProviders;
 
-import java.util.HashMap;
-
 import mobileserver.Mobileserver;
 
 public class MainActivity extends AppCompatActivity {
     static {
         System.loadLibrary("signal_handler");
     }
     public native void initsignalhandler();
-    private final int PERMISSIONS_REQUEST_CAMERA_QRCODE = 0;
-    private static final String ACTION_USB_PERMISSION = "ch.shiftcrypto.bitboxapp.USB_PERMISSION";
-    // The WebView is configured with this as the base URL. The purpose is so that requests made
-    // from the app include shiftcrypto.ch in the Origin header to allow Moonpay to load in the
-    // iframe. Moonpay compares the origin against a list of origins configured in the Moonpay admin.
-    // This is a security feature relevant for websites running in browsers, but in the case of the
-    // BitBoxApp, it is useless, as any app can do this.
-    //
-    // Unfortunately there seems to be no simple way to include this header only in requests to Moonpay.
-    private static final String BASE_URL = "https://shiftcrypto.ch/";
 
     GoService goService;
-
-    private BitBoxWebChromeClient webChrome;
+    private GoViewModel goViewModel;
+    private WebViewManager webViewManager;
+    private UsbDeviceManager usbDeviceManager;
 
     // Connection to bind with GoService
     private final ServiceConnection connection = new ServiceConnection() {
-
         @Override
-        public void onServiceConnected(ComponentName className,
-                                       IBinder service) {
+        public void onServiceConnected(ComponentName className, IBinder service) {
             GoService.GoServiceBinder binder = (GoService.GoServiceBinder) service;
             goService = binder.getService();
             goService.setViewModelStoreOwner(MainActivity.this);
@@ -78,12 +50,6 @@ public void onServiceDisconnected(ComponentName arg0) {
         }
     };
 
-    private final BroadcastReceiver usbStateReceiver = new BroadcastReceiver() {
-        public void onReceive(Context context, Intent intent) {
-            handleIntent(intent);
-        }
-    };
-
     @Override
     public void onConfigurationChanged(Configuration newConfig) {
         int currentNightMode = newConfig.uiMode & Configuration.UI_MODE_NIGHT_MASK;
@@ -118,89 +84,39 @@ public void setDarkTheme(boolean isDark) {
         }
     }
 
-    @SuppressLint("SetJavaScriptEnabled")
     @Override
     protected void onCreate(Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);
         Util.log("lifecycle: onCreate");
-
         initsignalhandler();
-
         ActionBar actionBar = getSupportActionBar();
         if (actionBar != null) {
             actionBar.hide(); // hide title bar with app name.
         }
         onConfigurationChanged(getResources().getConfiguration());
         setContentView(R.layout.activity_main);
         final WebView vw = findViewById(R.id.vw);
-        // For onramp iframe'd widgets like MoonPay.
-        CookieManager.getInstance().setAcceptThirdPartyCookies(vw, true);
 
         // GoModel manages the Go backend. It is in a ViewModel so it only runs once, not every time
         // onCreate is called (on a configuration change like orientation change).
-        final GoViewModel goViewModel = ViewModelProviders.of(this).get(GoViewModel.class);
+        goViewModel = ViewModelProviders.of(this).get(GoViewModel.class);
+        webViewManager = new WebViewManager(this, goViewModel);
+        webViewManager.initialize(vw);
+        usbDeviceManager = new UsbDeviceManager(this, goViewModel);
 
         // The backend is run inside GoService, to avoid (as much as possible) latency errors due to
         // the scheduling when the app is out of focus.
         Intent intent = new Intent(this, GoService.class);
         bindService(intent, connection, Context.BIND_AUTO_CREATE);
 
-        goViewModel.setMessageHandlers(
-                new Handler(Looper.getMainLooper(), msg -> {
-                        final GoAPI.Response response = (GoAPI.Response) msg.obj;
-                        vw.evaluateJavascript(
-                                "if (window.onMobileCallResponse) {" +
-                                        "window.onMobileCallResponse(" + response.queryID + ", " + response.response + ")};",
-                                null);
-                        return true;
-                    }),
-                new Handler(Looper.getMainLooper(), msg -> {
-                        vw.evaluateJavascript(
-                                "if (window.onMobilePushNotification) {" +
-                                        "window.onMobilePushNotification(" + msg.obj + ")};",
-                                null);
-                        return true;
-                }));
-        vw.clearCache(true);
-        vw.clearHistory();
-        vw.getSettings().setJavaScriptEnabled(true);
-        vw.getSettings().setAllowUniversalAccessFromFileURLs(true);
-        vw.getSettings().setAllowFileAccess(true);
-        // Allow widgets to open external links via window.open (handled in BitBoxWebChromeClient).
-        vw.getSettings().setSupportMultipleWindows(true);
-
-        // For Moonpay widget: DOM storage and WebRTC camera access required.
-        vw.getSettings().setDomStorageEnabled(true);
-        vw.getSettings().setMediaPlaybackRequiresUserGesture(false);
-
-        // vw.setWebContentsDebuggingEnabled(true); // enable remote debugging in chrome://inspect/#devices
-
-        vw.setWebViewClient(new BitBoxWebViewClient(BASE_URL, getAssets(), getApplication()));
-
-        ActivityResultLauncher<String> fileChooser = registerForActivityResult(new ActivityResultContracts.GetContent(), uri -> webChrome.onFilePickerResult(uri));
-        BitBoxWebChromeClient.CameraPermissionDelegate cameraPermissionDelegate = () -> ActivityCompat.requestPermissions(
-                this,
-                new String[]{Manifest.permission.CAMERA},
-                PERMISSIONS_REQUEST_CAMERA_QRCODE
-        );
-
-        webChrome = new BitBoxWebChromeClient(this,
-                cameraPermissionDelegate,
-                fileChooser
-        );
-        vw.setWebChromeClient(webChrome);
-
-        vw.addJavascriptInterface(new JavascriptBridge(this), "android");
-        vw.loadUrl(BASE_URL + "index.html");
-
-        // We call updateDevice() here in case the app was started while the device was already connected.
-        // In that case, handleIntent() is not called with ACTION_USB_DEVICE_ATTACHED.
-        this.updateDevice();
+        // We call refreshConnectedDevice() here in case the app was started while the device was already connected.
+        // In that case, no intent is fired with ACTION_USB_DEVICE_ATTACHED.
+        usbDeviceManager.refreshConnectedDevice();
 
         getOnBackPressedDispatcher().addCallback(this, new OnBackPressedCallback(true) {
             @Override
             public void handleOnBackPressed() {
-                backPressedHandler();
+                webViewManager.handleBackPressed();
             }
         });
 
@@ -261,17 +177,20 @@ public void noAuthConfigured() {
     @Override
     public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) {
         super.onRequestPermissionsResult(requestCode, permissions, grantResults);
-        if (requestCode == PERMISSIONS_REQUEST_CAMERA_QRCODE) {
-            webChrome.onCameraPermissionResult(grantResults.length > 0 && grantResults[0] == PackageManager.PERMISSION_GRANTED);
+        if (webViewManager != null) {
+            webViewManager.handleRequestPermissionsResult(requestCode, grantResults);
         }
     }
 
     private void startServer() {
-        final GoViewModel gVM = ViewModelProviders.of(this).get(GoViewModel.class);
-        goService.startServer(getApplicationContext().getFilesDir().getAbsolutePath(), gVM.getGoEnvironment(), gVM.getGoAPI());
+        goService.startServer(
+                getApplicationContext().getFilesDir().getAbsolutePath(),
+                goViewModel.getGoEnvironment(),
+                goViewModel.getGoAPI()
+        );
 
         // Trigger connectivity and mobile connection check (as the network may already be unavailable when the app starts).
-        gVM.getNetworkHelper().checkConnectivity();
+        goViewModel.getNetworkHelper().checkConnectivity();
     }
 
     @Override
@@ -287,7 +206,6 @@ protected void onNewIntent(Intent intent) {
     protected void onStart() {
         super.onStart();
         Util.log("lifecycle: onStart");
-        final GoViewModel goViewModel = ViewModelProviders.of(this).get(GoViewModel.class);
         goViewModel.getIsDarkTheme().observe(this, this::setDarkTheme);
         goViewModel.getNetworkHelper().registerNetworkCallback();
     }
@@ -298,104 +216,26 @@ protected void onResume() {
         Util.log("lifecycle: onResume");
         Mobileserver.triggerAuth();
 
-        // This is only called reliably when USB is attached with android:launchMode="singleTop"
-
-        // Usb device list is updated on ATTACHED / DETACHED intents.
-        // ATTACHED intent is an activity intent in AndroidManifest.xml so the app is launched when
-        // a device is attached. On launch or when it is already running, onIntent() is called
-        // followed by onResume(), where the intent is handled.
-        // DETACHED intent is a broadcast intent which we register here.
-        IntentFilter filter = new IntentFilter();
-        filter.addAction(UsbManager.ACTION_USB_DEVICE_DETACHED);
-        filter.addAction(ACTION_USB_PERMISSION);
-        ContextCompat.registerReceiver(
-                this,
-                usbStateReceiver,
-                filter,
-                ContextCompat.RECEIVER_NOT_EXPORTED
-        );
+        usbDeviceManager.startMonitoring();
 
         // Trigger connectivity check (as the network may already be unavailable when the app starts).
-        final GoViewModel goViewModel = ViewModelProviders.of(this).get(GoViewModel.class);
         goViewModel.getNetworkHelper().checkConnectivity();
 
         Intent intent = getIntent();
-        handleIntent(intent);
+        usbDeviceManager.handleUsbIntent(intent);
+        handleAOPPIntent(intent);
     }
 
     @Override
     protected void onPause() {
         super.onPause();
         Util.log("lifecycle: onPause");
-        unregisterReceiver(this.usbStateReceiver);
-    }
-
-    private void handleIntent(Intent intent) {
-        if (ACTION_USB_PERMISSION.equals(intent.getAction())) {
-            // See https://developer.android.com/guide/topics/connectivity/usb/host#permission-d
-            synchronized (this) {
-                UsbDevice device = intent.getParcelableExtra(UsbManager.EXTRA_DEVICE);
-                if (intent.getBooleanExtra(UsbManager.EXTRA_PERMISSION_GRANTED, false)) {
-                    if (device != null) {
-                        Util.log("usb: permission granted");
-                        final GoViewModel goViewModel = ViewModelProviders.of(this).get(GoViewModel.class);
-                        goViewModel.setDevice(device);
-                    }
-                } else {
-                    Util.log("usb: permission denied");
-                }
-            }
-        }
-        if (UsbManager.ACTION_USB_DEVICE_ATTACHED.equals(intent.getAction())) {
-            Util.log("usb: attached");
-            this.updateDevice();
-        }
-        if (UsbManager.ACTION_USB_DEVICE_DETACHED.equals(intent.getAction())) {
-            Util.log("usb: detached");
-            this.updateDevice();
-        }
-        // Handle 'aopp:' URIs. This is called when the app is launched and also if it is already
-        // running and brought to the foreground.
-        if (Intent.ACTION_VIEW.equals(intent.getAction())) {
-            Uri uri = intent.getData();
-            if (uri != null) {
-                if ("aopp".equals(uri.getScheme())) {
-                    Mobileserver.handleURI(uri.toString());
-                }
-            }
-        }
-    }
-
-    private void updateDevice() {
-        // Triggered by usb device attached intent and usb device detached broadcast events.
-        final GoViewModel goViewModel = ViewModelProviders.of(this).get(GoViewModel.class);
-        goViewModel.setDevice(null);
-        UsbManager manager = (UsbManager) getApplication().getSystemService(Context.USB_SERVICE);
-        HashMap<String, UsbDevice> deviceList = manager.getDeviceList();
-        for (UsbDevice device : deviceList.values()) {
-            // One other instance where we filter vendor/product IDs is in
-            // @xml/device_filter resource, which is used for USB_DEVICE_ATTACHED
-            // intent to launch the app when a device is plugged and the app is still
-            // closed. This filter, on the other hand, makes sure we feed only valid
-            // devices to the Go backend once the app is launched or opened.
-            //
-            // BitBox02 Vendor ID: 0x03eb, Product ID: 0x2403.
-            if (device.getVendorId() == 1003 && device.getProductId() == 9219) {
-                if (manager.hasPermission(device)) {
-                    goViewModel.setDevice(device);
-                } else {
-                    PendingIntent permissionIntent = PendingIntent.getBroadcast(this, 0, new Intent(ACTION_USB_PERMISSION), PendingIntent.FLAG_IMMUTABLE);
-                    manager.requestPermission(device, permissionIntent);
-                }
-                break; // only one device supported for now
-            }
-        }
+        usbDeviceManager.stopMonitoring();
     }
 
     @Override
     protected void onStop() {
         super.onStop();
-        final GoViewModel goViewModel = ViewModelProviders.of(this).get(GoViewModel.class);
         goViewModel.getNetworkHelper().unregisterNetworkCallback();
         Util.log("lifecycle: onStop");
     }
@@ -421,54 +261,15 @@ protected void onDestroy() {
         Util.quit(MainActivity.this);
     }
 
-
-
-    // Handle Android back button behavior:
-    //
-    // By default, if the webview can go back in browser history, we do that.
-    // If there is no more history, we prompt the user to quit the app. If
-    // confirmed, the app will be force quit.
-    //
-    // The default behavior can be modified by the frontend via the
-    // window.onBackButtonPressed() function. See the `useBackButton` React
-    // hook. It will be called first, and if it returns false, the default
-    // behavior is prevented, otherwise we proceed with the above default
-    // behavior.
-    //
-    // Without forced app process exit, some goroutines may remain active even after
-    // the app resumption at which point new copies of goroutines are spun up.
-    // Note that this is different from users tapping on "home" button or switching
-    // to another app and then back, in which case no extra goroutines are created.
-    //
-    // A proper fix is to make the backend process run in a separate system thread.
-    // Until such solution is implemented, forced app exit seems most appropriate.
-    //
-    // See the following for details about task and activity stacks:
-    // https://developer.android.com/guide/components/activities/tasks-and-back-stack
-    private void backPressedHandler() {
-        runOnUiThread(new Runnable() {
-            final WebView vw = findViewById(R.id.vw);
-            @Override
-            public void run() {
-                vw.evaluateJavascript("window.onBackButtonPressed();", value -> {
-                    boolean doDefault = Boolean.parseBoolean(value);
-                    if (doDefault) {
-                        // Default behavior: go back in history if we can, otherwise prompt user
-                        // if they want to quit the app.
-                        if (vw.canGoBack()) {
-                            vw.goBack();
-                            return;
-                        }
-                        new AlertDialog.Builder(MainActivity.this)
-                                .setTitle("Close BitBoxApp")
-                                .setMessage("Do you really want to exit?")
-                                .setPositiveButton(android.R.string.yes, (dialog, which) -> Util.quit(MainActivity.this))
-                                .setNegativeButton(android.R.string.no, (dialog, which) -> dialog.dismiss())
-                                .setIcon(android.R.drawable.ic_dialog_alert)
-                                .show();
-                    }
-                });
-            }
-        });
+    // Handle 'aopp:' URIs. This is called when the app is launched and also if it is already
+    // running and brought to the foreground.
+    private void handleAOPPIntent(Intent intent) {
+        if (intent == null || !Intent.ACTION_VIEW.equals(intent.getAction())) {
+            return;
+        }
+        Uri uri = intent.getData();
+        if (uri != null && "aopp".equals(uri.getScheme())) {
+            Mobileserver.handleURI(uri.toString());
+        }
     }
 }