ProfileService: Create it and move profile loading

The long-running service is needed for keeping track of which profiles
are enabled, for showing notifications, and for the tile service to use.
Since it has to know which profiles exist anyway, moving the main
ObservableList there avoids some code duplication. It ensures the list
is only loaded once, so it cannot get out of sync. It also makes the
ProfileList activity load faster, because it doesn't have to wait for
file I/O; and it provides a canonical place for storing the Profile
objects so they are accessible everywhere, instead of having to look
them up by name.

This does present some challenges with leaking activities, because all
listeners must be removed from the profiles list (and its contents) when
an activity is stopped.

Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>

app/src/main/AndroidManifest.xml

@@ -16,6 +16,10 @@
                 <category android:name="android.intent.category.LAUNCHER" />
             </intent-filter>
         </activity>
+
+        <service
+            android:name=".ProfileService"
+            android:exported="false" />
     </application>
 
 </manifest>

app/src/main/java/com/wireguard/android/ProfileListActivity.java

@@ -1,64 +1,57 @@
 package com.wireguard.android;
 
 import android.app.Activity;
+import android.content.ComponentName;
+import android.content.Context;
+import android.content.Intent;
+import android.content.ServiceConnection;
 import android.databinding.DataBindingUtil;
-import android.databinding.ObservableArrayList;
-import android.databinding.ObservableList;
-import android.os.AsyncTask;
 import android.os.Bundle;
-import android.util.Log;
+import android.os.IBinder;
 
 import com.wireguard.android.databinding.ProfileListActivityBinding;
-import com.wireguard.config.Profile;
-
-import java.io.File;
-import java.io.FileInputStream;
-import java.io.IOException;
-import java.util.ArrayList;
 
 public class ProfileListActivity extends Activity {
-    private final ObservableList<Profile> profiles = new ObservableArrayList<>();
+    private final ServiceConnection connection = new ProfileServiceConnection();
+    private ProfileListActivityBinding binding;
+    private ProfileServiceInterface service;
 
     @Override
     protected void onCreate(Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);
-        final ProfileListActivityBinding binding =
-                DataBindingUtil.setContentView(this, R.layout.profile_list_activity);
-        binding.setProfiles(profiles);
-        new ProfileLoader().execute(getFilesDir().listFiles());
+        binding = DataBindingUtil.setContentView(this, R.layout.profile_list_activity);
+        // Ensure the long-running service is started. This only needs to happen once.
+        Intent intent = new Intent(this, ProfileService.class);
+        startService(intent);
     }
 
-    private class ProfileLoader extends AsyncTask<File, Profile, ArrayList<Profile>> {
-        private static final String TAG = "WGProfileLoader";
+    @Override
+    public void onStart() {
+        super.onStart();
+        Intent intent = new Intent(this, ProfileService.class);
+        bindService(intent, connection, Context.BIND_AUTO_CREATE);
+    }
 
+    @Override
+    public void onStop() {
+        super.onStop();
+        if (service != null) {
+            unbindService(connection);
+            service = null;
+        }
+    }
+
+    private class ProfileServiceConnection implements ServiceConnection {
         @Override
-        protected ArrayList<Profile> doInBackground(File... files) {
-            final ArrayList<Profile> loadedProfiles = new ArrayList<>();
-            for (File file : files) {
-                final String fileName = file.getName();
-                final int suffixStart = fileName.lastIndexOf(".conf");
-                if (suffixStart <= 0) {
-                    Log.w(TAG, "Ignoring stray file " + fileName);
-                    continue;
-                }
-                final Profile profile = new Profile(fileName.substring(0, suffixStart));
-                try {
-                    final FileInputStream inputStream = openFileInput(fileName);
-                    profile.fromStream(inputStream);
-                    loadedProfiles.add(profile);
-                } catch (IOException e) {
-                    Log.w(TAG, "Failed to load profile from " + fileName, e);
-                }
-                if (isCancelled())
-                    break;
-            }
-            return loadedProfiles;
+        public void onServiceConnected(ComponentName component, IBinder binder) {
+            service = (ProfileServiceInterface) binder;
+            binding.setProfiles(service.getProfiles());
         }
 
         @Override
-        protected void onPostExecute(ArrayList<Profile> loadedProfiles) {
-            // FIXME: This should replace an existing profile if the name matches.
-            profiles.addAll(loadedProfiles);
+        public void onServiceDisconnected(ComponentName component) {
+            // This function is only called when the service crashes or goes away unexpectedly.
+            service = null;
         }
     }
 }

app/src/main/java/com/wireguard/android/ProfileService.java

@@ -0,0 +1,75 @@
+package com.wireguard.android;
+
+import android.app.Service;
+import android.content.Intent;
+import android.databinding.ObservableArrayList;
+import android.databinding.ObservableList;
+import android.os.AsyncTask;
+import android.os.Binder;
+import android.os.IBinder;
+import android.util.Log;
+
+import com.wireguard.config.Profile;
+
+import java.io.File;
+import java.io.IOException;
+import java.util.LinkedList;
+import java.util.List;
+
+/**
+ * Service that handles profile state coordination and all background processing for the app.
+ */
+
+public class ProfileService extends Service {
+    private static final String TAG = "ProfileService";
+
+    private final IBinder binder = new ProfileServiceBinder();
+    private final ObservableList<Profile> profiles = new ObservableArrayList<>();
+
+    @Override
+    public IBinder onBind(Intent intent) {
+        return binder;
+    }
+
+    @Override
+    public void onCreate() {
+        new ProfileLoader().execute(getFilesDir().listFiles());
+    }
+
+    @Override
+    public int onStartCommand(Intent intent, int flags, int startId) {
+        return START_STICKY;
+    }
+
+    private class ProfileLoader extends AsyncTask<File, Void, List<Profile>> {
+        @Override
+        protected List<Profile> doInBackground(File... files) {
+            final List<Profile> loadedProfiles = new LinkedList<>();
+            for (File file : files) {
+                final String fileName = file.getName();
+                final String profileName = fileName.substring(0, fileName.length() - 5);
+                final Profile profile = new Profile(profileName);
+                try {
+                    profile.parseFrom(openFileInput(fileName));
+                    loadedProfiles.add(profile);
+                } catch (IOException e) {
+                    Log.w(TAG, "Failed to load profile from " + fileName, e);
+                }
+                if (isCancelled())
+                    break;
+            }
+            return loadedProfiles;
+        }
+
+        @Override
+        protected void onPostExecute(List<Profile> loadedProfiles) {
+            profiles.addAll(loadedProfiles);
+        }
+    }
+
+    private class ProfileServiceBinder extends Binder implements ProfileServiceInterface {
+        public ObservableList<Profile> getProfiles() {
+            return profiles;
+        }
+    }
+}

app/src/main/java/com/wireguard/android/ProfileServiceInterface.java

@@ -0,0 +1,13 @@
+package com.wireguard.android;
+
+import android.databinding.ObservableList;
+
+import com.wireguard.config.Profile;
+
+/**
+ * Interface for the background connection service.
+ */
+
+public interface ProfileServiceInterface {
+    ObservableList<Profile> getProfiles();
+}