Added functionality to add contacts (with new Activity).

This requires confirmation from both devices involved, and
allows opening the ChatFragment for a device that is not currently
connected.

app/src/androidTest/scala/com.nutomic.ensichat.messages/DatabaseTest.scala

@@ -8,9 +8,10 @@ import android.database.sqlite.SQLiteDatabase
 import android.test.AndroidTestCase
 import android.test.mock.MockContext
 import com.nutomic.ensichat.messages.MessageTest._
+import com.nutomic.ensichat.util.Database
 import junit.framework.Assert._
 
-class MessageStoreTest extends AndroidTestCase {
+class DatabaseTest extends AndroidTestCase {
 
   private class TestContext(context: Context) extends MockContext {
     override def openOrCreateDatabase(file: String, mode: Int, factory:
@@ -22,10 +23,10 @@ class MessageStoreTest extends AndroidTestCase {
 
   private var dbFile: String = _
 
-  private var MessageStore: MessageStore = _
+  private var MessageStore: Database = _
 
   override def setUp(): Unit = {
-    MessageStore = new MessageStore(new TestContext(getContext))
+    MessageStore = new Database(new TestContext(getContext))
     MessageStore.addMessage(m1)
     MessageStore.addMessage(m2)
     MessageStore.addMessage(m3)

app/src/main/AndroidManifest.xml

@@ -23,6 +23,11 @@
             </intent-filter>
         </activity>
 
+        <activity
+            android:name=".activities.AddContactsActivity"
+            android:label="@string/add_contacts"
+            android:parentActivityName=".activities.MainActivity" />
+
         <activity
             android:name=".activities.SettingsActivity"
             android:label="@string/settings"

app/src/main/res/layout/activity_add_contacts.xml

@@ -0,0 +1,18 @@
+<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
+    android:layout_width="match_parent"
+    android:layout_height="match_parent" >
+
+    <ListView
+        android:id="@android:id/list"
+        android:layout_width="fill_parent"
+        android:layout_height="fill_parent" />
+
+    <TextView
+        android:id="@android:id/empty"
+        android:layout_width="wrap_content"
+        android:layout_height="wrap_content"
+        android:text="@string/no_devices_nearby"
+        android:layout_centerHorizontal="true"
+        android:layout_centerVertical="true" />
+
+</RelativeLayout>

app/src/main/res/menu/main.xml

@@ -2,6 +2,12 @@
 
 <menu xmlns:android="http://schemas.android.com/apk/res/android">
 
+    <item
+        android:id="@+id/add_contact"
+        android:title="@string/add_contacts"
+        android:icon="@drawable/ic_action_add_person"
+        android:showAsAction="ifRoom" />
+
     <item
         android:id="@+id/settings"
         android:icon="@drawable/ic_action_settings"
@@ -10,6 +16,6 @@
 
     <item
         android:id="@+id/exit"
-        android:title="Exit" />
+        android:title="@string/exit" />
 
 </menu>

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

@@ -11,14 +11,41 @@
     <!-- Toast shown if user denies request to enable bluetooth -->
     <string name="bluetooth_required">Bluetooth is required for this app.</string>
 
-    <!-- Menu item to close app and stop service -->
-    <string name="exit">Exit</string>
-
 
     <!-- ContactsFragment -->
 
     <!-- Empty text for contacts list -->
-    <string name="no_contacts_found">No contacts found :(</string>
+    <string name="no_contacts_found">You haven\'t added any contacts yet</string>
+
+    <!-- Menu item to close app and stop service -->
+    <string name="exit">Exit</string>
+
+
+    <!-- ChatFragment -->
+
+    <!-- Toast shown when trying to send a message to an offline contact -->
+    <string name="contact_offline_toast">Contact is offline, message not sent</string>
+
+
+    <!-- AddContactsActivity -->
+
+    <!-- Activity title -->
+    <string name="add_contacts">Add Contacts</string>
+
+    <!-- Title of dialog shown when clicking a device -->
+    <string name="add_contact_dialog">Do you want to add %1$s as a new contact?</string>
+
+    <!-- Empty text for devices list -->
+    <string name="no_devices_nearby">No nearby devices found</string>
+
+    <!-- Toast shown when trying to add a contact again -->
+    <string name="contact_already_added">You already added this contact</string>
+
+    <!-- Toast shown when a new contact was added. Parameter is contact name -->
+    <string name="contact_added">%1$s was added as a contact</string>
+
+    <!-- Toast shown when a contact is not added because it was not accepted on the other device -->
+    <string name="contact_not_added">Contact not added (denied by other device)</string>
 
 
     <!-- SettingsActivity -->

app/src/main/scala/com/nutomic/ensichat/activities/AddContactsActivity.scala

@@ -0,0 +1,178 @@
+package com.nutomic.ensichat.activities
+
+import java.util.Date
+
+import android.app.AlertDialog
+import android.content.DialogInterface
+import android.content.DialogInterface.OnClickListener
+import android.os.Bundle
+import android.view._
+import android.widget.AdapterView.OnItemClickListener
+import android.widget.{AdapterView, ListView, Toast}
+import com.nutomic.ensichat.R
+import com.nutomic.ensichat.bluetooth.ChatService.OnMessageReceivedListener
+import com.nutomic.ensichat.bluetooth.{ChatService, Device}
+import com.nutomic.ensichat.messages.{Message, RequestAddContactMessage, ResultAddContactMessage}
+import com.nutomic.ensichat.util.DevicesAdapter
+
+import scala.collection.SortedSet
+
+/**
+ * Lists all nearby, connected devices and allows adding them to contacts.
+ *
+ * Adding a contact requires confirmation on both sides.
+ */
+class AddContactsActivity extends EnsiChatActivity with ChatService.OnConnectionChangedListener
+  with OnItemClickListener with OnMessageReceivedListener {
+
+  private lazy val Adapter = new DevicesAdapter(this)
+
+  private lazy val Database = service.database
+
+  /**
+   * Map of devices that should be added.
+   */
+  private var currentlyAdding = Map[Device.ID, AddContactInfo]()
+    .withDefaultValue(new AddContactInfo(false, false))
+
+  /**
+   * Holds confirmation status for adding contacts.
+   *
+   * @param localConfirmed If true, the local user has accepted adding the contact.
+   * @param remoteConfirmed If true, the remote contact has accepted adding this device as contact.
+   */
+  private class AddContactInfo(val localConfirmed: Boolean, val remoteConfirmed: Boolean) {
+  }
+
+  /**
+   * Initializes layout, registers connection and message listeners.
+   */
+  override def onCreate(savedInstanceState: Bundle): Unit = {
+    super.onCreate(savedInstanceState)
+
+    setContentView(R.layout.activity_add_contacts)
+    val list = findViewById(android.R.id.list).asInstanceOf[ListView]
+    list.setAdapter(Adapter)
+    list.setOnItemClickListener(this)
+
+    runOnServiceConnected(() => {
+      service.registerConnectionListener(AddContactsActivity.this)
+      service.registerMessageListener(this)
+    })
+  }
+
+  /**
+   * Displays newly connected devices in the list.
+   */
+  override def onConnectionChanged(devices: Map[Device.ID, Device]): Unit = {
+    val filtered = devices.filter{ case (_, d) => d.Connected }
+    runOnUiThread(new Runnable {
+      override def run(): Unit  = {
+        Adapter.clear()
+        filtered.values.foreach(f => Adapter.add(f))
+      }
+    })
+  }
+
+  /**
+   * Initiates adding the device as contact if it hasn't been added yet.
+   */
+  override def onItemClick(parent: AdapterView[_], view: View, position: Int, id: Long): Unit = {
+    val device = Adapter.getItem(position)
+    if (Database.isContact(device.Id)) {
+      Toast.makeText(this, R.string.contact_already_added, Toast.LENGTH_SHORT).show()
+      return
+    }
+
+    service.send(new RequestAddContactMessage(service.localDeviceId, device.Id, new Date()))
+    addDeviceDialog(device)
+  }
+
+  /**
+   * Shows a dialog to accept/deny adding a device as a new contact.
+   */
+  private def addDeviceDialog(device: Device): Unit = {
+    val id = device.Id
+    // Listener for dialog button clicks.
+    val onClick = new OnClickListener {
+      override def onClick(dialogInterface: DialogInterface, i: Int): Unit = i match {
+        case DialogInterface.BUTTON_POSITIVE =>
+          // Local user accepted contact, update state and send info to other device.
+          currentlyAdding += (id -> new AddContactInfo(currentlyAdding(id).localConfirmed, true))
+          addContactIfBothConfirmed(device)
+          service.send(
+            new ResultAddContactMessage(service.localDeviceId, device.Id, new Date(), true))
+        case DialogInterface.BUTTON_NEGATIVE =>
+          // Local user denied adding contact, send info to other device.
+          service.send(
+            new ResultAddContactMessage(service.localDeviceId, device.Id, new Date(), false))
+      }
+    }
+
+    new AlertDialog.Builder(this)
+      .setTitle(getString(R.string.add_contact_dialog, device.Name))
+      .setPositiveButton(android.R.string.yes, onClick)
+      .setNegativeButton(android.R.string.no, onClick)
+      .show()
+  }
+
+  /**
+   * Handles incoming [[RequestAddContactMessage]] and [[ResultAddContactMessage]] messages.
+   *
+   * These are only handled here and require user action, so contacts can only be added if
+   * the user is in this activity.
+   */
+  override def onMessageReceived(messages: SortedSet[Message]): Unit = {
+    messages.foreach(m => {
+      if (m.receiver == service.localDeviceId) {
+        m.messageType match {
+        case Message.Type.RequestAddContact =>
+          // Remote device wants to add us as a contact, show dialog.
+          val sender = getDevice(m.sender)
+          addDeviceDialog(sender)
+        case Message.Type.ResultAddContact =>
+          if (m.asInstanceOf[ResultAddContactMessage].Accepted) {
+            // Remote device accepted us as a contact, update state.
+            currentlyAdding += (m.sender ->
+              new AddContactInfo(true, currentlyAdding(m.sender).remoteConfirmed))
+            addContactIfBothConfirmed(getDevice(m.sender))
+          } else {
+            // Remote device denied us as a contact, show a toast
+            // and remove from [[currentlyAdding]].
+            Toast.makeText(this, R.string.contact_not_added, Toast.LENGTH_LONG).show()
+            currentlyAdding -= m.sender
+          }
+        case _ =>
+        }
+      }
+    })
+  }
+
+  /**
+   * Returns the [[Device]] for a given [[Device.ID]] that is stored in the [[Adapter]].
+   */
+  private def getDevice(id: Device.ID): Device = {
+    // ArrayAdapter does not return the underlying array so we have to access it manually.
+    for (i <- 0 until Adapter.getCount) {
+      if (Adapter.getItem(i).Id == id) {
+        return Adapter.getItem(i)
+      }
+    }
+    throw new RuntimeException("Device to add was not found")
+  }
+
+  /**
+   * Add the given device to contacts if [[AddContactInfo.localConfirmed]] and
+   * [[AddContactInfo.remoteConfirmed]] are true for it in [[currentlyAdding]].
+   */
+  private def addContactIfBothConfirmed(device: Device): Unit = {
+    val info = currentlyAdding(device.Id)
+    if (info.localConfirmed && info.remoteConfirmed) {
+      Database.addContact(device)
+      Toast.makeText(this, getString(R.string.contact_added, device.Name), Toast.LENGTH_SHORT)
+        .show()
+    }
+    currentlyAdding -= device.Id
+  }
+
+}

app/src/main/scala/com/nutomic/ensichat/activities/MainActivity.scala

@@ -6,7 +6,7 @@ import android.content._
 import android.os.Bundle
 import android.widget.Toast
 import com.nutomic.ensichat.R
-import com.nutomic.ensichat.bluetooth.{ChatService, Device}
+import com.nutomic.ensichat.bluetooth.Device
 import com.nutomic.ensichat.fragments.{ChatFragment, ContactsFragment}
 
 /**
@@ -89,7 +89,7 @@ class MainActivity extends EnsiChatActivity {
     if (currentChat != None) {
       getFragmentManager
         .beginTransaction()
-        .remove(getFragmentManager().findFragmentById(android.R.id.content))
+        .remove(getFragmentManager.findFragmentById(android.R.id.content))
         .attach(ContactsFragment)
         .commit()
       currentChat = None

app/src/main/scala/com/nutomic/ensichat/bluetooth/ChatService.scala

@@ -1,5 +1,6 @@
 package com.nutomic.ensichat.bluetooth
 
+import java.security.InvalidParameterException
 import java.util.{Date, UUID}
 
 import android.app.Service
@@ -8,12 +9,13 @@ import android.content.{BroadcastReceiver, Context, Intent, IntentFilter}
 import android.os.Handler
 import android.preference.PreferenceManager
 import android.util.Log
-import com.nutomic.ensichat.R
 import com.nutomic.ensichat.bluetooth.ChatService.{OnConnectionChangedListener, OnMessageReceivedListener}
 import com.nutomic.ensichat.messages._
+import com.nutomic.ensichat.util.Database
+import com.nutomic.ensichat.{BuildConfig, R}
 
+import scala.collection.SortedSet
 import scala.collection.immutable.{HashMap, HashSet, TreeSet}
-import scala.collection.{SortedSet, mutable}
 import scala.ref.WeakReference
 
 object ChatService {
@@ -53,9 +55,7 @@ class ChatService extends Service {
    */
   private var connectionListeners = new HashSet[WeakReference[OnConnectionChangedListener]]()
 
-  private val messageListeners =
-    mutable.HashMap[Device.ID, mutable.Set[WeakReference[OnMessageReceivedListener]]]()
-      .withDefaultValue(mutable.Set[WeakReference[OnMessageReceivedListener]]())
+  private var messageListeners = Set[WeakReference[OnMessageReceivedListener]]()
 
   private var devices = new HashMap[Device.ID, Device]()
 
@@ -67,7 +67,7 @@ class ChatService extends Service {
 
   private val MainHandler = new Handler()
 
-  private var MessageStore: MessageStore = _
+  private lazy val Database = new Database(this)
 
   private lazy val Crypto = new Crypto(getFilesDir)
 
@@ -77,8 +77,6 @@ class ChatService extends Service {
   override def onCreate(): Unit = {
     super.onCreate()
 
-    MessageStore = new MessageStore(this)
-
     bluetoothAdapter = BluetoothAdapter.getDefaultAdapter
 
     registerReceiver(DeviceDiscoveredReceiver, new IntentFilter(BluetoothDevice.ACTION_FOUND))
@@ -137,7 +135,7 @@ class ChatService extends Service {
     override def onReceive(context: Context, intent: Intent) {
       val device: Device =
         new Device(intent.getParcelableExtra(BluetoothDevice.EXTRA_DEVICE), false)
-      devices += (device.id -> device)
+      devices += (device.Id -> device)
       new ConnectThread(device, onConnectionChanged).start()
     }
   }
@@ -191,13 +189,14 @@ class ChatService extends Service {
    * @param socket A socket for data transfer if device.connected is true, otherwise null.
    */
   def onConnectionChanged(device: Device, socket: BluetoothSocket): Unit = {
-    devices += (device.id -> device)
+    devices += (device.Id -> device)
 
-    if (device.connected) {
-      connections += (device.id ->
+    if (device.Connected) {
+      connections += (device.Id ->
         new TransferThread(device, socket, this, Crypto, handleNewMessage))
-      connections(device.id).start()
-      send(new DeviceInfoMessage(localDeviceId, device.id, new Date(), Crypto.getLocalPublicKey))
+      connections(device.Id).start()
+      connections.apply(device.Id).send(
+        new DeviceInfoMessage(localDeviceId, device.Id, new Date(), Crypto.getLocalPublicKey))
     }
 
     connectionListeners.foreach(l => l.get match {
@@ -210,6 +209,9 @@ class ChatService extends Service {
    * Sends message to the device specified as receiver,
    */
   def send(message: Message): Unit = {
+    if (BuildConfig.DEBUG && message.sender != localDeviceId) {
+      throw new InvalidParameterException("Message must be sent from local device")
+    }
     connections.apply(message.receiver).send(message)
     handleNewMessage(message)
   }
@@ -218,16 +220,22 @@ class ChatService extends Service {
    * Saves the message to database and sends it to registered listeners.
    *
    * If you want to send a new message, use [[send]].
+   *
+   * Messages must always be sent between local device and a contact.
    */
   private def handleNewMessage(message: Message): Unit = {
-    MessageStore.addMessage(message)
+    if (BuildConfig.DEBUG && message.sender != localDeviceId && message.receiver != localDeviceId) {
+      throw new InvalidParameterException("Message must be sent or received by local device")
+    }
+
+    Database.addMessage(message)
     MainHandler.post(new Runnable {
       override def run(): Unit = {
-        messageListeners(message.sender).foreach(l =>
+        messageListeners.foreach(l =>
           if (l.get != null)
             l.apply().onMessageReceived(new TreeSet[Message]()(Message.Ordering) + message)
           else
-            messageListeners(message.sender) -= l)
+            messageListeners -= l)
       }
     })
   }
@@ -235,9 +243,8 @@ class ChatService extends Service {
   /**
    * Registers a listener that is called whenever a new message is sent or received.
    */
-  def registerMessageListener(device: Device.ID, listener: OnMessageReceivedListener): Unit = {
-    messageListeners(device) += new WeakReference[OnMessageReceivedListener](listener)
-    listener.onMessageReceived(MessageStore.getMessages(device, 10))
+  def registerMessageListener(listener: OnMessageReceivedListener): Unit = {
+    messageListeners += new WeakReference[OnMessageReceivedListener](listener)
   }
 
   /**
@@ -245,4 +252,8 @@ class ChatService extends Service {
    */
   def localDeviceId = new Device.ID(bluetoothAdapter.getAddress)
 
+  def isConnected(device: Device.ID): Boolean = connections.keySet.contains(device)
+
+  def database = Database
+
 }

app/src/main/scala/com/nutomic/ensichat/bluetooth/ConnectThread.scala

@@ -32,7 +32,7 @@ class ConnectThread(device: Device, onConnected: (Device, BluetoothSocket) => Un
         return
     }
 
-    Log.i(Tag, "Successfully connected to device " + device.name)
+    Log.i(Tag, "Successfully connected to device " + device.Name)
     onConnected(new Device(device.bluetoothDevice, true), Socket)
   }
 

app/src/main/scala/com/nutomic/ensichat/bluetooth/Device.scala

@@ -28,16 +28,13 @@ object Device {
 /**
  * Holds information about a remote bluetooth device.
  */
-class Device(BluetoothDevice: BluetoothDevice, Connected: Boolean) {
+class Device(val Id: Device.ID, val Name: String, val Connected: Boolean,
+             btDevice: Option[BluetoothDevice] = None) {
 
-  def id = new Device.ID(bluetoothDevice.getAddress)
+  def this(btDevice: BluetoothDevice, connected: Boolean) {
+    this(new Device.ID(btDevice.getAddress), btDevice.getName, connected, Option(btDevice))
+  }
 
-  def name = BluetoothDevice.getName
-
-  def connected = Connected
-
-  def bluetoothDevice = BluetoothDevice
-
-  override def toString = "Device(" + name + ", " + bluetoothDevice.getAddress + ")"
+  def bluetoothDevice = btDevice.get
 
 }

app/src/main/scala/com/nutomic/ensichat/bluetooth/TransferThread.scala

@@ -4,7 +4,7 @@ import java.io._
 
 import android.bluetooth.BluetoothSocket
 import android.util.Log
-import com.nutomic.ensichat.messages.{Crypto, DeviceInfoMessage, Message, TextMessage}
+import com.nutomic.ensichat.messages.{Crypto, DeviceInfoMessage, Message}
 import org.msgpack.ScalaMessagePack
 
 /**
@@ -22,16 +22,6 @@ class TransferThread(device: Device, socket: BluetoothSocket, service: ChatServi
 
   private val Tag: String = "TransferThread"
 
-  /**
-   * First value in a message, indicates that content is not encrypted.
-   */
-  private val MessageUnencrypted = false
-
-  /**
-   * First value in a message, indicates that content is encrypted.
-   */
-  private val MessageEncrypted = true
-
   val InStream: InputStream =
     try {
       socket.getInputStream
@@ -56,53 +46,54 @@ class TransferThread(device: Device, socket: BluetoothSocket, service: ChatServi
     while (socket.isConnected) {
       try {
         val up = new ScalaMessagePack().createUnpacker(InStream)
-        val plain = up.readBoolean() match {
-          case MessageEncrypted =>
+        val isEncrypted = up.readBoolean() 
+        val plain =
+          if (isEncrypted) {
             val encrypted = up.readByteArray()
             val key = up.readByteArray()
             crypto.decrypt(encrypted, key)
-          case MessageUnencrypted =>
+          } else {
             up.readByteArray()
-        }
+          }
         val (message, signature) = Message.read(plain)
         var messageValid = true
 
-        if (message.sender != device.id) {
-          Log.i(Tag, "Dropping message with invalid sender from " + device.id)
+        if (message.sender != device.Id) {
+          Log.i(Tag, "Dropping message with invalid sender from " + device.Id)
           messageValid = false
         }
 
         if (message.receiver != service.localDeviceId) {
-          Log.i(Tag, "Dropping message with different receiver from " + device.id)
+          Log.i(Tag, "Dropping message with different receiver from " + device.Id)
           messageValid = false
         }
 
         // Add public key for new, directly connected device.
         // Explicitly check that message was not forwarded or spoofed.
         if (message.isInstanceOf[DeviceInfoMessage] && !crypto.havePublicKey(message.sender) &&
-            message.sender == device.id) {
+            message.sender == device.Id) {
           val dim = message.asInstanceOf[DeviceInfoMessage]
           // Permanently store public key for new local devices (also check signature).
           if (crypto.isValidSignature(message, signature, dim.publicKey)) {
-            crypto.addPublicKey(device.id, dim.publicKey)
-            Log.i(Tag, "Added public key for new device " + device.name)
+            crypto.addPublicKey(device.Id, dim.publicKey)
+            Log.i(Tag, "Added public key for new device " + device.Name)
           }
         }
 
         if (!crypto.isValidSignature(message, signature)) {
-          Log.i(Tag, "Dropping message with invalid signature from " + device.id)
+          Log.i(Tag, "Dropping message with invalid signature from " + device.Id)
           messageValid = false
         }
 
         if (messageValid) {
           message match {
-            case m: TextMessage => onReceive(m)
             case m: DeviceInfoMessage => crypto.addPublicKey(message.sender, m.publicKey)
+            case _ => onReceive(message)
           }
         }
       } catch {
         case e: IOException =>
-          Log.w(Tag, "Connection to " + device.name + " closed with exception", e)
+          Log.w(Tag, "Connection to " + device.Name + " closed with exception", e)
           service.onConnectionChanged(new Device(device.bluetoothDevice, false), null)
           return
       }
@@ -118,11 +109,13 @@ class TransferThread(device: Device, socket: BluetoothSocket, service: ChatServi
       message.messageType match {
         case Message.Type.Text =>
           val (encrypted, key) = crypto.encrypt(message.receiver, plain)
-          packer.write(MessageEncrypted)
+          // Message is encrypted.
+          packer.write(true)
             .write(encrypted)
             .write(key)
-        case Message.Type.DeviceInfo =>
-          packer.write(MessageUnencrypted)
+        case _ =>
+          // Message is not encrypted.
+          packer.write(false)
             .write(plain)
       }
     } catch {

app/src/main/scala/com/nutomic/ensichat/fragments/ChatFragment.scala

@@ -3,8 +3,7 @@ package com.nutomic.ensichat.fragments
 import java.util.Date
 
 import android.app.ListFragment
-import android.content.{ComponentName, Context, Intent, ServiceConnection}
-import android.os.{Bundle, IBinder}
+import android.os.Bundle
 import android.view.View.OnClickListener
 import android.view.inputmethod.EditorInfo
 import android.view.{KeyEvent, LayoutInflater, View, ViewGroup}
@@ -13,7 +12,7 @@ import android.widget._
 import com.nutomic.ensichat.R
 import com.nutomic.ensichat.activities.EnsiChatActivity
 import com.nutomic.ensichat.bluetooth.ChatService.OnMessageReceivedListener
-import com.nutomic.ensichat.bluetooth.{ChatService, ChatServiceBinder, Device}
+import com.nutomic.ensichat.bluetooth.{ChatService, Device}
 import com.nutomic.ensichat.messages.{Message, TextMessage}
 import com.nutomic.ensichat.util.MessagesAdapter
 
@@ -51,7 +50,8 @@ class ChatFragment extends ListFragment with OnClickListener
 
       // Read local device ID from service,
       adapter = new MessagesAdapter(getActivity, chatService.localDeviceId)
-      chatService.registerMessageListener(device, ChatFragment.this)
+      chatService.registerMessageListener(ChatFragment.this)
+      onMessageReceived(chatService.database.getMessages(device, 10))
 
       if (listView != null) {
         listView.setAdapter(adapter)
@@ -100,6 +100,10 @@ class ChatFragment extends ListFragment with OnClickListener
       case R.id.send =>
         val text: String = messageText.getText.toString
         if (!text.isEmpty) {
+          if (!chatService.isConnected(device)) {
+            Toast.makeText(getActivity, R.string.contact_offline_toast, Toast.LENGTH_SHORT).show()
+            return
+          }
           chatService.send(
             new TextMessage(chatService.localDeviceId, device, new Date(), text.toString))
           messageText.getText.clear()
@@ -111,7 +115,8 @@ class ChatFragment extends ListFragment with OnClickListener
    * Displays new messages in UI.
    */
   override def onMessageReceived(messages: SortedSet[Message]): Unit = {
-    messages.filter(_.isInstanceOf[TextMessage])
+    messages.filter(m => m.sender == device || m.receiver == device)
+      .filter(_.isInstanceOf[TextMessage])
       .foreach(m => adapter.add(m.asInstanceOf[TextMessage]))
   }
 

app/src/main/scala/com/nutomic/ensichat/fragments/ContactsFragment.scala

@@ -1,42 +1,43 @@
 package com.nutomic.ensichat.fragments
 
 import android.app.ListFragment
-import android.content.{ComponentName, Context, Intent, ServiceConnection}
-import android.os.{Bundle, IBinder}
+import android.content.Intent
+import android.os.Bundle
 import android.view._
-import android.widget.{ArrayAdapter, ListView}
+import android.widget.ListView
 import com.nutomic.ensichat.R
-import com.nutomic.ensichat.activities.{SettingsActivity, EnsiChatActivity, MainActivity}
-import com.nutomic.ensichat.bluetooth.{ChatService, ChatServiceBinder, Device}
-import com.nutomic.ensichat.util.{MessagesAdapter, DevicesAdapter}
+import com.nutomic.ensichat.activities.{AddContactsActivity, EnsiChatActivity, MainActivity, SettingsActivity}
+import com.nutomic.ensichat.bluetooth.ChatService
+import com.nutomic.ensichat.util.DevicesAdapter
 
 /**
  * Lists all nearby, connected devices.
  */
-class ContactsFragment extends ListFragment with ChatService.OnConnectionChangedListener {
+class ContactsFragment extends ListFragment {
 
-  private lazy val adapter = new DevicesAdapter(getActivity)
+  private lazy val Adapter = new DevicesAdapter(getActivity)
 
-  override def onActivityCreated(savedInstanceState: Bundle): Unit = {
-    super.onActivityCreated(savedInstanceState)
-
-    val activity = getActivity.asInstanceOf[EnsiChatActivity]
-    activity.runOnServiceConnected(() => {
-      activity.service.registerConnectionListener(ContactsFragment.this)
-    })
-  }
-
-  override def onCreateView(inflater: LayoutInflater, container: ViewGroup,
-        savedInstanceState: Bundle): View =
-    inflater.inflate(R.layout.fragment_contacts, container, false)
+  private lazy val Database = getActivity.asInstanceOf[EnsiChatActivity].service.database
 
   override def onCreate(savedInstanceState: Bundle): Unit = {
     super.onCreate(savedInstanceState)
 
-    setListAdapter(adapter)
+    setListAdapter(Adapter)
     setHasOptionsMenu(true)
+
+    getActivity.asInstanceOf[EnsiChatActivity].runOnServiceConnected(() => {
+      Database.getContacts.foreach(Adapter.add)
+      Database.runOnContactsUpdated(() => {
+        Adapter.clear()
+        Database.getContacts.foreach(Adapter.add)
+      })
+    })
   }
 
+  override def onCreateView(inflater: LayoutInflater, container: ViewGroup,
+                            savedInstanceState: Bundle): View =
+    inflater.inflate(R.layout.fragment_contacts, container, false)
+
   override def onCreateOptionsMenu(menu: Menu, inflater: MenuInflater): Unit = {
     super.onCreateOptionsMenu(menu, inflater)
     inflater.inflate(R.menu.main, menu)
@@ -44,6 +45,9 @@ class ContactsFragment extends ListFragment with ChatService.OnConnectionChanged
 
   override def onOptionsItemSelected(item: MenuItem): Boolean = {
     item.getItemId match {
+      case R.id.add_contact =>
+        startActivity(new Intent(getActivity, classOf[AddContactsActivity]))
+        true
       case R.id.settings =>
         startActivity(new Intent(getActivity, classOf[SettingsActivity]))
         true
@@ -56,26 +60,10 @@ class ContactsFragment extends ListFragment with ChatService.OnConnectionChanged
     }
   }
 
-  /**
-   * Displays newly connected devices in the list.
-   */
-  override def onConnectionChanged(devices: Map[Device.ID, Device]): Unit = {
-    if (getActivity == null)
-      return
-
-    val filtered = devices.filter{ case (_, d) => d.connected }
-    getActivity.runOnUiThread(new Runnable {
-      override def run(): Unit  = {
-        adapter.clear()
-        filtered.values.foreach(f => adapter.add(f))
-      }
-    })
-  }
-
   /**
    * Opens a chat with the clicked device.
    */
   override def onListItemClick(l: ListView, v: View, position: Int, id: Long): Unit =
-    getActivity.asInstanceOf[MainActivity].openChat(adapter.getItem(position).id)
+    getActivity.asInstanceOf[MainActivity].openChat(Adapter.getItem(position).Id)
 
 }

app/src/main/scala/com/nutomic/ensichat/fragments/SettingsFragment.scala

@@ -2,7 +2,6 @@ package com.nutomic.ensichat.fragments
 
 import android.os.Bundle
 import android.preference.PreferenceFragment
-
 import com.nutomic.ensichat.R
 
 class SettingsFragment extends PreferenceFragment {

app/src/main/scala/com/nutomic/ensichat/messages/Message.scala

@@ -11,11 +11,13 @@ object Message {
   /**
    * Types of messages that can be transfered.
    *
-   * There must be one type for each implementation.
+   * There must be one type for each implementation and vice versa.
    */
   object Type {
     val Text = 1
     val DeviceInfo = 2
+    val RequestAddContact = 3
+    val ResultAddContact = 4
   }
 
   /**
@@ -40,8 +42,10 @@ object Message {
     val date        = new Date(up.readLong())
     val sig         = up.readByteArray()
     (messageType match {
-      case Type.Text       => TextMessage.read(sender, receiver, date, up)
-      case Type.DeviceInfo => DeviceInfoMessage.read(sender, receiver, date, up)
+      case Type.Text              => TextMessage.read(sender, receiver, date, up)
+      case Type.DeviceInfo        => DeviceInfoMessage.read(sender, receiver, date, up)
+      case Type.RequestAddContact => RequestAddContactMessage.read(sender, receiver, date, up)
+      case Type.ResultAddContact  => ResultAddContactMessage.read(sender, receiver, date, up)
     }, sig)
   }
 

app/src/main/scala/com/nutomic/ensichat/messages/MessageStore.scala

@@ -1,79 +0,0 @@
-package com.nutomic.ensichat.messages
-
-import java.util.Date
-
-import android.content.{ContentValues, Context}
-import android.database.Cursor
-import android.database.sqlite.{SQLiteDatabase, SQLiteOpenHelper}
-import com.nutomic.ensichat.bluetooth.Device
-
-import scala.collection.SortedSet
-import scala.collection.immutable.TreeSet
-
-object MessageStore {
-
-  private val DatabaseName = "message_store.db"
-
-  private val DatabaseVersion = 1
-
-  private val DatabaseCreate = "CREATE TABLE messages(" +
-    "_id integer primary key autoincrement," +
-    "sender string not null," +
-    "receiver string not null," +
-    "text blob not null," +
-    "date integer not null);" // Unix timestamp of message.
-
-}
-
-/**
- * Stores all messages in SQL database.
- */
-class MessageStore(context: Context) extends SQLiteOpenHelper(context, MessageStore.DatabaseName,
-                                                              null, MessageStore.DatabaseVersion) {
-
-  private val Tag = "MessageStore"
-
-  override def onCreate(db: SQLiteDatabase): Unit = {
-    db.execSQL(MessageStore.DatabaseCreate)
-  }
-
-  /**
-   * Returns the count last messages for device.
-   */
-  def getMessages(device: Device.ID, count: Int): SortedSet[Message] = {
-    val c: Cursor = getReadableDatabase.query(true,
-      "messages", Array("sender", "receiver", "text", "date"),
-      "sender = ? OR receiver = ?", Array(device.toString, device.toString),
-      null, null, "date DESC", count.toString)
-    var messages: SortedSet[Message] = new TreeSet[Message]()(Message.Ordering)
-    while (c.moveToNext()) {
-      val m: TextMessage = new TextMessage(
-        new Device.ID(c.getString(c.getColumnIndex("sender"))),
-        new Device.ID(c.getString(c.getColumnIndex("receiver"))),
-        new Date(c.getLong(c.getColumnIndex("date"))),
-        new String(c.getString(c.getColumnIndex ("text"))))
-      messages += m
-    }
-    c.close()
-    messages
-  }
-
-  /**
-   * Inserts the given new message into the database.
-   */
-  def addMessage(message: Message): Unit = message match {
-    case msg: TextMessage =>
-      val cv: ContentValues =  new ContentValues()
-      cv.put("sender", msg.sender.toString)
-      cv.put("receiver", msg.receiver.toString)
-      // toString used as workaround for compile error with Long.
-      cv.put("date", msg.date.getTime.toString)
-      cv.put("text", msg.text)
-      getWritableDatabase.insert("messages", null, cv)
-    case msg: DeviceInfoMessage => // Never stored.
-  }
-
-  override def onUpgrade(db: SQLiteDatabase, oldVersion: Int, newVersion: Int): Unit = {
-  }
-
-}

app/src/main/scala/com/nutomic/ensichat/messages/RequestAddContactMessage.scala

@@ -0,0 +1,30 @@
+package com.nutomic.ensichat.messages
+
+import java.util.Date
+
+import com.nutomic.ensichat.activities.AddContactsActivity
+import com.nutomic.ensichat.bluetooth.Device
+import com.nutomic.ensichat.messages.Message._
+import org.msgpack.packer.Packer
+import org.msgpack.unpacker.Unpacker
+
+object RequestAddContactMessage {
+
+  def read(sender: Device.ID, receiver: Device.ID, date: Date, up: Unpacker) =
+    new RequestAddContactMessage(sender, receiver, date)
+
+}
+
+/**
+ * Message sent by [[AddContactsActivity]] to notify a device that it should be added as a contact.
+ */
+class RequestAddContactMessage(override val sender: Device.ID, override val receiver: Device.ID,
+                               override val date: Date) extends Message(Type.RequestAddContact) {
+
+  override def doWrite(packer: Packer) = {
+  }
+
+  override def toString = "RequestAddContactMessage(" + sender.toString + ", " + receiver.toString +
+    ", " + date.toString + ")"
+
+}

app/src/main/scala/com/nutomic/ensichat/messages/ResultAddContactMessage.scala

@@ -0,0 +1,36 @@
+package com.nutomic.ensichat.messages
+
+import java.util.Date
+
+import com.nutomic.ensichat.activities.AddContactsActivity
+import com.nutomic.ensichat.bluetooth.Device
+import com.nutomic.ensichat.messages.Message._
+import org.msgpack.packer.Packer
+import org.msgpack.unpacker.Unpacker
+
+object ResultAddContactMessage {
+
+  def read(sender: Device.ID, receiver: Device.ID, date: Date, up: Unpacker) =
+    new ResultAddContactMessage(sender, receiver, date, up.readBoolean())
+
+}
+
+/**
+ * Message sent by [[AddContactsActivity]] to tell a device whether the user confirmed adding it
+ * to contacts.
+ */
+class ResultAddContactMessage(override val sender: Device.ID, override val receiver: Device.ID,
+                              override val date: Date, val Accepted: Boolean)
+  extends Message(Type.ResultAddContact) {
+
+  override def doWrite(packer: Packer) = packer.write(Accepted)
+
+  override def equals(a: Any) =
+    super.equals(a) && a.asInstanceOf[ResultAddContactMessage].Accepted == Accepted
+
+  override def hashCode = super.hashCode + Accepted.hashCode
+
+  override def toString = "ResultAddContactMessage(" + sender.toString + ", " + receiver.toString +
+    ", " + date.toString + ", " + Accepted + ")"
+
+}

app/src/main/scala/com/nutomic/ensichat/util/Database.scala

@@ -0,0 +1,127 @@
+package com.nutomic.ensichat.util
+
+import java.util.Date
+
+import android.content.{ContentValues, Context}
+import android.database.sqlite.{SQLiteDatabase, SQLiteOpenHelper}
+import com.nutomic.ensichat.bluetooth.Device
+import com.nutomic.ensichat.messages.{Message, TextMessage}
+
+import scala.collection.SortedSet
+import scala.collection.immutable.TreeSet
+
+object Database {
+
+  private val DatabaseName = "message_store.db"
+
+  private val DatabaseVersion = 1
+
+  private val CreateMessagesTable = "CREATE TABLE messages(" +
+    "_id integer primary key autoincrement," +
+    "sender string not null," +
+    "receiver string not null," +
+    "text blob not null," +
+    "date integer not null);" // Unix timestamp of message.
+
+  private val CreateContactsTable = "CREATE TABLE contacts(" +
+    "_id integer primary key autoincrement," +
+    "device_id string not null," +
+    "name string not null)"
+
+}
+
+/**
+ * Stores all messages and contacts in SQL database.
+ */
+class Database(context: Context) extends SQLiteOpenHelper(context, Database.DatabaseName,
+                                                          null, Database.DatabaseVersion) {
+
+  private val Tag = "MessageStore"
+
+  private var contactsUpdatedListeners = Set[() => Unit]()
+
+  override def onCreate(db: SQLiteDatabase): Unit = {
+    db.execSQL(Database.CreateContactsTable)
+    db.execSQL(Database.CreateMessagesTable)
+  }
+
+  /**
+   * Returns the count last messages for device.
+   */
+  def getMessages(device: Device.ID, count: Int): SortedSet[Message] = {
+    val c = getReadableDatabase.query(true,
+      "messages", Array("sender", "receiver", "text", "date"),
+      "sender = ? OR receiver = ?", Array(device.toString, device.toString),
+      null, null, "date DESC", count.toString)
+    var messages = new TreeSet[Message]()(Message.Ordering)
+    while (c.moveToNext()) {
+      val m = new TextMessage(
+        new Device.ID(c.getString(c.getColumnIndex("sender"))),
+        new Device.ID(c.getString(c.getColumnIndex("receiver"))),
+        new Date(c.getLong(c.getColumnIndex("date"))),
+        new String(c.getString(c.getColumnIndex ("text"))))
+      messages += m
+    }
+    c.close()
+    messages
+  }
+
+  /**
+   * Inserts the given new message into the database.
+   */
+  def addMessage(message: Message): Unit = message match {
+    case msg: TextMessage =>
+      val cv =  new ContentValues()
+      cv.put("sender", msg.sender.toString)
+      cv.put("receiver", msg.receiver.toString)
+      // toString used as workaround for compile error with Long.
+      cv.put("date", msg.date.getTime.toString)
+      cv.put("text", msg.text)
+      getWritableDatabase.insert("messages", null, cv)
+    case _ => // Never stored.
+  }
+
+  /**
+   * Returns a list of all contacts of this device.
+   */
+  def getContacts: Set[Device] = {
+    val c = getReadableDatabase.query(true, "contacts", Array("device_id", "name"), "", Array(),
+      null, null, "name DESC", null)
+    var contacts = Set[Device]()
+    while (c.moveToNext()) {
+      contacts += new Device(new Device.ID(c.getString(c.getColumnIndex("device_id"))),
+                              c.getString(c.getColumnIndex("name")), false)
+    }
+    c.close()
+    contacts
+  }
+
+  /**
+   * Returns true if a contact with the given device ID exists.
+   */
+  def isContact(device: Device.ID): Boolean = {
+    val c = getReadableDatabase.query(true, "contacts", Array("_id"), "device_id = ?",
+      Array(device.toString), null, null, null, null)
+    c.getCount != 0
+  }
+
+  /**
+   * Inserts the given device into contacts.
+   */
+  def addContact(device: Device): Unit = {
+    val cv = new ContentValues()
+    cv.put("device_id", device.Id.toString)
+    cv.put("name", device.Name)
+    getWritableDatabase.insert("contacts", null, cv)
+    contactsUpdatedListeners.foreach(_())
+  }
+
+  /**
+   * Pass a callback that is called whenever a new contact is added.
+   */
+  def runOnContactsUpdated(l: () => Unit): Unit = contactsUpdatedListeners += l
+
+  override def onUpgrade(db: SQLiteDatabase, oldVersion: Int, newVersion: Int): Unit = {
+  }
+
+}

app/src/main/scala/com/nutomic/ensichat/util/DevicesAdapter.scala

@@ -11,11 +11,11 @@ import com.nutomic.ensichat.bluetooth.Device
 class DevicesAdapter(context: Context) extends
   ArrayAdapter[Device](context, android.R.layout.simple_list_item_1) {
 
-    override def getView(position: Int, convertView: View, parent: ViewGroup): View = {
-      val view = super.getView(position, convertView, parent)
-      val title: TextView = view.findViewById(android.R.id.text1).asInstanceOf[TextView]
-      title.setText(getItem(position).name)
-      view
-    }
+  override def getView(position: Int, convertView: View, parent: ViewGroup): View = {
+    val view = super.getView(position, convertView, parent)
+    val title: TextView = view.findViewById(android.R.id.text1).asInstanceOf[TextView]
+    title.setText(getItem(position).Name)
+    view
+  }
 
 }