Added IsWriting event on common, server and partially on client side

additionally fixed NullPointerException in ContactSearchScene and typo
in Javadoc

PS: this is the 1000th commit in Envoy! 🥳 🎉

client/src/main/java/envoy/client/data/Chat.java

@@ -9,6 +9,7 @@ import java.util.Objects;
 import envoy.client.net.WriteProxy;
 import envoy.data.*;
 import envoy.data.Message.MessageStatus;
+import envoy.event.IsWriting;
 import envoy.event.MessageStatusChange;
 
 /**
@@ -31,6 +32,12 @@ public class Chat implements Serializable {
 
 	protected int unreadAmount;
 
+	/**
+	 * Counts the milliseconds until another {@link IsWriting} event will be sent if
+	 * something is typed.
+	 */
+	protected transient long lastWritingEvent;
+
 	private static final long serialVersionUID = 1L;
 
 	/**
@@ -41,16 +48,14 @@ public class Chat implements Serializable {
 	 * @param recipient the user who receives the messages
 	 * @since Envoy Client v0.1-alpha
 	 */
-	public Chat(Contact recipient) {
-		this.recipient	= recipient;
-	}
+	public Chat(Contact recipient) { this.recipient = recipient; }
 
 	@Override
 	public String toString() { return String.format("Chat[recipient=%s,messages=%d]", recipient, messages.size()); }
 
 	/**
 	 * Generates a hash code based on the recipient.
-	 * 
+	 *
 	 * @since Envoy Client v0.1-beta
 	 */
 	@Override
@@ -58,14 +63,14 @@ public class Chat implements Serializable {
 
 	/**
 	 * Tests equality to another object based on the recipient.
-	 * 
+	 *
 	 * @since Envoy Client v0.1-beta
 	 */
 	@Override
 	public boolean equals(Object obj) {
 		if (this == obj) return true;
 		if (!(obj instanceof Chat)) return false;
-		Chat other = (Chat) obj;
+		final Chat other = (Chat) obj;
 		return Objects.equals(recipient, other.recipient);
 	}
 
@@ -101,7 +106,7 @@ public class Chat implements Serializable {
 
 	/**
 	 * Inserts a message at the correct place according to its creation date.
-	 * 
+	 *
 	 * @param message the message to insert
 	 * @since Envoy Client v0.1-beta
 	 */
@@ -116,13 +121,13 @@ public class Chat implements Serializable {
 
 	/**
 	 * Increments the amount of unread messages.
-	 * 
+	 *
 	 * @since Envoy Client v0.1-beta
 	 */
 	public void incrementUnreadAmount() { unreadAmount++; }
 
 	/**
-	 * @return the amount of unread mesages in this chat
+	 * @return the amount of unread messages in this chat
 	 * @since Envoy Client v0.1-beta
 	 */
 	public int getUnreadAmount() { return unreadAmount; }
@@ -150,4 +155,17 @@ public class Chat implements Serializable {
 	 * @since Envoy Client v0.1-beta
 	 */
 	public boolean isGroupChat() { return recipient instanceof Group; }
+
+	/**
+	 * @return the last known time a {@link IsWriting} event has been sent
+	 * @since Envoy Client v0.2-beta
+	 */
+	public long getLastWritingEvent() { return lastWritingEvent; }
+
+	/**
+	 * Sets the {@code lastWritingEvent} to {@code System#currentTimeMillis()}.
+	 *
+	 * @since Envoy Client v0.2-beta
+	 */
+	public void lastWritingEventWasNow() { lastWritingEvent = System.currentTimeMillis(); }
 }

client/src/main/java/envoy/client/net/Client.java

@@ -155,6 +155,9 @@ public class Client implements Closeable {
 		// Process group size changes
 		receiver.registerProcessor(GroupResize.class, evt -> { localDB.updateGroup(evt); eventBus.dispatch(evt); });
 
+		// Process IsWriting events
+		receiver.registerProcessor(IsWriting.class, eventBus::dispatch);
+
 		// Send event
 		eventBus.register(SendEvent.class, evt -> {
 			try {

client/src/main/java/envoy/client/ui/controller/ChatScene.java

@@ -33,6 +33,7 @@ import envoy.client.data.audio.AudioRecorder;
 import envoy.client.data.commands.SystemCommandBuilder;
 import envoy.client.data.commands.SystemCommandsMap;
 import envoy.client.event.MessageCreationEvent;
+import envoy.client.event.SendEvent;
 import envoy.client.net.Client;
 import envoy.client.net.WriteProxy;
 import envoy.client.ui.*;
@@ -444,10 +445,28 @@ public final class ChatScene implements Restorable {
 	private void checkKeyCombination(KeyEvent e) {
 		// Checks whether the text is too long
 		messageTextUpdated();
+		// Sending an IsWriting event if none has been sent for
+		// IsWriting#millisecondsActive
+		if (client.isOnline() && currentChat.getLastWritingEvent() + IsWriting.millisecondsActive <= System.currentTimeMillis()) {
+			eventBus.dispatch(new SendEvent(new IsWriting(getChatID(), currentChat.getRecipient().getID(), client.getSender().getName())));
+			currentChat.lastWritingEventWasNow();
+		}
 		// Automatic sending of messages via (ctrl +) enter
 		checkPostConditions(e);
 	}
 
+	/**
+	 * Returns the id that should be used to send things to the server:
+	 * the id of 'our' {@link User} if the recipient of that object is another User,
+	 * else the id of the {@link Group} 'our' user is sending to.
+	 *
+	 * @return an id that can be sent to the server
+	 * @since Envoy Client v0.2-beta
+	 */
+	private long getChatID() {
+		return currentChat.getRecipient() instanceof User ? client.getSender().getID() : currentChat.getRecipient().getID();
+	}
+
 	/**
 	 * @param e the keys that have been pressed
 	 * @since Envoy Client v0.1-beta
@@ -515,7 +534,7 @@ public final class ChatScene implements Restorable {
 			updateInfoLabel("You need to go online to send more messages", "infoLabel-error");
 			return;
 		}
-		final var	text					= messageTextArea.getText().strip();
+		final var text = messageTextArea.getText().strip();
 		if (!messageTextAreaCommands.executeIfAnyPresent(text)) try {
 			// Creating the message and its metadata
 			final var builder = new MessageBuilder(localDB.getUser().getID(), currentChat.getRecipient().getID(), localDB.getIDGenerator())

client/src/main/java/envoy/client/ui/controller/ContactSearchScene.java

@@ -60,8 +60,10 @@ public class ContactSearchScene {
 
 	private final Consumer<ContactOperation> handler = e -> {
 		final var contact = e.get();
-		if (e.getOperationType() == ElementOperation.ADD) Platform
-			.runLater(() -> { userList.getItems().remove(contact); if (currentlySelectedUser.equals(contact) && alert.isShowing()) alert.close(); });
+		if (e.getOperationType() == ElementOperation.ADD) Platform.runLater(() -> {
+			userList.getItems().remove(contact);
+			if (currentlySelectedUser != null && currentlySelectedUser.equals(contact) && alert.isShowing()) alert.close();
+		});
 	};
 
 	private static final EventBus	eventBus	= EventBus.getInstance();

client/src/main/java/envoy/client/ui/controller/LoginScene.java

@@ -138,7 +138,7 @@ public final class LoginScene {
 			localDB.setUser(localDB.getUsers().get(identifier));
 			localDB.initializeUserStorage();
 			localDB.loadUserData();
-		} catch (Exception e) {
+		} catch (final Exception e) {
 			// User storage empty, wrong user name etc. -> default lastSync
 		}
 		return localDB.getLastSync();
@@ -161,7 +161,7 @@ public final class LoginScene {
 		try {
 			// Try entering offline mode
 			localDB.loadUsers();
-			final User clientUser = (User) localDB.getUsers().get(credentials.getIdentifier());
+			final User clientUser = localDB.getUsers().get(credentials.getIdentifier());
 			if (clientUser == null) throw new EnvoyException("Could not enter offline mode: user name unknown");
 			client.setSender(clientUser);
 			loadChatScene();
@@ -223,7 +223,7 @@ public final class LoginScene {
 			// Initialize status tray icon
 			final var trayIcon = new StatusTrayIcon(sceneContext.getStage());
 			settings.getItems().get("hideOnClose").setChangeHandler(c -> {
-				if (((Boolean) c)) trayIcon.show();
+				if ((Boolean) c) trayIcon.show();
 				else trayIcon.hide();
 			});
 		}

client/src/main/java/envoy/client/ui/listcell/ChatControl.java

@@ -31,12 +31,12 @@ public class ChatControl extends HBox {
 
 		// Unread messages
 		if (chat.getUnreadAmount() != 0) {
-			Region spacing = new Region();
+			final Region spacing = new Region();
 			setHgrow(spacing, Priority.ALWAYS);
 			getChildren().add(spacing);
 			final var unreadMessagesLabel = new Label(Integer.toString(chat.getUnreadAmount()));
 			unreadMessagesLabel.setMinSize(15, 15);
-			var vBox2 = new VBox();
+			final var vBox2 = new VBox();
 			vBox2.setAlignment(Pos.CENTER_RIGHT);
 			unreadMessagesLabel.setAlignment(Pos.CENTER);
 			unreadMessagesLabel.getStyleClass().add("unreadMessagesAmount");