Improved readme, added JNA for windows terminal support.

README.md

@@ -1,11 +1,45 @@
 # Concord
 Console-based real-time messaging platform, inspired by Discord.
 
-This platform is organized by many independent servers, each of which supports the following:
+## Vision
+
+This platform will be organized by many independent servers, each of which will support the following:
 - Multiple message channels. By default, there's one `general` channel.
 - Broadcasting itself on certain discovery servers for users to find. The server decides where it wants to be discovered, if at all.
 - Starting threads as spin-offs of a source message (with infinite recursion, i.e. threads within threads).
 - Private message between users in a server. **No support for private messaging users outside the context of a server.**
 - Banning users from the server.
 
+# Concord Client
+
+To use the client, simply download the latest `concord-client.jar` JAR file from [the releases page](https://github.com/andrewlalis/Concord/releases) and run it with Java (version 16 or higher) from anywhere on your machine.
+
+Once you've started it, press **Enter** to click the button "Connect to Server". You will be prompted for the server IP address, and then a nickname for yourself, before you join the server. To disconnect, press **CTRL+C** at any time.
+
+# Concord Server
+
+To start up your own server, download the latest `concord-server.jar` JAR file from [the releases page](https://github.com/andrewlalis/Concord/releases) and run it with Java (version 16 or higher). The first time you run the server with `java -jar concord-server.jar`, it will generate a `server-config.json` configuration file, and a `concord-server.db` database file.
+
+## Configuring the Server
+
+You probably want to customize your server a bit. To do so, first stop your server by typing `stop` in the console where you started the server initially. Now you can edit `server-config.json` and restart the server once you're done. A description of the attributes is given below:
+
+- `name` The name of the server.
+- `description` A short description of what this server is for, or who it's run by.
+- `port` The port on which the server accepts client connections.
+- `chatHistoryMaxCount` The maximum amount of chat messages that a client can request from the server at any given time. Decrease this to improve performance.
+- `chatHistoryDefaultCount` The default number of chat messages that are provided to clients when they join a channel, if they don't explicitly request a certain amount. Decrease this to improve performance.
+- `maxMessageLength` The maximum length of a message. Messages longer than this will be rejected.
+- `channels` Contains a list of all channels that the server uses. Each channel has an `id`, `name`, and `description`. **It is advised that you do not add or remove channels manually!** Instead, use the `add-channel` and `remove-channel` CLI commands that are available while the server is running.
+- `discoveryServers` A list of URLs to which this server should send its metadata for publishing. Keep this empty if you don't want your server to be publicly visible.
+
+## Server CLI
+
+As mentioned briefly, the server supports a basic command-line-interface with some commands. You can show which commands are available via the `help` command. The following is a list of some of the most useful commands and a description of their functionality:
+
+- `add-channel <name>` Adds a new channel to the server with the given name. Channel names cannot be blank, and they cannot be duplicates of an existing channel name.
+- `remove-channel <name>` Removes a channel.
+- `list-clients` Shows a list of all connected clients.
+- `stop` Stops the server, disconnecting all clients.
+
 Each server uses a single [Nitrite](https://www.dizitart.org/nitrite-database/#what-is-nitrite) database to hold messages and other information.

client/pom.xml

@@ -23,6 +23,16 @@
             <artifactId>lanterna</artifactId>
             <version>3.2.0-alpha1</version>
         </dependency>
+        <dependency>
+            <groupId>net.java.dev.jna</groupId>
+            <artifactId>jna</artifactId>
+            <version>5.9.0</version>
+        </dependency>
+        <dependency>
+            <groupId>net.java.dev.jna</groupId>
+            <artifactId>jna-platform</artifactId>
+            <version>5.9.0</version>
+        </dependency>
     </dependencies>
 
     <build>

client/src/main/java/module-info.java

@@ -1,5 +1,7 @@
 module concord_client {
 	requires concord_core;
 	requires com.googlecode.lanterna;
+	requires com.sun.jna;
+	requires com.sun.jna.platform;
 	requires static lombok;
 }

server/src/main/java/nl/andrewl/concord_server/ChannelManager.java

@@ -17,6 +17,15 @@ public class ChannelManager {
 		this.server = server;
 		this.channelNameMap = new ConcurrentHashMap<>();
 		this.channelIdMap = new ConcurrentHashMap<>();
+		// Initialize the channels according to what's defined in the server's config.
+		for (var channelConfig : server.getConfig().getChannels()) {
+			this.addChannel(new Channel(
+					server,
+					UUID.fromString(channelConfig.getId()),
+					channelConfig.getName(),
+					server.getDb().getCollection("channel-" + channelConfig.getId())
+			));
+		}
 	}
 
 	public Set<Channel> getChannels() {

server/src/main/java/nl/andrewl/concord_server/ConcordServer.java

@@ -1,8 +1,5 @@
 package nl.andrewl.concord_server;
 
-import com.fasterxml.jackson.core.JsonProcessingException;
-import com.fasterxml.jackson.databind.ObjectMapper;
-import com.fasterxml.jackson.databind.node.ObjectNode;
 import lombok.Getter;
 import nl.andrewl.concord_core.msg.Message;
 import nl.andrewl.concord_core.msg.Serializer;
@@ -16,15 +13,9 @@ import org.dizitart.no2.Nitrite;
 
 import java.io.ByteArrayOutputStream;
 import java.io.IOException;
-import java.io.UncheckedIOException;
 import java.net.ServerSocket;
 import java.net.Socket;
-import java.net.URI;
-import java.net.http.HttpClient;
-import java.net.http.HttpRequest;
-import java.net.http.HttpResponse;
 import java.nio.file.Path;
-import java.time.Duration;
 import java.util.Comparator;
 import java.util.List;
 import java.util.Map;
@@ -36,45 +27,62 @@ import java.util.stream.Collectors;
  * The main server implementation, which handles accepting new clients.
  */
 public class ConcordServer implements Runnable {
+	private static final Path CONFIG_FILE = Path.of("server-config.json");
+	private static final Path DATABASE_FILE = Path.of("concord-server.db");
+
 	private final Map<UUID, ClientThread> clients;
 	private volatile boolean running;
+	private final ServerSocket serverSocket;
 
+	/**
+	 * Server configuration data. This is used to define channels, discovery
+	 * server addresses, and more.
+	 */
 	@Getter
 	private final ServerConfig config;
+
+	/**
+	 * The component that generates new user and channel ids.
+	 */
 	@Getter
 	private final IdProvider idProvider;
+
+	/**
+	 * The database that contains all messages and other server information.
+	 */
 	@Getter
 	private final Nitrite db;
+
+	/**
+	 * A general-purpose executor service that can be used to submit async tasks.
+	 */
 	@Getter
-	private final ExecutorService executorService;
+	private final ExecutorService executorService = Executors.newCachedThreadPool();
+
+	/**
+	 * Manager that handles incoming messages and events by clients.
+	 */
 	@Getter
 	private final EventManager eventManager;
+
+	/**
+	 * Manager that handles the collection of channels in this server.
+	 */
 	@Getter
 	private final ChannelManager channelManager;
 
-	// Components for communicating with discovery servers.
+	private final DiscoveryServerPublisher discoveryServerPublisher;
 	private final ScheduledExecutorService scheduledExecutorService = Executors.newSingleThreadScheduledExecutor();
-	private final HttpClient httpClient = HttpClient.newHttpClient();
-	private final ObjectMapper mapper = new ObjectMapper();
 
-	public ConcordServer() {
+	public ConcordServer() throws IOException {
 		this.idProvider = new UUIDProvider();
-		this.config = ServerConfig.loadOrCreate(Path.of("server-config.json"), idProvider);
-		this.db = Nitrite.builder()
-				.filePath("concord-server.db")
-				.openOrCreate();
+		this.config = ServerConfig.loadOrCreate(CONFIG_FILE, idProvider);
+		this.discoveryServerPublisher = new DiscoveryServerPublisher(this.config);
+		this.db = Nitrite.builder().filePath(DATABASE_FILE.toFile()).openOrCreate();
 		this.clients = new ConcurrentHashMap<>(32);
-		this.executorService = Executors.newCachedThreadPool();
 		this.eventManager = new EventManager(this);
 		this.channelManager = new ChannelManager(this);
-		for (var channelConfig : config.getChannels()) {
-			this.channelManager.addChannel(new Channel(
-					this,
-					UUID.fromString(channelConfig.getId()),
-					channelConfig.getName(),
-					this.db.getCollection("channel-" + channelConfig.getId())
-			));
-		}
+		this.serverSocket = new ServerSocket(this.config.getPort());
 	}
 
 	/**
@@ -115,10 +123,29 @@ public class ConcordServer implements Runnable {
 		}
 	}
 
+	/**
+	 * @return True if the server is currently running, meaning it is accepting
+	 * connections, or false otherwise.
+	 */
 	public boolean isRunning() {
 		return running;
 	}
 
+	/**
+	 * Stops the server. Has no effect if the server has not started yet or has
+	 * already been stopped.
+	 */
+	public void stop() {
+		this.running = false;
+		if (!this.serverSocket.isClosed()) {
+			try {
+				this.serverSocket.close();
+			} catch (IOException e) {
+				e.printStackTrace();
+			}
+		}
+	}
+
 	public List<UserData> getClients() {
 		return this.clients.values().stream()
 				.sorted(Comparator.comparing(ClientThread::getClientNickname))
@@ -153,64 +180,54 @@ public class ConcordServer implements Runnable {
 		}
 	}
 
-	private void publishMetaDataToDiscoveryServers() {
-		if (this.config.getDiscoveryServers().isEmpty()) return;
-		ObjectNode node = this.mapper.createObjectNode();
-		node.put("name", this.config.getName());
-		node.put("description", this.config.getDescription());
-		node.put("port", this.config.getPort());
-		String json;
-		try {
-			json = this.mapper.writeValueAsString(node);
-		} catch (JsonProcessingException e) {
-			throw new UncheckedIOException(e);
+	/**
+	 * Shuts down the server cleanly by doing the following things:
+	 * <ol>
+	 *     <li>Disconnecting all clients.</li>
+	 *     <li>Shutting down any executor services.</li>
+	 *     <li>Flushing and compacting the message database.</li>
+	 *     <li>Flushing the server configuration one last time.</li>
+	 * </ol>
+	 */
+	private void shutdown() {
+		System.out.println("Shutting down the server.");
+		for (var clientId : this.clients.keySet()) {
+			this.deregisterClient(clientId);
 		}
-		var discoveryServers = List.copyOf(this.config.getDiscoveryServers());
-		for (var discoveryServer : discoveryServers) {
-			System.out.println("Publishing this server's metadata to discovery server at " + discoveryServer);
-			var request = HttpRequest.newBuilder(URI.create(discoveryServer))
-					.POST(HttpRequest.BodyPublishers.ofString(json))
-					.header("Content-Type", "application/json")
-					.timeout(Duration.ofSeconds(3))
-					.build();
+		this.scheduledExecutorService.shutdown();
+		this.executorService.shutdown();
+		this.db.close();
 		try {
-				this.httpClient.send(request, HttpResponse.BodyHandlers.discarding());
-			} catch (IOException | InterruptedException e) {
-				e.printStackTrace();
-			}
+			this.config.save();
+		} catch (IOException e) {
+			System.err.println("Could not save configuration on shutdown: " + e.getMessage());
 		}
 	}
 
 	@Override
 	public void run() {
 		this.running = true;
-		this.scheduledExecutorService.scheduleAtFixedRate(this::publishMetaDataToDiscoveryServers, 0, 1, TimeUnit.MINUTES);
-		ServerSocket serverSocket;
-		try {
-			serverSocket = new ServerSocket(this.config.getPort());
+		this.scheduledExecutorService.scheduleAtFixedRate(this.discoveryServerPublisher::publish, 0, 1, TimeUnit.MINUTES);
 		StringBuilder startupMessage = new StringBuilder();
-			startupMessage.append("Opened server on port ").append(config.getPort()).append("\n");
+		startupMessage.append("Opened server on port ").append(config.getPort()).append("\n")
+				.append("The following channels are available:\n");
 		for (var channel : this.channelManager.getChannels()) {
 			startupMessage.append("\tChannel \"").append(channel).append('\n');
 		}
 		System.out.println(startupMessage);
 		while (this.running) {
 			try {
-					Socket socket = serverSocket.accept();
+				Socket socket = this.serverSocket.accept();
 				ClientThread clientThread = new ClientThread(socket, this);
 				clientThread.start();
 			} catch (IOException e) {
-					e.printStackTrace();
+				System.err.println("Could not accept new client connection: " + e.getMessage());
 			}
 		}
-			serverSocket.close();
-		} catch (IOException e) {
-			System.err.println("Could not open server socket: " + e.getMessage());
-		}
-		this.scheduledExecutorService.shutdown();
+		this.shutdown();
 	}
 
-	public static void main(String[] args) {
+	public static void main(String[] args) throws IOException {
 		var server = new ConcordServer();
 		new Thread(server).start();
 		new ServerCli(server).run();

server/src/main/java/nl/andrewl/concord_server/DiscoveryServerPublisher.java

@@ -0,0 +1,56 @@
+package nl.andrewl.concord_server;
+
+import com.fasterxml.jackson.core.JsonProcessingException;
+import com.fasterxml.jackson.databind.ObjectMapper;
+import com.fasterxml.jackson.databind.node.ObjectNode;
+import nl.andrewl.concord_server.config.ServerConfig;
+
+import java.io.IOException;
+import java.io.UncheckedIOException;
+import java.net.URI;
+import java.net.http.HttpClient;
+import java.net.http.HttpRequest;
+import java.net.http.HttpResponse;
+import java.time.Duration;
+import java.util.List;
+
+/**
+ * This component is responsible for publishing the server's metadata to any
+ * discovery servers that have been defined in the server's configuration file.
+ */
+public class DiscoveryServerPublisher {
+	private final ObjectMapper mapper = new ObjectMapper();
+	private final HttpClient httpClient = HttpClient.newHttpClient();
+	private final ServerConfig config;
+
+	public DiscoveryServerPublisher(ServerConfig config) {
+		this.config = config;
+	}
+
+	public void publish() {
+		if (this.config.getDiscoveryServers().isEmpty()) return;
+		ObjectNode node = this.mapper.createObjectNode();
+		node.put("name", this.config.getName());
+		node.put("description", this.config.getDescription());
+		node.put("port", this.config.getPort());
+		String json;
+		try {
+			json = this.mapper.writeValueAsString(node);
+		} catch (JsonProcessingException e) {
+			throw new UncheckedIOException(e);
+		}
+		var discoveryServers = List.copyOf(this.config.getDiscoveryServers());
+		for (var discoveryServer : discoveryServers) {
+			var request = HttpRequest.newBuilder(URI.create(discoveryServer))
+					.POST(HttpRequest.BodyPublishers.ofString(json))
+					.header("Content-Type", "application/json")
+					.timeout(Duration.ofSeconds(3))
+					.build();
+			try {
+				this.httpClient.send(request, HttpResponse.BodyHandlers.discarding());
+			} catch (IOException | InterruptedException e) {
+				System.err.println("Could not publish metadata to " + discoveryServer + " because of exception: " + e.getClass().getSimpleName());
+			}
+		}
+	}
+}

server/src/main/java/nl/andrewl/concord_server/cli/ServerCli.java

@@ -4,6 +4,7 @@ import nl.andrewl.concord_server.ConcordServer;
 import nl.andrewl.concord_server.cli.command.AddChannelCommand;
 import nl.andrewl.concord_server.cli.command.ListClientsCommand;
 import nl.andrewl.concord_server.cli.command.RemoveChannelCommand;
+import nl.andrewl.concord_server.cli.command.StopCommand;
 
 import java.io.BufferedReader;
 import java.io.InputStreamReader;
@@ -22,10 +23,19 @@ public class ServerCli implements Runnable {
 		this.commands.put("list-clients", new ListClientsCommand());
 		this.commands.put("add-channel", new AddChannelCommand());
 		this.commands.put("remove-channel", new RemoveChannelCommand());
+		this.commands.put("stop", new StopCommand());
+
+		this.commands.put("help", (s, args) -> {
+			System.out.println("The following commands are available:");
+			for (var key : commands.keySet().stream().sorted().toList()) {
+				System.out.println("\t" + key);
+			}
+		});
 	}
 
 	@Override
 	public void run() {
+		System.out.println("Server command-line-interface initialized. Type \"help\" for a list of available commands.");
 		BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
 		String line;
 		try {

server/src/main/java/nl/andrewl/concord_server/cli/command/StopCommand.java

@@ -0,0 +1,14 @@
+package nl.andrewl.concord_server.cli.command;
+
+import nl.andrewl.concord_server.ConcordServer;
+import nl.andrewl.concord_server.cli.ServerCliCommand;
+
+/**
+ * This command forcibly stops the server, disconnecting any clients.
+ */
+public class StopCommand implements ServerCliCommand {
+	@Override
+	public void handle(ConcordServer server, String[] args) throws Exception {
+		server.stop();
+	}
+}