Created the ServerManager.java

src/main/java/de/gnmyt/mcdash/api/ServerManager.java

@@ -0,0 +1,148 @@
+package de.gnmyt.mcdash.api;
+
+import de.gnmyt.mcdash.MCDashWrapper;
+import de.gnmyt.mcdash.entities.Server;
+import de.gnmyt.mcdash.entities.ServerConfiguration;
+import de.gnmyt.mcdash.entities.ServerStatus;
+
+import java.io.File;
+import java.util.ArrayList;
+
+public class ServerManager {
+
+    private static final Logger LOG = new Logger(ServerManager.class);
+    private static final ServerVersionManager versionManager = new ServerVersionManager();
+    private final ArrayList<Server> servers = new ArrayList<>();
+
+    private final File serverFolder;
+
+    /**
+     * Basic constructor of the {@link ServerManager}
+     */
+    public ServerManager() {
+        this.serverFolder = MCDashWrapper.getDataSource("servers");
+    }
+
+    /**
+     * Initializes the server manager
+     */
+    public void initialize() {
+        if (!serverFolder.exists() && !serverFolder.mkdirs()) {
+            LOG.error("An error occurred while creating the server folder");
+        }
+
+        refreshServers();
+    }
+
+    /**
+     * Starts all servers
+     */
+    public void startServers() {
+        LOG.info("Starting all servers...");
+
+        servers.forEach(server -> {
+            if (server.getStatus() == ServerStatus.ONLINE) return;
+            startServer(server);
+        });
+    }
+
+    /**
+     * Stops all servers
+     */
+    public void stopServers() {
+        LOG.info("Stopping all servers...");
+
+        servers.forEach(server -> {
+            if (server.getStatus() == ServerStatus.OFFLINE) return;
+            stopServer(server);
+        });
+    }
+
+    /**
+     * Refreshes the servers
+     */
+    public void refreshServers() {
+        servers.stream().filter(server -> server.getStatus() == ServerStatus.OFFLINE).forEach(servers::remove);
+
+        for (File file : serverFolder.listFiles()) {
+            if (file.isDirectory() && new File(file, "mcdash.json").exists()) {
+                if (getServer(file.getName()) != null) continue;
+
+                servers.add(new Server(file.getName(), ServerStatus.OFFLINE, new File(file, "mcdash.json")));
+            }
+        }
+    }
+
+    /**
+     * Gets a server by its name.
+     * <p>
+     * If the server does not exist, it will return null
+     * </p>
+     *
+     * @param name The name of the server
+     * @return the server with the given name
+     */
+    public Server getServer(String name) {
+        return servers.stream().filter(server -> server.getName().equals(name)).findFirst().orElse(null);
+    }
+
+    /**
+     * Starts a server
+     * @param server The server you want to start
+     */
+    public void startServer(Server server) {
+        if (server.getStatus() == ServerStatus.ONLINE) return;
+        LOG.info("Starting server {}", server.getName());
+
+        ServerConfiguration config = server.getConfiguration();
+
+        try {
+            ProcessBuilder processBuilder = new ProcessBuilder("java", "-jar", "-Xmx" + config.getMemory() + "M",
+                    "-Xms" + config.getMemory() + "M", "-Dcom.mojang.eula.agree=true", // "-Djava.awt.headless=true",
+                    versionManager.getPath(config.getType(), config.getVersion())//, "nogui"
+            );
+            processBuilder.directory(new File(serverFolder, server.getName()));
+            Process process = processBuilder.start();
+
+            server.keepAlive();
+
+            server.setStatus(ServerStatus.ONLINE);
+            server.setProcess(process);
+        } catch (Exception e) {
+            LOG.error("An error occurred while starting the server", e);
+        }
+
+        LOG.info("Server {} has been started", server.getName());
+    }
+
+    /**
+     * Stops a server
+     * @param server The server you want to stop
+     */
+    public void stopServer(Server server) {
+        if (server.getStatus() == ServerStatus.OFFLINE) return;
+
+        LOG.info("Stopping server {}", server.getName());
+
+        try {
+            server.getProcess().getOutputStream().write("stop\n".getBytes());
+
+            for (int i = 0; i < 10; i++) {
+                if (server.getProcess().isAlive()) {
+                    Thread.sleep(1000);
+                } else {
+                    break;
+                }
+            }
+
+            server.getProcess().destroy();
+            server.setStatus(ServerStatus.OFFLINE);
+            server.setProcess(null);
+        } catch (Exception e) {
+            LOG.error("An error occurred while stopping the server", e);
+        }
+
+        LOG.info("Server {} has been stopped", server.getName());
+    }
+
+}