feat: add api stuff

build.gradle

@@ -1,6 +1,7 @@
 plugins {
 	id 'fabric-loom' version '1.7-SNAPSHOT'
 	id 'maven-publish'
+    id 'com.github.johnrengelman.shadow' version '8.1.1'
 }
 
 version = project.mod_version
@@ -26,7 +27,8 @@ dependencies {
 
 	// Fabric API. This is technically optional, but you probably want it anyway.
 	modImplementation "net.fabricmc.fabric-api:fabric-api:${project.fabric_version}"
-	
+
+    implementation 'com.google.code.gson:gson:2.10.1'
 }
 
 processResources {
@@ -51,6 +53,10 @@ java {
 	targetCompatibility = JavaVersion.VERSION_1_8
 }
 
+shadowJar {
+    relocate('com.google.gson', 'cc.crss.mod.deps.gson')
+}
+
 jar {
 	from("LICENSE") {
 		rename { "${it}_${project.base.archivesName.get()}"}

src/main/java/cc/crss/mod/CRSSMod.java

@@ -1,16 +1,26 @@
 package cc.crss.mod;
+import cc.crss.mod.api.ApiServer;
 import net.fabricmc.api.DedicatedServerModInitializer;
+import net.fabricmc.fabric.api.event.lifecycle.v1.ServerLifecycleEvents;
+import net.minecraft.server.MinecraftServer;
 import org.apache.logging.log4j.LogManager;
 import org.apache.logging.log4j.Logger;
 import cc.crss.mod.util.CommandRegister;
 
 public class CRSSMod implements DedicatedServerModInitializer {
-
     public static final Logger LOGGER = LogManager.getLogger("crss");
+
 	@Override
 	public void onInitializeServer() {
-
 		LOGGER.info("CRSS initialising.");
+
+        ServerLifecycleEvents.SERVER_STARTED.register(ApiServer::createInstance);
+        ServerLifecycleEvents.SERVER_STOPPING.register(server -> {
+            ApiServer srv = ApiServer.getInstance();
+
+            srv.stop();
+        });
+
 		CommandRegister.registerCommands();
 	}
 }

src/main/java/cc/crss/mod/api/ApiServer.java

@@ -0,0 +1,127 @@
+package cc.crss.mod.api;
+
+import cc.crss.mod.api.data.ServerInfo;
+import net.minecraft.MinecraftVersion;
+import net.minecraft.server.MinecraftServer;
+import net.minecraft.server.dedicated.DedicatedServer;
+import net.minecraft.server.dedicated.MinecraftDedicatedServer;
+import net.minecraft.world.dimension.DimensionType;
+
+import java.io.*;
+import java.net.ServerSocket;
+import java.net.Socket;
+import java.util.ArrayList;
+import java.util.List;
+
+import static cc.crss.mod.CRSSMod.LOGGER;
+
+public class ApiServer {
+    private static ApiServer instance;
+
+    public static MinecraftServer server;
+
+    private Thread thread;
+
+    public ApiServer(MinecraftServer server) {
+        if (instance != null)
+            throw new RuntimeException("API Server already started.");
+
+        ApiServer.server = server;
+
+        start();
+    }
+
+    public static ApiServer getInstance() {
+        return instance;
+    }
+
+    public static void createInstance(MinecraftServer server) {
+        instance = new ApiServer(server);
+    }
+
+    private void start() {
+        this.thread = new Thread(
+            new ServerRunnable(25580)
+        );
+
+        this.thread.start();
+    }
+
+    public void stop() {
+        this.thread.interrupt();
+
+        instance = null;
+    }
+
+    static class ServerRunnable implements Runnable {
+        private int port;
+
+        public ServerRunnable(int port) {
+            this.port = port;
+        }
+
+        @Override
+        public void run() {
+            try (ServerSocket serverSocket = new ServerSocket(port)) {
+                System.out.println("Server is listening on port " + port);
+
+                while (true) {
+                    Socket clientSocket = serverSocket.accept();
+
+                    clientSocket.setTcpNoDelay(true);
+
+                    DataInputStream dataInputStream = new DataInputStream(
+                        clientSocket.getInputStream()
+                    );
+
+                    DataOutputStream dataOutputStream = new DataOutputStream(
+                        clientSocket.getOutputStream()
+                    );
+
+                    byte packetId = dataInputStream.readByte();
+
+                    switch (packetId) {
+                        case 0x00:
+                            MinecraftServer server = ApiServer.server;
+
+                            ArrayList<String> worlds = new ArrayList<>();
+
+                            server.getWorlds().forEach(world -> {
+                                worlds.add(world.getDimension().getType().toString());
+                            });
+
+                            String jsonData = new ServerInfo(
+                                server.getVersion(),
+                                server.getCurrentPlayerCount(),
+                                worlds.toArray(new String[0])
+                            ).toJson();
+
+                            int length = jsonData.length();
+
+                            byte[] responseBytes = new byte[1 + 4 + length];
+
+                            responseBytes[0] = 0x00;
+
+                            responseBytes[1] = (byte) ((length >> 24) & 0xFF);
+                            responseBytes[2] = (byte) ((length >> 16) & 0xFF);
+                            responseBytes[3] = (byte) ((length >> 8) & 0xFF);
+                            responseBytes[4] = (byte) (length & 0xFF);
+
+                            System.arraycopy(jsonData.getBytes(), 0, responseBytes, 5, length);
+
+                            dataOutputStream.write(responseBytes);
+                            dataOutputStream.flush();
+
+                            break;
+                        default:
+                            LOGGER.warn("Received unknown packet: {}", packetId);
+
+                            break;
+                    }
+                }
+            } catch (IOException e) {
+                LOGGER.error("Error starting API server", e);
+            }
+        }
+    }
+}

src/main/java/cc/crss/mod/api/Model.java

@@ -0,0 +1,13 @@
+package cc.crss.mod.api;
+
+import cc.crss.mod.util.JsonUtil;
+
+public class Model {
+    public String toJson() {
+        return JsonUtil.gson.toJson(this);
+    }
+
+    public static Object fromJson(String json, Class<? extends Model> clazz) {
+        return JsonUtil.gson.fromJson(json, clazz);
+    }
+}

src/main/java/cc/crss/mod/api/data/ServerInfo.java

@@ -0,0 +1,39 @@
+package cc.crss.mod.api.data;
+
+import cc.crss.mod.api.Model;
+
+public class ServerInfo extends Model {
+    private String version;
+    private Integer online;
+    private String[] worlds;
+
+    public ServerInfo(String version, Integer online, String[] worlds) {
+        this.version = version;
+        this.online = online;
+        this.worlds = worlds;
+    }
+
+    public String getVersion() {
+        return version;
+    }
+
+    public Integer getOnline() {
+        return online;
+    }
+
+    public String[] getWorlds() {
+        return worlds;
+    }
+
+    public void setVersion(String version) {
+        this.version = version;
+    }
+
+    public void setOnline(Integer online) {
+        this.online = online;
+    }
+
+    public void setWorlds(String[] worlds) {
+        this.worlds = worlds;
+    }
+}

src/main/java/cc/crss/mod/util/JsonUtil.java

@@ -0,0 +1,11 @@
+package cc.crss.mod.util;
+
+import com.google.gson.FieldNamingPolicy;
+import com.google.gson.Gson;
+import com.google.gson.GsonBuilder;
+
+public class JsonUtil {
+    public static Gson gson = new GsonBuilder()
+        .setFieldNamingPolicy(FieldNamingPolicy.LOWER_CASE_WITH_UNDERSCORES)
+        .create();
+}

src/main/resources/crss.mixins.json

@@ -8,5 +8,5 @@
   ],
   "injectors": {
     "defaultRequire": 1
-	}
+  }
 }