trying to set up a matrix bridge

.gitignore

@@ -40,3 +40,5 @@ target/
 # virtual machine crash logs, see http://www.java.com/en/download/help/error_hotspot.xml
 hs_err_pid
 !gradle/wrapper/gradle-wrapper.jar
+
+*.bat

api/build.gradle.kts

@@ -4,7 +4,7 @@ plugins {
 
 dependencies {
     // Cosmos
-    compileOnly("com.alttd.cosmos:cosmos-api:1.21.8-R0.1-SNAPSHOT") {
+    compileOnly("com.alttd.cosmos:cosmos-api:1.21.10-R0.1-SNAPSHOT") {
         isChanging = true
     }
     compileOnly("org.spongepowered:configurate-yaml:4.2.0") // Configurate

api/src/main/java/com/alttd/chat/config/Config.java

@@ -641,4 +641,14 @@ public final class Config {
         CHAT_LOG_DELETE_OLDER_THAN_DAYS = getLong("chat-log.delete-older-than-days", CHAT_LOG_DELETE_OLDER_THAN_DAYS);
         CHAT_LOG_SAVE_DELAY_MINUTES = getLong("chat-log.save-delay-minutes", CHAT_LOG_SAVE_DELAY_MINUTES);
     }
+
+    public static String MATRIX_SERVER = "http://127.0.0.1:8008";
+    public static String MATRIX_AS_TOKEN = "<token>";
+    public static String MATRIX_HS_TOKEN = "<token>";
+
+    private static void matrixSettings() {
+        MATRIX_SERVER = getString("matrix.server", MATRIX_SERVER);
+        MATRIX_AS_TOKEN = getString("matrix.as_token", MATRIX_AS_TOKEN);
+        MATRIX_HS_TOKEN = getString("matrix.hs_token", MATRIX_HS_TOKEN);
+    }
 }

galaxy/build.gradle.kts

@@ -5,7 +5,7 @@ plugins {
 
 dependencies {
     implementation(project(":api")) // API
-    compileOnly("com.alttd.cosmos:cosmos-api:1.21.8-R0.1-SNAPSHOT") {
+    compileOnly("com.alttd.cosmos:cosmos-api:1.21.10-R0.1-SNAPSHOT") {
         isChanging = true
     }
     compileOnly("com.gitlab.ruany:LiteBansAPI:0.6.1") // move to proxy

matrix/build.gradle.kts

@@ -0,0 +1,17 @@
+plugins {
+    `maven-publish`
+}
+
+dependencies {
+    api(project(":api"))
+    compileOnly("com.velocitypowered:velocity-api:3.2.0-SNAPSHOT")
+
+    api("com.fasterxml.jackson.core:jackson-databind:2.17.2")
+    api("com.fasterxml.jackson.core:jackson-core:2.17.2")
+    api("com.fasterxml.jackson.core:jackson-annotations:2.17.2")
+}
+
+tasks.withType<JavaCompile>().configureEach {
+    options.encoding = "UTF-8"
+    options.release.set(21)
+}

matrix/src/main/java/com/alttd/matrix/MatrixConfig.java

@@ -0,0 +1,12 @@
+package com.alttd.matrix;
+
+public record MatrixConfig(
+        String homeserver,   // e.g. "http://127.0.0.1:8008"
+        String asToken,      // from as registration yaml
+        String hsToken,      // from as registration yaml
+        String domain,       // "matrix.alttd.com"
+        String userPrefix,   // "mc_"
+        String bindHost,     // "127.0.0.1"
+        int bindPort         // 9000
+) {
+}

matrix/src/main/java/com/alttd/matrix/MatrixRuntime.java

@@ -0,0 +1,29 @@
+package com.alttd.matrix;
+
+import com.alttd.matrix.app_service.MatrixAppServiceHttpServer;
+import com.alttd.matrix.client.HttpMatrixClient;
+import com.alttd.matrix.interfaces.MatrixAppServiceServer;
+import com.alttd.matrix.interfaces.MatrixClient;
+
+import java.io.IOException;
+import java.net.InetSocketAddress;
+
+public final class MatrixRuntime {
+
+    private MatrixRuntime() {
+    }
+
+    public static MatrixAppServiceServer startAppService(MatrixConfig cfg) throws IOException {
+        var server = new MatrixAppServiceHttpServer(
+                new InetSocketAddress(cfg.bindHost(), cfg.bindPort()),
+                cfg.hsToken()
+        );
+        server.start();
+        return server;
+    }
+
+    public static MatrixClient createClient(MatrixConfig cfg) {
+        return new HttpMatrixClient(cfg.homeserver(), cfg.asToken());
+    }
+}
+

matrix/src/main/java/com/alttd/matrix/app_service/MatrixAppServiceHttpServer.java

@@ -0,0 +1,153 @@
+package com.alttd.matrix.app_service;
+
+import com.alttd.matrix.interfaces.MatrixAppServiceServer;
+import com.fasterxml.jackson.databind.JsonNode;
+import com.fasterxml.jackson.databind.ObjectMapper;
+import com.sun.net.httpserver.HttpExchange;
+import com.sun.net.httpserver.HttpServer;
+
+import java.io.IOException;
+import java.io.InputStream;
+import java.net.InetSocketAddress;
+import java.net.URLDecoder;
+import java.nio.charset.StandardCharsets;
+import java.util.Iterator;
+import java.util.Map;
+import java.util.concurrent.Executors;
+import java.util.function.Consumer;
+
+public final class MatrixAppServiceHttpServer implements MatrixAppServiceServer {
+
+    private final HttpServer server;
+    private final String hsToken;
+    private final ObjectMapper om = new ObjectMapper();
+
+    private volatile Consumer<TransactionEvent> txListener;
+
+    public MatrixAppServiceHttpServer(InetSocketAddress bind, String hsToken) throws IOException {
+        this.server = HttpServer.create(bind, 0);
+        this.hsToken = hsToken;
+
+        server.createContext("/_matrix/app/v1/transactions", this::handleTransactions);
+        server.createContext("/_matrix/app/v1/users", this::handleUsers);
+
+        server.setExecutor(Executors.newCachedThreadPool(r -> {
+            Thread t = new Thread(r, "matrix-as-http");
+            t.setDaemon(true);
+            return t;
+        }));
+    }
+
+    public void start() {
+        server.start();
+    }
+
+    @Override
+    public void setTransactionListener(Consumer<TransactionEvent> listener) {
+        this.txListener = listener;
+    }
+
+    @Override
+    public void close() {
+        server.stop(0);
+    }
+
+    private void handleUsers(HttpExchange ex) throws IOException {
+        if (!"GET".equals(ex.getRequestMethod())) {
+            send(ex, 405, "{}");
+            return;
+        }
+        if (!validHsToken(ex)) {
+            send(ex, 401, "{}");
+            return;
+        }
+
+        // Synapse asks "does this user exist?" -> for AS, answer 200 so Synapse will proceed.
+        // You can optionally restrict to your namespace by inspecting the path.
+        send(ex, 200, "{}");
+    }
+
+    private void handleTransactions(HttpExchange ex) throws IOException {
+        if (!"PUT".equals(ex.getRequestMethod())) {
+            send(ex, 405, "{}");
+            return;
+        }
+        if (!validHsToken(ex)) {
+            send(ex, 401, "{}");
+            return;
+        }
+
+        JsonNode root;
+        try (InputStream in = ex.getRequestBody()) {
+            root = om.readTree(in);
+        } catch (Exception e) {
+            send(ex, 400, "{}");
+            return;
+        }
+
+        Consumer<TransactionEvent> listener = txListener;
+        if (listener != null) {
+            JsonNode events = root.path("events");
+            if (events.isArray()) {
+                for (Iterator<JsonNode> it = events.elements(); it.hasNext(); ) {
+                    JsonNode ev = it.next();
+
+                    // only handle m.room.message text
+                    if (!"m.room.message".equals(ev.path("type").asText())) {
+                        continue;
+                    }
+                    if (!"m.text".equals(ev.path("content").path("msgtype").asText())) {
+                        continue;
+                    }
+
+                    String roomId = ev.path("room_id").asText(null);
+                    String sender = ev.path("sender").asText(null);
+                    String eventId = ev.path("event_id").asText(null);
+                    String body = ev.path("content").path("body").asText(null);
+
+                    if (roomId != null && body != null) {
+                        listener.accept(new TransactionEvent(roomId, sender, body, eventId));
+                    }
+                }
+            }
+        }
+
+        send(ex, 200, "{}");
+    }
+
+    private boolean validHsToken(HttpExchange ex) {
+        String q = ex.getRequestURI().getRawQuery();
+        if (q == null) {
+            return false;
+        }
+        Map<String, String> params = parseQuery(q);
+        String token = params.get("access_token");
+        return token != null && token.equals(hsToken);
+    }
+
+    private static Map<String, String> parseQuery(String raw) {
+        var map = new java.util.HashMap<String, String>();
+        for (String part : raw.split("&")) {
+            int i = part.indexOf('=');
+            if (i <= 0) {
+                continue;
+            }
+            String k = urlDecode(part.substring(0, i));
+            String v = urlDecode(part.substring(i + 1));
+            map.put(k, v);
+        }
+        return map;
+    }
+
+    private static String urlDecode(String s) {
+        return URLDecoder.decode(s, StandardCharsets.UTF_8);
+    }
+
+    private static void send(HttpExchange ex, int code, String body) throws IOException {
+        byte[] b = body.getBytes(StandardCharsets.UTF_8);
+        ex.getResponseHeaders().set("Content-Type", "application/json");
+        ex.sendResponseHeaders(code, b.length);
+        ex.getResponseBody().write(b);
+        ex.close();
+    }
+}

matrix/src/main/java/com/alttd/matrix/bridge/DefaultMatrixBridge.java

@@ -0,0 +1,76 @@
+package com.alttd.matrix.bridge;
+
+import com.alttd.matrix.MatrixConfig;
+import com.alttd.matrix.interfaces.MatrixAppServiceServer;
+import com.alttd.matrix.interfaces.MatrixBridge;
+import com.alttd.matrix.interfaces.MatrixClient;
+
+import java.util.UUID;
+import java.util.concurrent.Executor;
+import java.util.concurrent.Executors;
+
+public final class DefaultMatrixBridge implements MatrixBridge {
+
+    private final MatrixClient client;
+    private final MatrixConfig cfg;
+    private final Executor io = Executors.newSingleThreadExecutor(r -> {
+        Thread t = new Thread(r, "matrix-io");
+        t.setDaemon(true);
+        return t;
+    });
+
+    private volatile InboundHandler inbound;
+    private volatile RoomResolver rooms;
+
+    public DefaultMatrixBridge(MatrixConfig cfg, MatrixAppServiceServer asServer, MatrixClient client) {
+        this.cfg = cfg;
+        this.client = client;
+
+        asServer.setTransactionListener(evt -> {
+            InboundHandler h = inbound;
+            RoomResolver rr = rooms;
+            if (h == null || rr == null) {
+                return;
+            }
+
+            // drop our own puppets to prevent loops
+            if (evt.senderMxid() != null && evt.senderMxid().startsWith("@" + cfg.userPrefix())) {
+                return;
+            }
+
+            h.onMatrixChat(evt.roomId(), evt.senderMxid(), evt.body());
+        });
+    }
+
+    @Override
+    public void setInboundHandler(InboundHandler handler) {
+        this.inbound = handler;
+    }
+
+    @Override
+    public void setRoomResolver(RoomResolver resolver) {
+        this.rooms = resolver;
+    }
+
+    @Override
+    public void sendChat(UUID playerUuid, String mcUsername, String serverName, String message) {
+        RoomResolver rr = rooms;
+        if (rr == null) {
+            return;
+        }
+
+        String roomId = rr.roomIdForServer(serverName);
+        if (roomId == null) {
+            return;
+        }
+
+        String mxid = "@" + cfg.userPrefix() + playerUuid + ":" + cfg.domain();
+
+        io.execute(() -> {
+            client.ensureUser(mxid);
+            client.setDisplayName(mxid, mcUsername);
+            client.ensureJoined(mxid, roomId);
+            client.sendText(mxid, roomId, message);
+        });
+    }
+}

matrix/src/main/java/com/alttd/matrix/client/HttpMatrixClient.java

@@ -0,0 +1,155 @@
+package com.alttd.matrix.client;
+
+import com.alttd.matrix.interfaces.MatrixClient;
+import com.fasterxml.jackson.databind.ObjectMapper;
+
+import java.net.URI;
+import java.net.URLEncoder;
+import java.net.http.HttpClient;
+import java.net.http.HttpRequest;
+import java.net.http.HttpResponse;
+import java.nio.charset.StandardCharsets;
+import java.time.Duration;
+import java.util.UUID;
+
+public final class HttpMatrixClient implements MatrixClient {
+
+    private final HttpClient http = HttpClient.newBuilder()
+            .connectTimeout(Duration.ofSeconds(5))
+            .build();
+
+    private final ObjectMapper om = new ObjectMapper();
+
+    private final String hs;      // e.g. http://127.0.0.1:8008
+    private final String asToken; // AS access token
+
+    public HttpMatrixClient(String homeserver, String asToken) {
+        this.hs = homeserver.endsWith("/") ? homeserver.substring(0, homeserver.length() - 1) : homeserver;
+        this.asToken = asToken;
+    }
+
+    @Override
+    public void ensureUser(String mxid) {
+        String localpart = localpart(mxid);
+
+        String url = hs + "/_matrix/client/v3/register"
+                     + "?access_token=" + enc(asToken);
+
+        String body = "{\"type\":\"m.login.application_service\",\"username\":\"" + json(localpart) + "\"}";
+
+        HttpRequest req = HttpRequest.newBuilder(URI.create(url))
+                .timeout(Duration.ofSeconds(10))
+                .header("Content-Type", "application/json")
+                .POST(HttpRequest.BodyPublishers.ofString(body))
+                .build();
+
+        sendIgnoreConflict(req);
+    }
+
+    @Override
+    public void setDisplayName(String mxid, String displayName) {
+        String url = hs + "/_matrix/client/v3/profile/" + encPath(mxid) + "/displayname"
+                     + "?access_token=" + enc(asToken)
+                     + "&user_id=" + enc(mxid);
+
+        String body = "{\"displayname\":\"" + json(displayName) + "\"}";
+
+        HttpRequest req = HttpRequest.newBuilder(URI.create(url))
+                .timeout(Duration.ofSeconds(10))
+                .header("Content-Type", "application/json")
+                .PUT(HttpRequest.BodyPublishers.ofString(body))
+                .build();
+
+        sendOkOrIgnore(req);
+    }
+
+    @Override
+    public void ensureJoined(String mxid, String roomId) {
+        String url = hs + "/_matrix/client/v3/rooms/" + encPath(roomId) + "/join"
+                     + "?access_token=" + enc(asToken)
+                     + "&user_id=" + enc(mxid);
+
+        HttpRequest req = HttpRequest.newBuilder(URI.create(url))
+                .timeout(Duration.ofSeconds(10))
+                .header("Content-Type", "application/json")
+                .POST(HttpRequest.BodyPublishers.ofString("{}"))
+                .build();
+
+        sendOkOrIgnore(req);
+    }
+
+    @Override
+    public void sendText(String mxid, String roomId, String bodyText) {
+        String txnId = UUID.randomUUID().toString();
+
+        String url = hs + "/_matrix/client/v3/rooms/" + encPath(roomId) + "/send/m.room.message/" + encPath(txnId)
+                     + "?access_token=" + enc(asToken)
+                     + "&user_id=" + enc(mxid);
+
+        String body = "{\"msgtype\":\"m.text\",\"body\":\"" + json(bodyText) + "\"}";
+
+        HttpRequest req = HttpRequest.newBuilder(URI.create(url))
+                .timeout(Duration.ofSeconds(10))
+                .header("Content-Type", "application/json")
+                .PUT(HttpRequest.BodyPublishers.ofString(body))
+                .build();
+
+        sendOkOrIgnore(req);
+    }
+
+    private void sendIgnoreConflict(HttpRequest req) {
+        try {
+            HttpResponse<String> res = http.send(req, HttpResponse.BodyHandlers.ofString());
+            int c = res.statusCode();
+            if (c == 200) {
+                return;
+            }
+            if (c == 400 && res.body() != null && res.body().contains("M_USER_IN_USE")) {
+                return;
+            }
+            if (c == 401 || c == 403) {
+                throw new RuntimeException("Matrix auth failed: " + c + " " + res.body());
+            }
+        } catch (Exception e) {
+            throw new RuntimeException(e);
+        }
+    }
+
+    private void sendOkOrIgnore(HttpRequest req) {
+        try {
+            HttpResponse<String> res = http.send(req, HttpResponse.BodyHandlers.ofString());
+            int c = res.statusCode();
+            if (c >= 200 && c < 300) {
+                return;
+            }
+            if (c == 401 || c == 403) {
+                throw new RuntimeException("Matrix auth failed: " + c + " " + res.body());
+            }
+        } catch (Exception e) {
+            throw new RuntimeException(e);
+        }
+    }
+
+    private static String localpart(String mxid) {
+        // "@localpart:domain"
+        int at = mxid.indexOf('@');
+        int colon = mxid.indexOf(':');
+        if (at != 0 || colon < 0) {
+            throw new IllegalArgumentException("bad mxid: " + mxid);
+        }
+        return mxid.substring(1, colon);
+    }
+
+    private static String enc(String s) {
+        return URLEncoder.encode(s, StandardCharsets.UTF_8);
+    }
+
+    private static String encPath(String s) {
+        // safe enough for matrix path segments
+        return URLEncoder.encode(s, StandardCharsets.UTF_8);
+    }
+
+    private static String json(String s) {
+        return s.replace("\\", "\\\\").replace("\"", "\\\"").replace("\n", "\\n").replace("\r", "\\r");
+    }
+}

matrix/src/main/java/com/alttd/matrix/interfaces/MatrixAppServiceServer.java

@@ -0,0 +1,11 @@
+package com.alttd.matrix.interfaces;
+
+import java.io.Closeable;
+import java.util.function.Consumer;
+
+public interface MatrixAppServiceServer extends Closeable {
+    void setTransactionListener(Consumer<TransactionEvent> listener);
+
+    record TransactionEvent(String roomId, String senderMxid, String body, String eventId) {
+    }
+}

matrix/src/main/java/com/alttd/matrix/interfaces/MatrixBridge.java

@@ -0,0 +1,21 @@
+package com.alttd.matrix.interfaces;
+
+import java.util.UUID;
+
+public interface MatrixBridge {
+    void setInboundHandler(InboundHandler handler);
+
+    void setRoomResolver(RoomResolver resolver);
+
+    void sendChat(UUID playerUuid, String mcUsername, String serverName, String message);
+
+    interface InboundHandler {
+        void onMatrixChat(String roomId, String senderMxid, String body);
+    }
+
+    interface RoomResolver {
+        String roomIdForServer(String serverName);
+
+        String serverForRoomId(String roomId);
+    }
+}

matrix/src/main/java/com/alttd/matrix/interfaces/MatrixClient.java

@@ -0,0 +1,11 @@
+package com.alttd.matrix.interfaces;
+
+public interface MatrixClient {
+    void ensureUser(String mxid);
+
+    void setDisplayName(String mxid, String displayName);
+
+    void ensureJoined(String mxid, String roomId);
+
+    void sendText(String mxid, String roomId, String body);
+}

settings.gradle.kts

@@ -3,22 +3,13 @@ rootProject.name = "Chat"
 include(":api")
 include(":galaxy")
 include(":velocity")
+include(":matrix")
 
 val nexusUser = providers.gradleProperty("alttdSnapshotUsername").get()
 val nexusPass = providers.gradleProperty("alttdSnapshotPassword").get()
 
 dependencyResolutionManagement {
     repositories {
-//        mavenLocal()
-        mavenCentral()
-        maven("https://repo.alttd.com/snapshots") // Altitude - Galaxy
-        maven("https://oss.sonatype.org/content/groups/public/") // Adventure
-        maven("https://oss.sonatype.org/content/repositories/snapshots/") // Minimessage
-        maven("https://nexus.velocitypowered.com/repository/") // Velocity
-        maven("https://nexus.velocitypowered.com/repository/maven-public/") // Velocity
-        maven("https://repo.spongepowered.org/maven") // Configurate
-        maven("https://repo.extendedclip.com/content/repositories/placeholderapi/") // Papi
-        maven("https://jitpack.io")
         maven {
             name = "nexus"
             url = uri("https://repo.alttd.com/repository/alttd-snapshot/")
@@ -27,6 +18,13 @@ dependencyResolutionManagement {
                 password = nexusPass
             }
         }
+//        mavenLocal()
+        mavenCentral()
+        maven("https://oss.sonatype.org/content/groups/public/") // Adventure
+        maven("https://oss.sonatype.org/content/repositories/snapshots/") // Minimessage
+        maven("https://repo.spongepowered.org/maven") // Configurate
+        maven("https://repo.extendedclip.com/content/repositories/placeholderapi/") // Papi
+        maven("https://jitpack.io")
     }
     repositoriesMode.set(RepositoriesMode.FAIL_ON_PROJECT_REPOS)
 }
@@ -36,3 +34,5 @@ pluginManagement {
         gradlePluginPortal()
     }
 }
+
+include("matrix")

velocity/src/main/java/com/alttd/velocitychat/VelocityChat.java

@@ -2,23 +2,33 @@ package com.alttd.velocitychat;
 
 import com.alttd.chat.ChatAPI;
 import com.alttd.chat.ChatImplementation;
+import com.alttd.chat.config.Config;
+import com.alttd.chat.database.DatabaseConnection;
 import com.alttd.chat.managers.ChatUserManager;
 import com.alttd.chat.managers.PartyManager;
 import com.alttd.chat.objects.ChatUser;
 import com.alttd.chat.objects.chat_log.ChatLogHandler;
+import com.alttd.chat.util.ALogger;
+import com.alttd.matrix.MatrixConfig;
+import com.alttd.matrix.MatrixRuntime;
+import com.alttd.matrix.bridge.DefaultMatrixBridge;
+import com.alttd.matrix.interfaces.MatrixAppServiceServer;
+import com.alttd.matrix.interfaces.MatrixBridge;
+import com.alttd.matrix.interfaces.MatrixClient;
 import com.alttd.velocitychat.commands.*;
-import com.alttd.chat.config.Config;
-import com.alttd.chat.database.DatabaseConnection;
 import com.alttd.velocitychat.handlers.ChatHandler;
 import com.alttd.velocitychat.handlers.ServerHandler;
 import com.alttd.velocitychat.listeners.ChatListener;
 import com.alttd.velocitychat.listeners.LiteBansListener;
-import com.alttd.velocitychat.listeners.ProxyPlayerListener;
 import com.alttd.velocitychat.listeners.PluginMessageListener;
-import com.alttd.chat.util.ALogger;
+import com.alttd.velocitychat.listeners.ProxyPlayerListener;
+import com.alttd.velocitychat.matrix.MatrixRoomMap;
+import com.alttd.velocitychat.matrix.VelocityMatrixInbound;
+import com.alttd.velocitychat.matrix.VelocityMatrixOutbound;
 import com.google.common.io.ByteArrayDataOutput;
 import com.google.common.io.ByteStreams;
 import com.google.inject.Inject;
+import com.velocitypowered.api.event.EventManager;
 import com.velocitypowered.api.event.Subscribe;
 import com.velocitypowered.api.event.proxy.ProxyInitializeEvent;
 import com.velocitypowered.api.plugin.Dependency;
@@ -43,7 +53,9 @@ public class VelocityChat {
     private final ProxyServer server;
     private final Logger logger;
     private final Path dataDirectory;
+    private final EventManager eventManager;
 
+    private MatrixAppServiceServer matrixAsServer;
     private ChatAPI chatAPI;
     private ChatHandler chatHandler;
     private ServerHandler serverHandler;
@@ -51,11 +63,12 @@ public class VelocityChat {
     private ChannelIdentifier channelIdentifier;
 
     @Inject
-    public VelocityChat(ProxyServer proxyServer, Logger proxyLogger, @DataDirectory Path proxydataDirectory) {
+    public VelocityChat(ProxyServer proxyServer, Logger proxyLogger, @DataDirectory Path proxydataDirectory, EventManager eventManager) {
         plugin = this;
         server = proxyServer;
         logger = proxyLogger;
         dataDirectory = proxydataDirectory;
+        this.eventManager = eventManager;
     }
 
     @Subscribe
@@ -80,6 +93,7 @@ public class VelocityChat {
         ChatUser console = new ChatUser(Config.CONSOLEUUID, -1, null);
         console.setDisplayName(Config.CONSOLENAME);
         ChatUserManager.addUser(console);
+        initMatrix();
     }
 
     public void reloadConfig() {
@@ -92,6 +106,42 @@ public class VelocityChat {
         getProxy().getAllServers().stream().forEach(registeredServer -> registeredServer.sendPluginMessage(getChannelIdentifier(), buf.toByteArray()));
     }
 
+    //TODO call initMatrix
+    private void initMatrix() {
+        MatrixConfig cfg = new MatrixConfig(
+                Config.MATRIX_SERVER,
+                Config.MATRIX_AS_TOKEN,
+                Config.MATRIX_HS_TOKEN,
+                "matrix.alttd.com",
+                "mc_",
+                "127.0.0.1",
+                9000
+        );
+
+        MatrixAppServiceServer asServer;
+        try {
+            asServer = MatrixRuntime.startAppService(cfg);
+        } catch (Exception e) {
+            logger.error("Failed to start Matrix AppService server", e);
+            return;
+        }
+
+        MatrixClient client = MatrixRuntime.createClient(cfg);
+
+        initMatrix(cfg, asServer, client);
+    }
+
+    public void initMatrix(MatrixConfig matrixConfig, MatrixAppServiceServer asServer, MatrixClient client) {
+        MatrixRoomMap roomMap = new MatrixRoomMap();
+        roomMap.put("bayou", "!bayou:matrix.alttd.com");
+
+        MatrixBridge matrix = new DefaultMatrixBridge(matrixConfig, asServer, client);
+        matrix.setRoomResolver(roomMap);
+        matrix.setInboundHandler(new VelocityMatrixInbound(server, roomMap));
+
+        eventManager.register(this, new VelocityMatrixOutbound(matrix));
+    }
+
     public File getDataDirectory() {
         return dataDirectory.toFile();
     }

velocity/src/main/java/com/alttd/velocitychat/matrix/MatrixRoomMap.java

@@ -0,0 +1,26 @@
+package com.alttd.velocitychat.matrix;
+
+import com.alttd.matrix.interfaces.MatrixBridge;
+
+import java.util.Map;
+import java.util.concurrent.ConcurrentHashMap;
+
+public final class MatrixRoomMap implements MatrixBridge.RoomResolver {
+    private final Map<String, String> serverToRoom = new ConcurrentHashMap<>();
+    private final Map<String, String> roomToServer = new ConcurrentHashMap<>();
+
+    public void put(String serverName, String roomId) {
+        serverToRoom.put(serverName, roomId);
+        roomToServer.put(roomId, serverName);
+    }
+
+    @Override
+    public String roomIdForServer(String serverName) {
+        return serverToRoom.get(serverName);
+    }
+
+    @Override
+    public String serverForRoomId(String roomId) {
+        return roomToServer.get(roomId);
+    }
+}

velocity/src/main/java/com/alttd/velocitychat/matrix/VelocityMatrixInbound.java

@@ -0,0 +1,38 @@
+package com.alttd.velocitychat.matrix;
+
+import com.alttd.matrix.interfaces.MatrixBridge;
+import com.velocitypowered.api.proxy.ProxyServer;
+import com.velocitypowered.api.proxy.server.RegisteredServer;
+import net.kyori.adventure.text.Component;
+
+import java.util.Optional;
+
+public final class VelocityMatrixInbound implements MatrixBridge.InboundHandler {
+    private final ProxyServer proxy;
+    private final MatrixRoomMap rooms;
+
+    public VelocityMatrixInbound(ProxyServer proxy, MatrixRoomMap rooms) {
+        this.proxy = proxy;
+        this.rooms = rooms;
+    }
+
+    @Override
+    public void onMatrixChat(String roomId, String senderMxid, String body) {
+        final String serverName = rooms.serverForRoomId(roomId);
+        if (serverName == null) {
+            return;
+        }
+
+        // route to backend server players connected to that server
+        Optional<RegisteredServer> rs = proxy.getServer(serverName);
+        if (rs.isEmpty()) {
+            return;
+        }
+
+        // minimal formatting; adjust to your chat format
+        String sender = senderMxid != null ? senderMxid : "matrix";
+        Component msg = Component.text("[M] " + sender + ": " + body);
+
+        rs.get().getPlayersConnected().forEach(p -> p.sendMessage(msg));
+    }
+}

velocity/src/main/java/com/alttd/velocitychat/matrix/VelocityMatrixOutbound.java

@@ -0,0 +1,35 @@
+package com.alttd.velocitychat.matrix;
+
+import com.alttd.matrix.interfaces.MatrixBridge;
+import com.velocitypowered.api.event.Subscribe;
+import com.velocitypowered.api.event.player.PlayerChatEvent;
+import com.velocitypowered.api.proxy.Player;
+import net.kyori.adventure.text.serializer.plain.PlainTextComponentSerializer;
+
+public final class VelocityMatrixOutbound {
+    private final MatrixBridge matrix;
+
+    public VelocityMatrixOutbound(MatrixBridge matrix) {
+        this.matrix = matrix;
+    }
+
+    @Subscribe
+    public void onChat(PlayerChatEvent e) {
+        if (!e.getResult().isAllowed()) {
+            return;
+        }
+
+        Player p = e.getPlayer();
+        String serverName = p.getCurrentServer().map(s -> s.getServerInfo().getName()).orElse(null);
+        if (serverName == null) {
+            return;
+        }
+
+        String msg = PlainTextComponentSerializer.plainText().serialize(e.getMessage());
+        if (msg == null || msg.isBlank()) {
+            return;
+        }
+
+        matrix.sendChat(p.getUniqueId(), p.getUsername(), serverName, msg);
+    }
+}