Add WebSocket support with routing, origin validation, session management, and broadcasting

src/main/java/dev/coph/nextusweb/server/websocket/WebSocketGroup.java

@@ -0,0 +1,83 @@
+package dev.coph.nextusweb.server.websocket;
+
+import dev.coph.nextusweb.server.json.JsonMapper;
+import io.netty.channel.group.ChannelGroup;
+import io.netty.channel.group.DefaultChannelGroup;
+import io.netty.handler.codec.http.websocketx.BinaryWebSocketFrame;
+import io.netty.handler.codec.http.websocketx.TextWebSocketFrame;
+import io.netty.util.concurrent.GlobalEventExecutor;
+import tools.jackson.core.JacksonException;
+
+public final class WebSocketGroup {
+
+    private final ChannelGroup channels;
+    private final String name;
+
+    public WebSocketGroup() {
+        this("anonymous");
+    }
+
+    public WebSocketGroup(String name) {
+        this.name = name;
+        this.channels = new DefaultChannelGroup(name, GlobalEventExecutor.INSTANCE);
+    }
+
+    public String name() {
+        return name;
+    }
+
+    public WebSocketGroup add(WebSocketSession session) {
+        channels.add(session.channel());
+        return this;
+    }
+
+    public WebSocketGroup remove(WebSocketSession session) {
+        channels.remove(session.channel());
+        return this;
+    }
+
+    public int size() {
+        return channels.size();
+    }
+
+    public WebSocketGroup broadcast(String text) {
+        channels.writeAndFlush(new TextWebSocketFrame(text));
+        return this;
+    }
+
+    public WebSocketGroup broadcastJson(Object value) {
+        try {
+            byte[] bytes = JsonMapper.MAPPER.writeValueAsBytes(value);
+            String text = new String(bytes, java.nio.charset.StandardCharsets.UTF_8);
+            channels.writeAndFlush(new TextWebSocketFrame(text));
+        } catch (JacksonException e) {
+            throw new RuntimeException("JSON serialization failed", e);
+        }
+        return this;
+    }
+
+    public WebSocketGroup broadcastBinary(byte[] data) {
+        for (var ch : channels) {
+            if (ch.isActive()) {
+                var buf = ch.alloc().buffer(data.length).writeBytes(data);
+                ch.writeAndFlush(new BinaryWebSocketFrame(buf));
+            }
+        }
+        return this;
+    }
+
+    public WebSocketGroup broadcastExcept(WebSocketSession exclude, String text) {
+        var excludeCh = exclude == null ? null : exclude.channel();
+        for (var ch : channels) {
+            if (ch.isActive() && ch != excludeCh) {
+                ch.writeAndFlush(new TextWebSocketFrame(text));
+            }
+        }
+        return this;
+    }
+
+    public WebSocketGroup closeAll() {
+        channels.close();
+        return this;
+    }
+}