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

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

@@ -0,0 +1,70 @@
+package dev.coph.nextusweb.server.websocket;
+
+import java.util.ArrayList;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+import java.util.concurrent.ConcurrentHashMap;
+
+public final class WebSocketRouter {
+
+    private final Node root = new Node();
+
+    public WebSocketRouter on(String path, WebSocketHandler handler) {
+        Node node = root;
+        for (String segment : split(path)) {
+            if (segment.startsWith("{") && segment.endsWith("}")) {
+                if (node.paramChild == null) {
+                    node.paramChild = new Node();
+                    node.paramName = segment.substring(1, segment.length() - 1);
+                }
+                node = node.paramChild;
+            } else {
+                node = node.children.computeIfAbsent(segment, k -> new Node());
+            }
+        }
+        node.handler = handler;
+        return this;
+    }
+
+    public Resolution resolve(String path) {
+        Map<String, String> params = new HashMap<>(4);
+        Node node = root;
+        for (String segment : split(path)) {
+            Node next = node.children.get(segment);
+            if (next != null) {
+                node = next;
+            } else if (node.paramChild != null) {
+                params.put(node.paramName, segment);
+                node = node.paramChild;
+            } else {
+                return null;
+            }
+        }
+        if (node.handler == null) return null;
+        return new Resolution(node.handler, params);
+    }
+
+    private static List<String> split(String path) {
+        List<String> out = new ArrayList<>();
+        int start = path.startsWith("/") ? 1 : 0;
+        for (int i = start; i < path.length(); i++) {
+            if (path.charAt(i) == '/') {
+                if (i > start) out.add(path.substring(start, i));
+                start = i + 1;
+            }
+        }
+        if (start < path.length()) out.add(path.substring(start));
+        return out;
+    }
+
+    public record Resolution(WebSocketHandler handler, Map<String, String> pathParams) {
+    }
+
+    private static final class Node {
+        final Map<String, Node> children = new ConcurrentHashMap<>();
+        Node paramChild;
+        String paramName;
+        WebSocketHandler handler;
+    }
+}