Add rate limiting, CORS support, custom HTTP method annotations, and HTTP server enhancements

- Introduced rate limiting functionality with multiple algorithms (Token Bucket, Fixed Window, Leaky Bucket, Sliding Window) via `RateLimiter` interface.
- Added CORS handling with `CorsConfig` and `CorsHandler` for flexible origin, headers, and method configuration.
- Implemented support for custom HTTP methods via `PATCH` and `CUSTOM` annotations in `AnnotationScanner`.
- Enhanced `HttpServer` to support builder pattern and optional integrations for CORS and rate limiting.
- Updated `HttpRequestHandler` to incorporate CORS and rate limiting logic.

src/main/java/dev/coph/nextusweb/server/HttpRequestHandler.java

@@ -1,5 +1,8 @@
 package dev.coph.nextusweb.server;
 
+import dev.coph.nextusweb.server.cores.CorsHandler;
+import dev.coph.nextusweb.server.ratelimit.RateLimitGate;
+import dev.coph.nextusweb.server.ratelimit.RateLimiter;
 import dev.coph.nextusweb.server.router.Request;
 import dev.coph.nextusweb.server.router.Response;
 import dev.coph.nextusweb.server.router.Router;
@@ -10,6 +13,7 @@ import io.netty.channel.ChannelHandlerContext;
 import io.netty.channel.SimpleChannelInboundHandler;
 import io.netty.handler.codec.http.*;
 
+import java.net.InetSocketAddress;
 import java.util.concurrent.Executor;
 import java.util.concurrent.Executors;
 import java.util.stream.Collectors;
@@ -20,9 +24,14 @@ public final class HttpRequestHandler extends SimpleChannelInboundHandler<FullHt
             Executors.newVirtualThreadPerTaskExecutor();
 
     private final Router router;
+    private final CorsHandler cors;
+    private final RateLimitGate rateLimit;
 
-    public HttpRequestHandler(Router router) {
+
+    public HttpRequestHandler(Router router, CorsHandler cors, RateLimitGate rateLimit) {
         this.router = router;
+        this.cors = cors;
+        this.rateLimit = rateLimit;
     }
 
     @Override
@@ -38,7 +47,29 @@ public final class HttpRequestHandler extends SimpleChannelInboundHandler<FullHt
     }
 
     private void handle(ChannelHandlerContext ctx, FullHttpRequest raw) {
+        String origin = raw.headers().get("Origin");
+
+        if (cors != null && cors.isPreflight(raw.method(), raw.headers())) {
+            send(ctx, cors.handlePreflight(origin, raw.headers()));
+            return;
+        }
+
         String path = new QueryStringDecoder(raw.uri()).path();
+
+        RateLimiter.Result rlResult = null;
+        if (rateLimit != null) {
+            String remote = ((InetSocketAddress) ctx.channel().remoteAddress()).getAddress().getHostAddress();
+            rlResult = rateLimit.check(raw, path, remote);
+            if (rlResult != null && !rlResult.allowed()) {
+                Response res = new Response().status(429).json("{\"error\":\"Too Many Requests\"}");
+                RateLimitGate.applyHeaders(rlResult, res);
+                if (cors != null) cors.applyHeaders(origin, res);
+                send(ctx, res);
+                return;
+            }
+        }
+
+
         Router.Resolution resolution = router.resolve(raw.method(), path);
 
         Response res = new Response();
@@ -67,6 +98,8 @@ public final class HttpRequestHandler extends SimpleChannelInboundHandler<FullHt
             case Router.Resolution.NotFound nf -> res.status(404).json("{\"error\":\"Not Found\"}");
         }
 
+        RateLimitGate.applyHeaders(rlResult, res);
+        if (cors != null) cors.applyHeaders(origin, res);
         send(ctx, res);
     }