add metrics websocket

pom.xml

@@ -61,6 +61,12 @@
             <artifactId>spring-boot-starter-web</artifactId>
         </dependency>
 
+        <!-- Websockets -->
+        <dependency>
+            <groupId>org.springframework.boot</groupId>
+            <artifactId>spring-boot-starter-websocket</artifactId>
+        </dependency>
+
         <!-- Redis for caching -->
         <dependency>
             <groupId>org.springframework.boot</groupId>

src/main/java/xyz/mcutils/backend/common/WebRequest.java

@@ -1,6 +1,5 @@
 package xyz.mcutils.backend.common;
 
-import com.google.gson.JsonObject;
 import lombok.experimental.UtilityClass;
 import org.springframework.http.HttpStatus;
 import org.springframework.http.HttpStatusCode;

src/main/java/xyz/mcutils/backend/config/WebSocketConfig.java

@@ -0,0 +1,22 @@
+package xyz.mcutils.backend.config;
+
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.context.annotation.Configuration;
+import org.springframework.web.socket.config.annotation.EnableWebSocket;
+import org.springframework.web.socket.config.annotation.WebSocketConfigurer;
+import org.springframework.web.socket.config.annotation.WebSocketHandlerRegistry;
+import xyz.mcutils.backend.service.MetricService;
+import xyz.mcutils.backend.websocket.MetricsWebSocketHandler;
+
+@Configuration
+@EnableWebSocket
+public class WebSocketConfig implements WebSocketConfigurer {
+
+    @Autowired
+    private MetricService metricService;
+
+    @Override
+    public void registerWebSocketHandlers(WebSocketHandlerRegistry registry) {
+        registry.addHandler(new MetricsWebSocketHandler(metricService), "/websocket/metrics").setAllowedOrigins("*");
+    }
+}

src/main/java/xyz/mcutils/backend/model/cache/CachedEndpointStatus.java

@@ -2,14 +2,16 @@ package xyz.mcutils.backend.model.cache;
 
 import com.fasterxml.jackson.annotation.JsonIgnore;
 import com.fasterxml.jackson.annotation.JsonUnwrapped;
-import lombok.*;
+import lombok.Getter;
+import lombok.NonNull;
+import lombok.Setter;
+import lombok.ToString;
 import org.springframework.data.annotation.Id;
 import org.springframework.data.redis.core.RedisHash;
 import xyz.mcutils.backend.common.CachedResponse;
 import xyz.mcutils.backend.model.mojang.EndpointStatus;
 
 import java.io.Serializable;
-import java.util.Map;
 
 @Setter @Getter @ToString
 @RedisHash(value = "mojangEndpointStatus", timeToLive = 60L) // 1 minute (in seconds)

src/main/java/xyz/mcutils/backend/model/metric/WebsocketMetrics.java

@@ -0,0 +1,15 @@
+package xyz.mcutils.backend.model.metric;
+
+import lombok.AllArgsConstructor;
+import lombok.Getter;
+
+import java.util.Map;
+
+@AllArgsConstructor
+@Getter
+public class WebsocketMetrics {
+    /**
+     * The metrics to send to the client.
+     */
+    private final Map<String, Object> metrics;
+}

src/main/java/xyz/mcutils/backend/model/mojang/EndpointStatus.java

@@ -1,12 +1,7 @@
 package xyz.mcutils.backend.model.mojang;
 
-import com.fasterxml.jackson.annotation.JsonIgnore;
 import lombok.AllArgsConstructor;
 import lombok.Getter;
-import lombok.NonNull;
-import org.springframework.data.annotation.Id;
-import xyz.mcutils.backend.common.CachedResponse;
-import xyz.mcutils.backend.model.cache.CachedEndpointStatus;
 
 import java.util.Map;
 

src/main/java/xyz/mcutils/backend/websocket/MetricsWebSocketHandler.java

@@ -0,0 +1,54 @@
+package xyz.mcutils.backend.websocket;
+
+import lombok.extern.log4j.Log4j2;
+import org.jetbrains.annotations.NotNull;
+import org.springframework.web.socket.CloseStatus;
+import org.springframework.web.socket.TextMessage;
+import org.springframework.web.socket.WebSocketSession;
+import org.springframework.web.socket.handler.TextWebSocketHandler;
+import xyz.mcutils.backend.Main;
+import xyz.mcutils.backend.common.Timer;
+import xyz.mcutils.backend.model.metric.WebsocketMetrics;
+import xyz.mcutils.backend.service.MetricService;
+import xyz.mcutils.backend.service.metric.metrics.TotalRequestsMetric;
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Map;
+import java.util.concurrent.TimeUnit;
+
+@Log4j2(topic = "WebSocket/Metrics")
+public class MetricsWebSocketHandler extends TextWebSocketHandler {
+    private final long interval = TimeUnit.SECONDS.toMillis(5); 
+    public final List<WebSocketSession> sessions = new ArrayList<>();
+
+    public MetricsWebSocketHandler(MetricService metricService) {
+        Timer.scheduleRepeating(() -> {
+            try {
+                WebsocketMetrics metrics = new WebsocketMetrics(Map.of(
+                        "totalRequests", metricService.getMetric(TotalRequestsMetric.class).getValue())
+                );
+
+                for (WebSocketSession session : sessions) {
+                    session.sendMessage(new TextMessage(Main.GSON.toJson(metrics)));
+                }
+            } catch (Exception e) {
+                log.error("An error occurred while sending metrics to the client", e);
+            }
+        }, interval, interval);
+    }
+
+    @Override
+    public void afterConnectionEstablished(WebSocketSession session) {
+        log.info("WebSocket connection established with session id: {}", session.getId());
+
+        sessions.add(session);
+    }
+
+    @Override
+    public void afterConnectionClosed(WebSocketSession session, @NotNull CloseStatus status) {
+        log.info("WebSocket connection closed with session id: {}", session.getId());
+
+        sessions.remove(session);
+    }
+}