Add FabricTPSRetriever for tracking and calculating TPS metrics

Author: renvins

fabric/src/main/java/it/renvins/serverpulse/fabric/metrics/FabricTPSRetriever.java

@@ -0,0 +1,67 @@
+package it.renvins.serverpulse.fabric.metrics;
+
+import java.util.LinkedList;
+import java.util.Queue;
+
+import it.renvins.serverpulse.api.metrics.ITPSRetriever;
+import it.renvins.serverpulse.fabric.task.FabricScheduler;
+import it.renvins.serverpulse.fabric.task.FabricTask;
+import lombok.RequiredArgsConstructor;
+
+@RequiredArgsConstructor
+public class FabricTPSRetriever implements ITPSRetriever {
+
+    private static final int TICK_PER_SECOND = 20;
+    private static final int TICK_PER_MIN = TICK_PER_SECOND * 60; // 1200
+    private static final int TICK_FIVE_MIN = TICK_PER_MIN * 5;
+    private static final int TICK_FIFTEEN_MIN = TICK_PER_MIN * 15;
+
+    private static final int MAX_HISTORY_SIZE = TICK_FIFTEEN_MIN;
+
+    private final Queue<Long> tickHistory = new LinkedList<>();
+
+    private final FabricScheduler scheduler;
+
+    private long lastTickTimeNano = -1;
+
+    private double tps1m = 20.0;
+    private double tps5m = 20.0;
+    private double tps15m = 20.0;
+
+    @Override
+    public double[] getTPS() {
+        return new double[0];
+    }
+
+    public void startTickMonitor() {
+        lastTickTimeNano = System.nanoTime();
+
+        scheduler.runTaskTimerAsync(() -> {
+            long currentTimeNano = System.nanoTime();
+            long elapsedTime = currentTimeNano - lastTickTimeNano;
+            lastTickTimeNano = currentTimeNano;
+
+            tickHistory.offer(elapsedTime);
+            if (tickHistory.size() > MAX_HISTORY_SIZE) {
+                tickHistory.poll();
+            }
+        }, 1, 1);
+    }
+
+    public void calculateAverages() {
+        // Calculate TPS for 1m, 5m, and 15m
+    }
+
+    public double calculateTPSFromAvgNano(long totalNano, int count) {
+        if (count == 0) {
+            return 20.0;
+        }
+        double avgTickTimeMillis = (double) totalNano / count / 1_000_000.0;
+        if (avgTickTimeMillis <= 0) {
+            return 20.0;
+        }
+        // TPS: 1 second (1000ms) / avg tick time (ms)
+        double tps = 1000.0 / avgTickTimeMillis;
+        return Math.min(tps, 20.0);
+    }
+}