Added file to increment for each use (Issue #4864)

app/core/src/main/java/stirling/software/SPDF/service/UsageMetricsService.java

@@ -0,0 +1,66 @@
+package stirling.software.SPDF.service;
+
+import com.fasterxml.jackson.databind.ObjectMapper;
+import lombok.extern.slf4j.Slf4j;
+import org.springframework.scheduling.annotation.Scheduled;
+import org.springframework.stereotype.Service;
+
+import java.io.File;
+import java.io.IOException;
+import java.util.Map;
+import java.util.concurrent.ConcurrentHashMap;
+import java.util.concurrent.atomic.LongAdder;
+import java.util.stream.Collectors;
+
+@Slf4j
+@Service
+public class UsageMetricsService {
+
+    private final Map<String, LongAdder> globalCounts = new ConcurrentHashMap<>();
+
+    // toolName -> userName -> count
+    private final Map<String, Map<String, LongAdder>> perUserCounts = new ConcurrentHashMap<>();
+
+    private final ObjectMapper mapper = new ObjectMapper();
+    private final File statsFile = new File("configs/usage-stats.json");
+
+    public void recordUsage(String toolName, String username) {
+        // global
+        globalCounts.computeIfAbsent(toolName, k -> new LongAdder()).increment();
+
+        // per–user
+        if (username != null && !username.isBlank()) {
+            perUserCounts
+                .computeIfAbsent(toolName, k -> new ConcurrentHashMap<>())
+                .computeIfAbsent(username, k -> new LongAdder())
+                .increment();
+        }
+    }
+
+    // optional getters if you want to expose stats later
+    public Map<String, Long> getGlobalCounts() {
+        return globalCounts.entrySet().stream()
+                .collect(Collectors.toMap(Map.Entry::getKey, e -> e.getValue().sum()));
+    }
+
+    @Scheduled(fixedDelay = 60_000)
+    public void persistStats() {
+        try {
+            Map<String, Object> dto = Map.of(
+                "global", getGlobalCounts(),
+                "perUser", perUserCounts.entrySet().stream()
+                    .collect(Collectors.toMap(
+                        Map.Entry::getKey,
+                        e -> e.getValue().entrySet().stream()
+                                .collect(Collectors.toMap(
+                                    Map.Entry::getKey, x -> x.getValue().sum()
+                                ))
+                    ))
+            );
+            statsFile.getParentFile().mkdirs();
+            mapper.writerWithDefaultPrettyPrinter().writeValue(statsFile, dto);
+        } catch (IOException e) {
+            log.warn("Failed to persist usage stats", e);
+        }
+    }
+}