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src/main/java/stirling/software/SPDF/config/UserBasedRateLimitingFilter.java

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+package stirling.software.SPDF.config;
+
+import java.io.IOException;
+import java.time.Duration;
+import java.util.Map;
+import java.util.concurrent.ConcurrentHashMap;
+import org.springframework.security.core.userdetails.UserDetails;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.http.HttpStatus;
+import org.springframework.security.core.Authentication;
+import org.springframework.security.core.context.SecurityContextHolder;
+import org.springframework.security.core.userdetails.UserDetailsService;
+import org.springframework.stereotype.Component;
+import org.springframework.web.filter.OncePerRequestFilter;
+
+import io.github.bucket4j.Bandwidth;
+import io.github.bucket4j.Bucket;
+import io.github.bucket4j.Bucket4j;
+import io.github.bucket4j.Refill;
+import jakarta.servlet.FilterChain;
+import jakarta.servlet.ServletException;
+import jakarta.servlet.http.HttpServletRequest;
+import jakarta.servlet.http.HttpServletResponse;
+@Component
+public class UserBasedRateLimitingFilter extends OncePerRequestFilter {
+
+    private final Map<String, Bucket> buckets = new ConcurrentHashMap<>();
+
+
+    @Override
+    protected void doFilterInternal(HttpServletRequest request,
+                                    HttpServletResponse response,
+                                    FilterChain filterChain) throws ServletException, IOException {
+    	String method = request.getMethod();
+    	if (!"POST".equalsIgnoreCase(method)) {
+            filterChain.doFilter(request, response);
+            return;
+        }
+    	
+
+        String identifier;
+        Authentication authentication = SecurityContextHolder.getContext().getAuthentication();
+        
+        if (authentication != null && authentication.isAuthenticated()) {
+            UserDetails userDetails = (UserDetails) authentication.getPrincipal();
+            identifier = userDetails.getUsername();
+        } else {
+            identifier = request.getRemoteAddr(); // Use IP as identifier if not authenticated
+        }
+
+        Bucket userBucket = buckets.computeIfAbsent(identifier, k -> createUserBucket());
+        
+        if (userBucket.tryConsume(1)) {
+            filterChain.doFilter(request, response);
+        } else {
+            response.setStatus(HttpStatus.TOO_MANY_REQUESTS.value());
+            response.getWriter().write("Rate limit exceeded.");
+            return;
+        }
+    }
+//https://www.baeldung.com/spring-bucket4j
+    private Bucket createUserBucket() {
+        Refill refill = Refill.of(3, Duration.ofDays(1));
+        Bandwidth limit = Bandwidth.classic(3, refill).withInitialTokens(3);
+        return Bucket4j.builder().addLimit(limit).build();
+    }
+}
+