Add DAU statistics module

src/main/java/com/openisle/config/SecurityConfig.java

@@ -1,6 +1,7 @@
 package com.openisle.config;
 
 import com.openisle.service.JwtService;
+import com.openisle.service.UserVisitService;
 import com.openisle.repository.UserRepository;
 import lombok.RequiredArgsConstructor;
 import org.springframework.context.annotation.Bean;
@@ -38,6 +39,7 @@ public class SecurityConfig {
     private final JwtService jwtService;
     private final UserRepository userRepository;
     private final AccessDeniedHandler customAccessDeniedHandler;
+    private final UserVisitService userVisitService;
 
     @Bean
     public PasswordEncoder passwordEncoder() {
@@ -103,7 +105,8 @@ public class SecurityConfig {
                     .requestMatchers("/api/admin/**").hasAuthority("ADMIN")
                     .anyRequest().authenticated()
             )
-            .addFilterBefore(jwtAuthenticationFilter(), UsernamePasswordAuthenticationFilter.class);
+            .addFilterBefore(jwtAuthenticationFilter(), UsernamePasswordAuthenticationFilter.class)
+            .addFilterAfter(userVisitFilter(), UsernamePasswordAuthenticationFilter.class);
         return http.build();
     }
 
@@ -150,4 +153,18 @@ public class SecurityConfig {
             }
         };
     }
+
+    @Bean
+    public OncePerRequestFilter userVisitFilter() {
+        return new OncePerRequestFilter() {
+            @Override
+            protected void doFilterInternal(HttpServletRequest request, HttpServletResponse response, FilterChain filterChain) throws ServletException, IOException {
+                var auth = org.springframework.security.core.context.SecurityContextHolder.getContext().getAuthentication();
+                if (auth != null && auth.isAuthenticated() && !(auth instanceof org.springframework.security.authentication.AnonymousAuthenticationToken)) {
+                    userVisitService.recordVisit(auth.getName());
+                }
+                filterChain.doFilter(request, response);
+            }
+        };
+    }
 }

src/main/java/com/openisle/controller/StatController.java

@@ -0,0 +1,26 @@
+package com.openisle.controller;
+
+import com.openisle.service.UserVisitService;
+import lombok.RequiredArgsConstructor;
+import org.springframework.format.annotation.DateTimeFormat;
+import org.springframework.web.bind.annotation.GetMapping;
+import org.springframework.web.bind.annotation.RequestMapping;
+import org.springframework.web.bind.annotation.RequestParam;
+import org.springframework.web.bind.annotation.RestController;
+
+import java.time.LocalDate;
+import java.util.Map;
+
+@RestController
+@RequestMapping("/api/stats")
+@RequiredArgsConstructor
+public class StatController {
+    private final UserVisitService userVisitService;
+
+    @GetMapping("/dau")
+    public Map<String, Long> dau(@RequestParam(value = "date", required = false)
+                                 @DateTimeFormat(iso = DateTimeFormat.ISO.DATE) LocalDate date) {
+        long count = userVisitService.countDau(date);
+        return Map.of("dau", count);
+    }
+}

src/main/java/com/openisle/repository/UserVisitRepository.java

@@ -10,4 +10,5 @@ import java.util.Optional;
 public interface UserVisitRepository extends JpaRepository<UserVisit, Long> {
     Optional<UserVisit> findByUserAndVisitDate(User user, LocalDate visitDate);
     long countByUser(User user);
+    long countByVisitDate(LocalDate visitDate);
 }

src/main/java/com/openisle/service/UserVisitService.java

@@ -32,4 +32,9 @@ public class UserVisitService {
                 .orElseThrow(() -> new com.openisle.exception.NotFoundException("User not found"));
         return userVisitRepository.countByUser(user);
     }
+
+    public long countDau(LocalDate date) {
+        LocalDate d = date != null ? date : LocalDate.now();
+        return userVisitRepository.countByVisitDate(d);
+    }
 }