feat: 알림 요청 API 구현

build.gradle

@@ -32,6 +32,12 @@ dependencies {
 	runtimeOnly 'com.mysql:mysql-connector-j'
 
 	testImplementation 'org.springframework.boot:spring-boot-starter-data-jpa-test'
+
+	compileOnly 'org.projectlombok:lombok'
+	annotationProcessor 'org.projectlombok:lombok'
+
+	testCompileOnly 'org.projectlombok:lombok'
+	testAnnotationProcessor 'org.projectlombok:lombok'
 }
 
 tasks.named('test') {

src/main/java/com/backendsystemdesignlab/notification/notification/controller/NotificationController.java

@@ -0,0 +1,27 @@
+package com.backendsystemdesignlab.notification.notification.controller;
+
+import com.backendsystemdesignlab.notification.notification.dto.SendNotificationRequest;
+import com.backendsystemdesignlab.notification.notification.dto.SendNotificationResponse;
+import com.backendsystemdesignlab.notification.notification.service.NotificationService;
+import jakarta.validation.Valid;
+import lombok.RequiredArgsConstructor;
+import org.springframework.http.ResponseEntity;
+import org.springframework.web.bind.annotation.PostMapping;
+import org.springframework.web.bind.annotation.RequestBody;
+import org.springframework.web.bind.annotation.RequestMapping;
+import org.springframework.web.bind.annotation.RestController;
+
+@RestController
+@RequestMapping("/api/v1/notifications")
+@RequiredArgsConstructor
+public class NotificationController {
+
+    private final NotificationService notificationService;
+
+    @PostMapping
+    public ResponseEntity<SendNotificationResponse> send(@Valid @RequestBody SendNotificationRequest request) {
+        SendNotificationResponse response = notificationService.send(request);
+        return ResponseEntity.accepted().body(response); // 아직 실제 전송이 완료된 게 아니라 요청 접수 단계 (202 Accepted)
+    }
+
+}

src/main/java/com/backendsystemdesignlab/notification/notification/dto/SendNotificationRequest.java

@@ -0,0 +1,21 @@
+package com.backendsystemdesignlab.notification.notification.dto;
+
+import com.backendsystemdesignlab.notification.user.domain.NotificationChannel;
+import jakarta.validation.constraints.NotBlank;
+import jakarta.validation.constraints.NotEmpty;
+import jakarta.validation.constraints.NotNull;
+
+import java.util.Set;
+
+public record SendNotificationRequest(
+
+        @NotBlank
+        String eventId,
+
+        @NotNull
+        Long userId,
+
+        @NotEmpty
+        Set<NotificationChannel> channels
+) {
+}

src/main/java/com/backendsystemdesignlab/notification/notification/dto/SendNotificationResponse.java

@@ -0,0 +1,10 @@
+package com.backendsystemdesignlab.notification.notification.dto;
+
+import com.backendsystemdesignlab.notification.notification.domain.NotificationStatus;
+
+public record SendNotificationResponse(
+        Long notificationId,
+        NotificationStatus status,
+        long deliveryCount
+) {
+}

src/main/java/com/backendsystemdesignlab/notification/notification/repository/NotificationDeliveryRepository.java

@@ -0,0 +1,8 @@
+package com.backendsystemdesignlab.notification.notification.repository;
+
+import com.backendsystemdesignlab.notification.notification.domain.NotificationDelivery;
+import org.springframework.data.jpa.repository.JpaRepository;
+
+public interface NotificationDeliveryRepository extends JpaRepository<NotificationDelivery, Long> {
+    long countByNotificationId(Long notificationId);
+}

src/main/java/com/backendsystemdesignlab/notification/notification/repository/NotificationRepository.java

@@ -0,0 +1,10 @@
+package com.backendsystemdesignlab.notification.notification.repository;
+
+import com.backendsystemdesignlab.notification.notification.domain.Notification;
+import org.springframework.data.jpa.repository.JpaRepository;
+
+import java.util.Optional;
+
+public interface NotificationRepository extends JpaRepository<Notification, Long> {
+    Optional<Notification> findByEventId(String eventId);
+}

src/main/java/com/backendsystemdesignlab/notification/notification/service/NotificationService.java

@@ -0,0 +1,136 @@
+package com.backendsystemdesignlab.notification.notification.service;
+
+import com.backendsystemdesignlab.notification.notification.domain.Notification;
+import com.backendsystemdesignlab.notification.notification.domain.NotificationDelivery;
+import com.backendsystemdesignlab.notification.notification.dto.SendNotificationRequest;
+import com.backendsystemdesignlab.notification.notification.dto.SendNotificationResponse;
+import com.backendsystemdesignlab.notification.notification.repository.NotificationDeliveryRepository;
+import com.backendsystemdesignlab.notification.notification.repository.NotificationRepository;
+import com.backendsystemdesignlab.notification.user.domain.NotificationChannel;
+import com.backendsystemdesignlab.notification.user.domain.NotificationPreference;
+import com.backendsystemdesignlab.notification.user.domain.User;
+import com.backendsystemdesignlab.notification.user.domain.UserDevice;
+import com.backendsystemdesignlab.notification.user.repository.NotificationPreferenceRepository;
+import com.backendsystemdesignlab.notification.user.repository.UserDeviceRepository;
+import com.backendsystemdesignlab.notification.user.repository.UserRepository;
+import lombok.RequiredArgsConstructor;
+import org.springframework.stereotype.Service;
+import org.springframework.transaction.annotation.Transactional;
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Set;
+import java.util.stream.Collectors;
+
+@Service
+@RequiredArgsConstructor
+public class NotificationService {
+
+    private final UserRepository userRepository;
+    private final UserDeviceRepository userDeviceRepository;
+    private final NotificationPreferenceRepository preferenceRepository;
+    private final NotificationRepository notificationRepository;
+    private final NotificationDeliveryRepository deliveryRepository;
+
+    @Transactional
+    public SendNotificationResponse send(SendNotificationRequest request) {
+
+        // 동일 eventId가 이미 처리된 경우 기존 결과 반환
+        var existing = notificationRepository.findByEventId(request.eventId());
+
+        if (existing.isPresent()) {
+            Notification notification = existing.get();
+
+            return new SendNotificationResponse(
+                    notification.getId(),
+                    notification.getStatus(),
+                    deliveryRepository.countByNotificationId(notification.getId())
+            );
+        }
+
+        User user = userRepository.findById(request.userId())
+                .orElseThrow(() -> new IllegalArgumentException("사용자를 찾을 수 없습니다."));
+
+        Set<NotificationChannel> enabledChannels = preferenceRepository.findAllByUserIdAndEnabledTrue(user.getId())
+                .stream()
+                .map(NotificationPreference::getChannel)
+                .collect(Collectors.toSet());
+
+        Notification notification = notificationRepository.save(new Notification(request.eventId(), user));
+
+        List<NotificationDelivery> deliveries = new ArrayList<>();
+
+        for (NotificationChannel channel : request.channels()) {
+
+            if (!enabledChannels.contains(channel)) {
+                continue;
+            }
+
+            switch (channel) {
+                case PUSH -> createPushDeliveries(
+                        user,
+                        notification,
+                        deliveries
+                );
+
+                case SMS -> createSmsDelivery(
+                        user,
+                        notification,
+                        deliveries
+                );
+
+                case EMAIL -> createEmailDelivery(
+                        user,
+                        notification,
+                        deliveries
+                );
+            }
+        }
+
+        deliveryRepository.saveAll(deliveries);
+
+        return new SendNotificationResponse(
+                notification.getId(),
+                notification.getStatus(),
+                deliveries.size()
+        );
+    }
+
+    private void createPushDeliveries(User user, Notification notification, List<NotificationDelivery> deliveries) {
+        List<UserDevice> devices = userDeviceRepository.findAllByUserIdAndActiveTrue(user.getId());
+
+        for (UserDevice device : devices) {
+            deliveries.add(
+                    new NotificationDelivery(
+                            notification,
+                            NotificationChannel.PUSH,
+                            device.getDeviceToken()
+                    )
+            );
+        }
+    }
+
+    private void createSmsDelivery(User user, Notification notification, List<NotificationDelivery> deliveries) {
+        if (user.getPhoneNumber() == null || user.getPhoneNumber().isBlank()) return;
+
+        deliveries.add(
+                new NotificationDelivery(
+                        notification,
+                        NotificationChannel.SMS,
+                        user.getPhoneNumber()
+                )
+        );
+    }
+
+    private void createEmailDelivery(User user, Notification notification, List<NotificationDelivery> deliveries) {
+        if (user.getEmail() == null || user.getEmail().isBlank()) return;
+
+        deliveries.add(
+                new NotificationDelivery(
+                        notification,
+                        NotificationChannel.EMAIL,
+                        user.getEmail()
+                )
+        );
+    }
+}

src/main/java/com/backendsystemdesignlab/notification/user/repository/NotificationPreferenceRepository.java

@@ -0,0 +1,10 @@
+package com.backendsystemdesignlab.notification.user.repository;
+
+import com.backendsystemdesignlab.notification.user.domain.NotificationPreference;
+import org.springframework.data.jpa.repository.JpaRepository;
+
+import java.util.List;
+
+public interface NotificationPreferenceRepository extends JpaRepository<NotificationPreference, Long> {
+    List<NotificationPreference> findAllByUserIdAndEnabledTrue(Long userId);
+}

src/main/java/com/backendsystemdesignlab/notification/user/repository/UserDeviceRepository.java

@@ -0,0 +1,10 @@
+package com.backendsystemdesignlab.notification.user.repository;
+
+import com.backendsystemdesignlab.notification.user.domain.UserDevice;
+import org.springframework.data.jpa.repository.JpaRepository;
+
+import java.util.List;
+
+public interface UserDeviceRepository extends JpaRepository<UserDevice, Long> {
+    List<UserDevice> findAllByUserIdAndActiveTrue(Long userId);
+}

src/main/java/com/backendsystemdesignlab/notification/user/repository/UserRepository.java

@@ -0,0 +1,7 @@
+package com.backendsystemdesignlab.notification.user.repository;
+
+import com.backendsystemdesignlab.notification.user.domain.User;
+import org.springframework.data.jpa.repository.JpaRepository;
+
+public interface UserRepository extends JpaRepository<User, Long> {
+}