add event-driven architecture

Author: ColtonRandall

src/main/java/com/taskmanagerapi/event/TaskCompletedEvent.java

@@ -0,0 +1,23 @@
+package com.taskmanagerapi.event;
+
+import org.springframework.context.ApplicationEvent;
+
+public class TaskCompletedEvent extends ApplicationEvent {
+
+    private String id;
+    private String name;
+
+    public TaskCompletedEvent(Object source, String id, String name) {
+        super(source);
+        this.id = id;
+        this.name = name;
+    }
+
+    public String getId() {
+        return id;
+    }
+
+    public String getName() {
+        return name;
+    }
+}

src/main/java/com/taskmanagerapi/event/TaskCreatedEvent.java

@@ -0,0 +1,23 @@
+package com.taskmanagerapi.event;
+
+import org.springframework.context.ApplicationEvent;
+
+public class TaskCreatedEvent extends ApplicationEvent {
+
+    private String id;
+    private String name;
+
+    public TaskCreatedEvent(Object source, String id, String name) {
+        super(source);
+        this.id = id;
+        this.name = name;
+    }
+
+    public String getId() {
+        return id;
+    }
+
+    public String getName() {
+        return name;
+    }
+}

src/main/java/com/taskmanagerapi/event/TaskDeletedEvent.java

@@ -0,0 +1,17 @@
+package com.taskmanagerapi.event;
+
+import org.springframework.context.ApplicationEvent;
+
+public class TaskDeletedEvent extends ApplicationEvent {
+
+    private String id;
+
+    public TaskDeletedEvent(Object source, String id) {
+        super(source);
+        this.id = id;
+    }
+
+    public String getId() {
+        return id;
+    }
+}

src/main/java/com/taskmanagerapi/listener/TaskEventListener.java

@@ -0,0 +1,32 @@
+package com.taskmanagerapi.listener;
+
+import com.taskmanagerapi.event.TaskCompletedEvent;
+import com.taskmanagerapi.event.TaskCreatedEvent;
+import com.taskmanagerapi.event.TaskDeletedEvent;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+import org.springframework.context.event.EventListener;
+import org.springframework.stereotype.Component;
+
+@Component
+public class TaskEventListener {
+
+    private static final Logger log = LoggerFactory.getLogger(TaskEventListener.class);
+
+    @EventListener
+    public void onTaskCreated(TaskCreatedEvent event) {
+        log.info("Task created: id={}, name={}",
+                event.getId(), event.getName());
+    }
+
+    @EventListener
+    public void onTaskCompleted(TaskCompletedEvent event) {
+        log.info("Task completed: id={}, name={}",
+                event.getId(), event.getName());
+    }
+
+    @EventListener
+    public void onTaskDeleted(TaskDeletedEvent event) {
+        log.info("Task deleted: id={}", event.getId());
+    }
+}

src/main/java/com/taskmanagerapi/service/TaskService.java

@@ -1,12 +1,16 @@
 package com.taskmanagerapi.service;
 
 import com.taskmanagerapi.dto.TaskResponse;
+import com.taskmanagerapi.event.TaskCompletedEvent;
+import com.taskmanagerapi.event.TaskCreatedEvent;
+import com.taskmanagerapi.event.TaskDeletedEvent;
 import com.taskmanagerapi.exception.TaskNotFoundException;
 import com.taskmanagerapi.model.Task;
 import com.taskmanagerapi.model.TaskStatus;
 import com.taskmanagerapi.repository.TaskRepository;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
+import org.springframework.context.ApplicationEventPublisher;
 import org.springframework.stereotype.Service;
 import org.springframework.transaction.annotation.Transactional;
 
@@ -20,14 +24,23 @@ public class TaskService {
     private static final Logger log = LoggerFactory.getLogger(TaskService.class);
 
     private final TaskRepository taskRepository;
+    private final ApplicationEventPublisher eventPublisher;
 
-    public TaskService(TaskRepository taskRepository) {
+    public TaskService(TaskRepository taskRepository, ApplicationEventPublisher eventPublisher) {
         this.taskRepository = taskRepository;
+        this.eventPublisher = eventPublisher;
     }
 
     public TaskResponse addTask(String name, String description) {
         Task task = new Task(name, description);
         TaskResponse response = TaskResponse.from(taskRepository.save(task));
+        eventPublisher.publishEvent(
+                new TaskCreatedEvent(
+                        this,
+                        task.getId(),
+                        task.getName()
+                )
+        );
         log.info("Task created: id={}, name={}", response.getId(), response.getName());
         return response;
     }
@@ -66,6 +79,13 @@ public TaskResponse completeTask(String id) {
                 .orElseThrow(() -> new TaskNotFoundException(id));
         task.setStatus(DONE);
         log.info("Task completed: id={}", id);
+        eventPublisher.publishEvent(
+                new TaskCompletedEvent(
+                        this,
+                        task.getId(),
+                        task.getName()
+                )
+        );
         return TaskResponse.from(task);
     }
 
@@ -75,6 +95,12 @@ public TaskResponse deleteTask(String id) {
                 .orElseThrow(() -> new TaskNotFoundException(id));
         task.setStatus(DELETED);
         log.info("Task deleted: id={}", id);
+        eventPublisher.publishEvent(
+                new TaskDeletedEvent(
+                        this,
+                        task.getId()
+                )
+        );
         return TaskResponse.from(task);
     }
 

src/test/java/com/taskmanagerapi/TaskServiceTest.java

@@ -11,6 +11,7 @@
 import org.mockito.InjectMocks;
 import org.mockito.Mock;
 import org.mockito.junit.jupiter.MockitoExtension;
+import org.springframework.context.ApplicationEventPublisher;
 
 import java.util.List;
 import java.util.Optional;
@@ -24,6 +25,9 @@ class TaskServiceTest {
     @Mock
     private TaskRepository taskRepository;
 
+    @Mock
+    private ApplicationEventPublisher eventPublisher;
+
     @InjectMocks
     private TaskService taskService;