CLAP-267 Feat: 조회된 작업 보드에서 하나의 작업만 존재하고, 이 작업을 이동할 때의 case 구현

<footer>
- 관련: #302

Author: joowojr

src/main/java/clap/server/application/service/task/UpdateTaskBoardService.java

@@ -53,15 +53,15 @@ public void updateTaskOrder(Long processorId, UpdateTaskOrderRequest request) {
         if (request.prevTaskId() == 0) {
             Task nextTask = findByIdAndStatus(request.nextTaskId(), targetTask.getTaskStatus());
             // 해당 상태에서 바로 앞에 있는 작업 찾기
-            Task prevTask = loadTaskPort.findPrevOrderTaskByProcessorIdAndStatus(processorId, targetTask.getTaskStatus(), nextTask.getProcessorOrder()).orElse(null);
+            Task prevTask = loadTaskPort.findPrevOrderTaskByProcessorOrderAndStatus(processorId, targetTask.getTaskStatus(), nextTask.getProcessorOrder()).orElse(null);
             long newOrder = taskOrderCalculationPolicy.calculateOrderForTop(prevTask, nextTask);
             updateNewTaskOrder(targetTask, newOrder);
         }
         // 가장 하위로 이동
         else if (request.nextTaskId() == 0) {
             Task prevTask = findByIdAndStatus(request.prevTaskId(), targetTask.getTaskStatus());
             // 해당 상태에서 바로 뒤에 있는 작업 찾기
-            Task nextTask = loadTaskPort.findNextOrderTaskByProcessorIdAndStatus(processorId, targetTask.getTaskStatus(), prevTask.getProcessorOrder()).orElse(null);
+            Task nextTask = loadTaskPort.findNextOrderTaskByProcessorOrderAndStatus(processorId, targetTask.getTaskStatus(), prevTask.getProcessorOrder()).orElse(null);
             long newOrder = taskOrderCalculationPolicy.calculateOrderForBottom(prevTask, nextTask);
             updateNewTaskOrder(targetTask, newOrder);
         } else {
@@ -98,21 +98,50 @@ public void updateTaskOrderAndStatus(Long processorId, UpdateTaskOrderRequest re
         Task targetTask = taskService.findById(request.targetTaskId());
         processorValidationPolicy.validateProcessor(processorId, targetTask);
 
-        if (request.prevTaskId() == 0) {
-            Task nextTask = findByIdAndStatus(request.nextTaskId(), targetStatus);
+        Task prevTask;
+        Task nextTask;
+
+        // 조회된 작업 보드에서 하나의 작업만 존재하고, 이 작업을 이동할 때
+        if (request.prevTaskId() == 0 && request.nextTaskId() == 0) {
+
+            // 요청 시간 기준으로 가장 가장 근접한 이전의 Task를 조회
+            prevTask = loadTaskPort.findPrevOrderTaskByTaskIdAndStatus(processorId, targetStatus, targetTask.getTaskId()).orElse(null);
+            if (prevTask != null) {
+                // 이전 Task가 있다면 바로 다음의 Task 조회
+                nextTask = loadTaskPort.findNextOrderTaskByProcessorOrderAndStatus(processorId, targetStatus, prevTask.getProcessorOrder()).orElse(null);
+            } // 요청 시간 기준으로 가장 가장 근접한 이후의 Task를 조회
+            else
+                nextTask = loadTaskPort.findNextOrderTaskByTaskIdAndStatus(processorId, targetStatus, targetTask.getTaskId()).orElse(null);
+
+            // 하나의 task만 존재할 경우 상태만 update
+            if (prevTask == null && nextTask == null) {
+                targetTask.updateTaskStatus(targetStatus);
+                taskService.upsert(targetTask);
+            } else if (prevTask == null) {
+                long newOrder = taskOrderCalculationPolicy.calculateOrderForBottom(null, nextTask);
+                updateNewTaskOrderAndStatus(targetStatus, targetTask, newOrder);
+            } else if (nextTask == null) {
+                long newOrder = taskOrderCalculationPolicy.calculateOrderForBottom(prevTask, null);
+                updateNewTaskOrderAndStatus(targetStatus, targetTask, newOrder);
+            } else {
+                long newOrder = taskOrderCalculationPolicy.calculateNewProcessorOrder(prevTask.getProcessorOrder(), nextTask.getProcessorOrder());
+                updateNewTaskOrderAndStatus(targetStatus, targetTask, newOrder);
+            }
+        } else if (request.prevTaskId() == 0) {
+            nextTask = findByIdAndStatus(request.nextTaskId(), targetStatus);
             // 해당 상태에서 바로 앞 있는 작업 찾기
-            Task prevTask = loadTaskPort.findPrevOrderTaskByProcessorIdAndStatus(processorId, targetStatus, nextTask.getProcessorOrder()).orElse(null);
+            prevTask = loadTaskPort.findPrevOrderTaskByProcessorOrderAndStatus(processorId, targetStatus, nextTask.getProcessorOrder()).orElse(null);
             long newOrder = taskOrderCalculationPolicy.calculateOrderForTop(prevTask, nextTask);
             updateNewTaskOrderAndStatus(targetStatus, targetTask, newOrder);
         } else if (request.nextTaskId() == 0) {
-            Task prevTask = findByIdAndStatus(request.prevTaskId(), targetStatus);
+            prevTask = findByIdAndStatus(request.prevTaskId(), targetStatus);
             // 해당 상태에서 바로 뒤에 있는 작업 찾기
-            Task nextTask = loadTaskPort.findNextOrderTaskByProcessorIdAndStatus(processorId, targetStatus, prevTask.getProcessorOrder()).orElse(null);
+            nextTask = loadTaskPort.findNextOrderTaskByProcessorOrderAndStatus(processorId, targetStatus, prevTask.getProcessorOrder()).orElse(null);
             long newOrder = taskOrderCalculationPolicy.calculateOrderForBottom(prevTask, nextTask);
             updateNewTaskOrderAndStatus(targetStatus, targetTask, newOrder);
         } else {
-            Task prevTask = findByIdAndStatus(request.prevTaskId(), targetStatus);
-            Task nextTask = findByIdAndStatus(request.nextTaskId(), targetStatus);
+            prevTask = findByIdAndStatus(request.prevTaskId(), targetStatus);
+            nextTask = findByIdAndStatus(request.nextTaskId(), targetStatus);
             long newOrder = taskOrderCalculationPolicy.calculateNewProcessorOrder(prevTask.getProcessorOrder(), nextTask.getProcessorOrder());
             updateNewTaskOrderAndStatus(targetStatus, targetTask, newOrder);
         }
@@ -131,11 +160,6 @@ private void updateNewTaskOrderAndStatus(TaskStatus targetStatus, Task targetTas
      * 순서 변경 요청의 유효성을 검증하는 메서드
      */
     public void validateRequest(UpdateTaskOrderRequest request, TaskStatus targetStatus) {
-        // 이전 및 다음 작업 ID가 모두 0인 경우 예외 발생
-        if (request.prevTaskId() == 0 && request.nextTaskId() == 0) {
-            throw new ApplicationException(TaskErrorCode.INVALID_TASK_STATUS_TRANSITION);
-        }
-
         // 타겟 상태가 유효한지 검증
         if (targetStatus != null && !TaskPolicyConstants.TASK_BOARD_STATUS_FILTER.contains(targetStatus)) {
             throw new ApplicationException(TaskErrorCode.INVALID_TASK_STATUS_TRANSITION);