feat: 结束会话时返回有效时间不足的提示信息

- StudySessionsServiceImpl: 检测 effectiveTime 被清零时返回提示消息
- StudySessionController: 将提示消息通过 CommonResult.success(message) 传给前端

src/main/java/com/guo/learningprogresstracker/controller/StudySessionController.java

@@ -67,8 +67,8 @@ public class StudySessionController {
     @PostMapping("/{sessionNum}/study-sessions/ended")
     public CommonResult<Void> endedStudySession(@PathVariable("sessionNum") String sessionNum,
                                                 @Valid @RequestBody EndedStudySessionRequest request) throws ErrorParameterException {
-        studySessionsServiceImpl.endedStudySession(sessionNum, request.getContent());
-        return CommonResult.success();
+        String message = studySessionsServiceImpl.endedStudySession(sessionNum, request.getContent());
+        return message != null ? CommonResult.success(message) : CommonResult.success();
     }
 
     /**

src/main/java/com/guo/learningprogresstracker/service/impl/StudySessionsServiceImpl.java

@@ -93,16 +93,21 @@ public class StudySessionsServiceImpl extends ServiceImpl<StudySessionsMapper, S
 
 
     @Override
-    public void endedStudySession(String sessionNum, String content) throws ErrorParameterException {
+    public String endedStudySession(String sessionNum, String content) throws ErrorParameterException {
         StudySessionsEntity studySessionsEntity = this.getOneOpt(Wrappers.lambdaQuery(StudySessionsEntity.class)
                         .eq(StudySessionsEntity::getSessionNum, sessionNum))
                 .orElseThrow(() -> new ErrorParameterException("会话[" + sessionNum + "]不存在"));
+        boolean wasOngoing = StudySessionStateEnum.ONGOING.name().equals(studySessionsEntity.getSessionState());
         studySessionsEntity.endedStudySession();
         this.updateById(studySessionsEntity);
         StudyReportsEntity studyReportsEntity = new StudyReportsEntity();
         studyReportsEntity.setSessionNum(sessionNum);
         studyReportsEntity.setContent(content);
         studyReportsMapper.insert(studyReportsEntity);
+        if (wasOngoing && studySessionsEntity.getEffectiveTime() == 0) {
+            return "本次有效学习时间不足10分钟，不计入总学习时间";
+        }
+        return null;
     }
 
     @Override