fix(intrusion): 修复代码质量问题 - 空值检查和常量提取

修复内容：
1. 添加 state_start_time 空值检查（CONFIRMING_INTRUSION 和 CONFIRMING_CLEAR 状态）
2. 移除 get_state() 未使用的 roi_id 参数
3. get_state() 接受 current_time 参数，避免直接调用 datetime.now()
4. 提取魔法数字：ALARM_LEVEL_INTRUSION = 3

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

algorithms.py

@@ -389,6 +389,9 @@ class IntrusionAlgorithm:
     STATE_ALARMED = "ALARMED"                        # 已告警（等待入侵消失）
     STATE_CONFIRMING_CLEAR = "CONFIRMING_CLEAR"      # 入侵消失确认中
 
+    # 告警级别常量
+    ALARM_LEVEL_INTRUSION = 3
+
     def __init__(
         self,
         cooldown_seconds: int = 300,
@@ -472,6 +475,11 @@ class IntrusionAlgorithm:
 
         elif self.state == self.STATE_CONFIRMING_INTRUSION:
             # 入侵确认中：需要持续检测到人
+            if self.state_start_time is None:
+                # 防御性编程：如果状态时间为空，重置到IDLE
+                self.state = self.STATE_IDLE
+                logger.error(f"ROI {roi_id}: CONFIRMING_INTRUSION 状态异常，state_start_time为None，重置到IDLE")
+            else:
                 elapsed = (current_time - self.state_start_time).total_seconds()
 
                 if not roi_has_person:
@@ -493,7 +501,7 @@ class IntrusionAlgorithm:
                             "camera_id": camera_id,
                             "bbox": bbox,
                             "alert_type": "intrusion",
-                        "alarm_level": 3,
+                            "alarm_level": self.ALARM_LEVEL_INTRUSION,
                             "message": "检测到周界入侵",
                             "first_frame_time": self._intrusion_start_time.strftime('%Y-%m-%d %H:%M:%S'),
                         })
@@ -518,6 +526,11 @@ class IntrusionAlgorithm:
 
         elif self.state == self.STATE_CONFIRMING_CLEAR:
             # 入侵消失确认中：需要持续未检测到人
+            if self.state_start_time is None:
+                # 防御性编程：如果状态时间为空，重置到IDLE
+                self.state = self.STATE_IDLE
+                logger.error(f"ROI {roi_id}: CONFIRMING_CLEAR 状态异常，state_start_time为None，重置到IDLE")
+            else:
                 elapsed = (current_time - self.state_start_time).total_seconds()
 
                 if roi_has_person:
@@ -564,8 +577,10 @@ class IntrusionAlgorithm:
         self.alert_triggered.clear()
         self.detection_start.clear()
 
-    def get_state(self, roi_id: str) -> Dict[str, Any]:
+    def get_state(self, current_time: Optional[datetime] = None) -> Dict[str, Any]:
         """获取当前状态（用于调试和监控）"""
+        current_time = current_time or datetime.now()
+
         state_info = {
             "state": self.state,
             "state_start_time": self.state_start_time.isoformat() if self.state_start_time else None,
@@ -573,7 +588,7 @@ class IntrusionAlgorithm:
 
         # 添加状态特定信息
         if self.state == self.STATE_ALARMED and self._intrusion_start_time:
-            total_intrusion_sec = (datetime.now() - self._intrusion_start_time).total_seconds()
+            total_intrusion_sec = (current_time - self._intrusion_start_time).total_seconds()
             state_info["total_intrusion_sec"] = total_intrusion_sec
             state_info["alarm_id"] = self._last_alarm_id