feat: 初始化告警平台后端项目

- 创建 FastAPI 项目结构
- 实现告警数据模型（SQLAlchemy）
- 实现 multipart/form-data 告警接收接口
- 实现阿里云 OSS 图片上传模块
- 实现告警查询和处理 API
- 实现异步大模型分析模块

app/models.py

@@ -0,0 +1,119 @@
+import enum
+from datetime import datetime, timezone
+from typing import Optional
+from sqlalchemy import Column, String, Integer, DateTime, Text, Enum, JSON, create_engine
+from sqlalchemy.orm import declarative_base, sessionmaker
+from sqlalchemy.pool import StaticPool
+
+from app.config import settings
+
+Base = declarative_base()
+
+
+class AlertStatus(str, enum.Enum):
+    PENDING = "pending"
+    CONFIRMED = "confirmed"
+    IGNORED = "ignored"
+    RESOLVED = "resolved"
+
+
+class AlertLevel(str, enum.Enum):
+    LOW = "low"
+    MEDIUM = "medium"
+    HIGH = "high"
+    CRITICAL = "critical"
+
+
+class Alert(Base):
+    __tablename__ = "alerts"
+
+    id = Column(Integer, primary_key=True, autoincrement=True)
+    alert_no = Column(String(32), unique=True, nullable=False, index=True)
+
+    camera_id = Column(String(64), nullable=False, index=True)
+    roi_id = Column(String(64), nullable=True)
+    alert_type = Column(String(64), nullable=False)
+    algorithm = Column(String(128), nullable=True)
+    confidence = Column(Integer, nullable=True)
+    duration_minutes = Column(Integer, nullable=True)
+    trigger_time = Column(DateTime, nullable=False)
+    message = Column(Text, nullable=True)
+
+    snapshot_url = Column(String(512), nullable=True)
+    snapshot_path = Column(String(512), nullable=True)
+
+    status = Column(Enum(AlertStatus), default=AlertStatus.PENDING)
+    handle_remark = Column(Text, nullable=True)
+    handled_by = Column(String(64), nullable=True)
+    handled_at = Column(DateTime, nullable=True)
+
+    ai_analysis = Column(JSON, nullable=True)
+
+    created_at = Column(DateTime, default=lambda: datetime.now(timezone.utc))
+    updated_at = Column(DateTime, default=lambda: datetime.now(timezone.utc), onupdate=lambda: datetime.now(timezone.utc))
+
+    def to_dict(self) -> dict:
+        return {
+            "id": self.id,
+            "alert_no": self.alert_no,
+            "camera_id": self.camera_id,
+            "roi_id": self.roi_id,
+            "alert_type": self.alert_type,
+            "algorithm": self.algorithm,
+            "confidence": self.confidence,
+            "duration_minutes": self.duration_minutes,
+            "trigger_time": self.trigger_time.isoformat() if self.trigger_time else None,
+            "message": self.message,
+            "snapshot_url": self.snapshot_url,
+            "status": self.status.value if self.status else None,
+            "handle_remark": self.handle_remark,
+            "handled_by": self.handled_by,
+            "handled_at": self.handled_at.isoformat() if self.handled_at else None,
+            "ai_analysis": self.ai_analysis,
+            "created_at": self.created_at.isoformat() if self.created_at else None,
+            "updated_at": self.updated_at.isoformat() if self.updated_at else None,
+        }
+
+
+_engine = None
+_SessionLocal = None
+
+
+def get_engine():
+    global _engine
+    if _engine is None:
+        db_url = settings.database.url
+        connect_args = {}
+        if "sqlite" in db_url:
+            db_path = db_url.replace("sqlite:///", "")
+            os.makedirs(os.path.dirname(db_path) if os.path.dirname(db_path) else ".", exist_ok=True)
+            connect_args = {"check_same_thread": False}
+            _engine = create_engine(
+                db_url,
+                echo=settings.app.debug,
+                poolclass=StaticPool if "sqlite" in db_url else None,
+                connect_args=connect_args,
+            )
+        else:
+            _engine = create_engine(db_url, echo=settings.app.debug)
+    return _engine
+
+
+def get_session():
+    global _SessionLocal
+    if _SessionLocal is None:
+        _SessionLocal = sessionmaker(bind=get_engine(), autocommit=False, autoflush=False)
+    return _SessionLocal()
+
+
+def init_db():
+    engine = get_engine()
+    Base.metadata.create_all(bind=engine)
+
+
+def close_db():
+    global _engine, _SessionLocal
+    if _engine:
+        _engine.dispose()
+        _engine = None
+    _SessionLocal = None