Add complete project structure and all files

backend/app/db.py

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+import logging
+from typing import Generator, AsyncGenerator
+from contextlib import asynccontextmanager
+
+from sqlalchemy import create_engine, event
+from sqlalchemy.orm import declarative_base, sessionmaker, Session
+from sqlalchemy.pool import StaticPool
+from sqlalchemy.engine import Engine
+import time
+
+from .config import settings
+
+logger = logging.getLogger(__name__)
+
+# Configure SQLAlchemy engine with connection pooling
+engine = create_engine(
+    settings.SQLALCHEMY_DATABASE_URI,
+    echo=settings.DEBUG,
+    pool_size=10,
+    max_overflow=20,
+    pool_pre_ping=True,  # Validates connections before use
+    pool_recycle=3600,   # Recycle connections every hour
+    connect_args={
+        "connect_timeout": 10,
+        "application_name": settings.PANEL_NAME,
+    }
+)
+
+# Add connection event listeners for monitoring
+@event.listens_for(Engine, "before_cursor_execute")
+def before_cursor_execute(conn, cursor, statement, parameters, context, executemany):
+    context._query_start_time = time.time()
+    if settings.DEBUG:
+        logger.debug("Start Query: %s", statement)
+
+
+@event.listens_for(Engine, "after_cursor_execute")  
+def after_cursor_execute(conn, cursor, statement, parameters, context, executemany):
+    total = time.time() - context._query_start_time
+    if settings.DEBUG:
+        logger.debug("Query Complete in %.3f seconds", total)
+    if total > 1.0:  # Log slow queries
+        logger.warning("Slow query detected (%.3f seconds): %s", total, statement)
+
+
+SessionLocal = sessionmaker(
+    autocommit=False,
+    autoflush=False,
+    bind=engine,
+)
+
+Base = declarative_base()
+
+
+def get_db() -> Generator[Session, None, None]:
+    """Dependency to get database session"""
+    db = SessionLocal()
+    try:
+        yield db
+    except Exception as e:
+        logger.error(f"Database session error: {e}")
+        db.rollback()
+        raise
+    finally:
+        db.close()
+
+
+@asynccontextmanager
+async def get_async_db() -> AsyncGenerator[Session, None]:
+    """Async context manager for database session"""
+    db = SessionLocal()
+    try:
+        yield db
+        db.commit()
+    except Exception as e:
+        logger.error(f"Database session error: {e}")
+        db.rollback()
+        raise
+    finally:
+        db.close()
+
+
+def init_db() -> None:
+    """Initialize database tables"""
+    try:
+        Base.metadata.create_all(bind=engine)
+        logger.info("Database initialized successfully")
+        
+        # Initialize default panel settings if not exist
+        init_default_settings()
+        
+    except Exception as e:
+        logger.error(f"Failed to initialize database: {e}")
+        raise
+
+
+def init_default_settings() -> None:
+    """Initialize default panel settings"""
+    try:
+        from .models import PanelSettings
+        
+        db = SessionLocal()
+        try:
+            # Check if settings already exist
+            existing = db.query(PanelSettings).count()
+            if existing > 0:
+                logger.info(f"Panel settings already initialized ({existing} settings found)")
+                return
+            
+            # Add default settings
+            defaults = [
+                PanelSettings(
+                    key="refresh_interval",
+                    value="5",
+                    description="Интервал обновления данных на панели (секунды)"
+                ),
+                PanelSettings(
+                    key="log_retention_days",
+                    value="30",
+                    description="Срок хранения логов перед автоматической очисткой (дни)"
+                ),
+                PanelSettings(
+                    key="language",
+                    value="ru",
+                    description="Язык интерфейса панели (ru/en)"
+                ),
+            ]
+            
+            for setting in defaults:
+                db.add(setting)
+            
+            db.commit()
+            logger.info(f"Added {len(defaults)} default panel settings")
+            
+        finally:
+            db.close()
+            
+    except Exception as e:
+        logger.warning(f"Failed to initialize default settings: {e}")
+        # Don't raise - this is not critical for app startup
+
+
+def check_db_connection() -> bool:
+    """Check if database connection is working"""
+    try:
+        with engine.connect() as conn:
+            from sqlalchemy import text
+            conn.execute(text("SELECT 1"))
+        return True
+    except Exception as e:
+        logger.error(f"Database connection check failed: {e}")
+        return False