"""
Database Configuration and Session Management
支持 SQLite 和 PostgreSQL
"""
import logging
from contextlib import asynccontextmanager
from typing import AsyncGenerator
from sqlalchemy.ext.asyncio import AsyncSession, create_async_engine, async_sessionmaker
from sqlalchemy.orm import DeclarativeBase
from sqlalchemy import create_engine, event, inspect, text
from sqlalchemy.pool import NullPool

from app.core.config import get_settings

logger = logging.getLogger(__name__)
settings = get_settings()


def get_engine_config():
    """根据数据库类型返回引擎配置"""
    if settings.DATABASE_URL.startswith("sqlite"):
        return {"echo": settings.DEBUG, "poolclass": NullPool}
    else:
        return {
            "echo": settings.DEBUG,
            "pool_pre_ping": True,
            "pool_size": 10,
            "max_overflow": 20,
            "pool_recycle": 3600,
            "pool_timeout": 30,
        }


# Async engine for FastAPI
async_engine = create_async_engine(
    settings.DATABASE_URL,
    **get_engine_config()
)

# Sync engine for migrations (use NullPool for SQLite)
sync_engine = create_engine(
    settings.DATABASE_URL_SYNC,
    echo=settings.DEBUG,
    pool_pre_ping=True,
    poolclass=NullPool if settings.DATABASE_URL_SYNC.startswith("sqlite") else None,
)

# Async session factory
AsyncSessionLocal = async_sessionmaker(
    async_engine,
    class_=AsyncSession,
    expire_on_commit=False,
    autocommit=False,
    autoflush=False,
)


class Base(DeclarativeBase):
    """Base class for all models"""
    pass


async def init_db():
    """Initialize database tables"""
    logger.info("Initializing database...")
    async with async_engine.begin() as conn:
        await conn.run_sync(Base.metadata.create_all)
        await conn.run_sync(_ensure_legacy_columns)
    logger.info("Database initialized successfully")


def _ensure_legacy_columns(sync_conn):
    """Patch legacy tables with newly introduced columns."""
    inspector = inspect(sync_conn)
    if "model_configs" not in inspector.get_table_names():
        return

    columns = {column["name"] for column in inspector.get_columns("model_configs")}
    if "model_type" in columns:
        return

    logger.info("Adding missing model_type column to model_configs table")
    dialect = sync_conn.dialect.name
    if dialect == "postgresql":
        sync_conn.execute(text("ALTER TABLE model_configs ADD COLUMN model_type VARCHAR(50) NOT NULL DEFAULT 'chat'"))
    else:
        sync_conn.execute(text("ALTER TABLE model_configs ADD COLUMN model_type VARCHAR(50) NOT NULL DEFAULT 'chat'"))


async def close_db():
    """Close database connections"""
    logger.info("Closing database connections...")
    await async_engine.dispose()
    logger.info("Database connections closed")


@asynccontextmanager
async def get_db_session() -> AsyncGenerator[AsyncSession, None]:
    """Context manager for database sessions with automatic cleanup"""
    session = AsyncSessionLocal()
    try:
        yield session
    except Exception as e:
        logger.error(f"Database session error: {str(e)}")
        await session.rollback()
        raise
    finally:
        await session.close()


async def get_db() -> AsyncSession:
    """Dependency for getting database session"""
    async with AsyncSessionLocal() as session:
        try:
            yield session
        except Exception as e:
            logger.error(f"Database error in dependency: {str(e)}")
            await session.rollback()
            raise
        finally:
            await session.close()


# Import all models to register them with Base.metadata
# This ensures all models are loaded before create_all is called
from app.models.models import *  # noqa: F401, F403, E402