"""
Database Configuration
Async SQLAlchemy engine with PostgreSQL support
Unicode support for Marathi text
"""

from sqlalchemy.ext.asyncio import AsyncSession, create_async_engine, async_sessionmaker
from sqlalchemy.orm import DeclarativeBase
from sqlalchemy import MetaData
from .config import settings

# Naming convention for constraints
convention = {
    "ix": "ix_%(column_0_label)s",
    "uq": "uq_%(table_name)s_%(column_0_name)s",
    "ck": "ck_%(table_name)s_%(constraint_name)s",
    "fk": "fk_%(table_name)s_%(column_0_name)s_%(referred_table_name)s",
    "pk": "pk_%(table_name)s"
}

metadata = MetaData(naming_convention=convention)


class Base(DeclarativeBase):
    """Base class for all models"""
    metadata = metadata


# Create async engine with PostgreSQL support
engine = create_async_engine(
    settings.DATABASE_URL,
    echo=False,  # Disable SQL logging
    pool_size=5,           # Number of connections to keep in pool
    max_overflow=10,       # Max additional connections beyond pool_size
    pool_pre_ping=True,    # Verify connections before using
    pool_recycle=3600,     # Recycle connections after 1 hour
)

# Async session factory
async_session = async_sessionmaker(
    engine,
    class_=AsyncSession,
    expire_on_commit=False
)


async def get_db() -> AsyncSession:
    """Dependency to get database session"""
    async with async_session() as session:
        try:
            yield session
            await session.commit()
        except Exception:
            await session.rollback()
            raise
        finally:
            await session.close()


async def init_db():
    """Initialize database tables"""
    async with engine.begin() as conn:
        await conn.run_sync(Base.metadata.create_all)


async def close_db():
    """Close database connections"""
    await engine.dispose()