"""Database connection and session management.

This module handles database engine creation, session management,
and connection lifecycle for the application.
"""

from collections.abc import AsyncGenerator
from contextlib import asynccontextmanager

from sqlalchemy.ext.asyncio import (
    AsyncEngine,
    AsyncSession,
    async_sessionmaker,
    create_async_engine,
)

from app.infrastructure.config import settings


def _get_database_url() -> str:
    """Get database URL with SQLite async compatibility.

    Converts SQLite URL to async format if needed.

    Returns:
        Database URL string ready for async engine.
    """
    url = settings.database_url
    if url.startswith("sqlite:///") and not url.startswith("sqlite+aiosqlite:///"):
        return url.replace("sqlite:///", "sqlite+aiosqlite:///")
    return url


engine: AsyncEngine = create_async_engine(
    _get_database_url(),
    echo=settings.db.echo,
    future=True,
)

AsyncSessionLocal = async_sessionmaker(
    engine,
    class_=AsyncSession,
    expire_on_commit=False,
    autoflush=False,
    autocommit=False,
)


async def get_session() -> AsyncGenerator[AsyncSession]:
    """Get database session.

    Yields:
        AsyncSession instance for database operations.
    """
    async with AsyncSessionLocal() as session:
        try:
            yield session
        finally:
            await session.close()


@asynccontextmanager
async def get_session_context() -> AsyncGenerator[AsyncSession]:
    """Get database session as context manager.

    Yields:
        AsyncSession instance for database operations.
    """
    async with AsyncSessionLocal() as session:
        try:
            yield session
        finally:
            await session.close()


async def init_db() -> None:
    """Initialize database tables.

    Creates all tables defined in the metadata.
    Should be called on application startup.
    Skipped in CI/production where alembic manages schema.
    """
    import os

    if os.environ.get("SKIP_INIT_DB", "").lower() in ("1", "true", "yes"):
        return

    from app.infrastructure.database.models import Base

    async with engine.begin() as conn:
        await conn.run_sync(Base.metadata.create_all)


async def close_db() -> None:
    """Close database connections.

    Disposes of the engine and all connections.
    Should be called on application shutdown.
    """
    await engine.dispose()