"""Database schema migrations via Alembic."""
from __future__ import annotations

import asyncio
import logging
from collections.abc import AsyncGenerator
from pathlib import Path

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

from app.config import settings

logger = logging.getLogger(__name__)

engine = create_async_engine(settings.database_url, echo=False, pool_pre_ping=True)
SessionLocal = async_sessionmaker(engine, class_=AsyncSession, expire_on_commit=False)


class Base(DeclarativeBase):
    pass


async def get_db() -> AsyncGenerator[AsyncSession, None]:
    async with SessionLocal() as session:
        yield session


def _run_alembic_upgrade() -> None:
    from alembic import command
    from alembic.config import Config

    ini = Path(__file__).resolve().parent.parent / "alembic.ini"
    cfg = Config(str(ini))
    command.upgrade(cfg, "head")


async def init_db() -> None:
    """Apply Alembic migrations to head."""
    try:
        await asyncio.to_thread(_run_alembic_upgrade)
    except Exception as exc:  # noqa: BLE001
        logger.exception("Database migration failed")
        raise RuntimeError("Database migration failed") from exc