"""
Alembic environment — async engine against Base.metadata.

Two entry paths:
- CLI (``alembic upgrade head``): builds an async engine from
  Settings.database_url and runs migrations on it.
- App startup (db.database.init_db): passes an already-open
  connection via ``config.attributes["connection"]`` so migrations
  run inside the app's engine instead of opening a second one.
"""

import asyncio
from logging.config import fileConfig

from alembic import context
from sqlalchemy import pool
from sqlalchemy.ext.asyncio import create_async_engine

from config import get_settings
from db.database import Base

config = context.config

# Only configure logging on standalone CLI runs — inside the app this
# would clobber uvicorn's logger setup.
if config.config_file_name is not None and config.attributes.get("connection") is None:
    fileConfig(config.config_file_name, disable_existing_loggers=False)

target_metadata = Base.metadata


def run_migrations_offline() -> None:
    """Emit SQL to stdout without a live connection (--sql mode)."""
    context.configure(
        url=get_settings().database_url,
        target_metadata=target_metadata,
        literal_binds=True,
        dialect_opts={"paramstyle": "named"},
    )
    with context.begin_transaction():
        context.run_migrations()


def do_run_migrations(connection) -> None:
    context.configure(connection=connection, target_metadata=target_metadata)
    with context.begin_transaction():
        context.run_migrations()


async def run_async_migrations() -> None:
    engine = create_async_engine(get_settings().database_url, poolclass=pool.NullPool)
    async with engine.connect() as connection:
        await connection.run_sync(do_run_migrations)
    await engine.dispose()


def run_migrations_online() -> None:
    connection = config.attributes.get("connection")
    if connection is not None:
        do_run_migrations(connection)
    else:
        asyncio.run(run_async_migrations())


if context.is_offline_mode():
    run_migrations_offline()
else:
    run_migrations_online()