"""Alembic migration environment configuration for async SQLAlchemy."""

import asyncio

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

from sensei.config import settings
from sensei.database.models import Base

config = context.config

# Use DATABASE_URL from settings only as a fallback.
# This allows tests to override the URL via config.set_main_option() before running migrations.
if not config.get_main_option("sqlalchemy.url") and settings.database_url:
    config.set_main_option("sqlalchemy.url", settings.database_url)

target_metadata = Base.metadata


def run_migrations_offline() -> None:
    """Run migrations in 'offline' mode.

    Generates SQL script without connecting to the database.
    """
    url = config.get_main_option("sqlalchemy.url")
    context.configure(
        url=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:
    """Configure context and run migrations."""
    context.configure(
        connection=connection,
        target_metadata=target_metadata,
        compare_type=True,
        compare_server_default=True,
    )

    with context.begin_transaction():
        context.run_migrations()


async def run_async_migrations() -> None:
    """Run migrations in async mode."""
    connectable = async_engine_from_config(
        config.get_section(config.config_ini_section, {}),
        prefix="sqlalchemy.",
        poolclass=pool.NullPool,
    )

    async with connectable.connect() as connection:
        await connection.run_sync(do_run_migrations)

    await connectable.dispose()


def run_migrations_online() -> None:
    """Run migrations in 'online' mode."""
    asyncio.run(run_async_migrations())


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