"""Alembic migration environment — async-compatible.

At runtime the app uses ``postgresql+asyncpg://``.  Alembic's CLI is
synchronous, so we derive a *sync* psycopg2 URL from the same DATABASE_URL
env var by replacing the driver prefix.

Run migrations with:
    alembic upgrade head
"""

from __future__ import annotations

import asyncio
import os
import re
from logging.config import fileConfig

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

# Alembic Config object (gives access to alembic.ini values).
config = context.config

# Set up Python logging from alembic.ini.
if config.config_file_name is not None:
    fileConfig(config.config_file_name)

# Import the Base so that Alembic can detect model changes for --autogenerate.
from app.models import Base  # noqa: E402

target_metadata = Base.metadata


def _sync_url(async_url: str) -> str:
    """Convert an asyncpg URL to a psycopg2 URL for Alembic CLI."""
    return re.sub(r"postgresql\+asyncpg", "postgresql+psycopg2", async_url)


def _get_url() -> str:
    db_url = os.environ.get("DATABASE_URL", "")
    if not db_url:
        # Fall back to settings if env var not set directly.
        from app.config.settings import settings  # noqa: PLC0415
        db_url = settings.DATABASE_URL
    return _sync_url(db_url)


def run_migrations_offline() -> None:
    """Emit SQL without a live DB connection."""
    url = _get_url()
    context.configure(
        url=url,
        target_metadata=target_metadata,
        literal_binds=True,
        dialect_opts={"paramstyle": "named"},
        compare_type=True,
    )
    with context.begin_transaction():
        context.run_migrations()


def do_run_migrations(connection):  # type: ignore[no-untyped-def]
    context.configure(
        connection=connection,
        target_metadata=target_metadata,
        compare_type=True,
    )
    with context.begin_transaction():
        context.run_migrations()


async def run_migrations_online_async() -> None:
    """Run migrations against a live DB using the async engine."""
    async_url = os.environ.get("DATABASE_URL", "")
    if not async_url:
        from app.config.settings import settings  # noqa: PLC0415
        async_url = settings.DATABASE_URL

    connectable = create_async_engine(async_url, poolclass=pool.NullPool)
    async with connectable.connect() as connection:
        await connection.run_sync(do_run_migrations)
    await connectable.dispose()


def run_migrations_online() -> None:
    asyncio.run(run_migrations_online_async())


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