"""Alembic environment configuration for smart-support."""

from __future__ import annotations

import os
from logging.config import fileConfig

from sqlalchemy import engine_from_config, pool

from alembic import context

config = context.config

if config.config_file_name is not None:
    fileConfig(config.config_file_name)

# No SQLAlchemy ORM models -- we use raw DDL migrations
target_metadata = None


def _get_url() -> str:
    """Read DATABASE_URL from environment, falling back to alembic.ini."""
    return os.environ.get("DATABASE_URL", "") or config.get_main_option(
        "sqlalchemy.url", ""
    )


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

    Configures the context with just a URL so that an Engine
    is not required.
    """
    url = _get_url()
    context.configure(
        url=url,
        target_metadata=target_metadata,
        literal_binds=True,
        dialect_opts={"paramstyle": "named"},
    )

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


def run_migrations_online() -> None:
    """Run migrations in 'online' mode with a live database connection."""
    configuration = config.get_section(config.config_ini_section, {})
    configuration["sqlalchemy.url"] = _get_url()

    connectable = engine_from_config(
        configuration,
        prefix="sqlalchemy.",
        poolclass=pool.NullPool,
    )

    with connectable.connect() as connection:
        context.configure(connection=connection, target_metadata=target_metadata)

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


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