from logging.config import fileConfig
import os

from alembic import context
from sqlalchemy import engine_from_config, pool

from l4d2web.models import Base


config = context.config

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

target_metadata = Base.metadata


def _database_url() -> str:
    return os.getenv("DATABASE_URL", "sqlite:///l4d2web.db")


def run_migrations_offline() -> None:
    context.configure(
        url=_database_url(),
        target_metadata=target_metadata,
        literal_binds=True,
        dialect_opts={"paramstyle": "named"},
        render_as_batch=True
    )

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


def run_migrations_online() -> None:
    configuration = config.get_section(config.config_ini_section) or {}
    configuration["sqlalchemy.url"] = _database_url()
    connectable = engine_from_config(
        configuration,
        prefix="sqlalchemy.",
        poolclass=pool.NullPool,
    )

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

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


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