from logging.config import fileConfig

from alembic import context

from tofu_api.app import create_app
from tofu_api.models import BaseModel

# This is the Alembic Config object, which provides access to the values within the .ini file in use.
alembic_config = context.config

# Interpret the config file for Python logging. This line sets up loggers basically.
if alembic_config.config_file_name is not None:
    fileConfig(alembic_config.config_file_name)

# Create Flask app, which loads the app config and initializes the database engine.
app = create_app()
db = app.dependencies.get_sqlalchemy()


def process_revision_directives(_context, _revision, directives):
    """
    Callback used to prevent generating empty migrations with autogenerate.
    Source: https://alembic.sqlalchemy.org/en/latest/cookbook.html#don-t-generate-empty-migrations-with-autogenerate
    """
    if alembic_config.cmd_opts.autogenerate and directives[0].upgrade_ops.is_empty():
        directives[:] = []


context_parameters = {
    'target_metadata': BaseModel.metadata,
    'process_revision_directives': process_revision_directives,
    'user_module_prefix': 'tofu_types.',
}


def run_migrations_offline():
    """
    Run migrations in 'offline' mode, which does not require an actual database engine and can be used to generate SQL scripts.
    """
    context.configure(
        url=app.config.sqlalchemy_database_uri,
        literal_binds=True,
        dialect_opts={"paramstyle": "named"},
        **context_parameters,
    )

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


def run_migrations_online():
    """
    Run migrations in 'online' mode, which requires a database engine.
    """
    with db.engine.connect() as connection:
        context.configure(
            connection=connection,
            **context_parameters,
        )

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


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