import logging
import sys
from logging.config import fileConfig

from sqlalchemy import engine_from_config
from sqlalchemy import pool

from alembic import context

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

# Interpret the config file for Python logging.
# This line sets up loggers basically.
if 'jupyterhub' in sys.modules:
    from traitlets.config import MultipleInstanceError
    from jupyterhub.app import JupyterHub

    app = None
    if JupyterHub.initialized():
        try:
            app = JupyterHub.instance()
        except MultipleInstanceError:
            # could have been another Application
            pass
    if app is not None:
        alembic_logger = logging.getLogger('alembic')
        alembic_logger.propagate = True
        alembic_logger.parent = app.log
    else:
        fileConfig(config.config_file_name, disable_existing_loggers=False)
else:
    fileConfig(config.config_file_name)

version_table = config.get_main_option('version_table')

# add your model's MetaData object here
# for 'autogenerate' support
from cdsdashboards.orm import Dashboard
target_metadata = Dashboard.metadata

# other values from the config, defined by the needs of env.py,
# can be acquired:
# my_important_option = config.get_main_option("my_important_option")
# ... etc.

def run_migrations_offline():
    """Run migrations in 'offline' mode.

    This configures the context with just a URL
    and not an Engine, though an Engine is acceptable
    here as well.  By skipping the Engine creation
    we don't even need a DBAPI to be available.

    Calls to context.execute() here emit the given string to the
    script output.

    """
    url = config.get_main_option("sqlalchemy.url")
    context.configure(
        url=url,
        target_metadata=target_metadata,
        render_as_batch=True,
        literal_binds=True,
        dialect_opts={"paramstyle": "named"},
        version_table=version_table
    )

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


def run_migrations_online():
    """Run migrations in 'online' mode.

    In this scenario we need to create an Engine
    and associate a connection with the context.

    """
    connectable = engine_from_config(
        config.get_section(config.config_ini_section),
        prefix="sqlalchemy.",
        poolclass=pool.NullPool
    )

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

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



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