"""Mysql Connector."""

from sqlalchemy import create_engine
from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy.orm import sessionmaker

from grass import config

DEFAULT_POOL_RECYCLE_TIMEOUT = 3600


def get_pool_recycle_timeout(conf):
    is_dev_environment = conf.environment == conf.DEV_ENVIRONMENT
    if is_dev_environment and conf.DB_POOL_RECYCLE_TIMEOUT:
        return int(conf.DB_POOL_RECYCLE_TIMEOUT)
    else:
        return DEFAULT_POOL_RECYCLE_TIMEOUT


if config.environment == config.TEST_ENVIRONMENT:
    # For the test environment the database used is a in-memory sqlite db. This
    # db gets dropped immediately after the execution of the tests.
    engine = create_engine('sqlite://')
else:
    # For all other environments we use pooled connections like ows-users.
    engine = create_engine(
        config.DB_URL,
        pool_size=5,
        max_overflow=-1,
        pool_recycle=get_pool_recycle_timeout(config),
        connect_args={},
    )

BaseModel = declarative_base()

# A DBSession() instance establishes all conversations with the database
# and represents a "staging zone" for all the objects loaded into the
# database session object. Any change made against the objects in the
# session won't be persisted into the database until you call
# session.commit(). If you're not happy about the changes, you can
# revert all of them back to the last commit by calling
# session.rollback()
#
# Description taken from:
# pythoncentral.io/introductory-tutorial-python-sqlalchemy/


session = sessionmaker(bind=engine, expire_on_commit=False)