"""
automatically invoked app factory
"""
import logging
import os
from flask import Flask

from inventory_provider import environment


def create_app():
    """
    overrides default settings with those found
    in the file read from env var SETTINGS_FILENAME

    :return: a new flask app instance
    """

    required_env_vars = [
        'FLASK_SETTINGS_FILENAME', 'INVENTORY_PROVIDER_CONFIG_FILENAME']

    assert all([n in os.environ for n in required_env_vars]), \
        'environment variables %r must be defined' % required_env_vars

    assert os.path.isfile(os.environ['INVENTORY_PROVIDER_CONFIG_FILENAME']), (
        'config file %r not found' %
        os.environ['INVENTORY_PROVIDER_CONFIG_FILENAME'])

    from inventory_provider import config
    with open(os.environ['INVENTORY_PROVIDER_CONFIG_FILENAME']) as f:
        logging.info(
            'loading config from: %r'
            % os.environ['INVENTORY_PROVIDER_CONFIG_FILENAME'])
        inventory_provider_config = config.load(f)

    app = Flask(__name__)
    app.secret_key = 'super secret session key'

    logging.info(
        'initializing Flask with config from: %r' %
        os.environ['FLASK_SETTINGS_FILENAME'])
    app.config.from_envvar('FLASK_SETTINGS_FILENAME')

    app.config['INVENTORY_PROVIDER_CONFIG'] = inventory_provider_config

    from inventory_provider.routes import default
    app.register_blueprint(default.routes, url_prefix='/')

    from inventory_provider.routes import data
    app.register_blueprint(data.routes, url_prefix='/data')

    from inventory_provider.routes import jobs
    app.register_blueprint(jobs.routes, url_prefix='/jobs')

    from inventory_provider.routes import classifier
    app.register_blueprint(classifier.routes, url_prefix='/classifier')

    from inventory_provider.routes import poller
    app.register_blueprint(poller.routes, url_prefix='/poller')

    if app.config.get('ENABLE_TESTING_ROUTES', False):
        from inventory_provider.routes import testing
        app.register_blueprint(testing.routes, url_prefix='/testing')
        logging.warning('DANGER!!! testing routes enabled')

    logging.info('Inventory Provider Flask app initialized')

    environment.setup_logging()

    return app