import os
import sys

from flask import Flask
from flask_login import LoginManager

from app.models import db, User

login_manager = LoginManager()

login_manager.login_view = "auth.login"
login_manager.login_message = "Veuillez vous connecter s'il vous plait"


@login_manager.user_loader
def load_user(user_id):
    return User.query.get(int(user_id))


# Please, set a config file on top project dir
# find example in ressources/pdc_config.py
try:
    from pdc_config import Config, ProdConfig, DevConfig, TestConfig
except ImportError:
    # TODO: use logging system
    print("Please set an pdc_config.py file in you PYTHON_PATH")
    print("See INSTALL.md for more info")
    sys.exit(-1)


def create_app(config_class=None):
    """ App Factory.
    can be called with configuration class as argument.
    """

    # Configuration Switcher
    # try to set configuration depending on environment
    # if no configuration class was given
    #
    if config_class is None:
        flask_env = os.environ.get('FLASK_ENV')
        if not flask_env:
            flask_env = 'testing'

        if flask_env == 'production':
            config_class = ProdConfig
        elif flask_env == 'development':
            config_class = DevConfig
        elif flask_env == 'testing':
            config_class = TestConfig
        else:
            config_class = Config

    # Main flask app
    #
    app = Flask(__name__)
    app.config.from_object(config_class)

    db.init_app(app)
    login_manager.init_app(app)

    # Get and activate blueprints
    #
    from .main import bp as main_bp
    app.register_blueprint(main_bp)
    from .auth import bp as auth_bp
    app.register_blueprint(auth_bp)

    return app