import os
import warnings

from flask import Flask, g, request, session
from flask_babel import Babel
from flask_migrate import Migrate, upgrade, stamp
from raven.contrib.flask import Sentry

from web import main, db, mail
from api import api
from utils import PrefixedWSGI
from utils import minimal_round


app = Flask(__name__)


def pre_alembic_db():
    """ Checks if we are migrating from a pre-alembic ihatemoney
    """
    con = db.engine.connect()
    tables_exist = db.engine.dialect.has_table(con, 'project')
    alembic_setup = db.engine.dialect.has_table(con, 'alembic_version')
    return tables_exist and not alembic_setup


def configure():
    """ A way to (re)configure the app, specially reset the settings
    """
    config_obj = os.environ.get('FLASK_SETTINGS_MODULE', 'merged_settings')
    app.config.from_object(config_obj)
    app.wsgi_app = PrefixedWSGI(app)

    # Deprecations
    if 'DEFAULT_MAIL_SENDER' in app.config:
        # Since flask-mail  0.8
        warnings.warn(
            "DEFAULT_MAIL_SENDER is deprecated in favor of MAIL_DEFAULT_SENDER"
            +" and will be removed in further version",
            UserWarning
        )
        if not 'MAIL_DEFAULT_SENDER' in app.config:
            app.config['MAIL_DEFAULT_SENDER'] = DEFAULT_MAIL_SENDER

configure()


app.register_blueprint(main)
app.register_blueprint(api)

# custom jinja2 filters
app.jinja_env.filters['minimal_round'] = minimal_round

# db
db.init_app(app)
db.app = app

# db migrations
migrate = Migrate(app, db)

if pre_alembic_db():
    with app.app_context():
        # fake the first migration
        stamp(revision='b9a10d5d63ce')

# auto-execute migrations on runtime
with app.app_context():
    upgrade()

# mail
mail.init_app(app)

# translations
babel = Babel(app)

# sentry
sentry = Sentry(app)

@babel.localeselector
def get_locale():
    # get the lang from the session if defined, fallback on the browser "accept
    # languages" header.
    lang = session.get('lang', request.accept_languages.best_match(['fr', 'en']))
    setattr(g, 'lang', lang)
    return lang

def main():
    app.run(host="0.0.0.0", debug=True)

if __name__ == '__main__':
    main()