# Calendar.social
# Copyright (C) 2018 Gergely Polonkai
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU Affero General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU Affero General Public License for more details.
#
# You should have received a copy of the GNU Affero General Public License
# along with this program.  If not, see <https://www.gnu.org/licenses/>.

"""Main module for the Calendar.social app
"""

from datetime import datetime
from functools import wraps
import os

from flask import Flask, current_app, redirect, render_template, request, url_for
from flask_babelex import Babel, get_locale as babel_get_locale
from flask_security import SQLAlchemyUserDatastore, current_user, login_required


def get_locale():
    """Locale selector

    Selects the best locale based on values sent by the browser.
    """

    supported_languages = ['en', 'hu']

    if 'l' in request.args and request.args['l'].lower() in supported_languages:
        return request.args['l'].lower()

    return request.accept_languages.best_match(supported_languages)


def template_vars():
    """Function to inject global template variables
    """

    now = datetime.utcnow()

    return {
        'lang': babel_get_locale().language,
        'now': now,
        'now_ts': now.timestamp(),
    }


def route(*args, **kwargs):
    """Mark a function as a future route

    Such functions will be iterated over when the application is initialised.  ``*args`` and
    ``**kwargs`` will be passed verbatim to `Flask.route()`.
    """

    def decorator(func):  # pylint: disable=missing-docstring
        setattr(func, 'routing', (args, kwargs))

        return func

    return decorator


class CalendarSocialApp(Flask):
    """The Calendar.social app
    """

    def __init__(self, name, config=None):
        from .forms import LoginForm
        from .models import db, User, Role
        from .security import security, AnonymousUser

        Flask.__init__(self, name)

        self._timezone = None

        config_name = os.environ.get('ENV', config or 'dev')
        self.config.from_pyfile(f'config_{config_name}.py', True)
        # Make sure we look up users both by their usernames and email addresses
        self.config['SECURITY_USER_IDENTITY_ATTRIBUTES'] = ('username', 'email')
        db.init_app(self)
        babel = Babel(app=self)
        babel.localeselector(get_locale)

        user_store = SQLAlchemyUserDatastore(db, User, Role)
        security.init_app(self, datastore=user_store, anonymous_user=AnonymousUser, login_form=LoginForm)

        self.context_processor(template_vars)

        for attr_name in self.__dir__():
            attr = getattr(self, attr_name)

            if not callable(attr):
                continue

            args, kwargs = getattr(attr, 'routing', (None, None))

            if args is None:
                continue

            self.route(*args, **kwargs)(attr)

    @property
    def timezone(self):
        """The default time zone of the app
        """

        from warnings import warn

        from flask import has_app_context
        from pytz import timezone, utc
        from pytz.exceptions import UnknownTimeZoneError

        if not has_app_context():
            return utc

        if not self._timezone:
            timezone_str = current_app.settings.get('DEFAULT_TIMEZONE', 'UTC')

            try:
                self._timezone = timezone(timezone_str)
            except UnknownTimeZoneError:
                warn(f'Timezone of {self} (or the default timezone) "{timezone_str}" is invalid')

                self._timezone = utc

        return self._timezone

    @staticmethod
    @route('/')
    def hello():
        """View for the main page

        This will display a welcome message for users not logged in; for others, their main
        calendar view is displayed.
        """

        from .calendar_system.gregorian import GregorianCalendar

        if not current_user.is_authenticated:
            return render_template('welcome.html')

        try:
            timestamp = datetime.fromtimestamp(float(request.args.get('date')))
        except TypeError:
            timestamp = datetime.utcnow()

        calendar = GregorianCalendar(timestamp.timestamp())

        return render_template('index.html', calendar=calendar)

    @staticmethod
    @route('/register', methods=['POST', 'GET'])
    def register():
        """View for user registration

        If the ``REGISTRATION_FAILED`` configuration value is set to ``True`` it displays the
        registration disabled template.  Otherwise, it performs user registration.
        """

        if not current_app.config['REGISTRATION_ENABLED']:
            return render_template('registration-disabled.html')

        from .forms import RegistrationForm
        from .models import db, User

        form = RegistrationForm()

        if form.validate_on_submit():
            # TODO: This might become False later, if we want registrations to be confirmed via
            #       e-mail
            user = User(active=True)

            form.populate_obj(user)
            db.session.add(user)
            db.session.commit()

            return redirect(url_for('hello'))

        return render_template('registration.html', form=form)

    @staticmethod
    @route('/new-event', methods=['GET', 'POST'])
    @login_required
    def new_event():
        """View for creating a new event

        This presents a form to the user that allows entering event details.
        """

        from .forms import EventForm
        from .models import db, Event

        form = EventForm()

        if form.validate_on_submit():
            event = Event(user=current_user)
            form.populate_obj(event)

            db.session.add(event)
            db.session.commit()

            return redirect(url_for('hello'))

        return render_template('event-edit.html', form=form)

    @staticmethod
    @route('/settings', methods=['GET', 'POST'])
    @login_required
    def settings():
        """View for user settings
        """

        from .forms import SettingsForm
        from .models import db

        form = SettingsForm(current_user)

        if form.validate_on_submit():
            form.populate_obj(current_user)

            db.session.commit()

            return redirect(url_for('hello'))

        return render_template('user-settings.html', form=form)

    @staticmethod
    @route('/event/<int:event_id>')
    def event_details(event_id):
        """View to display event details
        """

        from .models import Event

        event = Event.query.get_or_404(event_id)

        return render_template('event-details.html', event=event)


app = CalendarSocialApp(__name__)