# 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/>.

"""Database models for Calendar.social
"""

from datetime import datetime

from flask_security import UserMixin, RoleMixin
from flask_sqlalchemy import SQLAlchemy

db = SQLAlchemy()
users_roles = db.Table(
    'users_roles',
    db.Column('user_id', db.Integer(), db.ForeignKey('users.id')),
    db.Column('role_id', db.Integer(), db.ForeignKey('roles.id')))


class User(db.Model, UserMixin):
    """Database model for users
    """

    __tablename__ = 'users'
    id = db.Column(db.Integer(), primary_key=True)

    #: The username of the user.  This is also the display name and thus is immutable
    username = db.Column(db.String(length=50), unique=True, nullable=False)

    #: The email address of the user
    email = db.Column(db.String(length=255), unique=True, nullable=True)

    #: The (hashed) password of the user
    password = db.Column(db.String(length=255))

    #: A flag to show whether the user is enabled (active) or not
    active = db.Column(db.Boolean(), default=False)

    #: The timestamp when this user was created
    created_at = db.Column(db.DateTime(), default=datetime.utcnow)

    #: The timestamp when the user was activated
    confirmed_at = db.Column(db.DateTime())

    #: The roles of the user
    roles = db.relationship('Role',
                            secondary=users_roles,
                            backref=db.backref('users', lazy='dynamic'))

    def __repr__(self):
        return f'<User {self.id}({self.username})>'


class Role(db.Model, RoleMixin):
    """Database model for roles
    """

    __tablename__ = 'roles'
    id = db.Column(db.Integer(), primary_key=True)

    #: The name of the role
    name = db.Column(db.Unicode(length=80), unique=True)

    #: A description of the role
    description = db.Column(db.UnicodeText)

    def __repr__(self):
        return f'<Role {self.id}({self.name})>'


class Event(db.Model):
    """Database model for events
    """

    __tablename__ = 'events'
    id = db.Column(db.Integer(), primary_key=True)

    #: The ID of the user who created the event
    user_id = db.Column(db.Integer(), db.ForeignKey('users.id'), nullable=False)

    user = db.relationship('User', backref=db.backref('events', lazy='dynamic'))

    #: The title of the event
    title = db.Column(db.Unicode(length=200), nullable=False)

    #: The time zone to be used for `start_time` and `end_time`
    time_zone = db.Column(db.String(length=80), nullable=False)

    #: The starting timestamp of the event.  It is in the UTC time zone
    start_time = db.Column(db.DateTime(), nullable=False)

    #: The ending timestamp of the event.  It is in the UTC time zone
    end_time = db.Column(db.DateTime(), nullable=False)

    #: If `True`, the event is a whole-day event
    all_day = db.Column(db.Boolean(), default=False)

    #: The description of the event
    description = db.Column(db.UnicodeText())

    def __as_tz(self, timestamp, as_timezone=None):
        from pytz import timezone, UTC

        utc_timestamp = UTC.localize(timestamp)

        return utc_timestamp.astimezone(as_timezone or timezone(self.time_zone))

    @property
    def start_time_tz(self):
        """The same timestamp as `start_time`, but in the time zone specified by `time_zone`.
        """

        return self.__as_tz(self.start_time)

    @property
    def end_time_tz(self):
        """The same timestamp as `end_time`, but in the time zone specified by `time_zone`.
        """

        return self.__as_tz(self.end_time)

    def __repr__(self):
        return f'<Event {self.id} ({self.title}) of {self.user}>'