# 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 warnings import warn

from flask_babelex import lazy_gettext
from flask_security import UserMixin, RoleMixin
from flask_sqlalchemy import SQLAlchemy
from sqlalchemy.orm.exc import NoResultFound
from sqlalchemy_utils.types.choice import ChoiceType

from .utils import force_locale

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 SettingsProxy:
    """Proxy object to get settings for a user
    """

    def __init__(self, user):
        self.user = user

    def __getitem__(self, key):
        setting = UserSetting.query \
                             .filter(UserSetting.user == self.user) \
                             .filter(UserSetting.key == key) \
                             .first()

        if setting is None:
            return None

        return setting.value

    def __setitem__(self, key, value):
        try:
            setting = UserSetting.query \
                                 .filter(UserSetting.user == self.user) \
                                 .filter(UserSetting.key == key) \
                                 .one()
        except NoResultFound:
            setting = UserSetting(user=self.user, key=key)

        setting.value = str(value)
        db.session.add(setting)

    def __repr__(self):
        return f'<SettingsProxy for {self.user}>'


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

    __tablename__ = 'users'
    # pylint: disable=invalid-name
    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'))

    @property
    def settings(self):
        """Get a settings proxy for the user
        """

        proxy = getattr(self, '_settings', None)

        if proxy is None:
            proxy = SettingsProxy(self)
            setattr(self, '_settings', proxy)

        return proxy

    @property
    def timezone(self):
        from flask import current_app
        from pytz import timezone
        from pytz.exceptions import UnknownTimeZoneError

        timezone_str = self.settings['timezone']

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

        return current_app.timezone

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


class Role(db.Model, RoleMixin):  # pylint: disable=too-few-public-methods
    """Database model for roles
    """

    __tablename__ = 'roles'
    # pylint: disable=invalid-name
    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 Profile(db.Model):  # pylint: disable=too-few-public-methods
    """Database model for user profiles
    """

    __tablename__ = 'profiles'
    # pylint: disable=invalid-name
    id = db.Column(db.Integer(), primary_key=True)

    #: The ID of the local user this profile belongs to
    user_id = db.Column(db.Integer(), db.ForeignKey('users.id'), nullable=True)

    #: The username this profile belongs to.  If ``None``, `user_id` must be set
    username = db.Column(db.String(length=50), nullable=True)

    #: The domain this profile originates from.  If ``None``, `user_id` must be set
    domain = db.Column(db.Unicode(length=100), nullable=True)

    #: The display name
    display_name = db.Column(db.Unicode(length=80), nullable=False)


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

    __tablename__ = 'events'
    # pylint: disable=invalid-name
    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 start_time_for_user(self, user):
        """The same timestamp as `start_time`, but in the time zone of `user`
        """

        return self.__as_tz(self.start_time, as_timezone=user.timezone)

    def end_time_for_user(self, user):
        """The same timestamp as `end_time`, but in the time zone of `user`
        """

        return self.__as_tz(self.end_time, as_timezone=user.timezone)

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


class UserSetting(db.Model):
    """Database model for user settings
    """

    __tablename__ = 'user_settings'

    #: The ID of the user this setting belongs to
    user_id = db.Column(db.Integer(), db.ForeignKey('users.id'), primary_key=True)

    user = db.relationship('User')

    #: The settings key
    key = db.Column(db.String(length=40), primary_key=True)

    #: The settings value
    value = db.Column(db.UnicodeText())

    def __repr__(self):
        return f'<UserSetting of {self.user}, {self.key}="{self.value}">'


def _(translate):  # pylint: disable=invalid-name
    """Function to mark strings as translatable

    The actual translation will be fetched later in `:meth:AuditLog.get_message`.
    """

    return translate


class AuditLog(db.Model):
    """Database model for audit log records
    """

    __tablename__ = 'audit_log'
    # pylint: disable=invalid-name
    id = db.Column(db.Integer(), primary_key=True)

    TYPE_LOGIN_SUCCESS = 'login'
    TYPE_LOGIN_FAIL = 'failed_login'
    TYPE_LOGOUT = 'logout'

    TYPES = (
        (TYPE_LOGIN_SUCCESS, _('%(user)s logged in')),
        (TYPE_LOGIN_FAIL, _('%(user)s failed to log in')),
        (TYPE_LOGOUT, _('%(user)s logged out')),
    )

    user_id = db.Column(db.Integer(), db.ForeignKey('users.id'))

    user = db.relationship('User')

    ip_address = db.Column(db.String(length=40), nullable=False)

    timestamp = db.Column(db.DateTime(), default=datetime.utcnow, nullable=False)

    log_type = db.Column(ChoiceType(TYPES), nullable=False, index=True)

    extra_data = db.Column(db.UnicodeText())

    def __str__(self):
        format_string = dict(self.TYPES).get(self.log_type,
                                             _('UNKNOWN RECORD "%(log_type)s" for %(user)s'))
        message = str(self.timestamp) + \
                  (format_string % {
                      'user': self.user.username,
                      'log_type': self.log_type
                  })

        if self.extra_data:
            message += f' {self.extra_data}'

        return message

    def __repr__(self):
        return f'<AuditLog {self.log_type} for {self.user} at {self.timestamp}>'

    @classmethod
    def get_message(cls, key, *args, **kwargs):
        """Get the translated message for ``key``
        """

        return lazy_gettext(dict(cls.TYPES).get(key), *args, **kwargs)

    @classmethod
    def log(cls, user, log_type, extra_data=None, logger=None):
        """Create a new audit log record

        :param user: the user the new record corresponds to
        :type user: User
        :param log_type: the type of the record.  Must be present in `TYPES`
        :type log_type: str
        :param extra_data: extra text to be added to the record
        :type extra_data: str, None
        :param logger: if set, logs will go to this logger instead of the default (calsocial)
        :type logger: Logger
        :raises TypeError: if ``user`` is not an instance of `User`
        :raises ValueError: if ``log_type`` is not a valid log type
        """

        from logging import getLogger

        from flask import has_request_context, request

        logger = logger or getLogger('calsocial')

        if not isinstance(user, User):
            raise TypeError('user must be a User instance')

        if log_type not in dict(cls.TYPES):
            raise ValueError('log_type must be a valid log type')

        if has_request_context():
            ip = request.remote_addr or 'UNKNOWN'
        else:
            ip = 'NON-REQUEST'

        record = cls(user=user,
                     timestamp=datetime.utcnow(),
                     log_type=log_type,
                     ip_address=ip,
                     extra_data=extra_data)
        db.session.add(record)
        db.session.commit()

        with force_locale('en'):
            message = f'Audit: [{ip}] [{user.id}] ' + cls.get_message(log_type, user=user.username)

        logger.info(message)