# -*- coding: utf-8 -*-
"""
Auth* related model.

This is where the models used by the authentication stack are defined.

It's perfectly fine to re-use this definition in the tracim application,
though.
"""
import os
import time
import uuid

from datetime import datetime
from hashlib import sha256
from typing import TYPE_CHECKING

from sqlalchemy import Column
from sqlalchemy import ForeignKey
from sqlalchemy import Sequence
from sqlalchemy import Table
from sqlalchemy.ext.hybrid import hybrid_property
from sqlalchemy.orm import relation
from sqlalchemy.orm import relationship
from sqlalchemy.orm import synonym
from sqlalchemy.types import Boolean
from sqlalchemy.types import DateTime
from sqlalchemy.types import Integer
from sqlalchemy.types import Unicode

from tracim.lib.utils.translation import fake_translator as l_
from tracim.models.meta import DeclarativeBase
from tracim.models.meta import metadata
if TYPE_CHECKING:
    from tracim.models.data import Workspace
    from tracim.models.data import UserRoleInWorkspace
__all__ = ['User', 'Group', 'Permission']

# This is the association table for the many-to-many relationship between
# groups and permissions.
group_permission_table = Table('group_permission', metadata,
    Column('group_id', Integer, ForeignKey('groups.group_id',
        onupdate="CASCADE", ondelete="CASCADE"), primary_key=True),
    Column('permission_id', Integer, ForeignKey('permissions.permission_id',
        onupdate="CASCADE", ondelete="CASCADE"), primary_key=True)
)

# This is the association table for the many-to-many relationship between
# groups and members - this is, the memberships.
user_group_table = Table('user_group', metadata,
    Column('user_id', Integer, ForeignKey('users.user_id',
        onupdate="CASCADE", ondelete="CASCADE"), primary_key=True),
    Column('group_id', Integer, ForeignKey('groups.group_id',
        onupdate="CASCADE", ondelete="CASCADE"), primary_key=True)
)


class Group(DeclarativeBase):

    TIM_NOBODY = 0
    TIM_USER = 1
    TIM_MANAGER = 2
    TIM_ADMIN = 3

    TIM_NOBODY_GROUPNAME = 'nobody'
    TIM_USER_GROUPNAME = 'users'
    TIM_MANAGER_GROUPNAME = 'managers'
    TIM_ADMIN_GROUPNAME = 'administrators'

    __tablename__ = 'groups'

    group_id = Column(Integer, Sequence('seq__groups__group_id'), autoincrement=True, primary_key=True)
    group_name = Column(Unicode(16), unique=True, nullable=False)
    display_name = Column(Unicode(255))
    created = Column(DateTime, default=datetime.utcnow)

    users = relationship('User', secondary=user_group_table, backref='groups')

    def __repr__(self):
        return '<Group: name=%s>' % repr(self.group_name)

    def __unicode__(self):
        return self.group_name

    @classmethod
    def by_group_name(cls, group_name, dbsession):
        """Return the user object whose email address is ``email``."""
        return dbsession.query(cls).filter_by(group_name=group_name).first()


class Profile(object):
    """This model is the "max" group associated to a given user."""

    _NAME = [Group.TIM_NOBODY_GROUPNAME,
             Group.TIM_USER_GROUPNAME,
             Group.TIM_MANAGER_GROUPNAME,
             Group.TIM_ADMIN_GROUPNAME]

    # TODO - G.M - 18-04-2018 [Cleanup] Drop this
    # _LABEL = [l_('Nobody'),
    #           l_('Users'),
    #           l_('Global managers'),
    #           l_('Administrators')]

    def __init__(self, profile_id):
        assert isinstance(profile_id, int)
        self.id = profile_id
        self.name = Profile._NAME[profile_id]
        # TODO - G.M - 18-04-2018 [Cleanup] Drop this
        # self.label = Profile._LABEL[profile_id]


class User(DeclarativeBase):
    """
    User definition.

    This is the user definition used by :mod:`repoze.who`, which requires at
    least the ``email`` column.
    """

    __tablename__ = 'users'

    user_id = Column(Integer, Sequence('seq__users__user_id'), autoincrement=True, primary_key=True)
    email = Column(Unicode(255), unique=True, nullable=False)
    display_name = Column(Unicode(255))
    _password = Column('password', Unicode(128))
    created = Column(DateTime, default=datetime.utcnow)
    is_active = Column(Boolean, default=True, nullable=False)
    imported_from = Column(Unicode(32), nullable=True)
    timezone = Column(Unicode(255), nullable=False, server_default='')
    # TODO - G.M - 04-04-2018 - [auth] Check if this is already needed
    # with new auth system
    auth_token = Column(Unicode(255))
    auth_token_created = Column(DateTime)

    @hybrid_property
    def email_address(self):
        return self.email

    def __repr__(self):
        return '<User: email=%s, display=%s>' % (
                repr(self.email), repr(self.display_name))

    def __unicode__(self):
        return self.display_name or self.email

    @property
    def permissions(self):
        """Return a set with all permissions granted to the user."""
        perms = set()
        for g in self.groups:
            perms = perms | set(g.permissions)
        return perms

    @property
    def profile(self) -> Profile:
        profile_id = 0
        if len(self.groups) > 0:
            profile_id = max(group.group_id for group in self.groups)
        return Profile(profile_id)

    # TODO - G-M - 20-04-2018 - [Calendar] Replace this in context model object
    # @property
    # def calendar_url(self) -> str:
    #     # TODO - 20160531 - Bastien: Cyclic import if import in top of file
    #     from tracim.lib.calendar import CalendarManager
    #     calendar_manager = CalendarManager(None)
    #
    #     return calendar_manager.get_user_calendar_url(self.user_id)

    @classmethod
    def by_email_address(cls, email, dbsession):
        """Return the user object whose email address is ``email``."""
        return dbsession.query(cls).filter_by(email=email).first()

    @classmethod
    def by_user_name(cls, username, dbsession):
        """Return the user object whose user name is ``username``."""
        return dbsession.query(cls).filter_by(email=username).first()

    @classmethod
    def _hash_password(cls, cleartext_password: str) -> str:
        salt = sha256()
        salt.update(os.urandom(60))
        salt = salt.hexdigest()

        hash = sha256()
        # Make sure password is a str because we cannot hash unicode objects
        hash.update((cleartext_password + salt).encode('utf-8'))
        hash = hash.hexdigest()

        ciphertext_password = salt + hash

        # Make sure the hashed password is a unicode object at the end of the
        # process because SQLAlchemy _wants_ unicode objects for Unicode cols
        # FIXME - D.A. - 2013-11-20 - The following line has been removed since using python3. Is this normal ?!
        # password = password.decode('utf-8')

        return ciphertext_password

    def _set_password(self, cleartext_password: str) -> None:
        """
        Set ciphertext password from cleartext password.

        Hash cleartext password on the fly,
        Store its ciphertext version,
        """
        self._password = self._hash_password(cleartext_password)

    def _get_password(self) -> str:
        """Return the hashed version of the password."""
        return self._password

    password = synonym('_password', descriptor=property(_get_password,
                                                        _set_password))

    def validate_password(self, cleartext_password: str) -> bool:
        """
        Check the password against existing credentials.

        :param cleartext_password: the password that was provided by the user
            to try and authenticate. This is the clear text version that we
            will need to match against the hashed one in the database.
        :type cleartext_password: unicode object.
        :return: Whether the password is valid.
        :rtype: bool

        """
        result = False
        if self.password:
            hash = sha256()
            hash.update((cleartext_password + self.password[:64]).encode('utf-8'))
            result = self.password[64:] == hash.hexdigest()
        return result

    def get_display_name(self, remove_email_part: bool=False) -> str:
        """
        Get a name to display from corresponding member or email.

        :param remove_email_part: If True and display name based on email,
            remove @xxx.xxx part of email in returned value
        :return: display name based on user name or email.
        """
        if self.display_name:
            return self.display_name
        else:
            if remove_email_part:
                at_pos = self.email.index('@')
                return self.email[0:at_pos]
            return self.email

    def get_role(self, workspace: 'Workspace') -> int:
        for role in self.roles:
            if role.workspace == workspace:
                return role.role

        return UserRoleInWorkspace.NOT_APPLICABLE

    def get_active_roles(self) -> ['UserRoleInWorkspace']:
        """
        :return: list of roles of the user for all not-deleted workspaces
        """
        roles = []
        for role in self.roles:
            if not role.workspace.is_deleted:
                roles.append(role)
        return roles

    # TODO - G.M - 04-04-2018 - [auth] Check if this is already needed
    # with new auth system
    def ensure_auth_token(self, validity_seconds, session) -> None:
        """
        Create auth_token if None, regenerate auth_token if too much old.

        auth_token validity is set in
        :return:
        """

        if not self.auth_token or not self.auth_token_created:
            self.auth_token = str(uuid.uuid4())
            self.auth_token_created = datetime.utcnow()
            session.flush()
            return

        now_seconds = time.mktime(datetime.utcnow().timetuple())
        auth_token_seconds = time.mktime(self.auth_token_created.timetuple())
        difference = now_seconds - auth_token_seconds

        if difference > validity_seconds:
            self.auth_token = str(uuid.uuid4())
            self.auth_token_created = datetime.utcnow()
            session.flush()


class Permission(DeclarativeBase):
    """
    Permission definition.

    Only the ``permission_name`` column is required.

    """

    __tablename__ = 'permissions'

    permission_id = Column(
        Integer,
        Sequence('seq__permissions__permission_id'),
        autoincrement=True,
        primary_key=True
    )
    permission_name = Column(Unicode(63), unique=True, nullable=False)
    description = Column(Unicode(255))

    groups = relation(Group, secondary=group_permission_table,
                      backref='permissions')

    def __repr__(self):
        return '<Permission: name=%s>' % repr(self.permission_name)

    def __unicode__(self):
        return self.permission_name