from uuid import uuid4

from flask import current_app as app
from sqlalchemy import Column
from sqlalchemy.dialects.postgresql import UUID
from sqlalchemy_utils import EmailType, PasswordType

from ereuse_devicehub.db import db
from ereuse_devicehub.resources.inventory.model import Inventory
from ereuse_devicehub.resources.models import STR_SIZE, Thing


class User(Thing):
    __table_args__ = {'schema': 'common'}
    id = Column(UUID(as_uuid=True), default=uuid4, primary_key=True)
    email = Column(EmailType, nullable=False, unique=True)
    password = Column(PasswordType(max_length=STR_SIZE,
                                   onload=lambda **kwargs: dict(
                                       schemes=app.config['PASSWORD_SCHEMES'],
                                       **kwargs
                                   )))
    token = Column(UUID(as_uuid=True), default=uuid4, unique=True, nullable=False)
    inventories = db.relationship(Inventory,
                                  backref=db.backref('users', lazy=True, collection_class=set),
                                  secondary=lambda: UserInventory.__table__,
                                  collection_class=set)
    # todo set restriction that user has, at least, one active db

    def __init__(self, email, password=None, inventories=None) -> None:
        """
        Creates an user.
        :param email:
        :param password:
        :param inventories: A set of Inventory where the user has
        access to. If none, the user is granted access to the current
        inventory.
        """
        inventories = inventories or {Inventory.current}
        super().__init__(email=email, password=password, inventories=inventories)

    def __repr__(self) -> str:
        return '<User {0.email}>'.format(self)

    @property
    def individual(self):
        """The individual associated for this database, or None."""
        return next(iter(self.individuals), None)


class UserInventory(db.Model):
    """Relationship between users and their inventories."""
    __table_args__ = {'schema': 'common'}
    user_id = db.Column(db.UUID(as_uuid=True), db.ForeignKey(User.id), primary_key=True)
    inventory_id = db.Column(db.Unicode(), db.ForeignKey(Inventory.id), primary_key=True)