import enum

from sqlalchemy import Column, ForeignKey, Integer, String, DateTime, Date, Enum, CheckConstraint
from sqlalchemy.sql.functions import now
from sqlalchemy.orm import relationship

from .database import Base


class User(Base):
    __tablename__ = "users"

    id = Column(Integer, primary_key=True, autoincrement=True, index=True)
    email = Column(String, unique=True, nullable=False)
    password = Column(String, nullable=False)
    created = Column(DateTime(timezone=True), nullable=False, server_default=now())
    updated = Column(DateTime(timezone=True), nullable=False, server_default=now(), onupdate=now())
    first_name = Column(String, nullable=False)
    last_name = Column(String, nullable=False)

    administrator = relationship("Administrator", back_populates="user", uselist=False, cascade="all, delete")
    patient = relationship("Patient", back_populates="user", uselist=False, cascade="all, delete")
    #patient = Column(Integer, ForeignKey('patients.id'), nullable=True)
    #CheckConstraint("(administrator=NULL AND patient!=NULL) OR (administrator!=NULL AND patient=NULL)")


class Administrator(Base):
    __tablename__ = "administrators"

    user_id = Column(Integer, ForeignKey('users.id', ondelete="CASCADE"), primary_key=True,)
    user = relationship("User", back_populates="administrator", uselist=False, cascade="all, delete")


class Gender(enum.Enum):
    male = 'm'
    female = 'f'


class Patient(Base):
    __tablename__ = "patients"

    user_id = Column(Integer, ForeignKey('users.id', ondelete="CASCADE"), primary_key=True)
    user = relationship("User", back_populates="patient", uselist=False, cascade="all, delete")
    date_of_birth = Column(Date, nullable=False)
    gender = Column(Enum(Gender), nullable=False)