from typing import List
from datetime import datetime
from sqlalchemy import Table, Column, Integer, String, ForeignKey, DateTime, UniqueConstraint
from sqlalchemy.orm import relationship, backref
from orm import Permission
from orm.base import Base


Connection = Table('topic_connections',
	Base.metadata,
    Column('child', Integer, ForeignKey('topic.id')),
    Column('parent', Integer, ForeignKey('topic.id')),
    UniqueConstraint('parent', 'child', name='unique_usage')
)


class Topic(Base):
	__tablename__ = 'topic'

	slug: str = Column(String, unique = True, nullable = False)
	org_id: str = Column(ForeignKey("organization.id"), nullable=False)
	createdAt: str = Column(DateTime, nullable=False, default = datetime.now, comment="Created at")
	createdBy: str = Column(ForeignKey("user.id"), nullable=False, comment="Author")
	value: str = Column(String, nullable=False, comment="Value")
	# list of Topics where the current node is the "other party" or "child"
	parents = relationship(lambda: Topic, secondary=Connection, primaryjoin=slug==Connection.c.parent, secondaryjoin=slug==Connection.c.child, viewonly=True)
	# list of Topics where the current node is the "parent" 
	children = relationship(lambda: Topic, secondary=Connection, primaryjoin=slug==Connection.c.child, secondaryjoin=slug==Connection.c.parent)