from sqlalchemy import Column, DateTime, ForeignKey, Integer, String, UniqueConstraint
from sqlalchemy.orm import relationship
from sqlalchemy.sql import func

from app.database import Base


class Follow(Base):
    __tablename__ = "follows"

    id = Column(Integer, primary_key=True, autoincrement=True)
    user_id = Column(Integer, ForeignKey("users.id", ondelete="CASCADE"), nullable=False)
    follow_type = Column(String(20), nullable=False)   # bill | member | topic
    follow_value = Column(String, nullable=False)       # bill_id | bioguide_id | tag string
    created_at = Column(DateTime(timezone=True), server_default=func.now())

    user = relationship("User", back_populates="follows")

    __table_args__ = (
        UniqueConstraint("user_id", "follow_type", "follow_value", name="uq_follows_user_type_value"),
    )