from src.extensions import db
import datetime

class CrossReference(db.Model):
    __tablename__ = 'cross_references'
    id = db.Column(db.Integer, primary_key=True)
    source_legislation_id = db.Column(db.Integer, db.ForeignKey('legislation.id'), nullable=False)
    target_legislation_id = db.Column(db.Integer, db.ForeignKey('legislation.id'), nullable=False)
    relationship_type = db.Column(db.String, nullable=False) # e.g., 'Cites', 'Amends', 'Conflicts With', 'Related To'
    details = db.Column(db.Text) # Optional: Specific section or context
    identified_at = db.Column(db.DateTime, default=datetime.datetime.utcnow)

    # Prevent duplicate references
    __table_args__ = (db.UniqueConstraint('source_legislation_id', 'target_legislation_id', 'relationship_type', name='_source_target_rel_uc'),)

    def __repr__(self):
        return f'<CrossRef {self.id}: {self.source_legislation_id} {self.relationship_type} {self.target_legislation_id}>'