"""Favorite (saved listing). One row per user+listing pair."""
from datetime import datetime
from app.extensions import db


class Favorite(db.Model):
    __tablename__ = "favorites"
    __table_args__ = (
        db.UniqueConstraint("user_id", "listing_id", name="uq_fav_user_listing"),
    )

    id = db.Column(db.BigInteger().with_variant(db.Integer, "sqlite"),
                   primary_key=True, autoincrement=True)
    user_id = db.Column(db.BigInteger().with_variant(db.Integer, "sqlite"),
                        db.ForeignKey("users.id"), nullable=False, index=True)
    listing_id = db.Column(db.BigInteger().with_variant(db.Integer, "sqlite"),
                           db.ForeignKey("listings.id"), nullable=False, index=True)
    created_at = db.Column(db.DateTime, default=datetime.utcnow, nullable=False)

    user = db.relationship("User",
                           backref=db.backref("favorites", lazy="dynamic"))
    listing = db.relationship("Listing",
                              backref=db.backref("favorited_by", lazy="dynamic"))

    def __repr__(self):
        return f"<Favorite u{self.user_id} l{self.listing_id}>"