"""好友关系模型"""

from datetime import datetime, timezone

from sqlalchemy import String, DateTime, ForeignKey, UniqueConstraint
from sqlalchemy.orm import Mapped, mapped_column, relationship

from app.database import Base


class Friend(Base):
    __tablename__ = "friends"
    __table_args__ = (
        UniqueConstraint("user_id", "friend_user_id", name="uq_friendship"),
    )

    id: Mapped[str] = mapped_column(String(36), primary_key=True)
    user_id: Mapped[str] = mapped_column(
        String(36), ForeignKey("users.id", ondelete="CASCADE"), nullable=False
    )
    friend_user_id: Mapped[str] = mapped_column(
        String(36), ForeignKey("users.id", ondelete="CASCADE"), nullable=False
    )
    remark: Mapped[str | None] = mapped_column(String(50), nullable=True)  # 好友备注
    created_at: Mapped[datetime] = mapped_column(DateTime, default=lambda: datetime.utcnow())

    # 关系
    user = relationship("User", foreign_keys=[user_id], back_populates="friends")
    friend_user = relationship("User", foreign_keys=[friend_user_id], back_populates="friend_of")