from sqlalchemy import String, Integer, ForeignKey, CheckConstraint, func
from sqlalchemy.orm import Mapped, mapped_column, relationship
from datetime import datetime
from typing import Optional, TYPE_CHECKING
from app.database import Base

if TYPE_CHECKING:
    from app.models.user import User


class ConnectionRequest(Base):
    __tablename__ = "connection_requests"
    __table_args__ = (
        CheckConstraint(
            "status IN ('pending', 'accepted', 'rejected', 'cancelled')",
            name="ck_connection_requests_status",
        ),
    )

    id: Mapped[int] = mapped_column(primary_key=True, index=True)
    sender_id: Mapped[int] = mapped_column(
        Integer, ForeignKey("users.id", ondelete="CASCADE"), nullable=False
    )
    receiver_id: Mapped[int] = mapped_column(
        Integer, ForeignKey("users.id", ondelete="CASCADE"), nullable=False
    )
    status: Mapped[str] = mapped_column(String(20), nullable=False, server_default="pending")
    created_at: Mapped[datetime] = mapped_column(default=func.now(), server_default=func.now())
    resolved_at: Mapped[Optional[datetime]] = mapped_column(nullable=True, default=None)
    person_id: Mapped[Optional[int]] = mapped_column(
        Integer, ForeignKey("people.id", ondelete="SET NULL"), nullable=True
    )

    # Relationships with explicit foreign_keys to disambiguate
    sender: Mapped["User"] = relationship(foreign_keys=[sender_id], lazy="selectin")
    receiver: Mapped["User"] = relationship(foreign_keys=[receiver_id], lazy="selectin")