"""Relationship — a typed, qualified edge between two Persons.

Modeling parentage as qualified edges (rather than assuming two biological
parents) is what makes adoption, donor conception, and blended families
first-class. ``qualifier`` applies to parent_child edges; partnership events
(marriage, divorce) attach to the Relationship via Event.relationship_id.
"""

import uuid

from sqlalchemy import CheckConstraint, ForeignKey, Text
from sqlalchemy import Enum as SAEnum
from sqlalchemy.orm import Mapped, mapped_column

from app.models.base import Base
from app.models.enums import ParentChildQualifier, RelationshipType
from app.models.mixins import SoftDelete, TenantScoped, Timestamps, UUIDPrimaryKey


class Relationship(Base, UUIDPrimaryKey, TenantScoped, Timestamps, SoftDelete):
    __tablename__ = "relationships"
    __table_args__ = (
        CheckConstraint("person_from_id <> person_to_id", name="different_persons"),
    )

    type: Mapped[RelationshipType] = mapped_column(
        SAEnum(RelationshipType, name="relationship_type")
    )
    # For parent_child: from = parent, to = child. For partnership/sibling: symmetric.
    person_from_id: Mapped[uuid.UUID] = mapped_column(
        ForeignKey("persons.id", ondelete="CASCADE"), index=True
    )
    person_to_id: Mapped[uuid.UUID] = mapped_column(
        ForeignKey("persons.id", ondelete="CASCADE"), index=True
    )
    # Only meaningful for parent_child edges.
    qualifier: Mapped[ParentChildQualifier | None] = mapped_column(
        SAEnum(ParentChildQualifier, name="parent_child_qualifier")
    )
    notes: Mapped[str | None] = mapped_column(Text)