"""ORM model for the materialised relationship graph.

One row = one directed edge ``(from_type, from_id) → (to_type, to_id)``
of a given ``rel_type``. The unique constraint on the 5-tuple makes the
sync handler's UPSERT trivial — bump ``last_seen_at`` on existing
edges, INSERT new ones.

Soft delete via ``deleted_at`` rather than hard delete so the timeline
of "when did this ownership end" stays queryable.
"""
from __future__ import annotations

import uuid
from datetime import datetime
from typing import Any

from sqlalchemy import (
    JSON,
    DateTime,
    Float,
    Index,
    String,
    UniqueConstraint,
)
from sqlalchemy.orm import Mapped, mapped_column
from sqlalchemy.sql import func

from app.core.database import Base
from app.core.sql_types import GUID as Uuid


class RelRelationship(Base):
    """One directed edge in the resource relationship graph."""

    __tablename__ = "rel_relationships"
    __mapper_args__ = {"eager_defaults": True}

    id: Mapped[uuid.UUID] = mapped_column(Uuid, primary_key=True, default=uuid.uuid4)
    from_type: Mapped[str] = mapped_column(String(32), nullable=False)
    from_id: Mapped[str] = mapped_column(String(64), nullable=False)
    from_label: Mapped[str | None] = mapped_column(String(255))
    to_type: Mapped[str] = mapped_column(String(32), nullable=False)
    to_id: Mapped[str] = mapped_column(String(64), nullable=False)
    to_label: Mapped[str | None] = mapped_column(String(255))
    rel_type: Mapped[str] = mapped_column(String(48), nullable=False)
    attributes: Mapped[dict[str, Any] | None] = mapped_column(JSON)
    source: Mapped[str] = mapped_column(
        String(48), nullable=False, default="sync",
    )
    weight: Mapped[float] = mapped_column(
        Float, nullable=False, default=1.0, server_default="1.0",
    )
    first_seen_at: Mapped[datetime] = mapped_column(
        DateTime(timezone=True), nullable=False,
    )
    last_seen_at: Mapped[datetime] = mapped_column(
        DateTime(timezone=True), nullable=False,
    )
    deleted_at: Mapped[datetime | None] = mapped_column(DateTime(timezone=True))

    created_at: Mapped[datetime] = mapped_column(
        DateTime(timezone=True), nullable=False, server_default=func.now(),
    )
    updated_at: Mapped[datetime] = mapped_column(
        DateTime(timezone=True), nullable=False, server_default=func.now(),
        onupdate=func.now(),
    )

    __table_args__ = (
        UniqueConstraint(
            "from_type", "from_id", "to_type", "to_id", "rel_type",
            name="uq_rel_edge",
        ),
        Index("idx_rel_from", "from_type", "from_id"),
        Index("idx_rel_to", "to_type", "to_id"),
        Index("idx_rel_type", "rel_type"),
        Index("idx_rel_last_seen", "last_seen_at"),
    )

    def __repr__(self) -> str:
        return (
            f"<RelRelationship {self.from_type}:{self.from_id} "
            f"--{self.rel_type}--> {self.to_type}:{self.to_id}>"
        )