"""Project Knowledge Graph evidence model."""

from __future__ import annotations

from typing import Any, Optional

from sqlalchemy import ForeignKey, Integer, TEXT, TIMESTAMP, VARCHAR, func
from sqlalchemy.orm import Mapped, mapped_column

from .base import Base
from .types import JSONB


class KGEvidence(Base):
    __tablename__ = "kg_evidences"

    id: Mapped[int] = mapped_column(Integer, primary_key=True, autoincrement=True)
    entity_id: Mapped[Optional[int]] = mapped_column(
        Integer,
        ForeignKey("kg_entities.id", ondelete="CASCADE"),
        nullable=True,
        index=True,
    )
    relation_id: Mapped[Optional[int]] = mapped_column(
        Integer,
        ForeignKey("kg_relations.id", ondelete="CASCADE"),
        nullable=True,
        index=True,
    )
    evidence_type: Mapped[str] = mapped_column(VARCHAR(40), nullable=False, index=True)
    content_hash: Mapped[str] = mapped_column(VARCHAR(64), nullable=False, index=True)
    content_excerpt: Mapped[str] = mapped_column(TEXT, nullable=False)
    source_type: Mapped[str] = mapped_column(VARCHAR(32), nullable=False, default="system", index=True)
    source_ref: Mapped[Optional[str]] = mapped_column(VARCHAR(255), nullable=True)
    meta_payload: Mapped[Optional[Any]] = mapped_column("metadata", JSONB, nullable=True)
    occurred_at: Mapped[Optional[TIMESTAMP]] = mapped_column(
        TIMESTAMP,
        nullable=False,
        server_default=func.now(),
        index=True,
    )