"""AnnotationState model — current working annotation layer per document."""

from datetime import datetime, timezone

from sqlalchemy import ForeignKey, Text
from sqlalchemy.orm import Mapped, mapped_column, relationship

from app.db import Base


def _now_iso() -> str:
    return datetime.now(timezone.utc).isoformat()


class AnnotationState(Base):
    """
    Current working annotation state for a document.

    One row per document. `data` is a JSON text column containing
    the full annotation array — opaque to the server except during export.
    """

    __tablename__ = "annotation_states"

    document_id: Mapped[str] = mapped_column(
        Text, ForeignKey("documents.id", ondelete="CASCADE"), primary_key=True
    )
    data: Mapped[str] = mapped_column(Text, default="[]")  # JSON array
    updated_at: Mapped[str] = mapped_column(Text, default=_now_iso, onupdate=_now_iso)

    # Relationships
    document: Mapped["Document"] = relationship("Document", back_populates="annotation_state")