import uuid
from datetime import datetime

from sqlalchemy import DateTime, ForeignKey, String, Text, func
from sqlalchemy.dialects.postgresql import JSONB, UUID
from sqlalchemy.orm import Mapped, mapped_column, relationship

from api.models.base import Base, new_uuid


class ProgressEvent(Base):
    """Append-only event log. No updated_at. No DELETE endpoint (constitution §5)."""

    __tablename__ = "progress_events"

    id: Mapped[uuid.UUID] = mapped_column(
        UUID(as_uuid=True), primary_key=True, default=new_uuid
    )
    topic_id: Mapped[uuid.UUID | None] = mapped_column(
        UUID(as_uuid=True), ForeignKey("topics.id", ondelete="RESTRICT"), nullable=True, index=True
    )
    workstream_id: Mapped[uuid.UUID | None] = mapped_column(
        UUID(as_uuid=True), ForeignKey("workstreams.id", ondelete="RESTRICT"), nullable=True, index=True
    )
    task_id: Mapped[uuid.UUID | None] = mapped_column(
        UUID(as_uuid=True), ForeignKey("tasks.id", ondelete="RESTRICT"), nullable=True, index=True
    )
    decision_id: Mapped[uuid.UUID | None] = mapped_column(
        UUID(as_uuid=True), ForeignKey("decisions.id", ondelete="RESTRICT"), nullable=True, index=True
    )
    event_type: Mapped[str] = mapped_column(String(50), nullable=False, index=True)
    summary: Mapped[str] = mapped_column(Text, nullable=False)
    detail: Mapped[dict | None] = mapped_column(JSONB, nullable=True)
    author: Mapped[str | None] = mapped_column(String(100), nullable=True)
    session_id: Mapped[str | None] = mapped_column(String(100), nullable=True)
    created_at: Mapped[datetime] = mapped_column(
        DateTime(timezone=True), server_default=func.now(), nullable=False, index=True
    )

    topic: Mapped["Topic | None"] = relationship("Topic", back_populates="progress_events")  # noqa: F821
    workstream: Mapped["Workstream | None"] = relationship("Workstream", back_populates="progress_events")  # noqa: F821
    task: Mapped["Task | None"] = relationship("Task", back_populates="progress_events")  # noqa: F821
    decision: Mapped["Decision | None"] = relationship("Decision", back_populates="progress_events")  # noqa: F821