"""processing_queue 테이블 ORM (비동기 가공 큐)"""

from datetime import datetime

from sqlalchemy import BigInteger, DateTime, Enum, ForeignKey, SmallInteger, Text, text
from sqlalchemy.dialects.postgresql import insert as pg_insert
from sqlalchemy.ext.asyncio import AsyncSession
from sqlalchemy.orm import Mapped, mapped_column

from core.database import Base


class ProcessingQueue(Base):
    __tablename__ = "processing_queue"

    id: Mapped[int] = mapped_column(BigInteger, primary_key=True)
    document_id: Mapped[int] = mapped_column(BigInteger, ForeignKey("documents.id"), nullable=False)
    stage: Mapped[str] = mapped_column(
        # 'stt' (audio): migration 150 / 'thumbnail' (video): queue_consumer 가 enqueue.
        # DB enum 변경은 마이그레이션이 처리하므로 create_type=False.
        Enum(
            "extract", "classify", "summarize", "embed", "chunk", "preview",
            "stt", "thumbnail",
            name="process_stage",
            create_type=False,
        ),
        nullable=False,
    )
    status: Mapped[str] = mapped_column(
        Enum("pending", "processing", "completed", "failed", name="process_status"),
        default="pending"
    )
    attempts: Mapped[int] = mapped_column(SmallInteger, default=0)
    max_attempts: Mapped[int] = mapped_column(SmallInteger, default=3)
    error_message: Mapped[str | None] = mapped_column(Text)
    created_at: Mapped[datetime] = mapped_column(
        DateTime(timezone=True), default=datetime.now
    )
    started_at: Mapped[datetime | None] = mapped_column(DateTime(timezone=True))
    completed_at: Mapped[datetime | None] = mapped_column(DateTime(timezone=True))

    # DB 제약은 partial unique index uq_queue_active로 관리 (migration 117)


async def enqueue_stage(
    session: AsyncSession, document_id: int, stage: str, *, status: str = "pending",
) -> bool:
    """ProcessingQueue에 행 추가 (DB 레벨 중복 방어).

    같은 (document_id, stage)에 활성 행(pending/processing)이 이미 있으면
    아무것도 하지 않고 False 반환.
    """
    stmt = (
        pg_insert(ProcessingQueue)
        .values(document_id=document_id, stage=stage, status=status)
        .on_conflict_do_nothing(
            index_elements=["document_id", "stage"],
            index_where=text("status IN ('pending', 'processing')"),
        )
    )
    result = await session.execute(stmt)
    return result.rowcount > 0