"""QA 会话模型。"""

from __future__ import annotations

from typing import Optional

from sqlalchemy import BigInteger, Integer, TIMESTAMP, VARCHAR, UniqueConstraint
from sqlalchemy.orm import Mapped, mapped_column

from .base import Base


class QASession(Base):
    __tablename__ = "qa_sessions"
    __table_args__ = (
        UniqueConstraint(
            "tenant_id",
            "external_conversation_key",
            name="uq_qa_sessions_tenant_external_conversation_key",
        ),
    )

    id: Mapped[int] = mapped_column(Integer, primary_key=True, autoincrement=True)
    user_id: Mapped[Optional[int]] = mapped_column(BigInteger, nullable=True, index=True)
    external_conversation_key: Mapped[Optional[str]] = mapped_column(VARCHAR(160), nullable=True, index=True)
    title: Mapped[str] = mapped_column(VARCHAR(120), nullable=False, default="新会话")
    project_id: Mapped[Optional[int]] = mapped_column(BigInteger, nullable=True, index=True)
    started_at: Mapped[Optional[TIMESTAMP]] = mapped_column(TIMESTAMP, nullable=True, index=True)
    last_message_at: Mapped[Optional[TIMESTAMP]] = mapped_column(TIMESTAMP, nullable=True, index=True)
    message_count: Mapped[int] = mapped_column(Integer, nullable=False, default=0)