"""外部客户会话（企微单聊/群聊维度）。"""
from datetime import datetime
from sqlalchemy import String, DateTime, ForeignKey
from sqlalchemy.orm import Mapped, mapped_column, relationship

from app.models.base import Base


class ChatSession(Base):
    __tablename__ = "chat_sessions"

    id: Mapped[int] = mapped_column(primary_key=True, autoincrement=True)
    external_user_id: Mapped[str] = mapped_column(String(128), nullable=False, index=True)  # 企微 external_userid
    external_name: Mapped[str | None] = mapped_column(String(128), nullable=True)
    status: Mapped[str] = mapped_column(String(32), default="open")  # open / transferred / closed
    created_at: Mapped[datetime] = mapped_column(DateTime(timezone=True), default=datetime.utcnow)
    updated_at: Mapped[datetime] = mapped_column(DateTime(timezone=True), default=datetime.utcnow, onupdate=datetime.utcnow)

    messages: Mapped[list["Message"]] = relationship("Message", back_populates="session", order_by="Message.id")