"""会话模型（私聊 + 群聊）"""

from datetime import datetime, timezone

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

from app.database import Base


class Conversation(Base):
    __tablename__ = "conversations"

    id: Mapped[str] = mapped_column(String(36), primary_key=True)
    type: Mapped[str] = mapped_column(String(20), nullable=False)  # private / group
    name: Mapped[str | None] = mapped_column(String(100), nullable=True)  # 群聊名称
    avatar_url: Mapped[str | None] = mapped_column(String(500), nullable=True)  # 群头像
    description: Mapped[str | None] = mapped_column(String(500), nullable=True)  # 群描述
    creator_id: Mapped[str | None] = mapped_column(String(36), ForeignKey("users.id", ondelete="SET NULL"), nullable=True)
    last_message_at: Mapped[datetime | None] = mapped_column(DateTime, nullable=True)
    last_message_preview: Mapped[str | None] = mapped_column(String(200), nullable=True)
    created_at: Mapped[datetime] = mapped_column(DateTime, default=lambda: datetime.utcnow())
    updated_at: Mapped[datetime] = mapped_column(
        DateTime,
        default=lambda: datetime.utcnow(),
        onupdate=lambda: datetime.utcnow(),
    )

    # 关系
    members = relationship("ConversationMember", back_populates="conversation", cascade="all, delete-orphan")
    messages = relationship("Message", back_populates="conversation", cascade="all, delete-orphan")
    creator = relationship("User", foreign_keys=[creator_id])