"""消息模型"""

from datetime import datetime, timezone

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

from app.database import Base


class Message(Base):
    __tablename__ = "messages"
    __table_args__ = (
        Index("ix_messages_conv_created", "conversation_id", "created_at"),
    )

    id: Mapped[str] = mapped_column(String(36), primary_key=True)
    conversation_id: Mapped[str] = mapped_column(
        String(36), ForeignKey("conversations.id", ondelete="CASCADE"), nullable=False
    )
    sender_id: Mapped[str] = mapped_column(
        String(36), ForeignKey("users.id", ondelete="CASCADE"), nullable=False
    )
    type: Mapped[str] = mapped_column(String(20), default="text")  # text / image / file / system
    content: Mapped[str] = mapped_column(Text, nullable=False)
    reply_to_id: Mapped[str | None] = mapped_column(
        String(36), ForeignKey("messages.id", ondelete="SET NULL"), nullable=True
    )
    is_deleted: Mapped[bool] = mapped_column(Boolean, default=False)
    created_at: Mapped[datetime] = mapped_column(
        DateTime, default=lambda: datetime.utcnow(), index=True
    )

    # 关系
    conversation = relationship("Conversation", back_populates="messages")
    sender = relationship("User", back_populates="sent_messages", foreign_keys=[sender_id])
    reply_to = relationship("Message", remote_side="Message.id")