"""
Chat Message 持久化模型 — 保存 Agent 会话中的每条消息
"""
from sqlalchemy import Column, String, Text, Integer, DateTime, ForeignKey, Index, func
from sqlalchemy.dialects.mysql import CHAR
from app.core.database import Base
import uuid


class ChatMessage(Base):
    """聊天消息表"""
    __tablename__ = "chat_messages"

    id = Column(CHAR(36), primary_key=True, default=lambda: str(uuid.uuid4()), comment="消息ID")
    session_id = Column(CHAR(36), nullable=False, comment="会话ID")
    agent_id = Column(CHAR(36), ForeignKey("agents.id", ondelete="SET NULL"), nullable=True, comment="智能体ID")
    user_id = Column(CHAR(36), ForeignKey("users.id", ondelete="SET NULL"), nullable=True, comment="用户ID")
    role = Column(String(20), nullable=False, comment="角色: user/assistant/tool/system")
    content = Column(Text, comment="消息内容")
    tool_name = Column(String(100), nullable=True, comment="工具名称(仅tool消息)")
    tool_input = Column(Text, nullable=True, comment="工具输入参数JSON(仅tool消息)")
    tool_output = Column(Text, nullable=True, comment="工具输出结果(仅tool消息)")
    iteration = Column(Integer, default=0, comment="Agent 迭代序号")
    created_at = Column(DateTime, default=func.now(), comment="创建时间")

    __table_args__ = (
        Index("ix_chat_messages_session_created", "session_id", "created_at"),
    )

    def to_dict(self):
        return {
            "id": self.id,
            "session_id": self.session_id,
            "agent_id": self.agent_id,
            "user_id": self.user_id,
            "role": self.role,
            "content": self.content,
            "tool_name": self.tool_name,
            "tool_input": self.tool_input,
            "tool_output": self.tool_output,
            "iteration": self.iteration,
            "created_at": self.created_at.isoformat() if self.created_at else None,
        }