# -*- coding: utf-8 -*-
"""
消息数据模型
统一所有中间件的消息格式
"""

import time
import uuid
from dataclasses import dataclass, field
from enum import Enum
from typing import Any, Dict, Optional


class MessagePriority(Enum):
    LOW    = 0
    NORMAL = 1
    HIGH   = 2
    URGENT = 3


@dataclass
class Message:
    """统一消息体"""
    topic:      str
    payload:    Any
    msg_id:     str                  = field(default_factory=lambda: str(uuid.uuid4()))
    timestamp:  float                = field(default_factory=time.time)
    headers:    Dict[str, str]       = field(default_factory=dict)
    priority:   MessagePriority      = MessagePriority.NORMAL
    reply_to:   Optional[str]        = None   # 用于 Request/Reply 模式
    correlation_id: Optional[str]   = None

    def to_dict(self) -> dict:
        return {
            "msg_id":         self.msg_id,
            "topic":          self.topic,
            "payload":        self.payload,
            "timestamp":      self.timestamp,
            "headers":        self.headers,
            "priority":       self.priority.value,
            "reply_to":       self.reply_to,
            "correlation_id": self.correlation_id,
        }

    @classmethod
    def from_dict(cls, data: dict) -> "Message":
        data["priority"] = MessagePriority(data.get("priority", 1))
        return cls(**{k: v for k, v in data.items() if k in cls.__dataclass_fields__})

    def __repr__(self):
        return (f"Message(id={self.msg_id[:8]}..., topic={self.topic!r}, "
                f"priority={self.priority.name})")