"""MCP 协议：JSON-RPC 消息定义"""
"""
mcp/mcp_protocol.py
MCP (Model Context Protocol) 协议数据结构定义
基于 JSON-RPC 2.0 规范封装请求/响应消息体
"""

import uuid
from dataclasses import dataclass, field
from typing import Any


# ── MCP 方法常量 ───────────────────────────────────────────────
class MCPMethod:
    TOOLS_LIST   = "tools/list"    # 列出所有可用工具
    TOOLS_CALL   = "tools/call"    # 调用指定工具
    RESOURCES_READ = "resources/read"  # 读取资源


# ── 请求消息 ───────────────────────────────────────────────────
@dataclass
class MCPRequest:
    """
    MCP 工具调用请求（JSON-RPC 2.0 格式）

    示例:
        {
            "jsonrpc": "2.0",
            "id": "abc-123",
            "method": "tools/call",
            "params": {
                "name": "calculator",
                "arguments": {"expression": "1+1"}
            }
        }
    """
    method:  str
    params:  dict[str, Any]         = field(default_factory=dict)
    jsonrpc: str                    = "2.0"
    id:      str                    = field(default_factory=lambda: str(uuid.uuid4())[:8])

    def to_dict(self) -> dict:
        return {
            "jsonrpc": self.jsonrpc,
            "id":      self.id,
            "method":  self.method,
            "params":  self.params,
        }


# ── 响应消息 ───────────────────────────────────────────────────
@dataclass
class MCPResponse:
    """
    MCP 工具调用响应（JSON-RPC 2.0 格式）

    成功示例:
        {"jsonrpc": "2.0", "id": "abc-123", "result": {"content": [...]}}

    失败示例:
        {"jsonrpc": "2.0", "id": "abc-123", "error": {"code": -32601, "message": "..."}}
    """
    id:      str
    result:  dict[str, Any] | None  = None
    error:   dict[str, Any] | None  = None
    jsonrpc: str                    = "2.0"

    @property
    def success(self) -> bool:
        return self.error is None

    @property
    def content(self) -> str:
        """提取响应中的文本内容"""
        if not self.success or not self.result:
            return self.error.get("message", "Unknown error") if self.error else ""
        items = self.result.get("content", [])
        return "\n".join(item.get("text", "") for item in items if item.get("type") == "text")

    def to_dict(self) -> dict:
        base = {"jsonrpc": self.jsonrpc, "id": self.id}
        if self.success:
            base["result"] = self.result
        else:
            base["error"] = self.error
        return base


# ── 工具描述 ───────────────────────────────────────────────────
@dataclass
class ToolSchema:
    """
    工具的元数据描述，用于 LLM 识别和选择工具
    """
    name:        str
    description: str
    parameters:  dict[str, Any]   # JSON Schema 格式的参数定义

    def to_dict(self) -> dict:
        return {
            "name":        self.name,
            "description": self.description,
            "inputSchema": {
                "type":       "object",
                "properties": self.parameters,
            },
        }