"""MCP client 适配器。

Agent 只依赖同步的 `call_tool(name, arguments)` 接口。本模块把普通
callable 或 SDK session 适配成这个接口，避免业务代码绑定具体 MCP SDK。
"""

from __future__ import annotations

import json
from collections.abc import Callable
from dataclasses import dataclass, field
from pathlib import Path
from typing import Any


@dataclass(frozen=True)
class McpClientConfig:
    """真实 MCP session 建立后需要传给 runner 的配置。"""

    server_name: str = "pam-node"
    tool_names: dict[str, str] = field(default_factory=dict)

    @classmethod
    def from_mapping(cls, payload: dict[str, Any]) -> "McpClientConfig":
        """从 JSON 字典构造 MCP client 配置。"""
        tool_names = payload.get("tool_names") or payload.get("tools") or {}
        if not isinstance(tool_names, dict):
            raise ValueError("MCP tool_names 必须是 JSON object")
        return cls(
            server_name=str(payload.get("server_name", "pam-node")),
            tool_names={str(key): str(value) for key, value in tool_names.items()},
        )


def load_mcp_client_config(path: str | Path) -> McpClientConfig:
    """读取 MCP client JSON 配置文件。"""
    payload = json.loads(Path(path).read_text(encoding="utf-8"))
    if not isinstance(payload, dict):
        raise ValueError("MCP client 配置必须是 JSON object")
    return McpClientConfig.from_mapping(payload)


class FunctionMcpToolClient:
    """把普通 Python callable 包装为 MCP tool client。"""

    def __init__(self, caller: Callable[[str, dict[str, Any]], Any]) -> None:
        """保存实际执行工具调用的函数。"""
        self.caller = caller

    def call_tool(self, tool_name: str, arguments: dict[str, Any]) -> Any:
        """调用底层函数并返回原始结果。"""
        return self.caller(tool_name, arguments)


class SessionMcpToolClient:
    """适配暴露 `call_tool` 的 MCP SDK session。

    适配器接受常见返回形态：

    - 原始 dict/list/string
    - 带有 `structuredContent` 的对象
    - 带有 `content` 的对象，其中 text 内容可能是 JSON
    """

    def __init__(self, session: Any) -> None:
        """校验并保存 MCP SDK session。"""
        if not hasattr(session, "call_tool"):
            raise TypeError("MCP session 必须暴露 call_tool 方法")
        self.session = session

    def call_tool(self, tool_name: str, arguments: dict[str, Any]) -> Any:
        """调用 SDK session，并把 SDK 返回值归一化。"""
        result = self.session.call_tool(tool_name, arguments)
        return normalize_mcp_sdk_result(result)


def normalize_mcp_sdk_result(result: Any) -> Any:
    """把常见 MCP SDK 返回结构归一化成 dict/list/string。"""
    if hasattr(result, "structuredContent"):
        structured = getattr(result, "structuredContent")
        if structured is not None:
            return structured

    if hasattr(result, "content"):
        content = getattr(result, "content")
        text_parts: list[str] = []
        for item in content or []:
            text = getattr(item, "text", None)
            if text is not None:
                text_parts.append(text)
        if text_parts:
            joined = "\n".join(text_parts)
            try:
                return json.loads(joined)
            except json.JSONDecodeError:
                return joined

    return result