/**
 * MNote MCP 扩展 — Pi Rust MCP 工具门面
 *
 * Pi Rust 0.1.21 的异步 pi.exec()/嵌套 HTTP hostcall 在真实网页工具调用中
 * 可能卡到扩展任务超时。官方 node:child_process shim 的 execFileSync 通过
 * __pi_exec_sync_native 执行，因此这里同步启动相邻 client.mjs。
 *
 * client.mjs 只读取扩展目录相邻的 .pi/mcp.json，并且请求只能选择其中已配置
 * 的 server，不接受任意命令或配置路径。
 */

import { execFileSync } from "node:child_process";
import path from "node:path";
import { fileURLToPath } from "node:url";

interface ExtensionAPI {
  registerTool: (spec: Record<string, unknown>) => void;
}

interface ToolResult {
  content?: Array<{ type: string; text?: string; [key: string]: unknown }>;
  details?: Record<string, unknown>;
  isError?: boolean;
  [key: string]: unknown;
}

const EXTENSION_DIR = path.dirname(fileURLToPath(import.meta.url));
const MCP_CLIENT_PATH = path.join(EXTENSION_DIR, "client.mjs");
const MCP_REQUEST_MAX_CHARS = 128 * 1024;
const MCP_CLIENT_TIMEOUT_MS = 90_000;
const MCP_CLIENT_MAX_BUFFER = 2 * 1024 * 1024;

const mcpToolParameters = {
  type: "object",
  properties: {
    server: {
      type: "string",
      description: "MCP 服务器名称（对应当前 MNote Pi session 的 mcp.json）",
    },
    mode: {
      type: "string",
      enum: ["list", "status", "call"],
      description: "操作模式：list=列出工具，status=检查服务器状态，call=调用工具",
    },
    tool: {
      type: "string",
      description: "mode=call 时需要调用的工具名称",
    },
    arguments: {
      type: "object",
      description: "mode=call 时传入工具的参数对象",
      additionalProperties: true,
    },
  },
  required: ["server", "mode"],
};

function executeMcpRequest(params: {
  server: string;
  mode: string;
  tool?: string;
  arguments?: Record<string, unknown>;
}): Record<string, unknown> {
  const requestJson = JSON.stringify({
    server: params.server,
    mode: params.mode,
    tool: params.tool,
    arguments: params.arguments || {},
  });
  if (requestJson.length > MCP_REQUEST_MAX_CHARS) {
    throw new Error(`MCP 请求超过 ${MCP_REQUEST_MAX_CHARS} 字符限制`);
  }
  const stdout = execFileSync("node", [
    MCP_CLIENT_PATH,
    "--request-json",
    requestJson,
  ], {
    cwd: EXTENSION_DIR,
    timeout: MCP_CLIENT_TIMEOUT_MS,
    maxBuffer: MCP_CLIENT_MAX_BUFFER,
  });
  const text = String(stdout || "").trim();
  if (!text) {
    throw new Error("MNote MCP client 未返回结果");
  }
  try {
    const payload = JSON.parse(text);
    if (!payload || typeof payload !== "object" || Array.isArray(payload)) {
      throw new Error("返回值不是 JSON 对象");
    }
    return payload as Record<string, unknown>;
  } catch (error) {
    throw new Error(
      `MNote MCP client 返回非 JSON: ${text.slice(0, 500)}`
      + (error instanceof Error ? ` (${error.message})` : ""),
    );
  }
}

export default function mnoteMcpExtension(pi: ExtensionAPI) {
  pi.registerTool({
    name: "mcp",
    label: "MNote MCP",
    description: "通过 Pi Rust 同步本地 client 调用当前 session 配置的 MCP 服务器。" +
      "支持 list（列出工具）、status（检查连通性）、call（调用工具）三种模式。",
    parameters: mcpToolParameters,

    async execute(
      _toolCallId: string,
      params: { server: string; mode: string; tool?: string; arguments?: Record<string, unknown> },
    ): Promise<ToolResult> {
      const { server, mode, tool, arguments: args } = params;
      if (!["list", "status", "call"].includes(mode)) {
        return {
          content: [{ type: "text", text: `无效 mode: "${mode}"。可选值: list, status, call` }],
          isError: true,
        };
      }
      if (mode === "call" && !tool) {
        return {
          content: [{ type: "text", text: 'mode=call 时缺少必填参数 "tool"' }],
          isError: true,
        };
      }

      try {
        const result = executeMcpRequest({ server, mode, tool, arguments: args });
        return {
          content: [{ type: "text", text: JSON.stringify(result, null, 2) }],
          details: {
            server,
            mode,
            tool: tool || null,
            result,
            transport: "pi-rust-sync-client",
          },
          isError: result.ok === false,
        };
      } catch (error) {
        return {
          content: [{
            type: "text",
            text: `MCP 调用失败: ${error instanceof Error ? error.message : String(error)}`,
          }],
          isError: true,
        };
      }
    },
  });
}