rea/tests/fixtures/jebMcp.ts

import { createServer } from "node:http";
import { z } from "zod";
import type { JsonValue } from "../../src/domain/jsonValue.js";
import { JEB_ENGINE_TOOLS } from "../../src/jeb/JebMcpConnection.js";

const messageSchema = z.object({
  id: z.union([z.string(), z.number()]).optional(),
  method: z.string(),
  params: z.object({ name: z.string().optional() }).passthrough().optional(),
});

/** Real HTTP MCP transport with caller-selected JEB response envelopes. */
export const startJebMcpFixture = async (
  respond: (tool: string) => JsonValue | Promise<JsonValue>,
  catalogReply?: JsonValue | (() => JsonValue | Promise<JsonValue>),
) => {
  const calls: string[] = [];
  const server = createServer(async (request, response) => {
    if (request.method !== "POST") {
      request.resume();
      response.writeHead(request.method === "DELETE" ? 200 : 405).end();
      return;
    }
    try {
      let body = "";
      for await (const chunk of request) body += String(chunk);
      const message = messageSchema.parse(JSON.parse(body));
      if (message.id === undefined) {
        response.writeHead(202).end();
        return;
      }
      let result: unknown;
      if (message.method === "initialize")
        result = {
          protocolVersion: "2025-11-25",
          capabilities: { tools: {} },
          serverInfo: { name: "jeb-response-fixture", version: "1" },
        };
      else if (message.method === "tools/list")
        result = (typeof catalogReply === "function"
          ? await catalogReply()
          : catalogReply) ?? {
          tools: Object.values(JEB_ENGINE_TOOLS).map((name) => ({
            name,
            inputSchema: { type: "object", properties: {} },
          })),
        };
      else if (
        message.method === "tools/call" &&
        message.params?.name !== undefined
      ) {
        calls.push(message.params.name);
        const payload = await respond(message.params.name);
        result = {
          structuredContent: payload,
          content: [{ type: "text", text: JSON.stringify(payload) }],
        };
      } else throw new Error(`Unexpected fixture request: ${message.method}`);
      response.writeHead(200, { "Content-Type": "application/json" });
      response.end(JSON.stringify({ jsonrpc: "2.0", id: message.id, result }));
    } catch (cause: unknown) {
      response.writeHead(500).end(String(cause));
    }
  });
  await new Promise<void>((resolve) => server.listen(0, "127.0.0.1", resolve));
  const address = server.address();
  if (address === null || typeof address === "string")
    throw new Error("Expected TCP fixture listener");
  return {
    endpoint: `http://127.0.0.1:${address.port}/mcp`,
    calls,
    close: async () => {
      server.closeAllConnections();
      await new Promise<void>((resolve, reject) =>
        server.close((cause) =>
          cause === undefined ? resolve() : reject(cause),
        ),
      );
    },
  };
};

export const jebPrimaryResponses: Readonly<Record<string, JsonValue>> = {
  get_client_information: {
    success: true,
    version: "5.48.0",
    gui_client: false,
  },
  list_units: {
    success: true,
    units: [{ unit_path: "sample.dex", unit_type: "dex" }],
  },
  decompile_code_item: { success: true, text: "int value() { return 1; }" },
  open_project: { success: true, name: "sample", input_files: [], units: [] },
};