import { readFile } from "node:fs/promises";
import type { Server } from "node:http";
import type { AddressInfo } from "node:net";
import { dirname, resolve } from "node:path";
import { fileURLToPath } from "node:url";
import { Client } from "@modelcontextprotocol/sdk/client/index.js";
import { StreamableHTTPClientTransport } from "@modelcontextprotocol/sdk/client/streamableHttp.js";
import { afterEach, describe, expect, it } from "vitest";
import { EXAMPLE_ECHO_TOOL_NAME } from "../src/capabilities/index.js";
import { startHttpServer } from "../src/http.js";

const testsDir = dirname(fileURLToPath(import.meta.url));
const projectRoot = resolve(testsDir, "..");
const packageJsonPath = resolve(projectRoot, "package.json");

let activeServer: Server | undefined;

afterEach(async () => {
  if (activeServer !== undefined) {
    await new Promise<void>((resolveClose, rejectClose) => {
      activeServer?.close((error) => {
        if (error) {
          rejectClose(error);
          return;
        }

        resolveClose();
      });
    });
    activeServer = undefined;
  }
});

async function startTestServer(): Promise<URL> {
  activeServer = await startHttpServer({ host: "127.0.0.1", port: 0 });
  const address = activeServer.address() as AddressInfo;
  return new URL(`http://127.0.0.1:${address.port}/mcp`);
}

describe("HTTP entrypoint", () => {
  it("supports streamable HTTP initialize flow and shared capabilities", async () => {
    const endpoint = await startTestServer();
    const transport = new StreamableHTTPClientTransport(endpoint);
    const client = new Client({ name: "http-test-client", version: "0.0.0" }, { capabilities: {} });

    await client.connect(transport);
    const tools = await client.listTools();

    expect(tools.tools.map((tool) => tool.name)).toContain(EXAMPLE_ECHO_TOOL_NAME);

    await client.close();
    await transport.close();
  });

  it("returns 404 on unknown routes", async () => {
    await startTestServer();
    const address = activeServer?.address() as AddressInfo;
    const response = await fetch(`http://127.0.0.1:${address.port}/not-mcp`);

    expect(response.status).toBe(404);
    await expect(response.json()).resolves.toMatchObject({
      error: "Not Found",
    });
  });

  it("returns explicit invalid-session errors", async () => {
    await startTestServer();
    const address = activeServer?.address() as AddressInfo;
    const response = await fetch(`http://127.0.0.1:${address.port}/mcp`, {
      method: "POST",
      headers: {
        "content-type": "application/json",
        "mcp-session-id": "missing-session",
      },
      body: JSON.stringify({
        jsonrpc: "2.0",
        id: "invalid-session",
        method: "ping",
        params: {},
      }),
    });

    expect(response.status).toBe(404);
    await expect(response.json()).resolves.toMatchObject({
      jsonrpc: "2.0",
      error: {
        message: "Session not found",
      },
      id: null,
    });
  });

  it("publishes an HTTP entry command", async () => {
    const packageJsonRaw = await readFile(packageJsonPath, "utf8");
    const packageJson = JSON.parse(packageJsonRaw) as {
      scripts?: Record<string, string>;
    };

    expect(packageJson.scripts?.["dev:http"]).toBe("tsx src/http.ts");
  });
});