import { describe, it, expect, vi, beforeEach, afterEach } from "vitest";

describe("loadConfig", () => {
  const originalEnv = { ...process.env };

  beforeEach(() => {
    vi.resetModules();
  });

  afterEach(() => {
    process.env = { ...originalEnv };
  });

  async function loadConfig() {
    const mod = await import("../config.js");
    return mod.loadConfig();
  }

  it("returns default port 3001 when WEB_PORT is undefined", async () => {
    delete process.env.WEB_PORT;
    const config = await loadConfig();
    expect(config.port).toBe(3001);
  });

  it("parses WEB_PORT as an integer", async () => {
    process.env.WEB_PORT = "8080";
    const config = await loadConfig();
    expect(config.port).toBe(8080);
    expect(typeof config.port).toBe("number");
  });

  it("returns default appview URL when APPVIEW_URL is undefined", async () => {
    delete process.env.APPVIEW_URL;
    const config = await loadConfig();
    expect(config.appviewUrl).toBe("http://localhost:3000");
  });

  it("uses provided environment variables", async () => {
    process.env.WEB_PORT = "9000";
    process.env.APPVIEW_URL = "https://api.atbb.space";
    const config = await loadConfig();
    expect(config.port).toBe(9000);
    expect(config.appviewUrl).toBe("https://api.atbb.space");
  });

  it("returns NaN for port when WEB_PORT is empty string (?? does not catch empty strings)", async () => {
    process.env.WEB_PORT = "";
    const config = await loadConfig();
    // Documents a gap: ?? only catches null/undefined, not ""
    expect(config.port).toBeNaN();
  });

  it("returns empty string for appviewUrl when APPVIEW_URL is empty string", async () => {
    process.env.APPVIEW_URL = "";
    const config = await loadConfig();
    // Documents a gap: ?? only catches null/undefined, not ""
    expect(config.appviewUrl).toBe("");
  });
});