import { switchToDarkMode, switchToLightMode, switchToAutoMode, getCurrentThemeMode } from "./themeMode";

function createMediaQueryList(initialMatches: boolean, query = "(prefers-color-scheme: dark)") {
  let currentMatches = initialMatches;
  const mql: Partial<MediaQueryList> = {
    get matches() {
      return currentMatches;
    },
    media: query,
    onchange: null,
    addListener: () => {},
    removeListener: () => {},
    addEventListener: () => {},
    removeEventListener: () => {},
    dispatchEvent: () => false,
  };
  return Object.assign(mql, {
    setMatches(newMatches: boolean) {
      currentMatches = newMatches;
    },
  }) as MediaQueryList & { setMatches: (matches: boolean) => void };
}

describe("themeMode helper", () => {
  let originalMatchMedia: typeof window.matchMedia;

  beforeAll(() => {
    originalMatchMedia = window.matchMedia;
  });

  afterAll(() => {
    window.matchMedia = originalMatchMedia;
  });

  beforeEach(() => {
    document.body.className = "";
  });

  it("should add the 'dark' class when switching to dark mode", () => {
    switchToDarkMode();
    expect(document.body.classList.contains("dark")).toBeTrue();
  });

  it("should remove the 'dark' class when switching to light mode", () => {
    document.body.classList.add("dark");
    switchToLightMode();
    expect(document.body.classList.contains("dark")).toBeFalse();
  });

  it("should apply dark mode automatically when user prefers dark", () => {
    window.matchMedia = (query: string): MediaQueryList =>
      createMediaQueryList(true, query);
    switchToAutoMode();
    expect(document.body.classList.contains("dark")).toBeTrue();
  });

  it("should apply light mode automatically when user does not prefer dark", () => {
    document.body.classList.add("dark");
    window.matchMedia = (query: string): MediaQueryList =>
      createMediaQueryList(false, query);
    switchToAutoMode();
    expect(document.body.classList.contains("dark")).toBeFalse();
  });

  it("should update theme when system preference changes in auto mode upon re-calling switchToAutoMode", () => {
    window.matchMedia = (query: string): MediaQueryList =>
      createMediaQueryList(false, query);
    switchToAutoMode();
    expect(document.body.classList.contains("dark")).toBeFalse();

    window.matchMedia = (query: string): MediaQueryList =>
      createMediaQueryList(true, query);
    switchToAutoMode();
    expect(document.body.classList.contains("dark")).toBeTrue();

    window.matchMedia = (query: string): MediaQueryList =>
      createMediaQueryList(false, query);
    switchToAutoMode();
    expect(document.body.classList.contains("dark")).toBeFalse();
  });

  it("should update theme when media query change event is triggered", () => {
    const dummyMediaQuery = createMediaQueryList(false);
    window.matchMedia = (query: string): MediaQueryList => dummyMediaQuery;

    switchToAutoMode();
    expect(document.body.classList.contains("dark")).toBeFalse();

    dummyMediaQuery.setMatches(true);
    if (dummyMediaQuery.onchange) {
      dummyMediaQuery.onchange({ matches: true } as MediaQueryListEvent);
    }
    expect(document.body.classList.contains("dark")).toBeTrue();

    dummyMediaQuery.setMatches(false);
    if (dummyMediaQuery.onchange) {
      dummyMediaQuery.onchange({ matches: false } as MediaQueryListEvent);
    }
    expect(document.body.classList.contains("dark")).toBeFalse();
  });

  it("getCurrentThemeMode should return 'dark' when dark mode is set manually", () => {
    switchToDarkMode();
    expect(getCurrentThemeMode()).toBe("dark");
  });

  it("getCurrentThemeMode should return 'light' when light mode is set manually", () => {
    switchToLightMode();
    expect(getCurrentThemeMode()).toBe("light");
  });

  it("getCurrentThemeMode should return 'auto' when auto mode is enabled", () => {
    window.matchMedia = (query: string): MediaQueryList =>
      createMediaQueryList(true, query);
    switchToAutoMode();
    expect(getCurrentThemeMode()).toBe("auto");
  });
});