import { describe, expect, test } from "vitest";
import {
  getNextUiTheme,
  isUiTheme,
  persistUiTheme,
  resolveInitialUiTheme,
  UI_THEME_STORAGE_KEY,
} from "./theme";

describe("UI theme preference", () => {
  test("defaults to dark when no stored preference exists", () => {
    const storage = new Map<string, string>();

    expect(resolveInitialUiTheme(storage)).toBe("dark");
  });

  test("restores a valid stored preference", () => {
    const storage = new Map<string, string>([[UI_THEME_STORAGE_KEY, "light"]]);

    expect(resolveInitialUiTheme(storage)).toBe("light");
  });

  test("ignores invalid stored preferences", () => {
    const storage = new Map<string, string>([[UI_THEME_STORAGE_KEY, "solarized"]]);

    expect(resolveInitialUiTheme(storage)).toBe("dark");
  });

  test("falls back when stored preferences cannot be read", () => {
    const storage = {
      getItem() {
        throw new Error("storage blocked");
      },
    };

    expect(resolveInitialUiTheme(storage)).toBe("dark");
  });

  test("ignores persistence failures", () => {
    const storage = {
      setItem() {
        throw new Error("quota exceeded");
      },
    };

    expect(() => persistUiTheme("light", storage)).not.toThrow();
  });

  test("detects and toggles supported themes", () => {
    expect(isUiTheme("light")).toBe(true);
    expect(isUiTheme("dark")).toBe(true);
    expect(isUiTheme("contrast")).toBe(false);
    expect(getNextUiTheme("dark")).toBe("light");
    expect(getNextUiTheme("light")).toBe("dark");
  });
});