import { describe, expect, it, vi } from "vitest";
import {
  createBrowserHostViewport,
  createMemoryHostViewport,
  HOST_COMPACT_MEDIA_QUERY,
} from "../src/browser/host-viewport.js";
import {
  createLocalSidebarPreference,
  createMemorySidebarPreference,
  SIDEBAR_PREFERENCE_KEY,
} from "../src/browser/sidebar-preference.js";

function fakeStorage(initial: Record<string, string> = {}) {
  const values = new Map(Object.entries(initial));
  return {
    getItem: vi.fn((key: string) => values.get(key) ?? null),
    setItem: vi.fn((key: string, value: string) => {
      values.set(key, value);
    }),
    values,
  };
}

describe("the sidebar preference (this browser only, ADR 0058)", () => {
  it("survives a reload: what one store writes, a new store over the same storage reads", () => {
    const storage = fakeStorage();
    createLocalSidebarPreference(storage).write("collapsed");

    expect(storage.values.get(SIDEBAR_PREFERENCE_KEY)).toBe("collapsed");
    expect(createLocalSidebarPreference(storage).read()).toBe("collapsed");

    createLocalSidebarPreference(storage).write("expanded");
    expect(createLocalSidebarPreference(storage).read()).toBe("expanded");
  });

  it("uses one namespaced key that names no person", () => {
    expect(SIDEBAR_PREFERENCE_KEY).toBe("ekklesia.dashboard.sidebar");
  });

  it("ignores a stored value it does not recognise rather than trusting it", () => {
    for (const value of ["", "COLLAPSED", "true", "{}", "collapsed "]) {
      expect(
        createLocalSidebarPreference(fakeStorage({ [SIDEBAR_PREFERENCE_KEY]: value })).read(),
        value,
      ).toBeUndefined();
    }
  });

  it("keeps working, for this page only, when storage is missing or throws", () => {
    const throwing = {
      getItem: () => {
        throw new Error("SecurityError");
      },
      setItem: () => {
        throw new Error("QuotaExceededError");
      },
    };
    for (const storage of [undefined, throwing]) {
      const preference = createLocalSidebarPreference(storage);
      expect(preference.read()).toBeUndefined();
      expect(() => preference.write("collapsed")).not.toThrow();
      expect(preference.read()).toBe("collapsed");
    }
  });

  it("has an in-memory store with the same contract, for tests and as the fallback", () => {
    const preference = createMemorySidebarPreference("collapsed");
    expect(preference.read()).toBe("collapsed");
    preference.write("expanded");
    expect(preference.read()).toBe("expanded");
    expect(createMemorySidebarPreference().read()).toBeUndefined();
  });
});

describe("the host viewport", () => {
  it("is compact below 48em, the phone layout's breakpoint", () => {
    expect(HOST_COMPACT_MEDIA_QUERY).toBe("(max-width: 47.999em)");
  });

  it("reads and follows a media query list", () => {
    let matches = false;
    const listeners = new Set<() => void>();
    const mediaQuery = {
      addEventListener: vi.fn((_type: "change", listener: () => void) => listeners.add(listener)),
      get matches() {
        return matches;
      },
      removeEventListener: vi.fn((_type: "change", listener: () => void) =>
        listeners.delete(listener),
      ),
    };
    const matchMedia = vi.fn(() => mediaQuery);
    const viewport = createBrowserHostViewport(matchMedia);
    expect(matchMedia).toHaveBeenCalledWith(HOST_COMPACT_MEDIA_QUERY);

    const listener = vi.fn();
    const unsubscribe = viewport.subscribe(listener);
    expect(viewport.isCompact()).toBe(false);
    matches = true;
    for (const notify of listeners) {
      notify();
    }
    expect(listener).toHaveBeenCalledTimes(1);
    expect(viewport.isCompact()).toBe(true);
    unsubscribe();
    expect(mediaQuery.removeEventListener).toHaveBeenCalledTimes(1);
  });

  it("falls back to the wide layout where media queries are unavailable", () => {
    const viewport = createBrowserHostViewport(undefined);
    expect(viewport.isCompact()).toBe(false);
    expect(() => viewport.subscribe(() => undefined)()).not.toThrow();
  });

  it("has an in-memory viewport a test can resize", () => {
    const viewport = createMemoryHostViewport(true);
    const listener = vi.fn();
    viewport.subscribe(listener);
    viewport.setCompact(false);
    expect(viewport.isCompact()).toBe(false);
    expect(listener).toHaveBeenCalledTimes(1);
    viewport.setCompact(false);
    expect(listener).toHaveBeenCalledTimes(1);
  });
});