/**
 * Cookie persistence round-trip specs — the non-React persistence surface
 * (`persistPresetOverrides` / `loadPresetOverrides` / `getCookieWatchList`)
 * that theme devtools and SSR hosts call directly. Locks down: overrides
 * survive a write→read round-trip through document.cookie, oversized
 * payloads chunk across `mp.ov.N` cookies and reassemble, stale chunks are
 * cleaned up, and the SSR path reads from a raw cookie map without touching
 * the document.
 */

import { beforeEach, describe, expect, it } from "vitest";
import type { Knobs } from "./knobs";
import {
  cookieOverridesPrefix,
  cookiePreset,
  getCookieWatchList,
  loadPresetOverrides,
  persistPresetOverrides,
} from "./cookies";

function clearThemeCookies() {
  for (const key of getCookieWatchList()) {
    document.cookie = `${key}=; path=/; expires=Thu, 01 Jan 1970 00:00:00 GMT`;
  }
}

beforeEach(() => {
  clearThemeCookies();
});

describe("getCookieWatchList", () => {
  it("watches the preset cookie plus every override chunk slot", () => {
    const list = getCookieWatchList();
    expect(list).toContain(cookiePreset);
    expect(list).toContain(`${cookieOverridesPrefix}.0`);
    expect(list).toContain(`${cookieOverridesPrefix}.9`);
    // preset + 10 chunk slots
    expect(list).toHaveLength(11);
  });
});

describe("persistPresetOverrides / loadPresetOverrides", () => {
  it("round-trips small overrides through document cookies", () => {
    persistPresetOverrides({ borderRadius: "large", fillStyle: "filled" } as Partial<Knobs>);
    expect(loadPresetOverrides()).toEqual({ borderRadius: "large", fillStyle: "filled" });
  });

  it("returns an empty object when nothing is persisted", () => {
    expect(loadPresetOverrides()).toEqual({});
  });

  it("overwrites previous overrides instead of merging them", () => {
    persistPresetOverrides({ borderRadius: "large" } as Partial<Knobs>);
    persistPresetOverrides({ elevation: "small" } as Partial<Knobs>);
    expect(loadPresetOverrides()).toEqual({ elevation: "small" });
  });

  it("chunks oversized overrides across multiple cookies and reassembles them", () => {
    const bigValue = "x".repeat(8000);
    persistPresetOverrides({ animation: bigValue } as unknown as Partial<Knobs>);
    // The serialized JSON exceeds the 3.5 KB split threshold → several chunks.
    expect(document.cookie).toContain(`${cookieOverridesPrefix}.0=`);
    expect(document.cookie).toContain(`${cookieOverridesPrefix}.1=`);
    expect(loadPresetOverrides()).toEqual({ animation: bigValue });
  });

  it("cleans up stale chunk cookies when the payload shrinks", () => {
    const bigValue = "y".repeat(8000);
    persistPresetOverrides({ animation: bigValue } as unknown as Partial<Knobs>);
    persistPresetOverrides({ borderRadius: "small" } as Partial<Knobs>);
    expect(loadPresetOverrides()).toEqual({ borderRadius: "small" });
    expect(document.cookie).not.toContain(`${cookieOverridesPrefix}.1=`);
  });

  it("reads from a raw cookie map (SSR) without touching the document", () => {
    const raw = {
      [`${cookieOverridesPrefix}.0`]: JSON.stringify({ space: "large" }),
    };
    expect(loadPresetOverrides(raw)).toEqual({ space: "large" });
  });

  it("treats corrupted cookie JSON as no overrides", () => {
    const raw = { [`${cookieOverridesPrefix}.0`]: "{broken" };
    expect(loadPresetOverrides(raw)).toEqual({});
  });
});