import {
  normalizeColorSchemePreference,
  resolveColorScheme,
} from "../application/policies/color-scheme.js";

/**
 * Applies the persisted public preference before React paints.
 *
 * @param {import("../application/ports/storage-port.js").StoragePort} storage
 * @param {{
 *   documentElement?: HTMLElement,
 *   matchMedia?: (query: string) => MediaQueryList
 * }} [browser]
 */
export function initializeColorScheme(storage, browser = {}) {
  const documentElement = browser.documentElement ?? document.documentElement;
  const matchMedia =
    browser.matchMedia ??
    (typeof window.matchMedia === "function"
      ? window.matchMedia.bind(window)
      : () => /** @type {MediaQueryList} */ ({ matches: false }));
  const stored = storage.read("COLOR_SCHEME");
  const preference = normalizeColorSchemePreference(
    stored.ok ? stored.value : undefined,
  );
  const resolved = resolveColorScheme(
    preference,
    matchMedia("(prefers-color-scheme: dark)").matches,
  );

  documentElement.dataset.theme = resolved;
  documentElement.dataset.themePreference = preference;
  documentElement.style.colorScheme = resolved;

  return Object.freeze({ preference, resolved });
}