export const DESKTOP_RECENT_ROUTES_KEY = "ctms_desktop_recent_routes";
export const DESKTOP_FAVORITE_ROUTES_KEY = "ctms_desktop_favorite_routes";
export const DESKTOP_THEME_KEY = "ctms_desktop_theme";
export const DESKTOP_THEME_CHANGED_EVENT = "ctms:desktop-theme-changed";

export type DesktopThemePreference = "light" | "dark";

export interface DesktopRoutePreference {
  path: string;
  title: string;
  group?: string;
  updatedAt: string;
}

const MAX_RECENT_ROUTES = 8;
const MAX_FAVORITE_ROUTES = 12;
const DEFAULT_DESKTOP_THEME: DesktopThemePreference = "light";
const DESKTOP_THEME_ATTRIBUTE = "data-ctms-theme";

const isStorageAvailable = () => typeof window !== "undefined" && typeof window.localStorage !== "undefined";

const sanitizeRoutePreference = (value: Partial<DesktopRoutePreference> | null | undefined): DesktopRoutePreference | null => {
  const path = typeof value?.path === "string" ? value.path.trim() : "";
  const title = typeof value?.title === "string" ? value.title.trim() : "";
  if (!path.startsWith("/") || !title) return null;
  return {
    path,
    title: title.slice(0, 80),
    group: typeof value?.group === "string" ? value.group.slice(0, 40) : undefined,
    updatedAt: typeof value?.updatedAt === "string" ? value.updatedAt : new Date().toISOString(),
  };
};

const readRoutePreferences = (key: string): DesktopRoutePreference[] => {
  if (!isStorageAvailable()) return [];
  try {
    const raw = window.localStorage.getItem(key);
    if (!raw) return [];
    const parsed = JSON.parse(raw);
    if (!Array.isArray(parsed)) return [];
    return parsed
      .map((item) => sanitizeRoutePreference(item))
      .filter(Boolean) as DesktopRoutePreference[];
  } catch {
    return [];
  }
};

const writeRoutePreferences = (key: string, routes: DesktopRoutePreference[]) => {
  if (!isStorageAvailable()) return;
  window.localStorage.setItem(key, JSON.stringify(routes));
};

const sanitizeDesktopThemePreference = (value: unknown): DesktopThemePreference =>
  value === "dark" ? "dark" : DEFAULT_DESKTOP_THEME;

export const readDesktopThemePreference = (): DesktopThemePreference => {
  if (!isStorageAvailable()) return DEFAULT_DESKTOP_THEME;
  return sanitizeDesktopThemePreference(window.localStorage.getItem(DESKTOP_THEME_KEY));
};

export const applyDesktopThemePreference = (theme: DesktopThemePreference = readDesktopThemePreference()): DesktopThemePreference => {
  const nextTheme = sanitizeDesktopThemePreference(theme);
  if (typeof document !== "undefined") {
    document.documentElement.setAttribute(DESKTOP_THEME_ATTRIBUTE, nextTheme);
    document.documentElement.style.colorScheme = nextTheme;
  }
  return nextTheme;
};

export const setDesktopThemePreference = (theme: DesktopThemePreference): DesktopThemePreference => {
  const nextTheme = sanitizeDesktopThemePreference(theme);
  if (isStorageAvailable()) {
    window.localStorage.setItem(DESKTOP_THEME_KEY, nextTheme);
  }
  applyDesktopThemePreference(nextTheme);
  if (typeof window !== "undefined") {
    window.dispatchEvent(new CustomEvent(DESKTOP_THEME_CHANGED_EVENT, { detail: nextTheme }));
  }
  return nextTheme;
};

export const readDesktopRecentRoutes = (): DesktopRoutePreference[] => readRoutePreferences(DESKTOP_RECENT_ROUTES_KEY);

export const readDesktopFavoriteRoutes = (): DesktopRoutePreference[] => readRoutePreferences(DESKTOP_FAVORITE_ROUTES_KEY);

export const recordDesktopRecentRoute = (route: Pick<DesktopRoutePreference, "path" | "title" | "group">): DesktopRoutePreference[] => {
  const item = sanitizeRoutePreference({ ...route, updatedAt: new Date().toISOString() });
  if (!item) return readDesktopRecentRoutes();
  const next = [
    item,
    ...readDesktopRecentRoutes().filter((existing) => existing.path !== item.path),
  ].slice(0, MAX_RECENT_ROUTES);
  writeRoutePreferences(DESKTOP_RECENT_ROUTES_KEY, next);
  return next;
};

export const isDesktopFavoriteRoute = (path: string): boolean =>
  readDesktopFavoriteRoutes().some((item) => item.path === path);

export const toggleDesktopFavoriteRoute = (
  route: Pick<DesktopRoutePreference, "path" | "title" | "group">,
): DesktopRoutePreference[] => {
  const item = sanitizeRoutePreference({ ...route, updatedAt: new Date().toISOString() });
  if (!item) return readDesktopFavoriteRoutes();
  const current = readDesktopFavoriteRoutes();
  const exists = current.some((existing) => existing.path === item.path);
  const next = exists
    ? current.filter((existing) => existing.path !== item.path)
    : [item, ...current].slice(0, MAX_FAVORITE_ROUTES);
  writeRoutePreferences(DESKTOP_FAVORITE_ROUTES_KEY, next);
  return next;
};