import type { Lang } from './types';

export interface Settings {
  lang: Lang;
  textScale: 100 | 125 | 150;
  highContrast: boolean;
  reduceMotion: boolean;
  showDemoPlaces: boolean;
}

export const defaultSettings = (lang: Lang): Settings => ({
  lang, textScale: 100, highContrast: false, reduceMotion: false, showDemoPlaces: true,
});

export function isSettings(v: unknown): v is Settings {
  if (typeof v !== 'object' || v === null) return false;
  const s = v as Record<string, unknown>;
  return (
    (s.lang === 'pl' || s.lang === 'en') && (s.textScale === 100 || s.textScale === 125 || s.textScale === 150) &&
    typeof s.highContrast === 'boolean' && typeof s.reduceMotion === 'boolean' && typeof s.showDemoPlaces === 'boolean'
  );
}

/** Applies display settings to the document root. */
export function applySettings(s: Settings) {
  const root = document.documentElement;
  root.lang = s.lang;
  root.style.fontSize = `${s.textScale}%`;
  root.dataset.contrast = s.highContrast ? 'high' : 'default';
  root.dataset.motion = s.reduceMotion ? 'reduce' : 'default';
}