modeling-app/src/lib/theme.ts

export enum Themes {
  Light = 'light',
  Dark = 'dark',
  System = 'system',
}

// Get the theme from the system settings manually
export function getSystemTheme(): Exclude<Themes, 'system'> {
  return typeof window !== 'undefined' && 'matchMedia' in window
    ? window.matchMedia('(prefers-color-scheme: dark)').matches
      ? Themes.Dark
      : Themes.Light
    : Themes.Light
}

// Set the theme class on the body element
export function setThemeClass(theme: Themes) {
  if (theme === Themes.Dark) {
    document.body.classList.add('dark')
  } else {
    document.body.classList.remove('dark')
  }
}