window.addEventListener("DOMContentLoaded", () => {
  
  var themeToggleDarkIcon = document.getElementById('theme-toggle-dark-icon');
  var themeToggleLightIcon = document.getElementById('theme-toggle-light-icon');

  // Change the icons inside the button based on previous settings
  if (localStorage.getItem('color-theme') === 'dark' || (!('color-theme' in localStorage) && window.matchMedia('(prefers-color-scheme: dark)').matches)) {
      themeToggleLightIcon.classList.remove('hidden');
  } else {
      themeToggleDarkIcon.classList.remove('hidden');
  }

  var themeToggleBtn = document.getElementById('theme-toggle');

  themeToggleBtn.addEventListener('click', function() {

      // toggle icons inside button
      themeToggleDarkIcon.classList.toggle('hidden');
      themeToggleLightIcon.classList.toggle('hidden');

      // if set via local storage previously
      if (localStorage.getItem('color-theme')) {
          if (localStorage.getItem('color-theme') === 'light') {
              document.documentElement.classList.add('dark');
              localStorage.setItem('color-theme', 'dark');
          } else {
              document.documentElement.classList.remove('dark');
              localStorage.setItem('color-theme', 'light');
          }

      // if NOT set via local storage previously
      } else {
          if (document.documentElement.classList.contains('dark')) {
              document.documentElement.classList.remove('dark');
              localStorage.setItem('color-theme', 'light');
          } else {
              document.documentElement.classList.add('dark');
              localStorage.setItem('color-theme', 'dark');
          }
      }
      
  });
});
