// Theme override: System (no attribute, the OS decides), Light or Dark.
//
// A classic script loaded from <head>, not a module, so the saved choice is on
// <html> before the first paint and a Dark user on a light OS never sees a
// flash. The CSP allows no inline script, hence a file of its own. Account
// (account.js) reads and writes the choice through window.terdutTheme.
(function () {
  var KEY = 'terdut.theme';
  var COLORS = { light: '#f5f6f8', dark: '#0f1115' };

  function get() {
    try {
      var v = localStorage.getItem(KEY);
      return v === 'light' || v === 'dark' ? v : 'system';
    } catch (e) {
      return 'system'; // storage unavailable
    }
  }

  // The browser chrome colour follows the choice too; the two <meta>s are
  // media-keyed to the OS, so a forced theme sets both to the same colour.
  function apply(theme) {
    var root = document.documentElement;
    if (theme === 'system') root.removeAttribute('data-theme');
    else root.setAttribute('data-theme', theme);
    var metas = document.querySelectorAll('meta[name="theme-color"]');
    for (var i = 0; i < metas.length; i++) {
      var scheme = /dark/.test(metas[i].media) ? 'dark' : 'light';
      metas[i].content = COLORS[theme === 'system' ? scheme : theme];
    }
  }

  function set(theme) {
    try {
      if (theme === 'system') localStorage.removeItem(KEY);
      else localStorage.setItem(KEY, theme);
    } catch (e) {
      /* storage unavailable: applies for this page view only */
    }
    apply(theme);
  }

  window.terdutTheme = { get: get, set: set };
  apply(get());
})();