ignis/shims/electron/remote/theme.js

// Shim for remote.nativeTheme
// Obsidian uses: shouldUseDarkColors, on('updated', cb)

const listeners = [];

const darkQuery = typeof window !== 'undefined'
  ? window.matchMedia('(prefers-color-scheme: dark)')
  : null;

if (darkQuery?.addEventListener) {
  darkQuery.addEventListener('change', () => {
    for (const fn of listeners) {
      fn();
    }
  });
}

export const themeShim = {
  get shouldUseDarkColors() {
    return darkQuery ? darkQuery.matches : true;
  },

  get themeSource() {
    return 'system';
  },

  set themeSource(val) {
    // No-op in browser; theme is controlled by OS
  },

  on(event, callback) {
    if (event === 'updated') {
      listeners.push(callback);
    }
    return themeShim;
  },

  once(event, callback) {
    if (event === 'updated') {
      const wrapped = () => {
        const idx = listeners.indexOf(wrapped);
        if (idx >= 0) listeners.splice(idx, 1);
        callback();
      };
      listeners.push(wrapped);
    }
    return themeShim;
  },

  removeListener(event, callback) {
    const idx = listeners.indexOf(callback);
    if (idx >= 0) listeners.splice(idx, 1);
    return themeShim;
  },

  removeAllListeners() {
    listeners.length = 0;
    return themeShim;
  },
};