Set up an options page with text fields for fb, twitter, & github

admin-settings.php

<?php
/**
 * Sets up theme-wide options
 *
 * @since _geekery_ 1.0
 */
use Carbon_Fields\Container;
use Carbon_Fields\Field;

Container::make('theme_options', 'Geekery settings')
  ->set_page_permissions('administrator')
  ->add_fields([
    Field::make("separator", "_geekery_social_handles_separator", "Social handles"),
    Field::make('text', 'crb_geekery_social_handle_facebook', 'Facebook'),
    Field::make('text', 'crb_geekery_social_handle_twitter', 'Twitter'),
    Field::make('text', 'crb_geekery_social_handle_github', 'Github'),
    Field::make("separator", "_geekery_homepage_jumbotron_image_separator", "Homepage Jumbotron"),
    Field::make('image', 'crb_geekery_homepage_jumbotron_image', 'Select image'),
  ]);

if (function_exists('carbon_get_theme_option')) {
  /*
   * Adds endpoint for the homepage jumbotron
   *
   * @since _geekery_ 1.0
   */
  function wp_api_get_home_jumbotron( WP_REST_Request $request ) {
    $_jumbotron = carbon_get_theme_option('crb_geekery_homepage_jumbotron_image');
    $jumbotron = wp_get_attachment_image_src($_jumbotron, 'full')[0];
    return ['jumbotron' => $jumbotron];
  }

  add_action('rest_api_init', function () {
    // full path will be /wp-json/geekery/v1/homepage/jumbotron
    register_rest_route( 'geekery/v1', '/homepage/jumbotron', [
      'methods' => 'GET',
      'callback' => 'wp_api_get_home_jumbotron',
    ]);
  });

  /*
   * Adds endpoint for social profile links
   *
   * @since _geekery_ 1.0
   */
  function wp_api_get_social_links( WP_REST_Request $request ) {
    //facebook
    $fbHandle = carbon_get_theme_option('crb_geekery_social_handle_facebook');
    //twitter
    $twHandle = carbon_get_theme_option('crb_geekery_social_handle_twitter');
    //github
    $ghHandle = carbon_get_theme_option('crb_geekery_social_handle_github');
    return [
      'facebook' => ($fbHandle ? $fbHandle : null),
      'twitter' => ($twHandle ? $twHandle : null),
      'github' => ($ghHandle ? $ghHandle : null)
    ];
  }

  add_action('rest_api_init', function () {
    // full path will be /wp-json/geekery/v1/social-links
    register_rest_route( 'geekery/v1', '/social-links', [
      'methods' => 'GET',
      'callback' => 'wp_api_get_social_links',
    ]);
  });
}