oliveskspaces/theme-settings.php

<?php

/**
 * @file
 * Functions to support Oliveskspaces theme settings.
 */

use Drupal\Core\Form\FormStateInterface;

/**
 * Implements hook_form_FORM_ID_alter() for system_theme_settings.
 */
function oliveskspaces_form_system_theme_settings_alter(&$form, FormStateInterface $form_state) {
  $form['#validate'][] = 'oliveskspaces_theme_settings_validate';
  $form['#attached']['library'][] = 'oliveskspaces/color-picker';

  $color_config = [
    'colors' => [
      'base_primary_color' => 'Primary base color',
    ],
    'schemes' => [
      'default' => [
        'label' => 'Blue Lagoon',
        'colors' => [
          'base_primary_color' => '#1b9ae4',
        ],
      ],
      'firehouse' => [
        'label' => 'Firehouse',
        'colors' => [
          'base_primary_color' => '#a30f0f',
        ],
      ],
      'ice' => [
        'label' => 'Ice',
        'colors' => [
          'base_primary_color' => '#57919e',
        ],
      ],
      'plum' => [
        'label' => 'Plum',
        'colors' => [
          'base_primary_color' => '#7a4587',
        ],
      ],
      'slate' => [
        'label' => 'Slate',
        'colors' => [
          'base_primary_color' => '#47625b',
        ],
      ],
    ],
  ];

  $form['#attached']['drupalSettings']['oliveskspaces']['colorSchemes'] = $color_config['schemes'];

  $form['oliveskspaces_settings']['oliveskspaces_utilities'] = [
    '#type' => 'fieldset',
    '#title' => t('Oliveskspaces Utilities'),
  ];
  $form['oliveskspaces_settings']['oliveskspaces_utilities']['mobile_menu_all_widths'] = [
    '#type' => 'checkbox',
    '#title' => t('Enable mobile menu at all widths'),
    '#default_value' => theme_get_setting('mobile_menu_all_widths'),
    '#description' => t('Enables the mobile menu toggle at all widths.'),
  ];
  $form['oliveskspaces_settings']['oliveskspaces_utilities']['site_branding_bg_color'] = [
    '#type' => 'select',
    '#title' => t('Header site branding background color'),
    '#options' => [
      'default' => t('Primary Branding Color'),
      'gray' => t('Gray'),
      'white' => t('White'),
    ],
    '#default_value' => theme_get_setting('site_branding_bg_color'),
  ];
  $form['oliveskspaces_settings']['oliveskspaces_utilities']['oliveskspaces_color_scheme'] = [
    '#type' => 'fieldset',
    '#title' => t('Oliveskspaces Color Scheme Settings'),
  ];
  $form['oliveskspaces_settings']['oliveskspaces_utilities']['oliveskspaces_color_scheme']['description'] = [
    '#type' => 'html_tag',
    '#tag' => 'p',
    '#value' => t('These settings adjust the look and feel of the Oliveskspaces theme. Changing the color below will change the base hue, saturation, and lightness values the Oliveskspaces theme uses to determine its internal colors.'),
  ];
  $form['oliveskspaces_settings']['oliveskspaces_utilities']['oliveskspaces_color_scheme']['color_scheme'] = [
    '#type' => 'select',
    '#title' => t('Oliveskspaces Color Scheme'),
    '#empty_option' => t('Custom'),
    '#empty_value' => '',
    '#options' => [
      'default' => t('Blue Lagoon (Default)'),
      'firehouse' => t('Firehouse'),
      'ice' => t('Ice'),
      'plum' => t('Plum'),
      'slate' => t('Slate'),
    ],
    '#input' => FALSE,
    '#wrapper_attributes' => [
      'style' => 'display:none;',
    ],
  ];

  foreach ($color_config['colors'] as $key => $title) {
    $form['oliveskspaces_settings']['oliveskspaces_utilities']['oliveskspaces_color_scheme'][$key] = [
      '#type' => 'textfield',
      '#maxlength' => 7,
      '#size' => 10,
      '#title' => t($title),
      '#description' => t('Enter color in full hexadecimal format (#abc123).') . '<br/>' . t('Derivatives will be formed from this color.'),
      '#default_value' => theme_get_setting($key),
      '#attributes' => [
        'pattern' => '^#[a-fA-F0-9]{6}',
      ],
      '#wrapper_attributes' => [
        'data-drupal-selector' => 'oliveskspaces-color-picker',
      ],
    ];
  }
}

/**
 * Validation handler for the Oliveskspaces system_theme_settings form.
 */
function oliveskspaces_theme_settings_validate($form, FormStateInterface $form_state) {
  if (!preg_match('/^#[a-fA-F0-9]{6}$/', $form_state->getValue('base_primary_color'))) {
    $form_state->setErrorByName('base_primary_color', t('Colors must be 7-character string specifying a color hexadecimal format.'));
  }
}