olivesbooks/theme-settings.php

<?php

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

use Drupal\Core\Form\FormStateInterface;

/**
 * Implements hook_form_FORM_ID_alter() for system_theme_settings.
 */
function olivesbooks_form_system_theme_settings_alter(&$form, FormStateInterface $form_state) {
  $form['#validate'][] = 'olivesbooks_theme_settings_validate';
  $form['#attached']['library'][] = 'olivesbooks/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']['olivesbooks']['colorSchemes'] = $color_config['schemes'];

  $form['olivesbooks_settings']['olivesbooks_utilities'] = [
    '#type' => 'fieldset',
    '#title' => t('Olivesbooks Utilities'),
  ];
  $form['olivesbooks_settings']['olivesbooks_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['olivesbooks_settings']['olivesbooks_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['olivesbooks_settings']['olivesbooks_utilities']['olivesbooks_color_scheme'] = [
    '#type' => 'fieldset',
    '#title' => t('Olivesbooks Color Scheme Settings'),
  ];
  $form['olivesbooks_settings']['olivesbooks_utilities']['olivesbooks_color_scheme']['description'] = [
    '#type' => 'html_tag',
    '#tag' => 'p',
    '#value' => t('These settings adjust the look and feel of the Olivesbooks theme. Changing the color below will change the base hue, saturation, and lightness values the Olivesbooks theme uses to determine its internal colors.'),
  ];
  $form['olivesbooks_settings']['olivesbooks_utilities']['olivesbooks_color_scheme']['color_scheme'] = [
    '#type' => 'select',
    '#title' => t('Olivesbooks 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) {
    $form['olivesbooks_settings']['olivesbooks_utilities']['olivesbooks_color_scheme'][$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' => 'olivesbooks-color-picker',
      ],
    ];
  }
}

/**
 * Validation handler for the Olivesbooks system_theme_settings form.
 */
function olivesbooks_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.'));
  }
}