<?php

namespace Drupal\dds_sendgrid_template_list\Element;

use Drupal\Core\Form\FormStateInterface;
use Drupal\Core\Render\Element\Select;

/**
 * Provides a form element for a drop-down menu or scrolling selection box.
 *
 * Properties:
 * - #options: An associative array, where the keys are the values for each
 *   option, and the values are the option labels to be shown in the drop-down
 *   list. If a value is an array, it will be rendered similarly, but as an
 *   optgroup. The key of the sub-array will be used as the label for the
 *   optgroup. Nesting optgroups is not allowed.
 *   The SendGrid templates will automatically get merged into the options so
 *   that you can add custom values alongside the templates.
 * - #empty_option: (optional) The label to show for the first default option.
 *   By default, the label is automatically set to "- Select -" for a required
 *   field and "- None -" for an optional field.
 * - #empty_value: (optional) The value for the first default option, which is
 *   used to determine whether the user submitted a value or not.
 *   - If #required is TRUE, this defaults to '' (an empty string).
 *   - If #required is not TRUE and this value isn't set, then no extra option
 *     is added to the select control, leaving the control in a slightly
 *     illogical state, because there's no way for the user to select nothing,
 *     since all user agents automatically preselect the first available
 *     option. But people are used to this being the behavior of select
 *     controls.
 *     @todo Address the above issue in Drupal 8.
 *   - If #required is not TRUE and this value is set (most commonly to an
 *     empty string), then an extra option (see #empty_option above)
 *     representing a "non-selection" is added with this as its value.
 * - #multiple: (optional) Indicates whether one or more options can be
 *   selected. Defaults to FALSE.
 * - #default_value: Must be NULL or not set in case there is no value for the
 *   element yet, in which case a first default option is inserted by default.
 *   Whether this first option is a valid option depends on whether the field
 *   is #required or not.
 * - #required: (optional) Whether the user needs to select an option (TRUE)
 *   or not (FALSE). Defaults to FALSE.
 * - #size: The size of the input element in characters.
 *
 * Usage example:
 * @code
 * $form['example_select'] = [
 *   '#type' => 'sendgrid_template_select',
 *   '#title' => $this->t('Select element'),
 *   '#options' => [
 *     '1' => $this->t('One'),
 *     '2' => [
 *       '2.1' => $this->t('Two point one'),
 *       '2.2' => $this->t('Two point two'),
 *     ],
 *     '3' => $this->t('Three'),
 *   ],
 * ];
 * @endcode
 *
 * @FormElement("sendgrid_template_select")
 */
class SendGridSelect extends Select {

  /**
   * {@inheritdoc}
   */
  public static function processSelect(&$element, FormStateInterface $form_state, &$complete_form) {
    $element = parent::processSelect($element, $form_state, $complete_form);

    /** @var \Drupal\dds_sendgrid_template_list\Controller\SendGridTemplateService $template_service */
    $template_service = \Drupal::service('dds_sendgrid.templates');
    $templates = $template_service->getTemplates();

    $formatted_templates = [];
    if (!empty($templates)) {
      foreach ($templates as $id => $template) {
        $formatted_templates[ucfirst($template['generation'])][$id] = $template['name'];
      }
    }

    // Sort the templates by name.
    _asort_recursive($formatted_templates);
    ksort($formatted_templates);

    // Add the SendGrid Templates into the options.
    $element['#options'] += $formatted_templates;

    return $element;
  }
}