yoast_seo.module

<?php
/**
 * @file
 * yoast_seo.module
 */


use Drupal\Core\Entity\Entity\EntityFormDisplay;
use Drupal\Core\Entity\EntityInterface;
use Drupal\Core\Field\BaseFieldDefinition;
use Drupal\Core\Form\FormStateInterface;
use Drupal\field\Entity\FieldConfig;
use Drupal\node\Entity\Node;
use Drupal\node\Entity\NodeType;
use Drupal\node\NodeTypeInterface;


/**
 * Implements hook_form_node_type_form_alter().
 */
function yoast_seo_form_node_type_form_alter(&$form, FormStateInterface $form_state, $form_id) {
  /** @var NodeTypeInterface $type */
  $type = $form_state->getFormObject()->getEntity();


  $field_manager = \Drupal::getContainer()->get('entity_field.manager');
  $field_config = $field_manager->getFieldDefinitions('node', $type->get('type'));
  $checkbox_disabled = TRUE;
  $description = t('The Yoast SEO plugin requires a Metatag field.');
  foreach ($field_config as $config) { /** @var BaseFieldDefinition $config */
    if ($config->getType() == 'metatag') {
      $checkbox_disabled = FALSE;
      $description = t('Enable the Yoast SEO plugin for this content type');
    }
  }

  // Add our settings as a separate tab
  $form['yoast_seo'] = [
    '#type' => 'details',
    '#title' => t('Yoast SEO settings'),
    '#group' => 'additional_settings',
    '#weight' => 20
  ];
  $form['yoast_seo']['yoast_enable'] = [
    '#type' => 'checkbox',
    '#title' => t('Enable'),
    '#description' => $description,
    '#default_value' => $type->getThirdPartySetting('yoast_seo', 'enabled', FALSE),
    '#disabled' => $checkbox_disabled
  ];

  // Save our settings onto the entity
  $form['#entity_builders'][] = 'yoast_seo_form_node_type_form_builder';
}

/**
 * Entity builder for the node type form with Yoast SEO options.
 *
 * @param $entity_type
 * @param \Drupal\node\NodeTypeInterface $type
 * @param $form
 * @param \Drupal\Core\Form\FormStateInterface $form_state
 */
function yoast_seo_form_node_type_form_builder($entity_type, NodeTypeInterface $type, &$form, FormStateInterface $form_state) {
  $type->setThirdPartySetting('yoast_seo', 'enabled', $form_state->getValue('yoast_enable', FALSE));

  // Look for an instance of the field
  /** @var FieldConfig $instance */
  $instance = \Drupal\field\Entity\FieldConfig::loadByName('node', $type->get('type'), 'field_node_yoast_seo');
  // Load the entity form display
  $display_id = sprintf('node.%s.default', $type->get('type'));
  /** @var EntityFormDisplay $form_display */
  $form_display = \Drupal\Core\Entity\Entity\EntityFormDisplay::load($display_id);

  if ($type->getThirdPartySetting('yoast_seo', 'enabled')) {
    // Load or create the field storage configuration
    $field = \Drupal\field\Entity\FieldStorageConfig::loadByName('node', 'field_node_yoast_seo');
    if (!$field) {
      $field = \Drupal\field\Entity\FieldStorageConfig::create([
        'type' => 'yoast_seo',
        'field_name' => 'field_node_yoast_seo',
        'weight' => 20,
        'cardinality' => 1,
        'entity_type' => 'node'
      ]);
      $field->save();
    }

    // Attach an instance to the content type
    if (!$instance) {
      $instance = \Drupal\field\Entity\FieldConfig::create([
        'entity_type' => 'node',
        'bundle' => $type->get('type'),
        'field_name' => 'field_node_yoast_seo',
        'label' => t('Yoast SEO')
      ]);
      $instance->save();
    }

    if (!$form_display->getComponent('field_node_yoast_seo')) {
      $form_display->setComponent('field_node_yoast_seo', [
        'type' => 'yoast_seo_default',
        'weight' => 20
      ]);
      $form_display->save();
    }
  }
  elseif ($instance) {
    // Remove the instance if the Yoast SEO support has been disabled
    $instance->delete();

    // Delete the component from the edit form
    if ($form_display->getComponent('field_node_yoast_seo')) {
      $form_display
        ->removeComponent('field_node_yoast_seo')
        ->save();
    }
  }
}

/**
 * Implements hook_form_FORM_ID_alter().
 */
function yoast_seo_form_field_config_edit_form_alter(&$form, \Drupal\Core\Form\FormStateInterface $form_state, $form_id) {
  /** @var FieldConfig $field_config */
  $field_config = $form_state->getFormObject()->getEntity();
  if ($field_config->getType() == 'yoast_seo') {
    drupal_set_message(t('You\'re not supposed to edit these settings, so I disabled them for you.'), 'warning');
    $form['label']['#disabled'] = TRUE;
    $form['description']['#disabled'] = TRUE;
    $form['required']['#disabled'] = TRUE;
    $form['default_value']['#access'] = FALSE;
    $form['actions']['#access'] = FALSE;
  }
}

/**
 * Implements hook_form_field_storage_config_edit_form_alter().
 */
function yoast_seo_form_field_storage_config_edit_form_alter(&$form, \Drupal\Core\Form\FormStateInterface $form_state) {
  if ($form_state->getFormObject()->getEntity()->getType() == 'yoast_seo') {
    // Disble the cardinality option on the field storage settings form
    $form['cardinality_container']['#prefix'] = t('Yoast SEO fields must be singular');
    $form['cardinality_container']['#disabled'] = TRUE;
    $form['cardinality_container']['cardinality']['#disabled'] = TRUE;
    $form['cardinality_container']['cardinality_number']['#disabled'] = TRUE;
    unset($form['cardinality_container']['cardinality_number']['#states']);
  }
}

/**
 * Implements hook_form_node_form_alter().
 */
function yoast_seo_form_node_form_alter(&$form, \Drupal\Core\Form\FormStateInterface $form_state, $form_id) {
  /** @var EntityInterface $node */
  $node = $form_state->getFormObject()->getEntity();
  /** @var NodeType $type */
  $type = NodeType::load($node->bundle());

  if ($type->getThirdPartySetting('yoast_seo', 'enabled')) {
    // Attach our custom Javascript, but we need the rendered ids for that
    $form['#after_build'][] = 'yoast_seo_node_form_after_build';
  }
}

/**
 * 'after_build' action of the node_form that will attach our custom Javascript
 *
 * @param $form
 * @param \Drupal\Core\Form\FormStateInterface $form_state
 * @return mixed
 */
function yoast_seo_node_form_after_build($form, FormStateInterface &$form_state) {
  /** @var Node $node */
  $node = $form_state->getFormObject()->getEntity();

  $yoast_service = \Drupal::getContainer()->get('yoast.config_service');
  $form['#attached']['drupalSettings']['yoast_seo'] = $yoast_service->getConfigration($form, $node);
  $form['#attached']['library'][] = 'yoast_seo/yoast_seo';
  $form['#attached']['library'][] = 'yoast_seo/init';

  return $form;
}