<?php
namespace Drupal\dds_devel\Form;

use Drupal\Component\Plugin\Exception\InvalidPluginDefinitionException;
use Drupal\Component\Plugin\Exception\PluginNotFoundException;
use Drupal\Core\Config\Entity\ConfigEntityType;
use Drupal\Core\Field\FieldItemList;
use Drupal\Core\Form\FormBase;
use Drupal\Core\Form\FormStateInterface;
use Drupal\Core\Url;
use Drupal\entity_reference_revisions\Plugin\Field\FieldType\EntityReferenceRevisionsItem;
use Drupal\node\Entity\Node;
use Drupal\paragraphs\Entity\Paragraph;
use InvalidArgumentException;

class ParagraphUsageForm extends FormBase {

  protected $paragraphStorage;

  /**
   * Returns a unique string identifying the form.
   *
   * The returned ID should be a unique string that can be a valid PHP function
   * name, since it's used in hook implementation names such as
   * hook_form_FORM_ID_alter().
   *
   * @return string
   *   The unique string identifying the form.
   */
  public function getFormId() {
    return 'dds_devel_paragraph_usage';
  }

  /**
   * Form constructor.
   *
   * @param array $form
   *   An associative array containing the structure of the form.
   * @param \Drupal\Core\Form\FormStateInterface $form_state
   *   The current state of the form.
   *
   * @return array
   *   The form structure.
   */
  public function buildForm(array $form, FormStateInterface $form_state) {
    $form = [];
    $type = $form_state->getValue('type');

    $paragraph_types = \Drupal::service('entity_type.bundle.info')->getBundleInfo('paragraph');
    $options = [];
    foreach ($paragraph_types as $paragraph_type_id => $paragraph_type) {
      $options[$paragraph_type_id] = $paragraph_type['label'];
    }
    $form['type'] = [
      '#type' => 'select',
      '#options' => $options,
      '#default_value' => $type
    ];
    $form['submit'] = [
      '#type' => 'submit',
      '#value' => $this->t('Find usage')
    ];

    if (!empty($type)) {
      $this->paragraphStorage = \Drupal::entityTypeManager()->getStorage('paragraph');

      $ids = \Drupal::entityQuery('paragraph')
        ->condition('type', $type)
        ->execute();

      try {
        $entities = \Drupal::entityTypeManager()->getStorage('paragraph')
          ->loadMultiple($ids);
      } catch (InvalidPluginDefinitionException $e) {
        // TODO: Error logging
      } catch (PluginNotFoundException $e) {
        // TODO: Error logging
      }

      $nodes = [];
      /** @var Paragraph $paragraph */
      foreach ($entities as $id => $paragraph) {
        $node = $this->getNodeParent($paragraph);
        if (!is_null($node) && empty($nodes[$node->id()])) {
          $nodes[$node->id()] = $node;
        }
      }
      $form['space'] = [ '#markup' => '<br/><br/>'];

      $form['list'] = array(
        '#type' => 'table',
        '#header' => array(
          $this->t('Title'),
          $this->t('Link'),
          $this->t('Count'),
          $this->t('Published')
        ),
        '#empty' => $this->t('No usage was found.'),
        // TableSelect: Injects a first column containing the selection widget into
        // each table row.
        // Note that you also need to set #tableselect on each form submit button
        // that relies on non-empty selection values (see below).
        '#tableselect' => FALSE,
      );
      /** @var Node $node */
      foreach ($nodes as $nid => $node) {
        $count = $this->getNodeCount($node, $type);
        if ($count > 0) {
          $form['list'][$node->id()]['title'] = [
            '#plain_text' => $node->label(),
          ];

          $alias = \Drupal::service('path_alias.manager')
            ->getAliasByPath('/node/' . $node->id());
          $url = $this->TextToUrl($alias);
          if ($url !== FALSE) {
            $form['list'][$node->id()]['link'] = [
              '#type' => 'link',
              '#title' => $alias,
              '#url' => $url,
            ];
          }


          $form['list'][$node->id()]['count'] = [
            '#plain_text' => $count
          ];

          $form['list'][$node->id()]['published'] = [
            '#plain_text' => $node->isPublished() ? $this->t('Published') : $this->t('Unpublished')
          ];
        }
      }
    } else {
      $form['list'] = [
        '#type' => 'hidden'
      ];
    }

    return $form;
  }

  /**
   * Form submission handler.
   *
   * @param array $form
   *   An associative array containing the structure of the form.
   * @param \Drupal\Core\Form\FormStateInterface $form_state
   *   The current state of the form.
   */
  public function submitForm(array &$form, FormStateInterface $form_state) {
    $form_state->setRebuild();
  }

  /**
   * @param \Drupal\paragraphs\Entity\Paragraph $paragraph
   *
   * @return \Drupal\Core\Entity\EntityInterface|null
   */
  protected function getNodeParent(Paragraph $paragraph) {
    $parent = $paragraph->getParentEntity();
    while (!is_null($parent) && $parent->getEntityTypeId() !== 'node') {
      if (method_exists($parent, 'getParentEntity')) {
        $parent = $parent->getParentEntity();
      } else {
        \Drupal::messenger()->addWarning($this->t('Paragraph usage found on entity of type %entity_type.', ['%entity_type' => $parent->getEntityType()->getLabel()]), FALSE);
        $parent = null;
      }
    }
    return $parent;
  }

  /**
   * @param \Drupal\node\Entity\Node $node
   * @param string $type
   *
   * @return int
   */
  protected function getNodeCount(Node $node, $type) {
    $count = 0;
    /** @var FieldItemList $field */
    foreach ($node->getFields() as $field) {
      if ($field->getFieldDefinition()->getType() == 'entity_reference_revisions') {
        /** @var \Drupal\entity_reference_revisions\EntityReferenceRevisionsFieldItemList $paragraphs */
        $paragraphs = $field;
        if ($paragraphs->getSetting('target_type') == 'paragraph') {
          /** @var EntityReferenceRevisionsItem $item */
          foreach ($paragraphs as $item) {
            /** @var Paragraph $paragraph */
            $paragraph = null;
            if (!empty($item->getValue()['entity'])) {
              $paragraph = $item->getValue()['entity'];
            } elseif (!empty($item->getValue()['target_revision_id'])) {
              $paragraph = $this->paragraphStorage->loadRevision($item->getValue()['target_revision_id']);
            }
            if (!is_null($paragraph)) {
              if ($paragraph->bundle() == $type) {
                $count++;
              }
              else {
                $count += $this->getParagraphCount($paragraph, $type);
              }
            }
          }
        }
      }
    }
    return $count;
  }

  /**
   * @param \Drupal\paragraphs\Entity\Paragraph $paragraph
   * @param string $type
   *
   * @return int
   */
  protected function getParagraphCount(Paragraph $paragraph, $type) {
    $count = 0;
    /** @var FieldItemList $field */
    foreach ($paragraph->getFields() as $field) {
      if ($field->getFieldDefinition()->getType() == 'entity_reference_revisions') {
        /** @var \Drupal\entity_reference_revisions\EntityReferenceRevisionsFieldItemList $paragraphs */
        $paragraphs = $field;
        if ($paragraphs->getSetting('target_type') == 'paragraph') {
          /** @var EntityReferenceRevisionsItem $item */
          foreach ($paragraphs as $item) {
            /** @var Paragraph $new_paragraph */
            $new_paragraph = null;
            if (!empty($item->getValue()['entity'])) {
              $new_paragraph = $item->getValue()['entity'];
            } elseif (!empty($item->getValue()['target_revision_id'])) {
              $new_paragraph = $this->paragraphStorage->loadRevision($item->getValue()['target_revision_id']);
            }
            if (!is_null($new_paragraph)) {
              if ($new_paragraph->bundle() == $type) {
                $count++;
              } else {
                $count += $this->getParagraphCount($new_paragraph, $type);
              }
            }
          }
        }
      }
    }
    return $count;
  }

  /**
   * @param string $text
   * @return \Drupal\Core\Url|bool
   */
  function TextToUrl($text) {
    if (empty($text)) {
      $text = '#';
    }
    if (strpos(strtolower($text), 'http:') === 0 || strpos(strtolower($text), 'https:') === 0) {
      try {
        $result = Url::fromUri($text);
      } catch(InvalidArgumentException $e) {
        $result = FALSE;
      }
    }
    else {
      try {
        $result = Url::fromUserInput($text);
      } catch (InvalidArgumentException $e) {
        $result = FALSE;
      }
    }
    return $result;
  }

}