<?php

/**
 * @file
 * This is the Taxonomy Machine Name module.
 */

use Drupal\Component\Utility\Unicode;
use Drupal\Core\Entity\EntityInterface;
use Drupal\Core\Entity\EntityTypeInterface;
use Drupal\Core\Field\BaseFieldDefinition;
use Drupal\Core\Form\FormStateInterface;
use Drupal\Core\Render\BubbleableMetadata;
use Drupal\Core\Render\Element;
use Drupal\Core\Routing\RouteMatchInterface;
use Drupal\taxonomy\Entity\Term;
use Drupal\taxonomy\TermInterface;

/**
 * Implements hook_entity_base_field_info().
 */
function taxonomy_machine_name_entity_base_field_info(EntityTypeInterface $entity_type) {
  $fields = [];

  if ($entity_type->id() == 'taxonomy_term') {
    $fields['machine_name'] = BaseFieldDefinition::create('string')
      ->setLabel('Machine name')
      ->setDescription('Machine name for internal use.')
      ->setRevisionable(FALSE);
  }

  return $fields;
}

/**
 * Implements hook_form_FORM_ID_alter().
 */
function taxonomy_machine_name_form_taxonomy_overview_terms_alter(&$form, FormStateInterface $form_state, $form_id) {
  if (isset($form['terms']['#header'])) {
    array_splice($form['terms']['#header'], 1, 0, [t('Machine name')]);
  }

  $position = FALSE;

  foreach (Element::children($form['terms']) as $key) {
    /** @var \Drupal\taxonomy\Entity\Term $term */
    $term = $form['terms'][$key]['#term'];
    if (!empty($term_machine_name = $term->get('machine_name')->first())) {
      $machine_name = $term_machine_name->getValue()['value'];
    }
    else {
      $machine_name = '';
    }

    // Look for term position to place machine name just after.
    if ($position === FALSE) {
      $position = array_search('term', array_keys($form['terms'][$key]));

      if ($position === FALSE) {
        $position = 0;
      }
    }

    $column = [
      '#type' => 'link',
      '#title' => $machine_name,
      '#url' => $form['terms'][$key]['term']['#url'],
    ];

    array_splice($form['terms'][$key], $position + 1, 0, ['machine_name' => $column]);
  }
}

/**
 * Implements hook_form_FORM_ID_alter().
 */
function taxonomy_machine_name_form_taxonomy_term_form_alter(&$form, FormStateInterface $form_state, $form_id) {
  // Only if 'name' field is enable in the current 'form display'.
  if (isset($form['name'])) {
    $default_value = '';

    /** @var \Drupal\taxonomy\Entity\Term $term */
    $term = $form_state->getFormObject()->getEntity();
    if (
      $term->hasField('machine_name')
      && !$term->get('machine_name')->isEmpty()
    ) {
      if (!empty($term->get('machine_name')->first()->getValue()['value'])) {
        $default_value = $term->get('machine_name')->first()->getValue()['value'];
      }
      elseif (isset($term->get('name')->first()->getValue()['value'])) {
        $default_value = taxonomy_machine_name_clean_name($term->get('name')->first()->getValue()['value']);
      }
    }

    $form['machine_name'] = [
      '#type' => 'machine_name',
      '#default_value' => $default_value,
      '#maxlength' => 255,
      '#machine_name' => [
        'exists' => 'taxonomy_term_machine_name_load',
        'source' => ['name', 'widget', 0, 'value'],
      ],
      '#weight' => $form['name']['#weight'] + 0.01,
    ];

    $form['#validate'][] = 'taxonomy_machine_name_form_validate';
  }
}

/**
 * Implements hook_form_validate().
 */
function taxonomy_machine_name_form_validate($form, FormStateInterface $form_state) {
  // During the deletion there is no 'machine_name' key.
  if ($form_state->hasValue('machine_name')) {
    // Do not allow machine names to conflict with taxonomy path arguments.
    $machine_name = $form_state->getValue('machine_name');
    $disallowed = ['add', 'list', 'delete', 'update'];

    if (in_array($machine_name, $disallowed)) {
      $form_state->setError(
        $form['machine_name'],
        t('The machine-readable name cannot be "add", "update", "delete" or "list".')
      );
    }
  }
}

/**
 * Try to map a string to an existing term, as for glossary use.
 *
 * Provides a case-insensitive and trimmed mapping, to maximize the
 * likelihood of a successful match.
 *
 * @param string $machine_name
 *   Name of the term to search for.
 * @param string $vocabulary
 *   Vocabulary machine name to limit the search. Defaults to NULL.
 * @param \Drupal\Core\Form\FormStateInterface $form_state
 *   Form state.
 *
 * @return \Drupal\taxonomy\TermInterface|null
 *   Taxonomy term object or NULL.
 */
function taxonomy_term_machine_name_load($machine_name, $vocabulary, FormStateInterface $form_state = NULL) {
  // Support for machine_name form callback.
  if (NULL !== $form_state) {
    $buildInfo = $form_state->getBuildInfo();
    /** @var \Drupal\taxonomy\TermForm $callbackObject */
    $callbackObject = $buildInfo['callback_object'];
    /** @var \Drupal\taxonomy\Entity\Term $term */
    $term = $callbackObject->getEntity();
    $vocabulary = $term->bundle();
  }

  $conditions = [
    'machine_name' => $machine_name,
    'vid' => $vocabulary,
  ];

  if ($terms = \Drupal::entityTypeManager()
    ->getStorage('taxonomy_term')
    ->loadByProperties($conditions)
  ) {
    if (isset($term) && key($terms) == $term->id()) {
      return NULL;
    }

    return reset($terms);
  }

  return NULL;
}

/**
 * Implements hook_ENTITY_TYPE_presave().
 */
function taxonomy_machine_name_taxonomy_term_presave(EntityInterface $term) {
  // Set default value based on current name term.
  /** @var \Drupal\taxonomy\Entity\Term $term */
  if ($term->get('machine_name')->isEmpty()) {
    $machine_name = $term->get('name')->first()->getValue()['value'];
  }
  else {
    // Clean by security.
    $machine_name = $term->get('machine_name')->first()->getValue()['value'];
  }

  $machine_name = taxonomy_machine_name_clean_name($machine_name);

  // If the alias already exists, generate a new,
  // hopefully unique, variant.
  taxonomy_machine_name_uniquify($machine_name, $term);

  $term->set('machine_name', $machine_name);
}

/**
 * Clean name to generate machine name.
 *
 * @param string $name
 *   Name to clean.
 * @param bool $force
 *   Force new machine name.
 *
 * @return string
 *   Cleaned name.
 */
function taxonomy_machine_name_clean_name($name, $force = FALSE) {
  if (!preg_match('/^[a-z0-9\_]+$/', $name) || $force) {
    $unknown_character = '_';
    // Transliterate and sanitize the destination filename.
    $langcode = \Drupal::languageManager()->getCurrentLanguage()->getId();
    $machine_name = \Drupal::transliteration()->transliterate($name, $langcode, $unknown_character);
    $machine_name = trim(mb_strtolower($machine_name));
    $machine_name = trim(preg_replace('/[^a-z0-9\_]+/', $unknown_character, $machine_name), $unknown_character);
  }
  else {
    // Nothing to do.
    $machine_name = $name;
  }

  \Drupal::moduleHandler()->alter('taxonomy_machine_name_clean_name', $machine_name, $name, $force);

  return $machine_name;
}

/**
 * Check and alter machine name to generate a unique value.
 *
 * @param string $machine_name
 *   Machine name to uniquify.
 * @param \Drupal\taxonomy\Entity\Term $term
 *   Taxonomy term of reference.
 */
function taxonomy_machine_name_uniquify(&$machine_name, Term $term) {
  /** @var \Drupal\taxonomy\Entity\Term $existing */
  $existing = taxonomy_term_machine_name_load($machine_name, $term->bundle());
  if (!$existing || $existing->id() == $term->id()) {
    return;
  }

  // If the machine name already exists, generate a new, variant.
  $original_machine_name = $machine_name;

  $i = 0;
  do {
    // Append an incrementing numeric suffix until we find a unique value.
    $unique_suffix = '_' . $i;
    $machine_name = Unicode::truncate(
        $original_machine_name,
        255 - mb_strlen($unique_suffix)
      ) . $unique_suffix;
    $i++;
  } while (taxonomy_term_machine_name_load($machine_name, $term->bundle()));
}

/**
 * Update term with machine name.
 *
 * @param \Drupal\taxonomy\TermInterface $term
 *   Taxonomy term storage.
 *
 * @return \Drupal\taxonomy\TermInterface
 *   The taxonomy term.
 */
function taxonomy_machine_name_update_term(TermInterface $term) {
  if (empty($term->get('machine_name')->first()) && !empty($term->get('name')->first())) {
    $name = $term->get('name')->first()->getValue()['value'];
    $term->machine_name = taxonomy_machine_name_clean_name($name);
    $term->save();
  }
  return $term;
}

/**
 * Implements hook_token_info_alter().
 */
function taxonomy_machine_name_token_info_alter(&$info) {
  $info['tokens']['term']['machine_name'] = [
    'name' => t('Machine name'),
    'description' => t('The machine name of the taxonomy term.'),
  ];
}

/**
 * Implements hook_tokens().
 */
function taxonomy_machine_name_tokens($type, $tokens, array $data, array $options, BubbleableMetadata $bubbleable_metadata) {
  $replacements = [];

  if ($type == 'term' && !empty($data['term'])) {
    $term = $data['term'];

    foreach ($tokens as $name => $original) {
      switch ($name) {
        case 'machine_name':
          $replacements[$original] = $term->machine_name->value;
          break;
      }
    }
  }

  return $replacements;
}

/**
 * Implements hook_help().
 */
function taxonomy_machine_name_help($route_name, RouteMatchInterface $route_match) {
  if ($route_name === 'help.page.taxonomy_machine_name') {
    $readme_file = file_exists(__DIR__ . '/README.md') ? __DIR__ . '/README.md' : __DIR__ . '/README.txt';
    if (!file_exists($readme_file)) {
      return NULL;
    }
    $text = file_get_contents($readme_file);
    if (!\Drupal::moduleHandler()->moduleExists('markdown')) {
      return '<pre>' . $text . '</pre>';
    }
    else {
      // Use the Markdown filter to render the README.
      $filter_manager = \Drupal::service('plugin.manager.filter');
      $settings = \Drupal::configFactory()
        ->get('markdown.settings')
        ->getRawData();
      $config = ['settings' => $settings];
      $filter = $filter_manager->createInstance('markdown', $config);
      return $filter->process($text, 'en');
    }
  }
  return NULL;
}