class DevelGenerateBase

abstract class DevelGenerateBase extends PluginBase implements DevelGenerateBaseInterface {
    
    /**
     * The plugin settings.
     *
     * @var array
     */
    protected $settings = [];
    
    /**
     * The random data generator.
     *
     * @var \Drupal\Component\Utility\Random
     */
    protected $random;
    
    /**
     * The entity type manager service.
     *
     * @var \Drupal\Core\Entity\EntityTypeManagerInterface
     */
    protected $entityTypeManager;
    
    /**
     * {@inheritdoc}
     */
    public function getSetting($key) {
        // Merge defaults if we have no value for the key.
        if (!array_key_exists($key, $this->settings)) {
            $this->settings = $this->getDefaultSettings();
        }
        return $this->settings[$key] ?? NULL;
    }
    
    /**
     * {@inheritdoc}
     */
    public function getDefaultSettings() {
        $definition = $this->getPluginDefinition();
        return $definition['settings'];
    }
    
    /**
     * {@inheritdoc}
     */
    public function getSettings() {
        return $this->settings;
    }
    
    /**
     * {@inheritdoc}
     */
    public function settingsForm(array $form, FormStateInterface $form_state) {
        return [];
    }
    
    /**
     * {@inheritdoc}
     */
    public function settingsFormValidate(array $form, FormStateInterface $form_state) {
        // Validation is optional.
    }
    
    /**
     * {@inheritdoc}
     */
    public function generate(array $values) {
        $this->generateElements($values);
        $this->setMessage('Generate process complete.');
    }
    
    /**
     * Business logic relating with each DevelGenerate plugin.
     *
     * @param array $values
     *   The input values from the settings form.
     */
    protected function generateElements(array $values) {
    }
    
    /**
     * Populate the fields on a given entity with sample values.
     *
     * @param \Drupal\Core\Entity\EntityInterface $entity
     *   The entity to be enriched with sample field values.
     *
     * @throws \Drupal\Component\Plugin\Exception\InvalidPluginDefinitionException
     * @throws \Drupal\Component\Plugin\Exception\PluginNotFoundException
     */
    public static function populateFields(EntityInterface $entity) {
        $properties = [
            'entity_type' => $entity->getEntityType()
                ->id(),
            'bundle' => $entity->bundle(),
        ];
        $field_config_storage = \Drupal::entityTypeManager()->getStorage('field_config');
        
        /** @var \Drupal\field\FieldConfigInterface[] $instances */
        $instances = $field_config_storage->loadByProperties($properties);
        // @todo not implemented for Drush9+. Possibly remove.
        if ($skips = @$_REQUEST['skip-fields']) {
            foreach (explode(',', $skips) as $skip) {
                unset($instances[$skip]);
            }
        }
        foreach ($instances as $instance) {
            $field_storage = $instance->getFieldStorageDefinition();
            $max = $cardinality = $field_storage->getCardinality();
            if ($cardinality == FieldStorageDefinitionInterface::CARDINALITY_UNLIMITED) {
                // Just an arbitrary number for 'unlimited'.
                $max = rand(1, 3);
            }
            $field_name = $field_storage->getName();
            $entity->{$field_name}
                ->generateSampleItems($max);
        }
    }
    
    /**
     * {@inheritdoc}
     */
    public function handleDrushParams($args) {
    }
    
    /**
     * Set a message for either drush or the web interface.
     *
     * @param string $msg
     *   The message to display.
     * @param string $type
     *   (optional) The message type, as defined in MessengerInterface. Defaults
     *   to MessengerInterface::TYPE_STATUS.
     */
    protected function setMessage($msg, $type = MessengerInterface::TYPE_STATUS) {
        if (function_exists('drush_log')) {
            $msg = strip_tags($msg);
            drush_log($msg);
        }
        else {
            \Drupal::messenger()->addMessage($msg, $type);
        }
    }
    
    /**
     * Check if a given param is a number.
     *
     * @param mixed $number
     *   The parameter to check.
     *
     * @return bool
     *   TRUE if the parameter is a number, FALSE otherwise.
     */
    public static function isNumber($number) {
        if ($number == NULL) {
            return FALSE;
        }
        if (!is_numeric($number)) {
            return FALSE;
        }
        return TRUE;
    }
    
    /**
     * Gets the entity type manager service.
     *
     * @return \Drupal\Core\Entity\EntityTypeManagerInterface
     *   The entity type manager service.
     */
    protected function getEntityTypeManager() {
        if (!$this->entityTypeManager) {
            $this->entityTypeManager = \Drupal::entityTypeManager();
        }
        return $this->entityTypeManager;
    }
    
    /**
     * Returns the random data generator.
     *
     * @return \Drupal\Component\Utility\Random
     *   The random data generator.
     */
    protected function getRandom() {
        if (!$this->random) {
            $this->random = new Random();
        }
        return $this->random;
    }
    
    /**
     * Generates a random sentence of specific length.
     *
     * Words are randomly selected with length from 2 up to the optional parameter
     * $max_word_length. The first word is capitalised. No ending period is added.
     *
     * @param int $sentence_length
     *   The total length of the sentence, including the word-separating spaces.
     * @param int $max_word_length
     *   (optional) Maximum length of each word. Defaults to 8.
     *
     * @return string
     *   A sentence of the required length.
     */
    protected function randomSentenceOfLength($sentence_length, $max_word_length = 8) {
        // Maximum word length cannot be longer than the sentence length.
        $max_word_length = min($sentence_length, $max_word_length);
        $words = [];
        $remainder = $sentence_length;
        do {
            if ($remainder <= $max_word_length) {
                // If near enough to the end then generate the exact length word to fit.
                $next_word = $remainder;
            }
            else {
                // Cannot fill the remaining space with one word, so choose a random
                // length, short enough for a following word of at least minimum length.
                $next_word = mt_rand(2, min($max_word_length, $remainder - 3));
            }
            $words[] = $this->getRandom()
                ->word($next_word);
            $remainder = $remainder - $next_word - 1;
        } while ($remainder > 0);
        $sentence = ucfirst(implode(' ', $words));
        return $sentence;
    }
    
    /**
     * Creates the language and translation section of the form.
     *
     * This is used by both Content and Term generation.
     *
     * @param string $items
     *   The name of the things that are being generated - 'nodes' or 'terms'.
     *
     * @return array
     *   The language details section of the form.
     */
    protected function getLanguageForm($items) {
        // We always need a language, even if the language module is not installed.
        $options = [];
        $languages = $this->languageManager
            ->getLanguages(LanguageInterface::STATE_CONFIGURABLE);
        foreach ($languages as $langcode => $language) {
            $options[$langcode] = $language->getName();
        }
        $language_module_exists = $this->moduleHandler
            ->moduleExists('language');
        $translation_module_exists = $this->moduleHandler
            ->moduleExists('content_translation');
        $form['language'] = [
            '#type' => 'details',
            '#title' => $this->t('Language'),
            '#open' => $language_module_exists,
        ];
        $form['language']['add_language'] = [
            '#type' => 'select',
            '#title' => $this->t('Select the primary language(s) for @items', [
                '@items' => $items,
            ]),
            '#multiple' => TRUE,
            '#description' => $language_module_exists ? '' : $this->t('Disabled - requires Language module'),
            '#options' => $options,
            '#default_value' => [
                $this->languageManager
                    ->getDefaultLanguage()
                    ->getId(),
            ],
            '#disabled' => !$language_module_exists,
        ];
        $form['language']['translate_language'] = [
            '#type' => 'select',
            '#title' => $this->t('Select the language(s) for translated @items', [
                '@items' => $items,
            ]),
            '#multiple' => TRUE,
            '#description' => $translation_module_exists ? $this->t('Translated @items will be created for each language selected.', [
                '@items' => $items,
            ]) : $this->t('Disabled - requires Content Translation module.'),
            '#options' => $options,
            '#disabled' => !$translation_module_exists,
        ];
        return $form;
    }
    
    /**
     * Return a language code.
     *
     * @param array $add_language
     *   Optional array of language codes from which to select one at random.
     *   If empty then return the site's default language.
     *
     * @return string
     *   The language code to use.
     */
    protected function getLangcode(array $add_language) {
        if (empty($add_language)) {
            return $this->languageManager
                ->getDefaultLanguage()
                ->getId();
        }
        return $add_language[array_rand($add_language)];
    }

}