<?php

namespace Drupal\language\Form;

use Drupal\Core\Entity\EntityInterface;
use Drupal\Core\Form\FormStateInterface;
use Drupal\Core\Language\LanguageManager;
use Drupal\Core\Url;
use Drupal\language\Entity\ConfigurableLanguage;

/**
 * Controller for language addition forms.
 *
 * @internal
 */
class LanguageAddForm extends LanguageFormBase {

  /**
   * {@inheritdoc}
   */
  public function getFormId() {
    // @todo Remove in favor of base method.
    return 'language_admin_add_form';
  }

  /**
   * {@inheritdoc}
   */
  public function form(array $form, FormStateInterface $form_state) {
    $form['#title'] = $this->t('Add language');

    $predefined_languages = $this->languageManager->getStandardLanguageListWithoutConfigured();

    $predefined_languages['custom'] = $this->t('Custom language...');
    $predefined_default = $form_state->getValue('predefined_langcode', key($predefined_languages));
    $form['predefined_langcode'] = [
      '#type' => 'select',
      '#title' => $this->t('Language name'),
      '#default_value' => $predefined_default,
      '#options' => $predefined_languages,
    ];
    $form['predefined_submit'] = [
      '#type' => 'submit',
      '#value' => $this->t('Add language'),
      '#name' => 'add_language',
      '#limit_validation_errors' => [['predefined_langcode'], ['predefined_submit']],
      '#states' => [
        'invisible' => [
          'select#edit-predefined-langcode' => ['value' => 'custom'],
        ],
      ],
      '#validate' => ['::validatePredefined'],
      '#submit' => ['::submitForm', '::save'],
      '#button_type' => 'primary',
    ];

    $custom_language_states_conditions = [
      'select#edit-predefined-langcode' => ['value' => 'custom'],
    ];
    $form['custom_language'] = [
      '#type' => 'container',
      '#states' => [
        'visible' => $custom_language_states_conditions,
      ],
    ];
    $this->commonForm($form['custom_language']);
    $form['custom_language']['langcode']['#states'] = [
      'required' => $custom_language_states_conditions,
    ];
    $form['custom_language']['label']['#states'] = [
      'required' => $custom_language_states_conditions,
    ];
    $form['custom_language']['submit'] = [
      '#type' => 'submit',
      '#value' => $this->t('Add custom language'),
      '#name' => 'add_custom_language',
      '#validate' => ['::validateCustom'],
      '#submit' => ['::submitForm', '::save'],
    ];

    return $form;
  }

  /**
   * {@inheritdoc}
   */
  public function save(array $form, FormStateInterface $form_state) {
    parent::save($form, $form_state);

    $t_args = ['%language' => $this->entity->label(), '%langcode' => $this->entity->id()];
    $this->logger('language')->notice('The %language (%langcode) language has been created.', $t_args);
    $this->messenger()->addStatus($this->t('The language %language has been created and can now be used.', $t_args));

    if ($this->moduleHandler->moduleExists('block')) {
      // Tell the user they have the option to add a language switcher block
      // to their theme so they can switch between the languages.
      $this->messenger()->addStatus($this->t('Use one of the language switcher blocks to allow site visitors to switch between languages. You can enable these blocks on the <a href=":block-admin">block administration page</a>.', [':block-admin' => Url::fromRoute('block.admin_display')->toString()]));
    }
    $form_state->setRedirectUrl($this->entity->toUrl('collection'));
  }

  /**
   * {@inheritdoc}
   */
  public function actions(array $form, FormStateInterface $form_state) {
    // No actions needed.
    return [];
  }

  /**
   * Validates the language addition form on custom language button.
   */
  public function validateCustom(array $form, FormStateInterface $form_state) {
    if ($form_state->getValue('predefined_langcode') == 'custom') {
      $langcode = $form_state->getValue('langcode');
      // Reuse the editing form validation routine if we add a custom language.
      $this->validateCommon($form['custom_language'], $form_state);

      if ($language = $this->languageManager->getLanguage($langcode)) {
        $form_state->setErrorByName('langcode', $this->t('The language %language (%langcode) already exists.', ['%language' => $language->getName(), '%langcode' => $langcode]));
      }
    }
    else {
      $form_state->setErrorByName('predefined_langcode', $this->t('Use the <em>Add language</em> button to save a predefined language.'));
    }
  }

  /**
   * Element specific validator for the Add language button.
   */
  public function validatePredefined($form, FormStateInterface $form_state) {
    $langcode = $form_state->getValue('predefined_langcode');
    if ($langcode == 'custom') {
      $form_state->setErrorByName('predefined_langcode', $this->t('Fill in the language details and save the language with <em>Add custom language</em>.'));
    }
    else {
      if ($language = $this->languageManager->getLanguage($langcode)) {
        $form_state->setErrorByName('predefined_langcode', $this->t('The language %language (%langcode) already exists.', ['%language' => $language->getName(), '%langcode' => $langcode]));
      }
    }
  }

  /**
   * {@inheritdoc}
   */
  protected function copyFormValuesToEntity(EntityInterface $entity, array $form, FormStateInterface $form_state) {
    $langcode = $form_state->getValue('predefined_langcode');
    if ($langcode == 'custom') {
      $langcode = $form_state->getValue('langcode');
      $label = $form_state->getValue('label');
      $direction = $form_state->getValue('direction');
    }
    else {
      $standard_languages = LanguageManager::getStandardLanguageList();
      $label = $standard_languages[$langcode][0];
      $direction = $standard_languages[$langcode][2] ?? ConfigurableLanguage::DIRECTION_LTR;
    }
    $entity->set('id', $langcode);
    $entity->set('label', $label);
    $entity->set('direction', $direction);
    // There is no weight on the edit form. Fetch all configurable languages
    // ordered by weight and set the new language to be placed after them.
    $languages = \Drupal::languageManager()->getLanguages(ConfigurableLanguage::STATE_CONFIGURABLE);
    $last_language = end($languages);
    $entity->setWeight($last_language->getWeight() + 1);
  }

}
