summaryrefslogtreecommitdiffstats
path: root/core/modules/language/language.module
blob: a21682b1695bb0dc7ddecae44f141dba9d1e954a (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
<?php

/**
 * @file
 * Add language handling functionality to Drupal.
 */

use Drupal\Core\Access\AccessResult;
use Drupal\Core\Entity\ContentEntityFormInterface;
use Drupal\Core\Entity\EntityFormInterface;
use Drupal\Core\Field\FieldDefinitionInterface;
use Drupal\Core\Field\FieldItemListInterface;
use Drupal\Core\Form\FormStateInterface;
use Drupal\Core\Language\LanguageInterface;
use Drupal\Core\Routing\RouteMatchInterface;
use Drupal\Core\Session\AccountInterface;
use Drupal\language\ConfigurableLanguageInterface;
use Drupal\language\Entity\ContentLanguageSettings;
use Drupal\language\Plugin\LanguageNegotiation\LanguageNegotiationUI;
use Drupal\language\Plugin\LanguageNegotiation\LanguageNegotiationUrl;
use Drupal\language\Plugin\LanguageNegotiation\LanguageNegotiationUrlFallback;

/**
 * Implements hook_help().
 */
function language_help($route_name, RouteMatchInterface $route_match) {
  switch ($route_name) {
    case 'help.page.language':
      $output = '';
      $output .= '<h3>' . t('About') . '</h3>';
      $output .= '<p>' . t('The Language module allows you to configure the languages used on your site, and provides information for the for <a href="!content">Content Translation</a>, <a href="!interface">Interface Translation</a>, and <a href="!configuration">Configuration Translation</a> modules, if they are enabled. For more information, see <a href="!doc_url">the online documentation for the Language module</a>.', array('!doc_url' => 'https://drupal.org/documentation/modules/language', '!content' => (\Drupal::moduleHandler()->moduleExists('content_translation')) ? \Drupal::url('help.page', array('name' => 'content_translation')) : '#', '!interface' => (\Drupal::moduleHandler()->moduleExists('locale')) ? \Drupal::url('help.page', array('name' => 'locale')) : '#', '!configuration' => (\Drupal::moduleHandler()->moduleExists('config_translation')) ? \Drupal::url('help.page', array('name' => 'config_translation')) : '#')) . '</p>';
      $output .= '<h3>' . t('Uses') . '</h3>';
      $output .= '<dl>';
      $output .= '<dt>' . t('Adding languages') . '</dt>';
      $output .= '<dd>' . t('You can add languages on the <a href="!language_list">Languages</a> page by selecting <em>Add language</em> and choosing a language from the drop-down menu. This language is then displayed in the languages list, where it can be configured further. If the <a href="!interface">Interface translation module</a> is enabled, and the <em>translation server</em> is set as a translation source, then the interface translation for this language is automatically downloaded as well.' , array('!language_list' => \Drupal::url('language.admin_overview'), '!interface' => (\Drupal::moduleHandler()->moduleExists('locale')) ? \Drupal::url('help.page', array('name' => 'locale')) : '#')) . '</dd>';
      $output .= '<dt>' . t('Adding custom languages') . '</dt>';
      $output .= '<dd>' . t('You can add a language that is not provided in the drop-down list by choosing <em>Custom language</em> at the end of the list. You then have to configure its language code, name, and direction in the form provided.') . '</dd>';
      $output .= '<dt>' . t('Configuring content languages') . '</dt>';
      $output .= '<dd>' . t('By default, content is created in the site\'s default language and no language selector is displayed on content creation pages. On the <a href="!content_language">Content language</a> page you can customize the language configuration for any supported content entity on your site (for example for content types or menu links). After choosing an entity, you are provided with a drop-down menu to set the default language and a check-box to display language selectors.', array('!content_language' => \Drupal::url('language.content_settings_page'))) . '</dd>';
      $output .= '<dt>' . t('Adding a language switcher block') . '</dt>';
      $output .= '<dd>' . t('If the Block module is enabled, then you can add a language switcher block on the <a href="!blocks">Block layout</a> page to allow users to switch between languages.', array('!blocks' => (\Drupal::moduleHandler()->moduleExists('block')) ? \Drupal::url('block.admin_display') : '#')) . '</dd>';
      $output .= '<dt>' . t('Making a block visible per language') . '</dt>';
      $output .= '<dd>' . t('If the Block module is enabled, then the Language module allows you to set the visibility of a block based on selected languages on the <a href="!blocks">Block layout</a> page.', array('!blocks' => (\Drupal::moduleHandler()->moduleExists('block')) ? \Drupal::url('block.admin_display') : '#')) . '</dd>';
      $output .= '<dt>' . t('Choosing user languages') . '</dt>';
      $output .= '<dd>' . t('Users can choose a <em>Site language</em> on their profile page. This language is used for email messages, and can be used by modules to determine a user\'s language. It can also be used for interface text, if the <em>User</em> method is enabled as a <em>Detection and selection</em> method (see below). Administrative users can choose a separate <em>Administration pages language</em> for the interface text on administration pages. This configuration is only available on the user\'s profile page if the <em>Account administration pages</em> method is enabled (see below).') . '</dd>';
      $output .= '<dt>' . t('Language detection and selection') . '</dt>';
      $output .= '<dd>' . t('The <a href="!detection">Detection and selection</a> page provides several methods for deciding which language is used for displaying interface text. When a method detects and selects an interface language, then the following methods in the list are not applied. You can order them by importance, with your preferred method at the top of the list, followed by one or several fall-back methods.', array('!detection' => \Drupal::url('language.negotiation')));
      $output .= '<ul><li>' . t('<em>URL</em> sets the interface language based on a path prefix or domain (for example specifying <em>de</em> for German would result in URLs like <em>example.com/de/contact</em>). The default language does not require a path prefix, but can have one assigned as well. If the language detection is done by domain name, a domain needs to be specified for each language.') . '</li>';
      $output .= '<li>' . t('<em>Session</em> determines the interface language from a request or session parameter (for example <em>example.com?language=de</em> would set the interface language to German based on the use of <em>de</em> as the <em>language</em> parameter).') . '</li>';
      $output .= '<li>' . t('<em>User</em> follows the language configuration set on the user\'s profile page.') . '</li>';
      $output .= '<li>' . t('<em>Browser</em> sets the interface language based on the browser\'s language settings. Since browsers use different language codes to refer to the same languages, you can add and edit languages codes to map the browser language codes to the <a href="!language_list">language codes</a> used on your site.',  array('!language_list' => \Drupal::url('language.admin_overview'))) . '</li>';
      $output .= '<li>' . t('<em>Account administration pages</em> follows the configuration set as <em>Administration pages language</em> on the profile page of an administrative user. This method is similar to the <em>User</em> method, but only sets the interface text language on administration pages, independent of the interface text language on other pages.') . '</li>';
      $output .= '<li>' . t('<em>Selected language</em> allows you to specify the site\'s default language or a specific language as the fall-back language. This method should be listed last.') . '</li></ul></dd>';
      $output .= '</dl>';
      return $output;

    case 'language.admin_overview':
      return '<p>' . t('Reorder the added languages to set their order in the language switcher block and, when editing content, in the list of selectable languages. This ordering does not impact <a href="@detection">detection and selection</a>.', array('@detection' => \Drupal::url('language.negotiation'))) . '</p>';

    case 'language.add':
      return '<p>' . t('Add a language to be supported by your site. If your desired language is not available, pick <em>Custom language...</em> at the end and provide a language code and other details manually.') . '</p>';

    case 'language.negotiation':
      $output = '<p>' . t('Define how to decide which language is used to display page elements (primarily text provided by modules, such as field labels and help text). This decision is made by evaluating a series of detection methods for languages; the first detection method that gets a result will determine which language is used for that type of text. Be aware that some language negotiation methods are unreliable under certain conditions, such as browser detection when page-caching is enabled and a user is not currently logged in. Define the order of evaluation of language detection methods on this page. The default language can be changed at the <a href="!region-settings">Regional settings</a> page.', array('!region-settings' => \Drupal::url('system.regional_settings'))) . '</p>';
      return $output;

    case 'language.negotiation_session':
      $output = '<p>' . t('Determine the language from a request/session parameter. Example: "http://example.com?language=de" sets language to German based on the use of "de" within the "language" parameter.') . '</p>';
      return $output;

    case 'language.negotiation_browser':
      $output = '<p>' . t('Browsers use different language codes to refer to the same languages. Internally, a best effort is made to determine the correct language based on the code that the browser sends. You can add and edit additional mappings from browser language codes to <a href="!configure-languages">site languages</a>.', array('!configure-languages' => \Drupal::url('language.admin_overview'))) . '</p>';
      return $output;

    case 'language.negotiation_selected':
      $output = '<p>' . t('Changing the selected language here (and leaving this option as the last among the detection and selection options) is the easiest way to change the fallback language for the website, if you need to change how your site works by default (e.g., when using an empty path prefix or using the default domain). <a href="!admin-change-language">Changing the site\'s default language</a> itself might have other undesired side effects.', array('!admin-change-language' => \Drupal::url('language.admin_overview'))) . '</p>';
      return $output;

    case 'entity.block.edit_form':
      if (($block = $route_match->getParameter('block')) && $block->get('plugin') == 'language_block:language_interface') {
        return '<p>' . t('With multiple languages added, registered users can select their preferred language and authors can assign a specific language to content.') . '</p>';
      }
      break;

    case 'block.admin_add':
      if ($route_match->getParameter('plugin_id') == 'language_block:language_interface') {
        return '<p>' . t('With multiple languages added, registered users can select their preferred language and authors can assign a specific language to content.') . '</p>';
      }
      break;

    case 'language.content_settings_page':
      return t('Change language settings for <em>content types</em>, <em>taxonomy vocabularies</em>, <em>user profiles</em>, or any other supported element on your site. By default, language settings hide the language selector and the language is the site\'s default language.');
  }
}

/**
 * Implements hook_theme().
 */
function language_theme() {
  return array(
    'language_negotiation_configure_form' => array(
      'render element' => 'form',
      'file' => 'language.admin.inc',
    ),
    'language_negotiation_configure_browser_form_table' => array(
      'render element' => 'form',
      'file' => 'language.admin.inc',
      'function' => 'theme_language_negotiation_configure_browser_form_table',
    ),
    'language_content_settings_table' => array(
      'render element' => 'element',
      'file' => 'language.admin.inc',
      'function' => 'theme_language_content_settings_table',
    ),
  );
}

/**
 * Implements hook_element_info_alter().
 */
function language_element_info_alter(&$type) {
  // Alter the language_select element so that it will be rendered like a select
  // field.
  if (isset($type['language_select'])) {
    if (!isset($type['language_select']['#process'])) {
      $type['language_select']['#process'] = array();
    }
    if (!isset($type['language_select']['#theme_wrappers'])) {
      $type['language_select']['#theme_wrappers'] = array();
    }
    $type['language_select']['#process'] = array_merge($type['language_select']['#process'], array(
      'language_process_language_select',
      array('Drupal\Core\Render\Element\Select', 'processSelect'),
      array('Drupal\Core\Render\Element\RenderElement', 'processAjaxForm'),
    ));
    $type['language_select']['#theme'] = 'select';
    $type['language_select']['#theme_wrappers'] = array_merge($type['language_select']['#theme_wrappers'], array('form_element'));
    $type['language_select']['#languages'] = LanguageInterface::STATE_CONFIGURABLE;
    $type['language_select']['#multiple'] = FALSE;
  }
}

/**
 * Processes a language select list form element.
 *
 * @param array $element
 *   The form element to process.
 *
 * @return array $element
 *   The processed form element.
 */
function language_process_language_select($element) {
  // Don't set the options if another module (translation for example) already
  // set the options.
  if (!isset($element['#options'])) {
    $element['#options'] = array();
    foreach (\Drupal::languageManager()->getLanguages($element['#languages']) as $langcode => $language) {
      $element['#options'][$langcode] = $language->isLocked() ? t('- @name -', array('@name' => $language->getName())) : $language->getName();
    }
  }
  // Add "Built-in English" language to the select when the default value is
  // set to English but it does not exist in the options list.
  //
  // Drupal core includes configuration shipped in English, including default
  // views, content types, user roles, filter formats, etc. To keep the Drupal
  // software update-able, as well as translations update-able, we keep these
  // configuration files in English even when installed in a foreign language.
  // However, administrators can remove English, in which case editing such a
  // configuration would lead to the language settings being changed on it. We
  // avoid that by including this option and letting administrators keep it
  // in English.
  if (isset($element['#default_value']) && $element['#default_value'] == 'en' && !isset($element['#options']['en'])) {
    // Prepend the default language at the beginning of the list.
    $element['#options'] = array('en' => t('Built-in English')) + $element['#options'];
  }
  return $element;
}

/**
 * Implements hook_entity_base_field_info_alter().
 */
function language_entity_base_field_info_alter(&$fields) {
  foreach ($fields as $definition) {
    // Set configurable form display for language fields with display options.
    if ($definition->getType() == 'language') {
      foreach (array('form', 'view') as $type)  {
        if ($definition->getDisplayOptions($type)) {
          // The related configurations will be purged manually on Language
          // module uninstallation. @see language_modules_uninstalled().
          $definition->setDisplayConfigurable($type, TRUE);
        }
      }
    }
  }
}

/**
 * Submit handler for the forms that have a language_configuration element.
 */
function language_configuration_element_submit(&$form, FormStateInterface $form_state) {
  // Iterate through all the language_configuration elements and save their
  // values.
  // In case we are editing a bundle, we must check the new bundle name,
  // because e.g. hook_ENTITY_update fired before.
  if ($language = $form_state->get('language')) {
    foreach ($language as $element_name => $values) {
      $entity_type_id = $values['entity_type'];
      $bundle = $values['bundle'];
      $form_object = $form_state->getFormObject();
      if ($form_object instanceof EntityFormInterface && !$form_object->getEntity()->isNew() && in_array($form_object->getOperation(), ['default', 'edit'])) {
        /** @var EntityFormInterface $form_object */
        $entity = $form_object->getEntity();
        if ($entity->getEntityType()->getBundleOf()) {
          $bundle = $entity->id();
        }
      }
      $config = ContentLanguageSettings::loadByEntityTypeBundle($entity_type_id, $bundle);
      $config->setDefaultLangcode($form_state->getValue(array($element_name, 'langcode')));
      $config->setLanguageAlterable($form_state->getValue(array($element_name, 'language_alterable')));
      $config->save();
    }
  }
}

/**
 * Implements hook_entity_bundle_rename().
 */
function language_entity_bundle_rename($entity_type_id, $bundle_old, $bundle_new) {
  ContentLanguageSettings::loadByEntityTypeBundle($entity_type_id, $bundle_old)
    ->setTargetBundle($bundle_new)
    ->save();
}

/**
 * Returns the default language code assigned to an entity type and a bundle.
 *
 * @param string $entity_type
 *   The entity type.
 * @param string $bundle
 *   The bundle name.
 *
 * @return string
 *   The language code.
 */
function language_get_default_langcode($entity_type, $bundle) {
  $configuration = ContentLanguageSettings::loadByEntityTypeBundle($entity_type, $bundle);

  $default_value = NULL;
  $language_interface = \Drupal::languageManager()->getCurrentLanguage();
  switch ($configuration->getDefaultLangcode()) {
    case LanguageInterface::LANGCODE_SITE_DEFAULT:
      $default_value = \Drupal::languageManager()->getDefaultLanguage()->getId();
      break;

    case 'current_interface':
      $default_value = $language_interface->getId();
      break;

    case 'authors_default':
      $user = \Drupal::currentUser();
      $language_code = $user->getPreferredLangcode();
      if (!empty($language_code)) {
        $default_value = $language_code;
      }
      else {
        $default_value = $language_interface->getId();
      }
      break;
  }
  if ($default_value) {
    return $default_value;
  }

  // If we still do not have a default value, just return the value stored in
  // the configuration; it has to be an actual language code.
  return $configuration->getDefaultLangcode();
}

/**
 * Implements hook_language_types_info().
 *
 * Defines the three core language types:
 * - Interface language is the only configurable language type in core. It is
 *   used by t() as the default language if none is specified.
 * - Content language is by default non-configurable and inherits the interface
 *   language negotiated value. It is used by the Field API to determine the
 *   display language for fields if no explicit value is specified.
 * - URL language is by default non-configurable and is determined through the
 *   URL language negotiation method or the URL fallback language negotiation
 *   method if no language can be detected. It is used by l() as the default
 *   language if none is specified.
 */
function language_language_types_info() {
  return array(
    LanguageInterface::TYPE_INTERFACE => array(
      'name' => t('User interface text'),
      'description' => t('Order of language detection methods for user interface text. If a translation of user interface text is available in the detected language, it will be displayed.'),
      'locked' => TRUE,
    ),
    LanguageInterface::TYPE_CONTENT => array(
      'name' => t('Content'),
      'description' => t('Order of language detection methods for content. If a version of content is available in the detected language, it will be displayed.'),
      'fixed' => array(LanguageNegotiationUI::METHOD_ID),
      'locked' => TRUE,
    ),
    LanguageInterface::TYPE_URL => array(
      'fixed' => array(LanguageNegotiationUrl::METHOD_ID, LanguageNegotiationUrlFallback::METHOD_ID),
      'locked' => TRUE,
    ),
  );
}

/**
 * Reads language prefixes and uses the langcode if no prefix is set.
 */
function language_negotiation_url_prefixes() {
  return \Drupal::config('language.negotiation')->get('url.prefixes');
}

/**
 * Update the list of prefixes from the installed languages.
 */
function language_negotiation_url_prefixes_update() {
  $prefixes = language_negotiation_url_prefixes();
  foreach (\Drupal::languageManager()->getLanguages() as $language) {
    // The prefix for this language should be updated if it's not assigned yet
    // or the prefix is set to the empty string.
    if (empty($prefixes[$language->getId()])) {
      // For the default language, set the prefix to the empty string,
      // otherwise use the langcode.
      $prefixes[$language->getId()] = $language->isDefault() ? '' : $language->getId();
    }
    // Otherwise we keep the configured prefix.
  }
  language_negotiation_url_prefixes_save($prefixes);
}

/**
 * Saves language prefix settings.
 */
function language_negotiation_url_prefixes_save(array $prefixes) {
  \Drupal::config('language.negotiation')
  ->set('url.prefixes', $prefixes)
  ->save();
}

/**
 * Reads language domains.
 */
function language_negotiation_url_domains() {
  return \Drupal::config('language.negotiation')->get('url.domains');
}

/**
 * Saves the language domain settings.
 */
function language_negotiation_url_domains_save(array $domains) {
  \Drupal::config('language.negotiation')
  ->set('url.domains', $domains)
  ->save();
}

/**
 * Implements hook_modules_installed().
 */
function language_modules_installed($modules) {
  if (!in_array('language', $modules)) {
    $negotiator = \Drupal::service('language_negotiator');
    $negotiator->updateConfiguration(array());
    $negotiator->purgeConfiguration();
  }
  else {
    // In language_entity_base_field_info_alter() we are altering view/form
    // display definitions to make language fields display configurable. Since
    // this is not a hard dependency, and thus is not detected by the config
    // system, we have to clean up the related values manually.
    foreach (array('entity_view_display', 'entity_form_display') as $key) {
      $displays = \Drupal::entityManager()->getStorage($key)->loadMultiple();
      /** @var \Drupal\Core\Entity\Display\EntityDisplayInterface $display */
      foreach ($displays as $display) {
        $display->save();
      }
    }
  }
}

/**
 * Implements hook_modules_uninstalled().
 */
function language_modules_uninstalled($modules) {
  language_modules_installed($modules);
}

/**
 * Implements hook_ENTITY_TYPE_insert() for 'configurable_language'.
 */
function language_configurable_language_insert(ConfigurableLanguageInterface $language) {
  if ($language->isLocked()) {
    return;
  }

  // Add language to the list of language domains.
  $domains = language_negotiation_url_domains();
  $domains[$language->id()] = '';
  language_negotiation_url_domains_save($domains);
}

/**
 * Implements hook_ENTITY_TYPE_delete() for 'configurable_language'.
 */
function language_configurable_language_delete(ConfigurableLanguageInterface $language) {
  // Remove language from language prefix list.
  $prefixes = language_negotiation_url_prefixes();
  unset($prefixes[$language->id()]);
  language_negotiation_url_prefixes_save($prefixes);

  // Remove language from language domain list.
  $domains = language_negotiation_url_domains();
  unset($domains[$language->id()]);
  language_negotiation_url_domains_save($domains);
}

/**
 * Implements hook_preprocess_HOOK() for block templates.
 */
function language_preprocess_block(&$variables) {
  if ($variables['configuration']['provider'] == 'language') {
    $variables['attributes']['role'] = 'navigation';
  }
}

/**
 * Returns language mappings between browser and Drupal language codes.
 *
 * @return array
 *   An array containing browser language codes as keys with corresponding
 *   Drupal language codes as values.
 */
function language_get_browser_drupal_langcode_mappings() {
  $config = \Drupal::config('language.mappings');
  if ($config->isNew()) {
    return array();
  }
  return $config->get();
}

/**
 * Stores language mappings between browser and Drupal language codes.
 *
 * @param array $mappings
 *   An array containing browser language codes as keys with corresponding
 *   Drupal language codes as values.
 */
function language_set_browser_drupal_langcode_mappings($mappings) {
  $config = \Drupal::config('language.mappings');
  $config->setData($mappings);
  $config->save();
}

/**
 * Implements hook_form_FORM_ID_alter for system_regional_settings().
 *
 * @see language_system_regional_settings_form_submit()
 */
function language_form_system_regional_settings_alter(&$form, FormStateInterface $form_state) {
  $languages = \Drupal::languageManager()->getLanguages();
  $default = \Drupal::languageManager()->getDefaultLanguage();
  foreach ($languages as $key => $language) {
    $language_options[$key] = $language->getName();
  }
  $form['locale']['site_default_language'] = array(
    '#type' => 'select',
    '#title' => t('Default language'),
    '#default_value' => $default->getId(),
    '#options' => $language_options,
    '#description' => t('It is not recommended to change the default language on a working site. <a href="@language-detection">Configure the Selected language</a> setting on the detection and selection page to change the fallback language for language selection.', array('@language-detection' => \Drupal::url('language.negotiation'))),
    '#weight' => -1,
  );
  // Add submit handler to save default language.
  $form['#submit'][] = 'language_system_regional_settings_form_submit';
}

/**
 * Implements hook_form_alter().
 */
function language_form_alter(&$form, FormStateInterface $form_state) {
  // Content entity forms may have added a langcode field. But content language
  // configuration should decide if it should be exposed or not in the forms.
  $form_object = $form_state->getFormObject();
  if ($form_object instanceof ContentEntityFormInterface) {
    /** @var \Drupal\Core\Entity\ContentEntityInterface $entity */
    $entity = $form_object->getEntity();
    $entity_type = $entity->getEntityType();
    $langcode_key = $entity_type->getKey('langcode');
    if (isset($form[$langcode_key]) && $entity_type->isTranslatable()) {
      $language_configuration = ContentLanguageSettings::loadByEntityTypeBundle($entity->getEntityTypeId(), $entity->bundle());
      $form[$langcode_key]['#access'] = $language_configuration->isLanguageAlterable();
    }
  }
}

/**
 * Form submission handler for system_regional_settings().
 *
 * @see language_form_system_regional_settings_alter()
 */
function language_system_regional_settings_form_submit($form, FormStateInterface $form_state) {
  \Drupal::config('system.site')->set('langcode', $form_state->getValue('site_default_language'))->save();
}

/**
 * Implements hook_field_info_alter().
 */
function language_field_info_alter(&$info) {
  // Change the default behavior of language field.
  $info['language']['class'] = '\Drupal\language\DefaultLanguageItem';
}

/**
 * Implements hook_entity_field_access()
 */
function language_entity_field_access($operation, FieldDefinitionInterface $field_definition, AccountInterface $account, FieldItemListInterface $items = NULL) {
  $langcode_key = $items->getEntity()->getEntityType()->getKey('langcode');
  if ($field_definition->getName() == $langcode_key) {
    $entity = $items->getEntity();
    $config = ContentLanguageSettings::loadByEntityTypeBundle($entity->getEntityTypeId(), $entity->bundle());
    return AccessResult::forbiddenIf(!$config->isLanguageAlterable());
  }
  return AccessResult::neutral();
}