class CommentLinkBuilder

class CommentLinkBuilder implements CommentLinkBuilderInterface {
    use StringTranslationTrait;
    
    /**
     * Current user.
     *
     * @var \Drupal\Core\Session\AccountInterface
     */
    protected $currentUser;
    
    /**
     * Comment manager service.
     *
     * @var \Drupal\comment\CommentManagerInterface
     */
    protected $commentManager;
    
    /**
     * Module handler service.
     *
     * @var \Drupal\Core\Extension\ModuleHandlerInterface
     */
    protected $moduleHandler;
    
    /**
     * The entity type manager service.
     *
     * @var \Drupal\Core\Entity\EntityTypeManagerInterface
     */
    protected $entityTypeManager;
    
    /**
     * Constructs a new CommentLinkBuilder object.
     *
     * @param \Drupal\Core\Session\AccountInterface $current_user
     *   Current user.
     * @param \Drupal\comment\CommentManagerInterface $comment_manager
     *   Comment manager service.
     * @param \Drupal\Core\Extension\ModuleHandlerInterface $module_handler
     *   Module handler service.
     * @param \Drupal\Core\StringTranslation\TranslationInterface $string_translation
     *   String translation service.
     * @param \Drupal\Core\Entity\EntityTypeManagerInterface $entity_type_manager
     *   The entity type manager.
     */
    public function __construct(AccountInterface $current_user, CommentManagerInterface $comment_manager, ModuleHandlerInterface $module_handler, TranslationInterface $string_translation, EntityTypeManagerInterface $entity_type_manager) {
        $this->currentUser = $current_user;
        $this->commentManager = $comment_manager;
        $this->moduleHandler = $module_handler;
        $this->stringTranslation = $string_translation;
        $this->entityTypeManager = $entity_type_manager;
    }
    
    /**
     * {@inheritdoc}
     */
    public function buildCommentedEntityLinks(FieldableEntityInterface $entity, array &$context) {
        $entity_links = [];
        $view_mode = $context['view_mode'];
        if ($view_mode == 'search_index' || $view_mode == 'search_result' || $view_mode == 'print' || $view_mode == 'rss') {
            // Do not add any links if the entity is displayed for:
            // - search indexing.
            // - constructing a search result excerpt.
            // - print.
            // - rss.
            return [];
        }
        $fields = $this->commentManager
            ->getFields($entity->getEntityTypeId());
        foreach ($fields as $field_name => $detail) {
            // Skip fields that the entity does not have.
            if (!$entity->hasField($field_name)) {
                continue;
            }
            $links = [];
            $commenting_status = $entity->get($field_name)->status;
            if ($commenting_status != CommentItemInterface::HIDDEN) {
                // Entity has commenting status open or closed.
                $field_definition = $entity->getFieldDefinition($field_name);
                if ($view_mode == 'teaser') {
                    // Teaser view: display the number of comments that have been posted,
                    // or a link to add new comments if the user has permission, the
                    // entity is open to new comments, and there currently are none.
                    if ($this->currentUser
                        ->hasPermission('access comments')) {
                        if (!empty($entity->get($field_name)->comment_count)) {
                            $links['comment-comments'] = [
                                'title' => $this->formatPlural($entity->get($field_name)->comment_count, '1 comment', '@count comments'),
                                'attributes' => [
                                    'title' => $this->t('Jump to the first comment.'),
                                ],
                                'fragment' => 'comments',
                                'url' => $entity->toUrl(),
                            ];
                            if ($this->moduleHandler
                                ->moduleExists('history')) {
                                $links['comment-new-comments'] = [
                                    'title' => '',
                                    'url' => Url::fromRoute('<current>'),
                                    'attributes' => [
                                        'class' => 'hidden',
                                        'title' => $this->t('Jump to the first new comment.'),
                                        'data-history-node-last-comment-timestamp' => $entity->get($field_name)->last_comment_timestamp,
                                        'data-history-node-field-name' => $field_name,
                                    ],
                                ];
                            }
                        }
                    }
                    // Provide a link to new comment form.
                    if ($commenting_status == CommentItemInterface::OPEN) {
                        $comment_form_location = $field_definition->getSetting('form_location');
                        if ($this->currentUser
                            ->hasPermission('post comments')) {
                            $links['comment-add'] = [
                                'title' => $this->t('Add new comment'),
                                'language' => $entity->language(),
                                'attributes' => [
                                    'title' => $this->t('Share your thoughts and opinions.'),
                                ],
                                'fragment' => 'comment-form',
                            ];
                            if ($comment_form_location == CommentItemInterface::FORM_SEPARATE_PAGE) {
                                $links['comment-add']['url'] = Url::fromRoute('comment.reply', [
                                    'entity_type' => $entity->getEntityTypeId(),
                                    'entity' => $entity->id(),
                                    'field_name' => $field_name,
                                ]);
                            }
                            else {
                                $links['comment-add'] += [
                                    'url' => $entity->toUrl(),
                                ];
                            }
                        }
                        elseif ($this->currentUser
                            ->isAnonymous()) {
                            $links['comment-forbidden'] = [
                                'title' => $this->commentManager
                                    ->forbiddenMessage($entity, $field_name),
                            ];
                        }
                    }
                }
                else {
                    // Entity in other view modes: add a "post comment" link if the user
                    // is allowed to post comments and if this entity is allowing new
                    // comments.
                    if ($commenting_status == CommentItemInterface::OPEN) {
                        $comment_form_location = $field_definition->getSetting('form_location');
                        if ($this->currentUser
                            ->hasPermission('post comments')) {
                            // Show the "post comment" link if the form is on another page, or
                            // if there are existing comments that the link will skip past.
                            if ($comment_form_location == CommentItemInterface::FORM_SEPARATE_PAGE || !empty($entity->get($field_name)->comment_count) && $this->currentUser
                                ->hasPermission('access comments')) {
                                $links['comment-add'] = [
                                    'title' => $this->t('Add new comment'),
                                    'attributes' => [
                                        'title' => $this->t('Share your thoughts and opinions.'),
                                    ],
                                    'fragment' => 'comment-form',
                                ];
                                if ($comment_form_location == CommentItemInterface::FORM_SEPARATE_PAGE) {
                                    $links['comment-add']['url'] = Url::fromRoute('comment.reply', [
                                        'entity_type' => $entity->getEntityTypeId(),
                                        'entity' => $entity->id(),
                                        'field_name' => $field_name,
                                    ]);
                                }
                                else {
                                    $links['comment-add']['url'] = $entity->toUrl();
                                }
                            }
                        }
                        elseif ($this->currentUser
                            ->isAnonymous()) {
                            $links['comment-forbidden'] = [
                                'title' => $this->commentManager
                                    ->forbiddenMessage($entity, $field_name),
                            ];
                        }
                    }
                }
            }
            if (!empty($links)) {
                $entity_links['comment__' . $field_name] = [
                    '#theme' => 'links__entity__comment__' . $field_name,
                    '#links' => $links,
                    '#attributes' => [
                        'class' => [
                            'links',
                            'inline',
                        ],
                    ],
                ];
                if ($view_mode == 'teaser' && $this->moduleHandler
                    ->moduleExists('history') && $this->currentUser
                    ->isAuthenticated()) {
                    $entity_links['comment__' . $field_name]['#cache']['contexts'][] = 'user';
                    $entity_links['comment__' . $field_name]['#attached']['library'][] = 'comment/drupal.node-new-comments-link';
                    // Embed the metadata for the "X new comments" link (if any) on this
                    // entity.
                    $entity_links['comment__' . $field_name]['#attached']['drupalSettings']['history']['lastReadTimestamps'][$entity->id()] = history_read($entity->id());
                    $new_comments = $this->commentManager
                        ->getCountNewComments($entity);
                    if ($new_comments > 0) {
                        $page_number = $this->entityTypeManager
                            ->getStorage('comment')
                            ->getNewCommentPageNumber($entity->{$field_name}->comment_count, $new_comments, $entity, $field_name);
                        $query = $page_number ? [
                            'page' => $page_number,
                        ] : NULL;
                        $value = [
                            'new_comment_count' => (int) $new_comments,
                            'first_new_comment_link' => $entity->toUrl('canonical', [
                                'query' => $query,
                                'fragment' => 'new',
                            ])
                                ->toString(),
                        ];
                        $parents = [
                            'comment',
                            'newCommentsLinks',
                            $entity->getEntityTypeId(),
                            $field_name,
                            $entity->id(),
                        ];
                        NestedArray::setValue($entity_links['comment__' . $field_name]['#attached']['drupalSettings'], $parents, $value);
                    }
                }
            }
        }
        return $entity_links;
    }

}