forum.module

<?php


/**
 * @file
 * Provides discussion forums.
 */
use Drupal\comment\CommentInterface;
use Drupal\comment\Plugin\Field\FieldType\CommentItemInterface;
use Drupal\Core\Entity\EntityInterface;
use Drupal\Core\Entity\EntityTypeInterface;
use Drupal\Core\Link;
use Drupal\Core\Url;
use Drupal\Core\Form\FormStateInterface;
use Drupal\Core\Routing\RouteMatchInterface;
use Drupal\language\Plugin\migrate\source\d7\LanguageContentSettingsTaxonomyVocabulary as D7LanguageContentSettingsTaxonomyVocabulary;
use Drupal\migrate\Plugin\MigrateSourceInterface;
use Drupal\migrate\Plugin\MigrationInterface;
use Drupal\migrate\Row;
use Drupal\taxonomy\Plugin\migrate\source\d6\Term as D6Term;
use Drupal\taxonomy\Plugin\migrate\source\d6\Vocabulary as D6Vocabulary;
use Drupal\taxonomy\Plugin\migrate\source\d6\VocabularyPerType as D6VocabularyPerType;
use Drupal\taxonomy\Plugin\migrate\source\d7\Term as D7Term;
use Drupal\taxonomy\Plugin\migrate\source\d7\TermEntityTranslation;
use Drupal\taxonomy\Plugin\migrate\source\d7\Vocabulary as D7Vocabulary;
use Drupal\taxonomy\Plugin\migrate\source\d7\VocabularyTranslation as D7VocabularyTranslation;
use Drupal\taxonomy\VocabularyInterface;
use Drupal\user\Entity\User;

/**
 * Implements hook_help().
 */
function forum_help($route_name, RouteMatchInterface $route_match) {
    switch ($route_name) {
        case 'help.page.forum':
            $output = '';
            $output .= '<h2>' . t('About') . '</h2>';
            $output .= '<p>' . t('The Forum module lets you create threaded discussion forums with functionality similar to other message board systems. In a forum, users post topics and threads in nested hierarchies, allowing discussions to be categorized and grouped.') . '</p>';
            $output .= '<p>' . t('The Forum module adds and uses a content type called <em>Forum topic</em>. For background information on content types, see the <a href=":node_help">Node module help page</a>.', [
                ':node_help' => Url::fromRoute('help.page', [
                    'name' => 'node',
                ])->toString(),
            ]) . '</p>';
            $output .= '<p>' . t('A forum is represented by a hierarchical structure, consisting of:');
            $output .= '<ul>';
            $output .= '<li>' . t('<em>Forums</em> (for example, <em>Recipes for cooking vegetables</em>)') . '</li>';
            $output .= '<li>' . t('<em>Forum topics</em> submitted by users (for example, <em>How to cook potatoes</em>), which start discussions.') . '</li>';
            $output .= '<li>' . t('Threaded <em>comments</em> submitted by users (for example, <em>You wash the potatoes first and then...</em>).') . '</li>';
            $output .= '<li>' . t('Optional <em>containers</em>, used to group similar forums. Forums can be placed inside containers, and vice versa.') . '</li>';
            $output .= '</ul>';
            $output .= '</p>';
            $output .= '<p>' . t('For more information, see the <a href=":forum">online documentation for the Forum module</a>.', [
                ':forum' => 'https://www.drupal.org/documentation/modules/forum',
            ]) . '</p>';
            $output .= '<h2>' . t('Uses') . '</h2>';
            $output .= '<dl>';
            $output .= '<dt>' . t('Setting up the forum structure') . '</dt>';
            $output .= '<dd>' . t('Visit the <a href=":forums">Forums page</a> to set up containers and forums to hold your discussion topics.', [
                ':forums' => Url::fromRoute('forum.overview')->toString(),
            ]) . '</dd>';
            $output .= '<dt>' . t('Starting a discussion') . '</dt>';
            $output .= '<dd>' . t('The <a href=":create-topic">Forum topic</a> link on the <a href=":content-add">Add content</a> page creates the first post of a new threaded discussion, or thread.', [
                ':create-topic' => Url::fromRoute('node.add', [
                    'node_type' => 'forum',
                ])->toString(),
                ':content-add' => Url::fromRoute('node.add_page')->toString(),
            ]) . '</dd>';
            $output .= '<dt>' . t('Navigating in the forum') . '</dt>';
            $output .= '<dd>' . t('Installing the Forum module provides a default <em>Forums</em> menu link in the Tools menu that links to the <a href=":forums">Forums page</a>.', [
                ':forums' => Url::fromRoute('forum.index')->toString(),
            ]) . '</dd>';
            $output .= '<dt>' . t('Moving forum topics') . '</dt>';
            $output .= '<dd>' . t('A forum topic (and all of its comments) may be moved between forums by selecting a different forum while editing a forum topic. When moving a forum topic between forums, the <em>Leave shadow copy</em> option creates a link in the original forum pointing to the new location.') . '</dd>';
            $output .= '<dt>' . t('Locking and disabling comments') . '</dt>';
            $output .= '<dd>' . t('Selecting <em>Closed</em> under <em>Comment settings</em> while editing a forum topic will lock (prevent new comments on) the thread. Selecting <em>Hidden</em> under <em>Comment settings</em> while editing a forum topic will hide all existing comments on the thread, and prevent new ones.') . '</dd>';
            $output .= '</dl>';
            return $output;
        case 'forum.overview':
            $output = '<p>' . t('Forums contain forum topics. Use containers to group related forums.') . '</p>';
            $more_help_link = [
                '#type' => 'link',
                '#url' => Url::fromRoute('help.page', [
                    'name' => 'forum',
                ]),
                '#title' => t('More help'),
                '#attributes' => [
                    'class' => [
                        'icon-help',
                    ],
                ],
            ];
            $container = [
                '#theme' => 'container',
                '#children' => $more_help_link,
                '#attributes' => [
                    'class' => [
                        'more-link',
                    ],
                ],
            ];
            $output .= \Drupal::service('renderer')->renderInIsolation($container);
            return $output;
        case 'forum.add_container':
            return '<p>' . t('Use containers to group related forums.') . '</p>';
        case 'forum.add_forum':
            return '<p>' . t('A forum holds related forum topics.') . '</p>';
        case 'forum.settings':
            return '<p>' . t('Adjust the display of your forum topics. Organize the forums on the <a href=":forum-structure">forum structure page</a>.', [
                ':forum-structure' => Url::fromRoute('forum.overview')->toString(),
            ]) . '</p>';
    }
}

/**
 * Implements hook_theme().
 */
function forum_theme() {
    return [
        'forums' => [
            'variables' => [
                'forums' => [],
                'topics' => [],
                'topics_pager' => [],
                'parents' => NULL,
                'term' => NULL,
                'sortby' => NULL,
                'forum_per_page' => NULL,
                'header' => [],
            ],
        ],
        'forum_list' => [
            'variables' => [
                'forums' => NULL,
                'parents' => NULL,
                'tid' => NULL,
            ],
        ],
        'forum_icon' => [
            'variables' => [
                'new_posts' => NULL,
                'num_posts' => 0,
                'comment_mode' => 0,
                'sticky' => 0,
                'first_new' => FALSE,
            ],
        ],
        'forum_submitted' => [
            'variables' => [
                'topic' => NULL,
            ],
        ],
        'forum_topic' => [
            'variables' => [
                'title_link' => NULL,
                'submitted' => NULL,
            ],
        ],
    ];
}

/**
 * Implements hook_entity_type_build().
 */
function forum_entity_type_build(array &$entity_types) {
    
    /** @var \Drupal\Core\Entity\EntityTypeInterface[] $entity_types */
    // Register forum specific forms.
    $entity_types['taxonomy_term']->setFormClass('forum', 'Drupal\\forum\\Form\\ForumForm')
        ->setFormClass('container', 'Drupal\\forum\\Form\\ContainerForm')
        ->setLinkTemplate('forum-edit-container-form', '/admin/structure/forum/edit/container/{taxonomy_term}')
        ->setLinkTemplate('forum-delete-form', '/admin/structure/forum/delete/forum/{taxonomy_term}')
        ->setLinkTemplate('forum-edit-form', '/admin/structure/forum/edit/forum/{taxonomy_term}');
}

/**
 * Implements hook_entity_bundle_info_alter().
 */
function forum_entity_bundle_info_alter(&$bundles) {
    // Take over URI construction for taxonomy terms that are forums.
    if ($vid = \Drupal::config('forum.settings')->get('vocabulary')) {
        if (isset($bundles['taxonomy_term'][$vid])) {
            $bundles['taxonomy_term'][$vid]['uri_callback'] = 'forum_uri';
        }
    }
}

/**
 * Entity URI callback used in forum_entity_bundle_info_alter().
 */
function forum_uri($forum) {
    return Url::fromRoute('forum.page', [
        'taxonomy_term' => $forum->id(),
    ]);
}

/**
 * Implements hook_entity_bundle_field_info_alter().
 */
function forum_entity_bundle_field_info_alter(&$fields, EntityTypeInterface $entity_type, $bundle) {
    if ($entity_type->id() == 'node' && !empty($fields['taxonomy_forums'])) {
        $fields['taxonomy_forums']->addConstraint('ForumLeaf', []);
    }
}

/**
 * Implements hook_ENTITY_TYPE_presave() for node entities.
 *
 * Assigns the forum taxonomy when adding a topic from within a forum.
 */
function forum_node_presave(EntityInterface $node) {
    if (\Drupal::service('forum_manager')->checkNodeType($node)) {
        // Make sure all fields are set properly:
        $node->icon = !empty($node->icon) ? $node->icon : '';
        if (!$node->taxonomy_forums
            ->isEmpty()) {
            $node->forum_tid = $node->taxonomy_forums->target_id;
            // Only do a shadow copy check if this is not a new node.
            if (!$node->isNew()) {
                $old_tid = \Drupal::service('forum.index_storage')->getOriginalTermId($node);
                if ($old_tid && isset($node->forum_tid) && $node->forum_tid != $old_tid && !empty($node->shadow)) {
                    // A shadow copy needs to be created. Retain new term and add old term.
                    $node->taxonomy_forums[count($node->taxonomy_forums)] = [
                        'target_id' => $old_tid,
                    ];
                }
            }
        }
    }
}

/**
 * Implements hook_ENTITY_TYPE_update() for node entities.
 */
function forum_node_update(EntityInterface $node) {
    if (\Drupal::service('forum_manager')->checkNodeType($node)) {
        // If this is not a new revision and does exist, update the forum record,
        // otherwise insert a new one.
        
        /** @var \Drupal\forum\ForumIndexStorageInterface $forum_index_storage */
        $forum_index_storage = \Drupal::service('forum.index_storage');
        if ($node->getRevisionId() == $node->original
            ->getRevisionId() && $forum_index_storage->getOriginalTermId($node)) {
            if (!empty($node->forum_tid)) {
                $forum_index_storage->update($node);
            }
            else {
                $forum_index_storage->delete($node);
            }
        }
        else {
            if (!empty($node->forum_tid)) {
                $forum_index_storage->create($node);
            }
        }
        // If the node has a shadow forum topic, update the record for this
        // revision.
        if (!empty($node->shadow)) {
            $forum_index_storage->deleteRevision($node);
            $forum_index_storage->create($node);
        }
        // If the node is published, update the forum index.
        if ($node->isPublished()) {
            $forum_index_storage->deleteIndex($node);
            $forum_index_storage->createIndex($node);
        }
        else {
            $forum_index_storage->deleteIndex($node);
        }
    }
}

/**
 * Implements hook_ENTITY_TYPE_insert() for node entities.
 */
function forum_node_insert(EntityInterface $node) {
    if (\Drupal::service('forum_manager')->checkNodeType($node)) {
        
        /** @var \Drupal\forum\ForumIndexStorageInterface $forum_index_storage */
        $forum_index_storage = \Drupal::service('forum.index_storage');
        if (!empty($node->forum_tid)) {
            $forum_index_storage->create($node);
        }
        // If the node is published, update the forum index.
        if ($node->isPublished()) {
            $forum_index_storage->createIndex($node);
        }
    }
}

/**
 * Implements hook_ENTITY_TYPE_predelete() for node entities.
 */
function forum_node_predelete(EntityInterface $node) {
    if (\Drupal::service('forum_manager')->checkNodeType($node)) {
        
        /** @var \Drupal\forum\ForumIndexStorageInterface $forum_index_storage */
        $forum_index_storage = \Drupal::service('forum.index_storage');
        $forum_index_storage->delete($node);
        $forum_index_storage->deleteIndex($node);
    }
}

/**
 * Implements hook_ENTITY_TYPE_storage_load() for node entities.
 */
function forum_node_storage_load($nodes) {
    $node_vids = [];
    foreach ($nodes as $node) {
        if (\Drupal::service('forum_manager')->checkNodeType($node)) {
            $node_vids[] = $node->getRevisionId();
        }
    }
    if (!empty($node_vids)) {
        $result = \Drupal::service('forum.index_storage')->read($node_vids);
        foreach ($result as $record) {
            $nodes[$record->nid]->forum_tid = $record->tid;
        }
    }
}

/**
 * Implements hook_ENTITY_TYPE_update() for comment entities.
 */
function forum_comment_update(CommentInterface $comment) {
    if ($comment->getCommentedEntityTypeId() == 'node') {
        \Drupal::service('forum.index_storage')->updateIndex($comment->getCommentedEntity());
    }
}

/**
 * Implements hook_ENTITY_TYPE_insert() for comment entities.
 */
function forum_comment_insert(CommentInterface $comment) {
    if ($comment->getCommentedEntityTypeId() == 'node') {
        \Drupal::service('forum.index_storage')->updateIndex($comment->getCommentedEntity());
    }
}

/**
 * Implements hook_ENTITY_TYPE_delete() for comment entities.
 */
function forum_comment_delete(CommentInterface $comment) {
    if ($comment->getCommentedEntityTypeId() == 'node') {
        \Drupal::service('forum.index_storage')->updateIndex($comment->getCommentedEntity());
    }
}

/**
 * Implements hook_form_BASE_FORM_ID_alter() for \Drupal\taxonomy\VocabularyForm.
 */
function forum_form_taxonomy_vocabulary_form_alter(&$form, FormStateInterface $form_state, $form_id) {
    $vid = \Drupal::config('forum.settings')->get('vocabulary');
    $vocabulary = $form_state->getFormObject()
        ->getEntity();
    if ($vid == $vocabulary->id()) {
        $form['help_forum_vocab'] = [
            '#markup' => t('This is the designated forum vocabulary. Some of the normal vocabulary options have been removed.'),
            '#weight' => -1,
        ];
        // Forum's vocabulary always has single hierarchy. Forums and containers
        // have only one parent or no parent for root items. By default this value
        // is 0.
        $form['hierarchy']['#value'] = VocabularyInterface::HIERARCHY_SINGLE;
        // Do not allow to delete forum's vocabulary.
        $form['actions']['delete']['#access'] = FALSE;
        // Do not allow to change a vid of forum's vocabulary.
        $form['vid']['#disabled'] = TRUE;
    }
}

/**
 * Implements hook_form_FORM_ID_alter() for \Drupal\taxonomy\TermForm.
 */
function forum_form_taxonomy_term_form_alter(&$form, FormStateInterface $form_state, $form_id) {
    $vid = \Drupal::config('forum.settings')->get('vocabulary');
    if (isset($form['vid']['#value']) && $form['vid']['#value'] == $vid) {
        // Hide multiple parents select from forum terms.
        $form['relations']['parent']['#access'] = FALSE;
    }
}

/**
 * Implements hook_form_BASE_FORM_ID_alter() for \Drupal\node\NodeForm.
 */
function forum_form_node_form_alter(&$form, FormStateInterface $form_state, $form_id) {
    $node = $form_state->getFormObject()
        ->getEntity();
    if (isset($node->taxonomy_forums) && !$node->isNew()) {
        $forum_terms = $node->taxonomy_forums;
        // If editing, give option to leave shadows.
        $shadow = count($forum_terms) > 1;
        $form['shadow'] = [
            '#type' => 'checkbox',
            '#title' => t('Leave shadow copy'),
            '#default_value' => $shadow,
            '#description' => t('If you move this topic, you can leave a link in the old forum to the new forum.'),
        ];
        $form['forum_tid'] = [
            '#type' => 'value',
            '#value' => $node->forum_tid,
        ];
    }
    if (isset($form['taxonomy_forums'])) {
        $widget =& $form['taxonomy_forums']['widget'];
        $widget['#multiple'] = FALSE;
        if (empty($widget['#default_value'])) {
            // If there is no default forum already selected, try to get the forum
            // ID from the URL (e.g., if we are on a page like node/add/forum/2, we
            // expect "2" to be the ID of the forum that was requested).
            $requested_forum_id = \Drupal::request()->query
                ->get('forum_id');
            $widget['#default_value'] = is_numeric($requested_forum_id) ? $requested_forum_id : '';
        }
    }
}

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

/**
 * Implements hook_theme_suggestions_HOOK().
 */
function forum_theme_suggestions_forums(array $variables) {
    $suggestions = [];
    $tid = $variables['term']->id();
    // Provide separate template suggestions based on what's being output. Topic
    // ID is also accounted for. Check both variables to be safe then the inverse.
    // Forums with topic IDs take precedence.
    if ($variables['forums'] && !$variables['topics']) {
        $suggestions[] = 'forums__containers';
        $suggestions[] = 'forums__' . $tid;
        $suggestions[] = 'forums__containers__' . $tid;
    }
    elseif (!$variables['forums'] && $variables['topics']) {
        $suggestions[] = 'forums__topics';
        $suggestions[] = 'forums__' . $tid;
        $suggestions[] = 'forums__topics__' . $tid;
    }
    else {
        $suggestions[] = 'forums__' . $tid;
    }
    return $suggestions;
}

/**
 * Prepares variables for forums templates.
 *
 * Default template: forums.html.twig.
 *
 * @param array $variables
 *   An array containing the following elements:
 *   - forums: An array of all forum objects to display for the given taxonomy
 *     term ID. If tid = 0 then all the top-level forums are displayed.
 *   - topics: An array of all the topics in the current forum.
 *   - parents: An array of taxonomy term objects that are ancestors of the
 *     current term ID.
 *   - term: Taxonomy term of the current forum.
 *   - sortby: One of the following integers indicating the sort criteria:
 *     - 1: Date - newest first.
 *     - 2: Date - oldest first.
 *     - 3: Posts with the most comments first.
 *     - 4: Posts with the least comments first.
 *   - forum_per_page: The maximum number of topics to display per page.
 */
function template_preprocess_forums(&$variables) {
    $variables['tid'] = $variables['term']->id();
    if ($variables['forums_defined'] = count($variables['forums']) || count($variables['parents'])) {
        if (!empty($variables['forums'])) {
            $variables['forums'] = [
                '#theme' => 'forum_list',
                '#forums' => $variables['forums'],
                '#parents' => $variables['parents'],
                '#tid' => $variables['tid'],
            ];
        }
        if ($variables['term'] && empty($variables['term']->forum_container->value) && !empty($variables['topics'])) {
            $forum_topic_list_header = $variables['header'];
            $table = [
                '#theme' => 'table__forum_topic_list',
                '#responsive' => FALSE,
                '#attributes' => [
                    'id' => 'forum-topic-' . $variables['tid'],
                ],
                '#header' => [],
                '#rows' => [],
            ];
            if (!empty($forum_topic_list_header)) {
                $table['#header'] = $forum_topic_list_header;
            }
            
            /** @var \Drupal\node\NodeInterface $topic */
            foreach ($variables['topics'] as $id => $topic) {
                $variables['topics'][$id]->icon = [
                    '#theme' => 'forum_icon',
                    '#new_posts' => $topic->new,
                    '#num_posts' => $topic->comment_count,
                    '#comment_mode' => $topic->comment_mode,
                    '#sticky' => $topic->isSticky(),
                    '#first_new' => $topic->first_new,
                ];
                // We keep the actual tid in forum table, if it's different from the
                // current tid then it means the topic appears in two forums, one of
                // them is a shadow copy.
                if ($variables['tid'] != $topic->forum_tid) {
                    $variables['topics'][$id]->moved = TRUE;
                    $variables['topics'][$id]->title = $topic->getTitle();
                    $variables['topics'][$id]->message = Link::fromTextAndUrl(t('This topic has been moved'), Url::fromRoute('forum.page', [
                        'taxonomy_term' => $topic->forum_tid,
                    ]))
                        ->toString();
                }
                else {
                    $variables['topics'][$id]->moved = FALSE;
                    $variables['topics'][$id]->title_link = Link::fromTextAndUrl($topic->getTitle(), $topic->toUrl())
                        ->toString();
                    $variables['topics'][$id]->message = '';
                }
                $forum_submitted = [
                    '#theme' => 'forum_submitted',
                    '#topic' => (object) [
                        'uid' => $topic->getOwnerId(),
                        'name' => $topic->getOwner()
                            ->getDisplayName(),
                        'created' => $topic->getCreatedTime(),
                    ],
                ];
                $variables['topics'][$id]->submitted = \Drupal::service('renderer')->render($forum_submitted);
                $forum_submitted = [
                    '#theme' => 'forum_submitted',
                    '#topic' => $topic->last_reply ?? NULL,
                ];
                $variables['topics'][$id]->last_reply = \Drupal::service('renderer')->render($forum_submitted);
                $variables['topics'][$id]->new_text = '';
                $variables['topics'][$id]->new_url = '';
                if ($topic->new_replies) {
                    $page_number = \Drupal::entityTypeManager()->getStorage('comment')
                        ->getNewCommentPageNumber($topic->comment_count, $topic->new_replies, $topic, 'comment_forum');
                    $query = $page_number ? [
                        'page' => $page_number,
                    ] : NULL;
                    $variables['topics'][$id]->new_text = \Drupal::translation()->formatPlural($topic->new_replies, '1 new post<span class="visually-hidden"> in topic %title</span>', '@count new posts<span class="visually-hidden"> in topic %title</span>', [
                        '%title' => $variables['topics'][$id]->label(),
                    ]);
                    $variables['topics'][$id]->new_url = Url::fromRoute('entity.node.canonical', [
                        'node' => $topic->id(),
                    ], [
                        'query' => $query,
                        'fragment' => 'new',
                    ])
                        ->toString();
                }
                // Build table rows from topics.
                $row = [];
                $row[] = [
                    'data' => [
                        $topic->icon,
                        [
                            '#theme' => 'forum_topic',
                            '#title_link' => $topic->title_link,
                            '#submitted' => $topic->submitted,
                        ],
                    ],
                    'class' => [
                        'forum__topic',
                    ],
                ];
                if ($topic->moved) {
                    $row[] = [
                        'data' => $topic->message,
                        'colspan' => '2',
                    ];
                }
                else {
                    $new_replies = '';
                    if ($topic->new_replies) {
                        $new_replies = '<br /><a href="' . $topic->new_url . '">' . $topic->new_text . '</a>';
                    }
                    $row[] = [
                        'data' => [
                            [
                                '#prefix' => $topic->comment_count,
                                '#markup' => $new_replies,
                            ],
                        ],
                        'class' => [
                            'forum__replies',
                        ],
                    ];
                    $row[] = [
                        'data' => $topic->last_reply,
                        'class' => [
                            'forum__last-reply',
                        ],
                    ];
                }
                $table['#rows'][] = $row;
            }
            $variables['topics_original'] = $variables['topics'];
            $variables['topics'] = $table;
            $variables['topics_pager'] = [
                '#type' => 'pager',
            ];
        }
    }
}

/**
 * Prepares variables for forum list templates.
 *
 * Default template: forum-list.html.twig.
 *
 * @param array $variables
 *   An array containing the following elements:
 *   - forums: An array of all forum objects to display for the given taxonomy
 *     term ID. If tid = 0 then all the top-level forums are displayed.
 *   - parents: An array of taxonomy term objects that are ancestors of the
 *     current term ID.
 *   - tid: Taxonomy term ID of the current forum.
 */
function template_preprocess_forum_list(&$variables) {
    $user = \Drupal::currentUser();
    $row = 0;
    // Sanitize each forum so that the template can safely print the data.
    foreach ($variables['forums'] as $id => $forum) {
        $variables['forums'][$id]->description = [
            '#markup' => $forum->description->value,
        ];
        $variables['forums'][$id]->link = forum_uri($forum);
        $variables['forums'][$id]->name = $forum->label();
        $variables['forums'][$id]->is_container = !empty($forum->forum_container->value);
        $variables['forums'][$id]->zebra = $row % 2 == 0 ? 'odd' : 'even';
        $row++;
        $variables['forums'][$id]->new_text = '';
        $variables['forums'][$id]->new_url = '';
        $variables['forums'][$id]->new_topics = 0;
        $variables['forums'][$id]->old_topics = $forum->num_topics;
        $variables['forums'][$id]->icon_class = 'default';
        $variables['forums'][$id]->icon_title = t('No new posts');
        if ($user->isAuthenticated()) {
            $variables['forums'][$id]->new_topics = \Drupal::service('forum_manager')->unreadTopics($forum->id(), $user->id());
            if ($variables['forums'][$id]->new_topics) {
                $variables['forums'][$id]->new_text = \Drupal::translation()->formatPlural($variables['forums'][$id]->new_topics, '1 new post<span class="visually-hidden"> in forum %title</span>', '@count new posts<span class="visually-hidden"> in forum %title</span>', [
                    '%title' => $variables['forums'][$id]->label(),
                ]);
                $variables['forums'][$id]->new_url = Url::fromRoute('forum.page', [
                    'taxonomy_term' => $forum->id(),
                ], [
                    'fragment' => 'new',
                ])
                    ->toString();
                $variables['forums'][$id]->icon_class = 'new';
                $variables['forums'][$id]->icon_title = t('New posts');
            }
            $variables['forums'][$id]->old_topics = $forum->num_topics - $variables['forums'][$id]->new_topics;
        }
        $forum_submitted = [
            '#theme' => 'forum_submitted',
            '#topic' => $forum->last_post,
        ];
        $variables['forums'][$id]->last_reply = \Drupal::service('renderer')->render($forum_submitted);
    }
    $variables['pager'] = [
        '#type' => 'pager',
    ];
    // Give meaning to $tid for themers. $tid actually stands for term ID.
    $variables['forum_id'] = $variables['tid'];
    unset($variables['tid']);
}

/**
 * Prepares variables for forum icon templates.
 *
 * Default template: forum-icon.html.twig.
 *
 * @param array $variables
 *   An array containing the following elements:
 *   - new_posts: Indicates whether or not the topic contains new posts.
 *   - num_posts: The total number of posts in all topics.
 *   - comment_mode: An integer indicating whether comments are open, closed,
 *     or hidden.
 *   - sticky: Indicates whether the topic is sticky.
 *   - first_new: Indicates whether this is the first topic with new posts.
 */
function template_preprocess_forum_icon(&$variables) {
    $variables['hot_threshold'] = \Drupal::config('forum.settings')->get('topics.hot_threshold');
    if ($variables['num_posts'] > $variables['hot_threshold']) {
        $variables['icon_status'] = $variables['new_posts'] ? 'hot-new' : 'hot';
        $variables['icon_title'] = $variables['new_posts'] ? t('Hot topic, new comments') : t('Hot topic');
    }
    else {
        $variables['icon_status'] = $variables['new_posts'] ? 'new' : 'default';
        $variables['icon_title'] = $variables['new_posts'] ? t('New comments') : t('Normal topic');
    }
    if ($variables['comment_mode'] == CommentItemInterface::CLOSED || $variables['comment_mode'] == CommentItemInterface::HIDDEN) {
        $variables['icon_status'] = 'closed';
        $variables['icon_title'] = t('Closed topic');
    }
    if ($variables['sticky'] == 1) {
        $variables['icon_status'] = 'sticky';
        $variables['icon_title'] = t('Sticky topic');
    }
    $variables['attributes']['title'] = $variables['icon_title'];
}

/**
 * Prepares variables for forum submission information templates.
 *
 * The submission information will be displayed in the forum list and topic
 * list.
 *
 * Default template: forum-submitted.html.twig.
 *
 * @param array $variables
 *   An array containing the following elements:
 *   - topic: The topic object.
 */
function template_preprocess_forum_submitted(&$variables) {
    $variables['author'] = '';
    if (isset($variables['topic']->uid)) {
        $username = [
            '#theme' => 'username',
            '#account' => User::load($variables['topic']->uid),
        ];
        $variables['author'] = \Drupal::service('renderer')->render($username);
    }
    $variables['time'] = isset($variables['topic']->created) ? \Drupal::service('date.formatter')->formatTimeDiffSince($variables['topic']->created) : '';
}

/**
 * Implements hook_migrate_prepare_row().
 */
function forum_migrate_prepare_row(Row $row, MigrateSourceInterface $source, MigrationInterface $migration) {
    $source_plugin = $migration->getSourcePlugin();
    if (is_a($source_plugin, D6Term::class) || is_a($source_plugin, D7Term::class) || is_a($source_plugin, TermEntityTranslation::class)) {
        $connection = $source_plugin->getDatabase();
        if ($connection) {
            if ($connection->schema()
                ->tableExists('variable')) {
                $query = $connection->select('variable', 'v')
                    ->fields('v', [
                    'value',
                ])
                    ->condition('name', 'forum_containers');
                $result = $query->execute()
                    ->fetchCol();
                if ($result) {
                    $forum_container_tids = unserialize($result[0], [
                        'allowed_classes' => FALSE,
                    ]);
                    $current_tid = $row->getSourceProperty('tid');
                    $row->setSourceProperty('is_container', in_array($current_tid, $forum_container_tids));
                }
            }
        }
    }
}

/**
 * Implements hook_migrate_MIGRATION_ID_prepare_row().
 */
function forum_migrate_d7_taxonomy_vocabulary_prepare_row(Row $row, MigrateSourceInterface $source, MigrationInterface $migration) {
    // If the vocabulary being migrated is the one defined in the
    // 'forum_nav_vocabulary' variable, set the 'forum_vocabulary' source
    // property to true so we know this is the vocabulary used by Forum.
    $connection = $migration->getSourcePlugin()
        ->getDatabase();
    if ($connection) {
        if ($connection->schema()
            ->tableExists('variable')) {
            $query = $connection->select('variable', 'v')
                ->fields('v', [
                'value',
            ])
                ->condition('name', 'forum_nav_vocabulary');
            $result = $query->execute()
                ->fetchCol();
            if ($result) {
                $forum_nav_vocabulary = unserialize($result[0], [
                    'allowed_classes' => FALSE,
                ]);
                if ($forum_nav_vocabulary == $row->getSourceProperty('vid')) {
                    $row->setSourceProperty('forum_vocabulary', TRUE);
                }
            }
        }
    }
}

/**
 * Implements hook_migration_plugins_alter().
 */
function forum_migration_plugins_alter(array &$migrations) {
    // Function to append the forum_vocabulary process plugin.
    $merge_forum_vocabulary = function ($process) {
        $process[] = [
            'plugin' => 'forum_vocabulary',
            'machine_name' => 'forums',
        ];
        return $process;
    };
    $merge_forum_field_name = function ($process) {
        $process[] = [
            'plugin' => 'forum_vocabulary',
            'machine_name' => 'taxonomy_forums',
        ];
        return $process;
    };
    foreach ($migrations as $migration_id => $migration) {
        // Add process for forum_nav_vocabulary.
        
        /** @var \Drupal\migrate\Plugin\migrate\source\SqlBase $source_plugin */
        $source_plugin = \Drupal::service('plugin.manager.migration')->createStubMigration($migration)
            ->getSourcePlugin();
        if (is_a($source_plugin, D6Vocabulary::class) || is_a($source_plugin, D6VocabularyPerType::class)) {
            if (isset($migration['process']['vid'])) {
                $migrations[$migration_id]['process']['vid'] = $merge_forum_vocabulary($migration['process']['vid']);
            }
            if (isset($migration['process']['field_name'])) {
                $migrations[$migration_id]['process']['field_name'] = $merge_forum_field_name($migration['process']['field_name']);
            }
        }
        if (is_a($source_plugin, D7Vocabulary::class) && !is_a($source_plugin, D7VocabularyTranslation::class) && !is_a($source_plugin, D7LanguageContentSettingsTaxonomyVocabulary::class)) {
            if (isset($migration['process']['vid'])) {
                $process[] = $migrations[$migration_id]['process']['vid'];
                $migrations[$migration_id]['process']['vid'] = $merge_forum_vocabulary($process);
            }
        }
        // Add process for forum_container.
        if (is_a($source_plugin, D6Term::class) || is_a($source_plugin, D7Term::class) || is_a($source_plugin, TermEntityTranslation::class)) {
            $migrations[$migration_id]['process']['forum_container'] = 'is_container';
        }
    }
}