WIP - expand/collapse block content.

migrations/layout_builder/uw_layout_builder_sections_expandable.yml

+id: uw_layout_builder_sections_expandable
+label: Layout builder sections (expandable groups)
+migration_tags:
+  - Drupal 7
+  - Content
+  - Layout Builder
+deriver: Drupal\uw_migrate\Plugin\migrate\UwLayoutBuilderDeriver
+source:
+  plugin: uw_layout
+  expandable: true
+  fields:
+    - entity_id
+  id_fields:
+    entity_id:
+      type: integer
+    delta:
+      type: integer
+  ignore_map: true
+  conditions:
+    - field: t.entity_id
+      value: 82
+process:
+  nid:
+    - plugin: migration_lookup
+      migration: uw_ct_expandable_group
+      source:
+        - entity_id
+        - delta
+      no_stub: true
+    - plugin: skip_on_empty
+      method: row
+      message: 'Destination node was not found.'
+  layout: layout
+  layout_settings: layout_settings
+  section: delta
+destination:
+  plugin: layout_builder:section
+migration_dependencies:
+  optional: {}

migrations/node/uw_ct_expandable_group.yml

+id: uw_ct_expandable_group
+label: 'Expand/collapse groups'
+migration_tags:
+  - Drupal 7
+  - Content
+deriver: Drupal\uw_migrate\Plugin\migrate\UwContentFieldsDeriver
+source:
+  plugin: uw_expandable_group
+  fields:
+    - entity_id
+  id_fields:
+    entity_id:
+      type: integer
+    delta:
+      type: integer
+  ignore_map: true
+process:
+  title:
+    plugin: callback
+    callable: strip_tags
+    source: title
+  uid:
+    - plugin: migration_lookup
+      migration: uw_user
+      source: node_uid
+      no_stub: true
+    - plugin: default_value
+      default_value: 0
+  langcode:
+    plugin: default_value
+    source: language
+    default_value: "und"
+  status: status
+  moderation_state:
+    plugin: static_map
+    source: status
+    map:
+      '0': draft
+      '1': published
+    default_value: draft
+  created: created
+  changed: changed
+  promote: promote
+  sticky: sticky
+  revision_uid:
+    - plugin: migration_lookup
+      migration: uw_user
+      source: revision_uid
+      no_stub: true
+    - plugin: default_value
+      default_value: 0
+  revision_log: log
+  revision_timestamp: timestamp
+destination:
+  plugin: entity:node
+  default_bundle: uw_ct_expand_collapse_group

src/Plugin/migrate/UwContentFieldsDeriver.php

@@ -73,9 +73,22 @@ class UwContentFieldsDeriver extends DeriverBase implements ContainerDeriverInte
         $values['process']['pseudo_field_uw_cta_details']['migration'] = 'uw_para_call_to_action:' . $field_name;
       }
 
-      /** @var \Drupal\migrate\Plugin\MigrationInterface $migration */
-      $migration = \Drupal::service('plugin.manager.migration')->createStubMigration($values);
-      $this->derivatives[$field_name] = $migration->getPluginDefinition();
+      // For some migrations, we have to split migration into 2 groups.
+      if (in_array($base_plugin_definition['id'], ['uw_cbl_blockquote', 'uw_cbl_copy_text'])) {
+        // Expandable groups content.
+        $values['source']['expandable'] = FALSE;
+        $migration = \Drupal::service('plugin.manager.migration')->createStubMigration($values);
+        $this->derivatives[$field_name] = $migration->getPluginDefinition();
+
+        // Non-expandable groups content.
+        $values['source']['expandable'] = TRUE;
+        $migration = \Drupal::service('plugin.manager.migration')->createStubMigration($values);
+        $this->derivatives[$field_name . '_expandable'] = $migration->getPluginDefinition();
+      }
+      else {
+        $migration = \Drupal::service('plugin.manager.migration')->createStubMigration($values);
+        $this->derivatives[$field_name] = $migration->getPluginDefinition();
+      }
     }
 
     return $this->derivatives;

src/Plugin/migrate/UwLayoutBuilderDeriver.php

@@ -96,7 +96,9 @@ class UwLayoutBuilderDeriver extends DeriverBase implements ContainerDeriverInte
       $values['source']['fields'][] = $value_column;
 
       // Specify content migrations.
-      $values['process']['nid'][0]['migration'] = $data['content_migrations'];
+      if ($values['process']['nid'][0]['migration'] !== 'placeholder') {
+        $values['process']['nid'][0]['migration'] = $data['content_migrations'];
+      }
       $values['migration_dependencies']['optional'] += $data['content_migrations'];
 
       if (isset($values['process']['bid'])) {

src/Plugin/migrate/source/UwContentComplete.php

@@ -23,10 +23,11 @@ class UwContentComplete extends UwEmbeddedContent {
     $iterator = parent::initializeIterator();
     $content_col = $this->configuration['content_column'];
     $format_col = $this->configuration['format_column'] ?? str_replace('value', 'format', $content_col);
+    $expandable = $this->configuration['expandable'];
     $new_rows = [];
 
     foreach ($iterator as $row) {
-      $layout_sections = $this->parser->getLayoutItems($row[$content_col]);
+      $layout_sections = $this->parser->getLayoutItems($row[$content_col], $expandable);
 
       $delta = 0;
       foreach ($layout_sections as $section_delta => $section) {

src/Plugin/migrate/source/UwExpandableGroups.php

+<?php
+
+namespace Drupal\uw_migrate\Plugin\migrate\source;
+
+/**
+ * Source plugin for retrieving expand/collapse groups from content.
+ *
+ * @MigrateSource(
+ *   id = "uw_expandable_group",
+ *   source_module = "system"
+ * )
+ */
+class UwExpandableGroups extends UwEmbeddedContent {
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function getItems($content) {
+    return $this->parser->getExpandableGroups($content);
+  }
+
+}

src/Plugin/migrate/source/UwLayout.php

@@ -22,10 +22,12 @@ class UwLayout extends UwEmbeddedContent {
   protected function initializeIterator() {
     $iterator = parent::initializeIterator();
     $content_col = $this->configuration['content_column'];
+    $expandable = $this->configuration['expandable'];
     $new_rows = [];
 
     foreach ($iterator as $row) {
-      $layout_sections = $this->parser->getLayoutItems($row[$content_col]);
+      $original_content = $row[$content_col];
+      $layout_sections = $this->parser->getLayoutItems($original_content, $expandable);
 
       foreach ($layout_sections as $delta => $section) {
         $new_row = $row;

src/UwContentParser.php

@@ -12,6 +12,8 @@ class UwContentParser {
 
   use UwMigrateTrait;
 
+  const EXPANDABLE_XPATH = "//div[contains(@class, 'expandable')][not(ancestor::div[contains(@class, 'expandable')])]";
+
   /**
    * Returns a list of content sections for the given HTML string.
    *
@@ -34,7 +36,7 @@ class UwContentParser {
       $parts = explode($delimiter, $content);
 
       // Append previous section if there is some meaningful content there.
-      if ($this->clean($parts[0])) {
+      if ($this->clean($parts[0], TRUE, TRUE)) {
         $sections[] = $parts[0];
       }
 
@@ -167,12 +169,60 @@ class UwContentParser {
     return $result;
   }
 
+  public function getExpandableGroups($content) {
+    $results = [];
+    $crawler = new Crawler($content);
+    // Get all <div class="expandable"></div> items, that are not children of
+    // other expandable divs.
+    $groups = $crawler->filterXPath(static::EXPANDABLE_XPATH);
+
+    foreach ($groups as $delta => $element) {
+      $expandable_group = new Crawler($element);
+      $title = $expandable_group->filterXPath('(//h2)[1]');
+      $content = $expandable_group->filterXPath("//div[@class='expandable-content']");
+
+      $results[] = [
+        'delta' => $delta,
+        // First occurrence of h2 title is supposed to be a group title.
+        'title' => $title ? $this->getInnerHtml($title->getNode(0)) : '',
+        'content' => $content ? $this->getInnerHtml($content->getNode(0)) : '',
+      ];
+    }
+    return $results;
+  }
+
   /**
    * Returns a list of formatted content items and their layout settings.
    */
-  public function getLayoutItems($content) {
-    $result = [];
-    $layout_sections = $this->getContentSections($content, $this->getLayoutsRegex());
+  public function getLayoutItems($content, $expandable = NULL) {
+    $result = $layout_sections = [];
+
+    // If "expandable" value is provided, then either get expandable content
+    // or everything else, which is outside of those groups.
+    if ($expandable !== NULL) {
+      $crawler = new Crawler($content);
+      if ($expandable) {
+        // Get only "expandable" sections.
+        foreach ($crawler->filterXPath(static::EXPANDABLE_XPATH) as $group_delta => $element) {
+          $expandable_group = new Crawler($element);
+          $group_content = $expandable_group->filterXPath("//div[@class='expandable-content']");
+          $layout_sections[$group_delta] = $this->getContentSections($this->getInnerHtml($group_content->getNode(0)), $this->getLayoutsRegex());
+        }
+      }
+      // Remove "expandable" content sections.
+      else {
+        $crawler->filterXPath("//div[contains(@class, 'expandable')]")->each(function ($crawler) {
+          foreach ($crawler as $node) {
+            $node->parentNode->removeChild($node);
+          }
+        });
+        $content = $crawler->outerHtml();
+        $layout_sections = $this->getContentSections($content, $this->getLayoutsRegex());
+      }
+    }
+    else {
+      $layout_sections = $this->getContentSections($content, $this->getLayoutsRegex());
+    }
 
     /** @var \DOMElement $element */
     $section = [];
@@ -180,7 +230,7 @@ class UwContentParser {
       $layout_data = $this->getSectionData($layout_section);
 
       // Skip if section content is empty.
-      if (empty($this->clean($layout_section))) {
+      if (empty($this->clean($layout_section, TRUE, TRUE))) {
         continue;
       }
 
@@ -303,11 +353,15 @@ class UwContentParser {
   /**
    * Removes HTML tags and whitespaces from HTML snippet.
    */
-  protected function clean($content, $strip_tags = TRUE) {
+  protected function clean($content, $strip_tags = TRUE, $strip_whitespaces = FALSE) {
     // Replace a commonly used non-breaking space: &nbsp.
     $content = str_replace('&nbsp;', ' ', $content);
     // Remove other special characters.
     $content = preg_replace("/&#?[a-z0-9]{2,8};/i", '', $content);
+    // Remove all non-printable characters.
+    if ($strip_whitespaces) {
+      $content = preg_replace('/[\x00-\x1F\x7F]/u', '', $content);
+    }
 
     if ($strip_tags) {
       $allowed_tags = array_merge([
@@ -350,6 +404,10 @@ class UwContentParser {
     return trim($innerHTML);
   }
 
+  protected function getOuterHtml(\DOMElement $element) {
+    return $element->ownerDocument->saveHTML($element);
+  }
+
   /**
    * Parses tweet parts from given embedded tweet code.
    */

src/UwMigrateTrait.php

@@ -243,8 +243,25 @@ trait UwMigrateTrait {
    * @see https://regex101.com/r/2FvaRw/1
    */
   public function getLayoutsRegex() {
-    $layouts = implode('|', array_keys($this->getLayoutMapping()));
-    return '/<div[^>]*class="[^"]*(' . $layouts . ')[^"]*"[^>]*>[\w\W]*<\/div>/Us';
+    $classes = implode('|', array_keys($this->getLayoutMapping()));
+    return '/<div[^>]*class="[^"]*(' . $classes . ')[^"]*"[^>]*>[\w\W]*<\/div>/Us';
+  }
+
+  public function getLayoutsXpath($expandable = FALSE) {
+    $classes = array_map(function ($class) {
+      return "contains (@class, '" . $class . "')";
+    }, array_keys($this->getLayoutMapping()));
+
+    $xpath = 'div[' . implode(' or ', $classes) . ']';
+
+    // Select everything, that are not inside "expandable" items.
+    if ($expandable) {
+      $xpath = "//div[@class='expandable']//{$xpath}";
+    }
+    else {
+      $xpath = "{$xpath}[not(ancestor::div[@class='expandable'])]";
+    }
+    return $xpath;
   }
 
 }