Issue #3264570 by Wim Leers: Fix D7 → D8|9 migration: version 3 of the...

    // Add mapping from filter_markdown to markdown for D7 migrations.

    $migration['process']['filters']['process']['id']['map']['filter_markdown'] = 'markdown';

    // Copied from https://www.drupal.org/project/migmag.

    // @see \Drupal\migmag\Utility\MigMagMigrationUtility::getAssociativeMigrationProcess()

    $get_associative_migration_process = function($process_pipeline): array {

      if (is_string($process_pipeline)) {

        return [['plugin' => 'get', 'source' => $process_pipeline]];

      }

      elseif (array_key_exists('plugin', $process_pipeline)) {

        $process_pipeline = [$process_pipeline];

      }

      return $process_pipeline;

    };

    // We have to generate settings for the markdown filter.

    $filter_plugin_settings_processes = $get_associative_migration_process($migrations['d7_filter_format']['process']['filters']['process']['settings']);

    $filter_plugin_settings_processes[] = [

      'plugin' => 'markdown_settings_generator',

    ];

    $migrations['d7_filter_format']['process']['filters']['process']['settings'] = $filter_plugin_settings_processes;

    // markdown_settings_generator needs to know the other filters that

    // enabled in order to generate valid settings.

    $migrations['d7_filter_format']['process']['filters']['include_source'] = TRUE;

    $migrations['d7_filter_format']['process']['filters']['source_key'] = 'source_format';

  }

}

<?php

namespace Drupal\markdown\Plugin\migrate\process;

use Drupal\migrate\ProcessPluginBase;

use Drupal\migrate\MigrateExecutableInterface;

use Drupal\migrate\Row;

/**

 * @MigrateProcessPlugin(

 *   id = "markdown_settings_generator",

 *   handle_multiples = TRUE

 * )

 */

class MarkdownSettingsGenerator extends ProcessPluginBase {

  /**

   * {@inheritdoc}

   */

  public function transform($value, MigrateExecutableInterface $migrate_executable, Row $row, $destination_property) {

    if ($row->getDestinationProperty('id') === 'markdown') {

      $parser_manager = \Drupal::service('plugin.manager.markdown.parser');

      // The markdown module during installation will automatically detect the

      // available parsers and select a default.

      // @see markdown_requirements()

      // @todo Add support for generating valid configuration for other parsers?

      if ($parser_manager->getDefaultParser()->getPluginId() === 'commonmark') {

        // @see markdown_migration_plugins_alter()

        $source_format = $row->getSourceProperty('source_format');

        $enabled_filters = array_column($source_format['filters'], 'name');

        $value = [

          'id' => 'commonmark',

          'enabled' => TRUE,

          'render_strategy' => [

            'type' => 'filter_output',

            'custom_allowed_html' => '',

            'plugins' => [

              'commonmark' => TRUE,

              // Footnotes were supported by default in the D7 version.

              'commonmark-footnotes' => TRUE,

              // Enable Markdown support for specific filters if the filters are

              // enabled.

              'filter_align' => in_array('filter_align', $enabled_filters),

              'filter_caption' => in_array('filter_caption', $enabled_filters),

              'media_embed' => in_array('filter_caption', $enabled_filters),

            ],

          ],

          'settings' => [

            'html_input' => 'allow',

            'max_nesting_level' => 0,

          ],

          'extensions' => [

            // Footnotes were supported by default in the D7 version.

            [

              'id' => 'commonmark-footnotes',

              'enabled' => TRUE,

              'weight' => 0,

              'settings' => [

                'container_add_hr' => TRUE,

              ],

            ],

          ],

          'override' => TRUE,

        ];

      }

    }

    return $value;

  }

}