<?php

/**
 * @file
 * Provides enhancements for implementing and managing migrations.
 */

use Drupal\migrate\Plugin\MigrationInterface;
use Drupal\migrate\Plugin\MigrateSourceInterface;
use Drupal\migrate\Row;
use Drupal\migrate_plus\Entity\MigrationGroup;
use Drupal\migrate_plus\Event\MigrateEvents;
use Drupal\migrate_plus\Event\MigratePrepareRowEvent;

/**
 * Implements hook_migration_plugins_alter().
 */
function migrate_plus_migration_plugins_alter(array &$migrations) {
  /** @var \Drupal\migrate\Plugin\MigrationInterface $migration */
  foreach ($migrations as $id => $migration) {
    // Add the default class where empty.
    if (empty($migration['class'])) {
      $migrations[$id]['class'] = 'Drupal\migrate\Plugin\Migration';
    }

    // For derived configuration entity-based migrations, strip the deriver
    // prefix so we can reference migrations by the IDs they specify (i.e.,
    // the migration that specifies "id: temp" can be referenced as "temp"
    // rather than "migration_config_deriver:temp").
    $prefix = 'migration_config_deriver:';
    if (strpos($id, $prefix) === 0) {
      $new_id = substr($id, strlen($prefix));
      $migrations[$new_id] = $migrations[$id];
      unset($migrations[$id]);
      $id = $new_id;
    }

    // Integrate shared group configuration into the migration.
    if (empty($migration['migration_group'])) {
      $migration['migration_group'] = 'default';
    }
    $group = MigrationGroup::load($migration['migration_group']);
    if (empty($group)) {
      // If the specified group does not exist, create it. Provide a little more
      // for the 'default' group.
      $group_properties = [];
      $group_properties['id'] = $migration['migration_group'];
      if ($migration['migration_group'] == 'default') {
        $group_properties['label'] = 'Default';
        $group_properties['description'] = 'A container for any migrations not explicitly assigned to a group.';
      }
      else {
        $group_properties['label'] = $group_properties['id'];
        $group_properties['description'] = '';
      }
      $group = MigrationGroup::create($group_properties);
      $group->save();
    }
    $shared_configuration = $group->get('shared_configuration');
    if (empty($shared_configuration)) {
      continue;
    }
    foreach ($shared_configuration as $key => $group_value) {
      $migration_value = $migration[$key];
      // Where both the migration and the group provide arrays, replace
      // recursively (so each key collision is resolved in favor of the
      // migration).
      if (is_array($migration_value) && is_array($group_value)) {
        $merged_values = array_replace_recursive($group_value, $migration_value);
        $migrations[$id][$key] = $merged_values;
      }
      // Where the group provides a value the migration doesn't, use the group
      // value.
      elseif (is_null($migration_value)) {
        $migrations[$id][$key] = $group_value;
      }
      // Otherwise, the existing migration value overrides the group value.
    }
  }
}

/**
 * Implements hook_migrate_prepare_row().
 */
function migrate_plus_migrate_prepare_row(Row $row, MigrateSourceInterface $source, MigrationInterface $migration) {
  \Drupal::service('event_dispatcher')->dispatch(MigrateEvents::PREPARE_ROW, new MigratePrepareRowEvent($row, $source, $migration));
}