<?php

namespace Drupal\workspaces;

use Drupal\Core\Database\Connection;
use Drupal\Core\Entity\EntityTypeManagerInterface;

/**
 * Default implementation of the workspace publisher.
 *
 * @internal
 */
class WorkspacePublisher implements WorkspacePublisherInterface {

  /**
   * The source workspace entity.
   *
   * @var \Drupal\workspaces\WorkspaceInterface
   */
  protected $sourceWorkspace;

  /**
   * The target workspace entity.
   *
   * @var \Drupal\workspaces\WorkspaceInterface
   */
  protected $targetWorkspace;

  /**
   * The entity type manager.
   *
   * @var \Drupal\Core\Entity\EntityTypeManagerInterface
   */
  protected $entityTypeManager;

  /**
   * The database connection.
   *
   * @var \Drupal\Core\Database\Connection
   */
  protected $database;

  /**
   * The workspace association storage.
   *
   * @var \Drupal\workspaces\WorkspaceAssociationStorageInterface
   */
  protected $workspaceAssociationStorage;

  /**
   * Constructs a new WorkspacePublisher.
   *
   * @param \Drupal\Core\Entity\EntityTypeManagerInterface $entity_type_manager
   *   The entity type manager.
   * @param \Drupal\Core\Database\Connection $database
   *   Database connection.
   */
  public function __construct(EntityTypeManagerInterface $entity_type_manager, Connection $database, WorkspaceInterface $source) {
    $this->entityTypeManager = $entity_type_manager;
    $this->database = $database;
    $this->workspaceAssociationStorage = $entity_type_manager->getStorage('workspace_association');
    $this->sourceWorkspace = $source;
    $this->targetWorkspace = $this->entityTypeManager->getStorage('workspace')->load(WorkspaceInterface::DEFAULT_WORKSPACE);
  }

  /**
   * {@inheritdoc}
   */
  public function publish() {
    if ($this->checkConflictsOnTarget()) {
      throw new WorkspaceConflictException();
    }

    $transaction = $this->database->startTransaction();
    try {
      // @todo Handle the publishing of a workspace with a batch operation in
      //   https://www.drupal.org/node/2958752.
      foreach ($this->getDifferringRevisionIdsOnSource() as $entity_type_id => $revision_difference) {
        $entity_revisions = $this->entityTypeManager->getStorage($entity_type_id)
          ->loadMultipleRevisions(array_keys($revision_difference));
        /** @var \Drupal\Core\Entity\EntityInterface|\Drupal\Core\Entity\RevisionableInterface $entity */
        foreach ($entity_revisions as $entity) {
          // When pushing workspace-specific revisions to the default workspace
          // (Live), we simply need to mark them as default revisions.
          // @todo Remove this dynamic property once we have an API for
          //   associating temporary data with an entity:
          //   https://www.drupal.org/node/2896474.
          $entity->_isReplicating = TRUE;
          $entity->isDefaultRevision(TRUE);
          $entity->save();
        }
      }
    }
    catch (\Exception $e) {
      $transaction->rollBack();
      watchdog_exception('workspaces', $e);
      throw $e;
    }

    // Notify the workspace association storage that a workspace has been
    // pushed.
    $this->workspaceAssociationStorage->postPush($this->sourceWorkspace);
  }

  /**
   * {@inheritdoc}
   */
  public function getSourceLabel() {
    return $this->sourceWorkspace->label();
  }

  /**
   * {@inheritdoc}
   */
  public function getTargetLabel() {
    return $this->targetWorkspace->label();
  }

  /**
   * {@inheritdoc}
   */
  public function checkConflictsOnTarget() {
    // Nothing to do for now, we can not get to a conflicting state because an
    // entity which is being edited in a workspace can not be edited in any
    // other workspace.
  }

  /**
   * {@inheritdoc}
   */
  public function getDifferringRevisionIdsOnTarget() {
    $target_revision_difference = [];

    $tracked_entities = $this->workspaceAssociationStorage->getTrackedEntities($this->sourceWorkspace->id());
    foreach ($tracked_entities as $entity_type_id => $tracked_revisions) {
      $entity_type = $this->entityTypeManager->getDefinition($entity_type_id);

      // Get the latest revision IDs for all the entities that are tracked by
      // the source workspace.
      $query = $this->entityTypeManager
        ->getStorage($entity_type_id)
        ->getQuery()
        ->condition($entity_type->getKey('id'), $tracked_revisions, 'IN')
        ->latestRevision();
      $result = $query->execute();

      // Now we compare the revision IDs which are tracked by the source
      // workspace to the latest revision IDs of those entities and the
      // difference between these two arrays gives us all the entities which
      // have been modified on the target.
      if ($revision_difference = array_diff_key($result, $tracked_revisions)) {
        $target_revision_difference[$entity_type_id] = $revision_difference;
      }
    }

    return $target_revision_difference;
  }

  /**
   * {@inheritdoc}
   */
  public function getDifferringRevisionIdsOnSource() {
    // Get the Workspace association revisions which haven't been pushed yet.
    return $this->workspaceAssociationStorage->getTrackedEntities($this->sourceWorkspace->id());
  }

  /**
   * {@inheritdoc}
   */
  public function getNumberOfChangesOnTarget() {
    $total_changes = $this->getDifferringRevisionIdsOnTarget();
    return count($total_changes, COUNT_RECURSIVE) - count($total_changes);
  }

  /**
   * {@inheritdoc}
   */
  public function getNumberOfChangesOnSource() {
    $total_changes = $this->getDifferringRevisionIdsOnSource();
    return count($total_changes, COUNT_RECURSIVE) - count($total_changes);
  }

}