<?php

final class PhabricatorProjectMoveController
  extends PhabricatorProjectController {

  private $id;

  public function willProcessRequest(array $data) {
    $this->id = $data['id'];
  }

  public function processRequest() {
    $request = $this->getRequest();
    $viewer = $request->getUser();

    $column_phid = $request->getStr('columnPHID');
    $object_phid = $request->getStr('objectPHID');
    $after_phid = $request->getStr('afterPHID');

    $project = id(new PhabricatorProjectQuery())
      ->setViewer($viewer)
      ->requireCapabilities(
        array(
          PhabricatorPolicyCapability::CAN_VIEW,
          PhabricatorPolicyCapability::CAN_EDIT,
        ))
      ->withIDs(array($this->id))
      ->executeOne();
    if (!$project) {
      return new Aphront404Response();
    }

    // NOTE: I'm not requiring EDIT on the object for now, since we require
    // EDIT on the project anyway and this relationship is more owned by the
    // project than the object. Maybe this is worth revisiting eventually.

    $object = id(new PhabricatorObjectQuery())
      ->setViewer($viewer)
      ->withPHIDs(array($object_phid))
      ->executeOne();

    if (!$object) {
      return new Aphront404Response();
    }

    $columns = id(new PhabricatorProjectColumnQuery())
      ->setViewer($viewer)
      ->withProjectPHIDs(array($project->getPHID()))
      ->execute();

    $columns = mpull($columns, null, 'getPHID');
    if (empty($columns[$column_phid])) {
      // User is trying to drop this object into a nonexistent column, just kick
      // them out.
      return new Aphront404Response();
    }

    $edge_type = PhabricatorEdgeConfig::TYPE_OBJECT_HAS_COLUMN;

    $query = id(new PhabricatorEdgeQuery())
      ->withSourcePHIDs(array($object->getPHID()))
      ->withEdgeTypes(array($edge_type))
      ->withDestinationPHIDs(array_keys($columns));

    $query->execute();

    $edge_phids = $query->getDestinationPHIDs();

    $this->rewriteEdges(
      $object->getPHID(),
      $edge_type,
      $column_phid,
      $edge_phids);

    // TODO: We also need to deal with priorities, so far this only gets stuff
    // in the correct column.

    return id(new AphrontAjaxResponse())->setContent(array());
  }

  private function rewriteEdges($src, $edge_type, $dst, array $edges) {
    $viewer = $this->getRequest()->getUser();

    // NOTE: Normally, we expect only one edge to exist, but this works in a
    // general way so it will repair any stray edges.

    $remove = array();
    $edge_missing = true;
    foreach ($edges as $phid) {
      if ($phid == $dst) {
        $edge_missing = false;
      } else {
        $remove[] = $phid;
      }
    }

    $add = array();
    if ($edge_missing) {
      $add[] = $dst;
    }

    if (!$add && !$remove) {
      return;
    }

    $editor = id(new PhabricatorEdgeEditor())
      ->setActor($viewer)
      ->setSuppressEvents(true);

    foreach ($add as $phid) {
      $editor->addEdge($src, $edge_type, $phid);
    }
    foreach ($remove as $phid) {
      $editor->removeEdge($src, $edge_type, $phid);
    }

    $editor->save();
  }

}