$ phabricator/ php -f reset-mentions.php T123

<?php

require_once 'scripts/init/init-script.php';

$args = id(new PhutilArgumentParser($argv))
  ->parseStandardArguments()
  ->parse(
    array(
      array(
        'name' => 'object',
        'wildcard' => true,
      )
    ));

$object_names = $args->getArg('object');
if (count($object_names) !== 1) {
  throw new PhutilArgumentUsageException(
    pht(
      'Specify exactly one object to reset mentions on.'));
}

$viewer = PhabricatorUser::getOmnipotentUser();
$query = id(new PhabricatorObjectQuery())
  ->setViewer($viewer)
  ->withNames($object_names);
$query->execute();

$objects = $query->getNamedResults();
foreach ($object_names as $object_name) {
  if (!isset($objects[$object_name])) {
    throw new PhutilArgumentUsageException(
      pht(
        'Unable to load object "%s".',
        $object_name));
  }
}

$mention_type = PhabricatorObjectMentionsObjectEdgeType::EDGECONST;

foreach ($objects as $object) {
  $okay = false;
  if ($object instanceof ManiphestTask) {
    $okay = true;
  }

  if (!$okay) {
    throw new PhutilArgumentUsageException(
      pht(
        'This script can only reset mentions on tasks.'));
  }

  $old_phids = PhabricatorEdgeQuery::loadDestinationPHIDs(
    $object->getPHID(),
    $mention_type);

  $remarkup_blocks = array();
  $remarkup_blocks[] = $object->getDescription();

  $custom_fields = PhabricatorCustomField::getObjectFields(
    $object,
    PhabricatorCustomField::ROLE_APPLICATIONTRANSACTIONS);

  $custom_fields
    ->setViewer($viewer)
    ->readFieldsFromStorage($object);

  foreach ($custom_fields->getFields() as $custom_field) {
    if ($custom_field instanceof ManiphestConfiguredCustomField) {
      $proxy = $custom_field->getProxy();
      if ($proxy instanceof PhabricatorStandardCustomFieldRemarkup) {
        $remarkup_blocks[] = $custom_field->getValueForStorage();
      }
    }
  }

  $xactions = id(new ManiphestTransactionQuery())
    ->setViewer($viewer)
    ->withObjectPHIDs(array($object->getPHID()))
    ->needComments(true)
    ->execute();

  foreach ($xactions as $xaction) {
    if ($xaction->hasComment()) {
      $remarkup_blocks[] = $xaction->getComment()->getContent();
    }
  }

  $engine = PhabricatorMarkupEngine::getEngine('extract');
  $engine->setConfig('viewer', $viewer);

  $new_phids = array();
  foreach ($remarkup_blocks as $remarkup_block) {
    $engine->markupText($remarkup_block);

    $new_phids += $engine->getTextMetadata(
      PhabricatorMentionRemarkupRule::KEY_MENTIONED,
      array());

    $new_phids += $engine->getTextMetadata(
      PhabricatorObjectRemarkupRule::KEY_MENTIONED_OBJECTS,
      array());
  }

  $old_phids = array_fuse($old_phids);
  $new_phids = array_fuse($new_phids);

  $all_phids = $old_phids + $new_phids;
  $add_phids = array_diff_key($new_phids, $old_phids);
  $rem_phids = array_diff_key($old_phids, $new_phids);
  $hold_phids = array_intersect_key($old_phids, $new_phids);

  $handles = $viewer->loadHandles($all_phids);
  $handles = iterator_to_array($handles);

  if ($rem_phids) {
    echo tsprintf(
      "%s\n\n%B\n",
      pht('These mentions will be removed:'),
      reset_mentions_format_handle_list(
        array_select_keys($handles, $rem_phids)));
  } else {
    echo tsprintf(
      "%s\n",
      pht('No mentions will be removed.'));
  }

  if ($add_phids) {
    echo tsprintf(
      "%s\n\n%B\n",
      pht('These mentions will be added:'),
      reset_mentions_format_handle_list(
        array_select_keys($handles, $add_phids)));
  } else {
    echo tsprintf(
      "%s\n",
      pht('No mentions will be added.'));
  }

  if ($hold_phids) {
    echo tsprintf(
      "%s\n\n%B\n",
      pht('These mentions will not be affected:'),
      reset_mentions_format_handle_list(
        array_select_keys($handles, $hold_phids)));
  }

  if (!$add_phids && !$rem_phids) {
    echo tsprintf(
      "%s\n",
      pht('Nothing to do.'));
    return 0;
  }

  $prompt = pht('Apply these changes?');
  if (!phutil_console_confirm($prompt)) {
    throw new PhutilArgumentUsageException(
      pht(
        'User aborted the workflow.'));
  }

  $editor = new PhabricatorEdgeEditor();

  foreach ($add_phids as $add_phid) {
    $editor->addEdge(
      $object->getPHID(),
      $mention_type,
      $add_phid);
  }

  foreach ($rem_phids as $rem_phid) {
    $editor->removeEdge(
      $object->getPHID(),
      $mention_type,
      $rem_phid);
  }

  $editor->save();

  echo tsprintf(
    "%s\n",
    pht('Saved changes.'));
}


function reset_mentions_format_handle_list(array $handles) {
  $result = array();

  foreach ($handles as $phid => $handle) {
    $result[] = tsprintf(
      "    - [%s] %s\n",
      $phid,
      $handle->getFullName());
  }

  return implode('', $result);
}