<?php

/**
 * @extends PhabricatorCursorPagedPolicyAwareQuery<PhabricatorFeedStoryData>
 */
final class PhabricatorFeedQuery
  extends PhabricatorCursorPagedPolicyAwareQuery {

  private $filterPHIDs;
  private $chronologicalKeys;
  private $rangeMin;
  private $rangeMax;

  public function withFilterPHIDs(array $phids) {
    $this->filterPHIDs = $phids;
    return $this;
  }

  public function withChronologicalKeys(array $keys) {
    $this->chronologicalKeys = $keys;
    return $this;
  }

  /**
   * @param int|null $range_min Minimum epoch value of feed stories
   * @param int|null $range_max Maximum epoch value of feed stories
   */
  public function withEpochInRange($range_min, $range_max) {
    if ($range_min && $range_max && $range_min > $range_max) {
      throw new PhutilArgumentUsageException(
        pht('Feed query minimum range must be lower than maximum range.'));
    }
    $this->rangeMin = $range_min;
    $this->rangeMax = $range_max;
    return $this;
  }

  public function newResultObject() {
    return new PhabricatorFeedStoryData();
  }

  protected function loadPage() {
    // NOTE: We return raw rows from this method, which is a little unusual.
    return $this->loadStandardPageRows($this->newResultObject());
  }

  protected function willFilterPage(array $data) {
    $stories = PhabricatorFeedStory::loadAllFromRows($data, $this->getViewer());

    foreach ($stories as $key => $story) {
      if (!$story->isVisibleInFeed()) {
        unset($stories[$key]);
      }
    }

    return $stories;
  }

  protected function buildJoinClauseParts(AphrontDatabaseConnection $conn) {
    $joins = parent::buildJoinClauseParts($conn);

    // NOTE: We perform this join unconditionally (even if we have no filter
    // PHIDs) to omit rows which have no story references. These story data
    // rows are notifications or realtime alerts.

    $ref_table = new PhabricatorFeedStoryReference();
    $joins[] = qsprintf(
      $conn,
      'JOIN %T ref ON ref.chronologicalKey = story.chronologicalKey',
      $ref_table->getTableName());

    return $joins;
  }

  protected function buildWhereClauseParts(AphrontDatabaseConnection $conn) {
    $where = parent::buildWhereClauseParts($conn);

    if ($this->filterPHIDs !== null) {
      $where[] = qsprintf(
        $conn,
        'ref.objectPHID IN (%Ls)',
        $this->filterPHIDs);
    }

    if ($this->chronologicalKeys !== null) {
      // NOTE: We can't use "%d" to format these large integers on 32-bit
      // systems. Historically, we formatted these into integers in an
      // awkward way because MySQL could sometimes (?) fail to use the proper
      // keys if the values were formatted as strings instead of integers.

      // After the "qsprintf()" update to use PhutilQueryString, we can no
      // longer do this in a sneaky way. However, the MySQL key issue also
      // no longer appears to reproduce across several systems. So: just use
      // strings until problems turn up?

      $where[] = qsprintf(
        $conn,
        'ref.chronologicalKey IN (%Ls)',
        $this->chronologicalKeys);
    }

    // NOTE: We may not have 64-bit PHP, so do the shifts in MySQL instead.
    // From EXPLAIN, it appears like MySQL is smart enough to compute the
    // result and make use of keys to execute the query.

    if ($this->rangeMin !== null) {
      $where[] = qsprintf(
        $conn,
        'ref.chronologicalKey >= (%d << 32)',
        $this->rangeMin);
    }

    if ($this->rangeMax !== null) {
      $where[] = qsprintf(
        $conn,
        'ref.chronologicalKey < (%d << 32)',
        $this->rangeMax);
    }

    return $where;
  }

  protected function buildGroupClause(AphrontDatabaseConnection $conn) {
    if ($this->filterPHIDs !== null) {
      return qsprintf($conn, 'GROUP BY ref.chronologicalKey');
    } else {
      return qsprintf($conn, 'GROUP BY story.chronologicalKey');
    }
  }

  protected function getDefaultOrderVector() {
    return array('key');
  }

  public function getBuiltinOrders() {
    return array(
      'newest' => array(
        'vector' => array('key'),
        'name' => pht('Creation (Newest First)'),
        'aliases' => array('created'),
      ),
      'oldest' => array(
        'vector' => array('-key'),
        'name' => pht('Creation (Oldest First)'),
      ),
    );
  }

  public function getOrderableColumns() {
    $table = ($this->filterPHIDs ? 'ref' : 'story');
    return array(
      'key' => array(
        'table' => $table,
        'column' => 'chronologicalKey',
        'type' => 'string',
        'unique' => true,
      ),
    );
  }

  protected function applyExternalCursorConstraintsToQuery(
    PhabricatorCursorPagedPolicyAwareQuery $subquery,
    $cursor) {
    $subquery->withChronologicalKeys(array($cursor));
  }

  protected function newExternalCursorStringForResult($object) {
    return $object->getChronologicalKey();
  }

  protected function newPagingMapFromPartialObject($object) {
    // This query is unusual, and the "object" is a raw result row.
    return array(
      'key' => $object['chronologicalKey'],
    );
  }

  protected function getPrimaryTableAlias() {
    return 'story';
  }

  public function getQueryApplicationClass() {
    return PhabricatorFeedApplication::class;
  }

}