<?
class Artists {
  /**
   * Given an array of GroupIDs, return their associated artists.
   *
   * @param array $GroupIDs
   * @return an array of the following form:
   *   GroupID => {
   *    [ArtistType] => {
   *      id, name, aliasid
   *    }
   *  }
   * ArtistType is an int. It can be:
   * 1 => Main artist
   * 2 => Guest artist
   * 4 => Composer
   * 5 => Conductor
   * 6 => DJ
   */
  public static function get_artists($GroupIDs) {
    $Results = array();
    $DBs = array();
    foreach ($GroupIDs as $GroupID) {
      if (!is_number($GroupID)) {
        continue;
      }
      $Artists = G::$Cache->get_value('groups_artists_'.$GroupID);
      if (is_array($Artists)) {
        $Results[$GroupID] = $Artists;
      } else {
        $DBs[] = $GroupID;
      }
    }
    if (count($DBs) > 0) {
      $IDs = implode(',', $DBs);
      if (empty($IDs)) {
        $IDs = "null";
      }
      $QueryID = G::$DB->get_query_id();
      G::$DB->query("
        SELECT ta.GroupID,
          ta.ArtistID,
          ag.Name
        FROM torrents_artists AS ta
          JOIN artists_group AS ag ON ta.ArtistID = ag.ArtistID
        WHERE ta.GroupID IN ($IDs)
        ORDER BY ta.GroupID ASC,
          ag.Name ASC;");
      while (list($GroupID, $ArtistID, $ArtistName) = G::$DB->next_record(MYSQLI_BOTH, false)) {
        $Results[$GroupID][] = array('id' => $ArtistID, 'name' => $ArtistName);
        $New[$GroupID][] = array('id' => $ArtistID, 'name' => $ArtistName);
      }
      G::$DB->set_query_id($QueryID);
      foreach ($DBs as $GroupID) {
        if (isset($New[$GroupID])) {
          G::$Cache->cache_value('groups_artists_'.$GroupID, $New[$GroupID]);
        }
        else {
          G::$Cache->cache_value('groups_artists_'.$GroupID, array());
        }
      }
      $Missing = array_diff($GroupIDs, array_keys($Results));
      if (!empty($Missing)) {
        $Results += array_fill_keys($Missing, array());
      }
    }
    return $Results;
  }


  /**
   * Convenience function for get_artists, when you just need one group.
   *
   * @param int $GroupID
   * @return array - see get_artists
   */
  public static function get_artist($GroupID) {
    $Results = Artists::get_artists(array($GroupID));
    return $Results[$GroupID];
  }


  /**
   * Format an array of artists for display.
   * TODO: Revisit the logic of this, see if we can helper-function the copypasta.
   *
   * @param array Artists an array of the form output by get_artists
   * @param boolean $MakeLink if true, the artists will be links, if false, they will be text.
   * @param boolean $IncludeHyphen if true, appends " - " to the end.
   * @param $Escape if true, output will be escaped. Think carefully before setting it false.
   */
  public static function display_artists($Artists, $MakeLink = true, $IncludeHyphen = true, $Escape = true) {
    if (!empty($Artists)) {
      $ampersand = ($Escape) ? ' &amp; ' : ' & ';
      $link = '';

      switch(count($Artists)) {
        case 0:
          break;
        case 3:
          $link .= Artists::display_artist($Artists[2], $MakeLink, $Escape). ", ";
        case 2:
          $link .= Artists::display_artist($Artists[1], $MakeLink, $Escape). ", ";
        case 1:
          $link .= Artists::display_artist($Artists[0], $MakeLink, $Escape).($IncludeHyphen?' – ':'');
          break;
        default:
          $link = "Various".($IncludeHyphen?' – ':'');
      }

      return $link;
    } else {
      return '';
    }
  }


  /**
   * Formats a single artist name.
   *
   * @param array $Artist an array of the form ('id'=>ID, 'name'=>Name)
   * @param boolean $MakeLink If true, links to the artist page.
   * @param boolean $Escape If false and $MakeLink is false, returns the unescaped, unadorned artist name.
   * @return string Formatted artist name.
   */
  public static function display_artist($Artist, $MakeLink = true, $Escape = true) {
    if ($MakeLink && !$Escape) {
      error('Invalid parameters to Artists::display_artist()');
    } elseif ($MakeLink) {
      return '<a href="artist.php?id='.$Artist['id'].'" dir="ltr">'.display_str($Artist['name']).'</a>';
    } elseif ($Escape) {
      return display_str($Artist['name']);
    } else {
      return $Artist['name'];
    }
  }

  /**
   * Deletes an artist and their requests, wiki, and tags.
   * Does NOT delete their torrents.
   *
   * @param int $ArtistID
   */
  public static function delete_artist($ArtistID) {
    $QueryID = G::$DB->get_query_id();
    G::$DB->query("
      SELECT Name
      FROM artists_group
      WHERE ArtistID = ".$ArtistID);
    list($Name) = G::$DB->next_record(MYSQLI_NUM, false);

    // Delete requests
    G::$DB->query("
      SELECT RequestID
      FROM requests_artists
      WHERE ArtistID = $ArtistID
        AND ArtistID != 0");
    $Requests = G::$DB->to_array();
    foreach ($Requests AS $Request) {
      list($RequestID) = $Request;
      G::$DB->query('DELETE FROM requests WHERE ID='.$RequestID);
      G::$DB->query('DELETE FROM requests_votes WHERE RequestID='.$RequestID);
      G::$DB->query('DELETE FROM requests_tags WHERE RequestID='.$RequestID);
      G::$DB->query('DELETE FROM requests_artists WHERE RequestID='.$RequestID);
    }

    // Delete artist
    G::$DB->query('DELETE FROM artists_group WHERE ArtistID='.$ArtistID);
    G::$Cache->decrement('stats_artist_count');

    // Delete wiki revisions
    G::$DB->query('DELETE FROM wiki_artists WHERE PageID='.$ArtistID);

    // Delete tags
    G::$DB->query('DELETE FROM artists_tags WHERE ArtistID='.$ArtistID);

    // Delete artist comments, subscriptions and quote notifications
    Comments::delete_page('artist', $ArtistID);

    G::$Cache->delete_value('artist_'.$ArtistID);
    G::$Cache->delete_value('artist_groups_'.$ArtistID);
    // Record in log

    if (!empty(G::$LoggedUser['Username'])) {
      $Username = G::$LoggedUser['Username'];
    } else {
      $Username = 'System';
    }
    Misc::write_log("Artist $ArtistID ($Name) was deleted by $Username");
    G::$DB->set_query_id($QueryID);
  }


  /**
   * Remove LRM (left-right-marker) and trims, because people copypaste carelessly.
   * If we don't do this, we get seemingly duplicate artist names.
   * TODO: make stricter, e.g. on all whitespace characters or Unicode normalisation
   *
   * @param string $ArtistName
   */
  public static function normalise_artist_name($ArtistName) {
    // \u200e is &lrm;
    $ArtistName = trim($ArtistName);
    $ArtistName = preg_replace('/^(\xE2\x80\x8E)+/', '', $ArtistName);
    $ArtistName = preg_replace('/(\xE2\x80\x8E)+$/', '', $ArtistName);
    return trim(preg_replace('/ +/', ' ', $ArtistName));
  }
}
?>