<?php

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 = [];
        $DBs = [];

        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", []);
                }
            }

            $Missing = array_diff($GroupIDs, array_keys($Results));
            if (!empty($Missing)) {
                $Results += array_fill_keys($Missing, []);
            }
        }
        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; ' : ' & ';
            $link = ($IncludeHyphen? '🧑&nbsp;' : '');
    
            switch (count($Artists)) {
            case 0:
                break;

            case 3:
                $link .= Artists::display_artist($Artists[2], $MakeLink, $Escape). ", ";
                // no break

            case 2:
                $link .= Artists::display_artist($Artists[1], $MakeLink, $Escape). ", ";
                // no break

            case 1:
                $link .= Artists::display_artist($Artists[0], $MakeLink, $Escape);
                break;

            default:
                $link = ($IncludeHyphen?'🧑&nbsp;':'').Artists::display_artist($Artists[0], $MakeLink, $Escape).' et al.';
                #$link = 'Various'.($IncludeHyphen?' &ndash; ':'');
        }
            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='.$Artist['id'].'">'.display_str($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));
    }
}