<?PHP
/**
* @name mru_manager.php
* Defines class CMRUManager that manages "Most Recently Used" objects
* PHP required: 5.2+
* Uses as_dbutiles.php module for MySQL data access
* @version 1.01 build 0002 2010-12-30
* @Author Alexander Selifonov, <alex [at] selifan {dot} ru>
* @Link: http://www.selifan.ru
* @license http://www.opensource.org/licenses/bsd-license.php    BSD
*
**/
class CMRUManager {
    private $_MRUlength = 4; # how many events to remember (default value for all item types)
    private $_MRUlengths = array(); # assoc/array with max lengths for registered item types
    private $_tableName = 'mru_data'; # SQL table name that will store MRU lists
    private $_userid = null; # permament logged user id
    /**
    * Class constructor
    *
    * @param mixed $options - assoc.array with all options, or "user id" value
    * @param mixed $mru_length - MRU capacity (how many items to store per "document/object type"
    * @return CMRUManager
    */
    function __construct($options=false, $mru_length=0){
        global $as_dbengine;
        if(is_array($options)) {
            if(!empty($options['mrulength'])) $this->_MRUlength = (int) $options['mrulength'];
            if(isset($options['mrulengths']) && is_array($options['mrulengths'])) $this->_MRUlengths = $options['mrulengths'];
            if(!empty($options['tablename'])) $this->_tableName = (string) $options['tablename'];
            if(!empty($options['userid'])) $this->_userid = (string) $options['userid'];
        }
        else { # if not an array, parameters treated as : first - user id, second - MRU length
            if(is_scalar($options)) $this->_userid = $options;
            if((int)$mru_length>0 ) $this->_MRUlength = (int) $mru_length;
        }
	}
    /**
    * Stores "access to document" event, placing it on "top" of the MRU list
    *
    * @param mixed $itemid accessed Document ID (or file name)
    * @param string/int $userid logged user Id (or unique login)
    * @param string/int $itemtype document/object type
    */
    public function RegisterEvent($itemid, $itemtype='', $userid=false) {
        global $as_dbengine;
        $MRUlength = empty($this->_MRUlengths[$itemtype]) ? $this->_MRUlength : (int)$this->_MRUlengths[$itemtype];
        if(empty($userid) && !empty($this->_userid)) $userid = $this->_userid;

        $curevt = $as_dbengine->GetQueryResult($this->_tableName,'recid,itemid, eventdate',"userid='$userid' AND itemtype='$itemtype'",1,1,0,'eventdate DESC');
        if(!is_array($curevt)) {
            $curevt = array();
            if($as_dbengine->sql_errno()) {
                if(stripos($as_dbengine->sql_error(),"doesn't exist") or 1146==$as_dbengine->sql_errno()) {
                    if( !$this->createMRUtable() ) return false;
                        # OR: throw new Exception('Cannot create MRU holder table '.$this->_tableName.', check Your DB connection params');
                }
            }
        }
        $inMRU = -1;
        for($ii=0; $ii<count($curevt); $ii++) { # seekeing if this item is already in MRU
            if($curevt[$ii]['itemid'] === $itemid) {
                $inMRU = $ii;
                break;
            }
        }
        if($inMRU==-1) { # no this item in MRU yet, so insert a record
            $as_dbengine->sql_query("INSERT INTO {$this->_tableName} (itemtype,itemid,userid) VALUES('$itemtype','$itemid','$userid')");

            if(count($curevt) >= $MRUlength) { # delete obsolete records for this event type/user (push from MRU stack)
                for($ii=$MRUlength-1; $ii<count($curevt); $ii++) {
                    $as_dbengine->sql_query("DELETE FROM {$this->_tableName} WHERE recid=".$curevt[$ii]['recid']);
                }
            }
        }
        else { # this item is somewhere in MRU stack, move it to the top by updating eventdate to current time
            $as_dbengine->sql_query("UPDATE {$this->_tableName} SET eventdate=NOW() WHERE recid={$curevt[$inMRU]['recid']}");
        }
        return true;
    }

    /**
    * Get current MRU list for desired user id [and itemtype]
    *
    * @param mixed $userid int/string user id
    * @param mixed $itemtype optional item type
    * @return array (may be empty), assoc.array with data: 'itemid'=>item id, 'itemtype'
    */
    public function GetMRUList($itemtype='', $uri_pattern=false, $userid=false) {
        global $as_dbengine;
        if(empty($userid) && !empty($this->_userid)) $userid = $this->_userid;
        $addcond = $itemtype ? " AND itemtype='$itemtype'" : '';
        $curevt = $as_dbengine->GetQueryResult($this->_tableName,'itemid, itemtype, eventdate',"userid='$userid' $addcond",1,1,0,'eventdate DESC');
        if(!is_array($curevt)) $curevt = array();
        if(is_string($uri_pattern) && stripos($uri_pattern, '{id}')!==false) {
            foreach($curevt as $cno => $item) {
                $curevt[$cno]['uri'] = str_ireplace('{id}',urlencode($item['itemid']), $uri_pattern);
            }
        }
        return $curevt;
    }

    /**
    * Clears all MRU list for passed user id and/or item type
    *
    * @param mixed $userid
    * @param mixed $itemtype
    */
    public function ClearMRUData($itemtype=false, $itemid=false, $userid=false) {
        global $as_dbengine;
        if(empty($userid) && !empty($this->_userid)) $userid = $this->_userid;

        if(!$userid and !$itemtype and !$itemid) $as_dbengine->sql_query('TRUNCATE TABLE ' . $this->_tableName);
        else {
            $cond = array();
            if($userid)   $cond[] = "userid='$userid'";
            if($itemtype) $cond[] = "itemtype='$itemtype'";
            if($itemid)   $cond[] = "itemid='$itemid'";
            $as_dbengine->sql_query("DELETE FROM ". $this->_tableName . ' WHERE '. implode(' AND ', $cond));
        }
    }
    /**
    * creates table for storing MRU data, returns true if table created, false otherwise
    */
    private function createMRUtable() {
        global $as_dbengine;
        $create_sql = <<<EOSQL
CREATE TABLE {$this->_tableName} (
      recid INT(20) not null auto_increment, itemtype CHAR(20) not null default '',
      itemid CHAR(80) not null default '', userid CHAR(20) not null default '',
      eventdate TIMESTAMP not null, primary key(recid), KEY ix_userid (userid)
)
EOSQL;
        $as_dbengine->sql_query($create_sql);
        return (0==$as_dbengine->sql_errno());
    }
} # CMRUManager definition end