/**
    * Searches the Digital Library database
    *
    * Note that $SubjectID and $CreatorID will
    * not affect the search if their respective
    * packages are not installed and enabled
    *
    * @param string $SearchQuery
    * @param integer $SearchFlags[optional]
    * @param integer $CollectionID[optional]
    * @param integer $CollectionContentID[optional]
    * @param integer $SubjectID[optional]
    * @param integer $CreatorID[optional]
    * @param integer $FileTypeID[optional]
    * @param integer $MediaTypeID[optional]
    * @param integer $Limit[optional]
    * @param integer $Offset[optional]
    * @return DigitalContent[]
    */
    public function searchDigitalLibrary($SearchQuery, $SearchFlags = SEARCH_DIGITALCONTENT, $CollectionID = 0, $CollectionContentID = 0, $SubjectID = 0, $CreatorID = 0, $FileTypeID = 0, $MediaTypeID = 0, $Limit = CONFIG_CORE_SEARCH_RESULTS_LIMIT, $Offset = 0)
    {
        $arrDigitalContent = array();
        $arrQueries = array();

        if(!($SearchFlags & SEARCH_DIGITALCONTENT))
        {
            return $arrDigitalContent;
        }

        $enabledquery = " AND (";
        if($SearchFlags & SEARCH_ENABLED_DIGITALCONTENT)
        {
            $enabledquery .= "tblDigitalLibrary_Content.Enabled = '1'";

            if($SearchFlags & SEARCH_DISABLED_DIGITALCONTENT)
            {
                $enabledquery .= " OR tblDigitalLibrary_Content.Enabled = '0'";
            }
        }
        else
        {
            $enabledquery = "tblDigitalLibrary_Content.Enabled = '0'";
        }
        $enabledquery .= ")";

        if((is_natural($Offset) && $Offset > 0) && (is_natural($Limit) && $Limit > 0))
        {
            $limitquery = "LIMIT $Offset, $Limit";
        }
        else if(is_natural($Offset) && $Offset > 0)
        {
            $limitquery = "LIMIT $Offset, 4294967295";
        }
        else if(is_natural($Limit) && $Limit > 0)
        {
            $limitquery = "LIMIT $Limit";
        }

        if($FileTypeID && is_natural($FileTypeID))
        {
            // Same enabled query needed, just on a different table.
            $enabledsubquery = str_replace('tblDigitalLibrary_Content', 'tblDigitalLibrary_Files', $enabledquery);
            $filetypequery = " AND EXISTS (SELECT tblDigitalLibrary_Files.ID FROM tblDigitalLibrary_Files WHERE tblDigitalLibrary_Files.ContentID = tblDigitalLibrary_Content.ID AND tblDigitalLibrary_Files.FileTypeID = '$FileTypeID'$enabledsubquery)";
        }
        if($MediaTypeID && is_natural($MediaTypeID))
        {
            $enabledsubquery = str_replace('tblDigitalLibrary_Content', 'tblDigitalLibrary_Files', $enabledquery);
            $mediatypequery = " AND EXISTS (SELECT tblDigitalLibrary_Files.ID FROM tblDigitalLibrary_Files INNER JOIN tblDigitalLibrary_FileTypes ON tblDigitalLibrary_FileTypes.ID = tblDigitalLibrary_Files.FileTypeID WHERE tblDigitalLibrary_Files.ContentID = tblDigitalLibrary_Content.ID AND tblDigitalLibrary_FileTypes.MediaTypeID = '$MediaTypeID'$enabledsubquery)";
        }


        if($SubjectID && is_natural($SubjectID) && defined('PACKAGE_SUBJECTS'))
        {
            $arrIndexSearch['Subject'] = array($SubjectID => NULL);
        }
        else if($CreatorID && is_natural($CreatorID) && defined('PACKAGE_CREATORS'))
        {
            $arrIndexSearch['Creator'] = array($CreatorID => NULL);
        }
        else
        {
            if($CollectionID && is_natural($CollectionID))
            {
                $collectionquery = " AND tblDigitalLibrary_Content.CollectionID = '$CollectionID'";
            }

            if($CollectionContentID && is_natural($CollectionContentID))
            {
                $collectioncontentquery = " AND tblDigitalLibrary_Content.CollectionContentID = '$CollectionContentID'";
            }

            $arrWords = $this->createSearchWordArray($SearchQuery);

            if(!empty($arrWords))
            {
                $i = 0;
                foreach($arrWords as $word)
                {
                    $i++;
                    if($word{0} == "-")
                    {
                        $word = encoding_substr($word, 1, encoding_strlen($word) - 1);
                        $textquery .= "(tblDigitalLibrary_Content.Title NOT LIKE '%$word%' AND tblDigitalLibrary_Content.Scope NOT LIKE '%$word%' AND tblDigitalLibrary_Content.PhysicalDescription NOT LIKE '%$word%' AND tblDigitalLibrary_Content.Contributor NOT LIKE '%$word%' AND tblDigitalLibrary_Content.Identifier NOT LIKE '%$word%')";
                    }
                    else
                    {
                        $textquery .= "(tblDigitalLibrary_Content.Title LIKE '%$word%' OR tblDigitalLibrary_Content.Scope LIKE '%$word%' OR tblDigitalLibrary_Content.PhysicalDescription LIKE '%$word%' OR tblDigitalLibrary_Content.Contributor LIKE '%$word%' OR tblDigitalLibrary_Content.Identifier LIKE '%$word%')";
                    }

                    if($i < count($arrWords))
                    {
                        $textquery .= " AND ";
                    }
                }
            }
            else
            {
                $textquery = "tblDigitalLibrary_Content.Title LIKE '%%'";
            }

            $wherequery = ($textquery || $mediatypequery || $filetypequery || $collectionquery || $collectioncontentquery || $enabledquery) ? "WHERE $textquery $mediatypequery $filetypequery $collectionquery $collectioncontentquery $enabledquery" : '';

            $arrQueries[] = "SELECT tblDigitalLibrary_Content.* FROM tblDigitalLibrary_Content$joinquery $wherequery ORDER BY tblDigitalLibrary_Content.Title $limitquery";

            if(defined('PACKAGE_SUBJECTS') && ($SearchFlags & SEARCH_SUBJECTS) && ($SearchFlags & SEARCH_RELATED))
            {
                $arrIndexSearch['Subject'] = $this->searchSubjects($SearchQuery);
            }

            if(defined('PACKAGE_CREATORS') && ($SearchFlags & SEARCH_CREATORS) && ($SearchFlags & SEARCH_RELATED))
            {
                $arrIndexSearch['Creator'] = $this->searchCreators($SearchQuery);
            }
        }

        if(!empty($arrIndexSearch))
        {
            foreach($arrIndexSearch as $Type => $arrObjects)
            {
                if(!empty($arrObjects))
                {
                    foreach($arrObjects as $ID => $junk)
                    {
                        $arrQueries[] = "SELECT tblDigitalLibrary_Content.* FROM tblDigitalLibrary_Content JOIN tblDigitalLibrary_{$Type}Index ON tblDigitalLibrary_{$Type}Index.ContentID = tblDigitalLibrary_Content.ID$joinquery WHERE tblDigitalLibrary_{$Type}Index.{$Type}ID = '$ID'$enabledquery$filetypequery$mediatypequery ORDER BY tblDigitalLibrary_Content.Title $limitquery";
                    }
                }
            }
        }


        if(!empty($arrQueries))
        {
            foreach($arrQueries as $query)
            {
                if($query)
                {
                    $result = $this->db->query($query);

                    while($row = $this->db->fetch_array($result))
                    {
                        $arrDigitalContent[$row['ID']] = New DigitalContent($row);
                    }
                }
            }
        }

        return $arrDigitalContent;
    }