PDO Select + Object Tree build

    //******************************************************************************************************************

    /**
     * Builds a PDO prepared statement with the given parameters
     *
     * @param array $args
     * Holds the WHERE clause
     * Expected Format: array("Column Name" => array("Comparison Operator", "Value"))
     *
     * @param bool $fetchImmediately
     * Defines whether or not the value is to be fetched immediately. If given FALSE the prepared statement is returned instead.
     *
     * @param bool $alwaysFetchArray
     * Defines whether or not there's always an array to be returned, even if the executed statement would only return one row.
     * Handy when multiple results are expected but when single ones are possible as well.
     */
    public static function select($columns,
                                  $table,
                                  $args = array(),
                                  $alwaysFetchArray = false,
                                  $orderBy = "",
                                  $orderDirection = "ASC",
                                  $limit = "",
                                  $groupBy = "",
                                  $fetchImmediately = true)
    {
        //The base query string.
        $sql = "SELECT ".$columns." FROM ".$table;

        //Adds the WHERE-clause and the necessary placeholders if specified
        if ($args)
        {
            $sql = $sql." WHERE ";

            $columnNames = array_keys($args);
            $columnVals = array();

            for ($i = 0; $i < count($columnNames); $i++)
            {
                $compOperator = array_values($args)[$i][0];

                array_push($columnVals, array_values($args)[$i][1]);

                if ($i == 0)
                {
                    $sql .= $columnNames[$i]." ".$compOperator." ?";
                    continue;
                }

                $sql .= " AND ".$columnNames[$i]." ".$compOperator." ?";
            }
        }

        //Adds the GROUP BY-clause, if specified
        if ($groupBy)
        {
            $sql .= " GROUP BY ".$groupBy;
        }

        //Adds the ORDER BY-clause, if specified
        if ($orderBy)
        {
            $sql .= " ORDER BY ".$orderBy." ".$orderDirection;
        }

        //Adds the LIMIT-clause, if specified
        if ($limit)
        {
            $sql .= " LIMIT ".$limit;
        }

        //Prepares the built statement
        $stmt = self::$db->prepare($sql);

        //Executes the statement either with the specified values or without any.
        if (count($args))
        {
            $stmt->execute(array_values($columnVals));
        }
        else
        {
            $stmt->execute();
        }

        //Determines that the result is to be fetched as an instance of a class. Table names are expected as T[classname]
        $stmt->setFetchMode(PDO::FETCH_CLASS, substr($table, 1));

        if (!$fetchImmediately)
        {
            return $stmt;
        }

        return self::buildComplexObjectTree($stmt, $alwaysFetchArray);
    }

    //**********************************************************************************************************

    public static function buildComplexObjectTree($stmt, $alwaysFetchArray)
    {
        //Fetches the query result
        $result = $stmt->fetchAll();

        foreach ($result as $obj)
        {
            //Look through columns to find potential foreign keys columns.
            $fkCols = array();
            for ($i = 0; $i < $stmt->columnCount(); $i++)
            {
                $m = $stmt->getColumnMeta($i);

                if (str_starts_with($m['name'], "fk"))
                {
                    array_push($fkCols, $m['name']);
                }
            }

            //Loops through all found foreign key columns and sets the respective values.
            foreach ($fkCols as $fkCol)
            {
                //Takes the fk columns name and returns substring representing the classname for the object
                $objName = substr($fkCol, 2);

                //Helps dealing with edge cases in which a table has multiple forein keys referencing the same table
                //e.g. private messages.
                //Expected Format: fkUserRecipient and fkUserSender
                if (preg_match("^(.*?[A-Z]){2,}.*$^", $objName))
                {
                    $arr = preg_split('#([A-Z][^A-Z]*)#', $objName, null, PREG_SPLIT_DELIM_CAPTURE | PREG_SPLIT_NO_EMPTY);
                    $objName = $arr[0];
                    $propertyName = $arr[1];
                }

                //Holds the name of the setter function
                $setterFunc = isset($propertyName) ? "set".$propertyName : "set".$objName;

                //Holds the current foreign key value in the format expected from the select method
                $argArray = array("pk".$objName => array("=", $obj->$fkCol));

                //Queries the Database for the entry with the specified foreign key
                $obj->$setterFunc(Database::select("*", "T".$objName, $argArray));
            }

            if (count($result) == 1 && !$alwaysFetchArray)
            {
                return $obj;
            }
        }

        return $result;
    }