PHP Multi-Column Record Sorting

    /**
     * @param unsortedRecords The array that needs to be sorted.  This array must be in the typical
     *                        format that our arrays are in after retrieving database data (i.e. array of records).
     * @param sortKeys        The record keys that we'll be sorting on.
     *                        If this is an array, multi-column sorting will be done.
     * @param sortDirections  The direction to sort the columns.
     *                        If this is an array, it should match up with the sort_keys array.
     * @param sortTypes       The type of sorting that should be done (SORT_NUMERIC, SORT_STRING, etc. )
     *                        If this is an array, it should match up with the sort_keys array.
     * @example To sort records by 'last_name' in descending order:
     *             $sortedArray = multisortRecords( $records, 'last_name', SORT_DESC )
     * @example To sort records by 'last_name' ascending, then 'first_name' descending:
     *             $sortedArray = multisortRecords( $records, array( 'last_name', 'first_name' ), array( SORT_ASC, SORT_DESC ) )
     * @author - Matthew Hayes <Matthew.Hayes@AllThingsCode.com
     */
    function multisortRecords( &$unsortedRecords, $sortKeys, $sortDirections = SORT_ASC, $sortTypes = null )
    {
        if( ( ! is_array( $unsortedRecords ) ) || ( ! count( $unsortedRecords ) ) ) {
            return array();
        }
        // Convert params to arrays if they are not already.
        if( ! is_array( $sortKeys ) ) {
            $_sort_keys = array( $sortKeys );
        }
        if( ! is_array( $sortDirections ) ) {
            $sortDirections = array_fill( 0, count( $sortKeys ), $sortDirections );
        }
        if( ! is_array( $sortTypes ) ) {
            $sortTypes = array_fill( 0, count( $sortKeys ), $sortTypes );
        }
 
        // Convert the sort directions in case they are plain text
        foreach( array_keys( $sortDirections ) as $key ) {
            switch( $sortDirections[ $key ] ) {
                case SORT_ASC:
                case SORT_DESC:
                    break;
                case 'DESC':
                case 'SORT_DESC':
                    $sortDirections[ $key ] = SORT_DESC;
                    break;
                case 'ASC':
                case 'SORT_ASC':
                default:
                    $sortDirections[ $key ] = SORT_ASC;
            }
        }
 
        // Convert the sort types in case they are plain text
        foreach( array_keys( $sortTypes ) as $key ) {
            switch( $sortTypes[ $key ] ) {
                case SORT_NUMERIC:
                case SORT_STRING:
                    break;
                case 'NUMERIC':
                case 'SORT_NUMERIC':
                    $sortTypes[ $key ] = SORT_NUMERIC;
                    break;
                case 'STRING':
                case 'SORT_STRING':
                    $sortTypes[ $key ] = SORT_STRING;
                    break;
                default:
                    $sortTypes[ $key ] = null;
            }
        }
 
        // Convert the data we'll be sorting on to column format
        $sortColumns = array();
        foreach( $unsortedRecords as $key => $record ) {
            $sortColumns['primary_key'][ $key ] = $key;
            foreach( $sortKeys as $sortKeyIndex => $sortKeyName ) {
                $sortColumns[ $sortKeyName ][ $key ] = $record[ $sortKeyName ];
            }
        }
 
        // Generate parameters for array_multisort()
        $arrayMultisortParams = array();
        for( $i = 0; $i < count( $sortKeys ); $i++ ) {
            $arrayMultisortParams[] = $sortColumns[ $sortKeys[ $i ] ];
            $arrayMultisortParams[] = $sortDirections[ $i ];
            if( ! is_null( $sortTypes[ $i ] ) ) {
                $arrayMultisortParams[] = $sortTypes[ $i ];
            }
        }
 
        // We HAVE to pass in the primary_key column so that we can put it all back together later.
        $arrayMultisortParams[] = $sortColumns['primary_key'];
 
        // This is where the actual sort is done.  See Also:  http://us.php.net/manual/en/function.array-multisort.php
        call_user_func_array( 'array_multisort', $arrayMultisortParams );
 
        // Convert back to record format.
        // We just build a new sorted array
        // using the primary_key column (which is in the correct order now).
        $sortedRows = array();
        foreach( $sortColumns['primary_key'] as $key ) {
            $sortedRows[ $key ] = $unsortedRecords[ $key ];
        }
 
        return $sortedRows;
    }