using System;

using System.Linq;

using System.Collections.Generic;

using System.Text.RegularExpressions;

public class Program

{

    public static void Main()

    {

        List<int> ids = new List<int>{ 1, 2, 3, 4, 5, 6 };

        string configuration = "var configuration = { 'title': 'wowowowowow', 'filter_group_ids': [], 'primary_message': '', 'windows_connect_instructions_html': null, 'mac_connect_instructions_html': null, 'show_windows_computers': true, 'show_mac_computers': true, 'custom_login_message': null, 'group_descriptions': [], 'support_vnc_for_mac': false, 'vnc_client_link': '', 'branding_image': null, 'branding_css': ''};";

        Console.WriteLine(UpdateGroupIds(configuration, ids));

    }

    public static string UpdateGroupIds( string configuration, List<int> ids )

    {

        Regex reg = new Regex( @"\s*'\s*filter_group_ids\s*'\s*:\s*" );

​

        string[] configurationParts = reg.Split( configuration );

​

        if ( configurationParts.Length != 2 )

        {

            return null;

        }

​

        string[] commaSplitConfig = configurationParts[1].Split( ',' );

        commaSplitConfig[0] = $"[{string.Join( ", ", ids )}]";

​

        configuration = $"{configurationParts[0]} 'filter_group_ids': {string.Join( ", ", commaSplitConfig )}";

​

        return configuration;

    }

}