Linear Signal Controller

System.Text.RegularExpressions.Regex reLinearSignalName = new System.Text.RegularExpressions.Regex(
    @"^((?<group>\w+)\s+Signal\s+#(?<number>[0-9]+))$",
    System.Text.RegularExpressions.RegexOptions.IgnoreCase |
    System.Text.RegularExpressions.RegexOptions.Singleline
);

IMyProgrammableBlock thisCPU;

void FindProgrammableBlock()
{
    List<IMyTerminalBlock> blocks = GridTerminalSystem.Blocks.FindAll(b => b is IMyProgrammableBlock && (b as IMyProgrammableBlock).IsRunning);

    if(blocks.Count > 1)
    {
        throw new Exception("More than one running CPU running; unable to find this executing CPU.");
    }

    thisCPU = blocks[0] as IMyProgrammableBlock;
}

void Main()
{
    FindProgrammableBlock();

    List<IMyTerminalBlock> lightList = new List<IMyTerminalBlock>();
    GridTerminalSystem.GetBlocksOfType<IMyInteriorLight>(lightList);

    Dictionary<string, List<IMyInteriorLight>> groupLightList = new Dictionary<string, List<IMyInteriorLight>>();

    for (int i = 0; i < lightList.Count; i++)
    {
        IMyInteriorLight light = lightList[i] as IMyInteriorLight;

        if (light.CubeGrid != thisCPU.CubeGrid)
        {
            continue;
        }

        string name = light.CustomName;

        System.Text.RegularExpressions.Match match = reLinearSignalName.Match(name);
        int signalId = 0;

        if (match != null && match.Success && match.Groups.Count > 1)
        {
            int.TryParse(match.Groups["number"].Value, out signalId);

            string groupName = (match.Groups["group"].Value ?? string.Empty).ToLower();
            bool isOn = (light as IMyFunctionalBlock).Enabled;

            List<IMyInteriorLight> l = new List<IMyInteriorLight>();

            if(groupLightList.ContainsKey(groupName))
            {
                l = groupLightList[groupName];
            }
            else
            {
                groupLightList.Add(groupName, l);
            }

            l.Add(light);
        }
    }

    ChangeLights(groupLightList);
}

void ChangeLights(Dictionary<string, List<IMyInteriorLight>> groupLightList)
{
    List<string> keys = new List<string>(groupLightList.Keys);

    for (int i = 0; i < keys.Count; i++)
    {
        string key = keys[i];
        List<IMyInteriorLight> l = groupLightList[key];

        l.Sort(SortLinearLightList);

        int turnOn = 0;

        for (int j = 0; j < l.Count; j++)
        {
            if ((l[j] as IMyFunctionalBlock).Enabled)
            {
                turnOn = j + 1;
                if (turnOn >= l.Count) turnOn = 0;
                break;
            }
        }

        for (int j = 0; j < l.Count; j++)
        {
            if (j == turnOn)
            {
                l[j].ApplyAction("OnOff_On");
            }
            else
            {
                l[j].ApplyAction("OnOff_Off");
            }
        }
    }
}

int SortLinearLightList(IMyInteriorLight x, IMyInteriorLight y)
{
    System.Text.RegularExpressions.Match xMatch = reLinearSignalName.Match(x.CustomName);
    int xNum = int.Parse(xMatch.Groups["number"].Value);

    System.Text.RegularExpressions.Match yMatch = reLinearSignalName.Match(y.CustomName);
    int yNum = int.Parse(yMatch.Groups["number"].Value);

    int ret = 0;

    if(xNum < yNum)
    {
        ret = -1;
    }
    else if(yNum > xNum)
    {
        ret = 1;
    }

    return ret;
}