using System;

using System.Text.RegularExpressions;

using System.Collections.Generic;

using System.Linq;

public class Program

{

    static Dictionary<string, List<string>> dupDetection = new Dictionary<string, List<string>>();

    static Dictionary<string, string> config = new Dictionary<string, string>

    {

       ["ServiceBus__eng_topic_one__Listen"] = "Listen",

       ["ServiceBus__engtopicone__Listen"] = "Listen",

       ["ServiceBus__another_topic__Send"] = "Send",

       ["ServiceBus__anothertopic__Send"] = "Send",

       ["Cosmos__db_name__AccountName"] = "AccountName",

       ["Cosmos__dbname__AccountName"] = "AccountName",

       ["Cosmos__dbname__AccountKey"] = "AccountKey",

       ["Cosmos__db_name__AccountKey"] = "AccountKey",

       ["Unrelated-Config-Value"] = "ConfigValue"

    };

    public static void Main()

    {

        var finalConfig = new Dictionary<string, string>();

        foreach (var key in config.Keys)

        {

            var val = config[key];

            MatchCollection matchRegEx = Regex.Matches(key, "(ServiceBus|Cosmos)__([a-zA-Z0-9_]+)__(Listen|Send|AccountName|AccountKey)");

            if (matchRegEx.Count > 0)

            {

                foreach (Match match in matchRegEx)

                {

                    var keyName = match.Groups[2].Value;

                    var cleanedKey = key.Replace(keyName, keyName.Replace("_", ""));

                    if (!dupDetection.ContainsKey(cleanedKey))

                    {

                        dupDetection[cleanedKey] = new List<string>();

                    }

​

                    dupDetection[cleanedKey].Add(key);

                }

            }

            else

            {

                finalConfig[key] = config[key];

            }

        }

​

        foreach (var key in dupDetection.Keys)

        {

            var dupVal = dupDetection[key];

            if (dupVal.Count == 1)

            {

                finalConfig[dupVal[0]] = config[dupVal[0]];

            }

            else

            {

                var chosenKey = dupVal.OrderBy(x => x).First();

                if (config.ContainsKey(chosenKey))

                {

                    var newKey = Regex.Replace(chosenKey, @"([^_])(_)([^_])", m => m.Groups[1].Value + "-" + m.Groups[3].Value);

                    finalConfig[newKey] = config[chosenKey];

                }

            }

        }

        finalConfig.Dump();

    }

}