using System;

using System.Collections.Generic;

using System.Text;

​

public static class Debug

{

    public static void Log(string msg) => Console.WriteLine(msg);   

    public static void LogWarning(string msg) => Console.WriteLine(msg);    

}

​

public class Program

{

    private static void ExtractParameters(string paramString, out string formatString, ISet<string> keys, List<string> keyOrder)

    {

        keyOrder.Clear();

        StringBuilder builder = new StringBuilder(paramString.Length);

​

        int left = 0;

        int right = 0;

​

        while (left < paramString.Length && right < paramString.Length)

        {

            int nextLeft = paramString.IndexOf('{', right);

            if (nextLeft == -1)

                break;

            left = nextLeft;

​

            builder.Append(paramString.Substring(right, (left + 1) - right));

​

            right = paramString.IndexOf('}', left + 1);

            if (right == -1)

            {

                Debug.LogWarning("no closing brace in parameter string");

                break;

            }

​

            if (right - left - 1 > 0)

            {

                string key = paramString.Substring(left + 1, right - left - 1);

                builder.Append(keyOrder.Count);

                left += 1;

​

                // Attempt to extract formatting

                int commaIndex = key.IndexOf(',');

                int colonIndex = key.IndexOf(':');

                if (commaIndex > -1 || colonIndex > -1)

                {

                    int divIndex = System.Math.Max(commaIndex, colonIndex);

                    string format = key.Substring(divIndex, key.Length - divIndex);

                    key = key.Substring(0, divIndex);

                    builder.Append(format);

                }

                keyOrder.Add(key);

                keys.Add(key);

            }

        }

​

        if (left == -1 && right == -1)

        {

            formatString = paramString;

            return;

        }

        else if (right == -1)

        {

            builder.Append(paramString.Substring(left + 1, paramString.Length - (left + 1)));

        }

        else

        {

            builder.Append(paramString.Substring(right, paramString.Length - right));

        }

​

        formatString = builder.ToString();

    }

    private static string FillParameterFormat(string formatString, List<string> keyOrder, Dictionary<string, string> paramValues)

    {

        List<string> keyParams = new List<string>(keyOrder.Count);

        foreach(string key in keyOrder)

        {

            string value = paramValues[key];

            keyParams.Add(value);

        }

        return string.Format(formatString, keyParams.ToArray());

    }

    public static void Main()

    {       

        HashSet<string> keys = new HashSet<string>();

        List<string> keyOrder = new List<string>();

        ExtractParameters("{a:0.00} {b:0} {a:0.1}", out string format, keys, keyOrder);

        foreach(var key in keys)

        {

            Debug.Log(key); 

        }

        var values = new Dictionary<string, object>() 

        {

            {"a", 0.123},

            {"b", 5}

        };

        //string final = FillParameterFormat(format, keyOrder, );

        //Console.WriteLine(final);

    }

}