using System;

using System.Linq;

using System.Text.RegularExpressions;

public class Program

{

    public static void Main()

    {

        string str = "{{printing|blue,bold,http://www.google.com/}} and {{Lorem Ipsum|bold}}";

        var formattedString  = Regex.Replace(str, @"{{(?<symbol>[^|]+?)\|(?<formats>.+?)}}", m =>

        {

            var path = "";

            var formatedPattern = m.Groups["formats"].Value.Split(',').Aggregate("{0}", (acc, f) =>

            {

                switch (f.ToLower())

                {

                    case "bold": return "<b>" + acc + "</b>";

                    case "red": return "<font color = \"red\">" + acc + "</font>";

                    case "blue": return "<font color = \"blue\">" + acc + "</font>";

                };

​

                Uri uriResult;

                if (Uri.TryCreate(f.ToLower(), UriKind.Absolute, out uriResult) && uriResult.Scheme == Uri.UriSchemeHttp)

                {

                    return "<a href = \"" + f + "\" target = \"_blank\">" + acc + "</a>";

                }

                else if (System.IO.File.Exists(path + f))

                {

                    string fileName = System.IO.Path.GetFileName(path + f);

                    return "<a href = \" \\s\\Download\\" + fileName + "\">" + acc + "</a>";

                }

                return acc;

            });

            return string.Format(formatedPattern, m.Groups["symbol"].Value);

        });

        Console.WriteLine(formattedString);

    }

}