using System;

using HtmlAgilityPack;

using System.Regex;

​

public class Program

{

    public static string ReplaceAssetLink(string content, string assetPath, string replacement)

    {

        // To avoid replacing where part of a longer path we don't replace where followed by any of dot, forward slash, hyphen, 

        // underscore or a letter or digit.  We also have to escape certain chars in assetPath before we start.

        // RRBUGS-1264 The original starts with // and is otherwise identical to the replacement which has https:// on the front.

        // Since the asset appears more than once this was resulting in https:https:// on the front.  To avoid this we will also not 

        // replace where the original is already prefixed with http: or https: 

        Console.WriteLine();

        Console.WriteLine("content    : {0}", content);

        Console.WriteLine("assetPath  : {0}", assetPath);

        Console.WriteLine("replacement: {0}", replacement);

        string one = Regex.Replace(assetPath, "[\\/\\?\\*\\+{}.\\^\\$\\|\\[\\]\\(\\)\\\\]", "\\$&");

        Console.WriteLine("one        : {0}", one);

        string two = string.Format("{0}{1}{2}", "(?<!https*:)", one, @"(?![\/.a-z0-9-_])");

        //string two = string.Format("{0}{1}", "(?<!https*:)", one);

        Console.WriteLine("two        : {0}", two);

        string result = Regex.Replace(content, two, replacement, RegexOptions.Multiline);

        Console.WriteLine("result 1   : {0}", result);

        result = Regex.Replace(result, one, "");

        Console.WriteLine("\nresult     : \n\n{0}", result);

        return result;

    }

​

    public static void Main()

    {

        string content     =       "//johnlewis.scene7.com/is/image/JohnLewis/Homepage_LHS_BlockVS_100221_2?$cms-max-image-threshold$&wid=288&fit=hfit,1 288w,\n//johnlewis.scene7.com/is/image/JohnLewis/Homepage_LHS_BlockVS_100221_2?$cms-max-image-threshold$&wid=576&fit=hfit,1 576w,\n//johnlewis.scene7.com/is/image/JohnLewis/Homepage_LHS_BlockVS_100221_2?$cms-max-image-threshold$&wid=672&fit=hfit,1 672w,\n//johnlewis.scene7.com/is/image/JohnLewis/Homepage_LHS_BlockVS_100221_2?$cms-max-image-threshold$&wid=768&fit=hfit,1 768w,\n//johnlewis.scene7.com/is/image/JohnLewis/Homepage_LHS_BlockVS_100221_2?$cms-max-image-threshold$&wid=896&fit=hfit,1 896w,\n//johnlewis.scene7.com/is/image/JohnLewis/Homepage_LHS_BlockVS_100221_2?$cms-max-image-threshold$&wid=1024&fit=hfit,1 1024w,\n//johnlewis.scene7.com/is/image/JohnLewis/Homepage_LHS_BlockVS_100221_2?$cms-max-image-threshold$&wid=1112&fit=hfit,1 1112w,\n//johnlewis.scene7.com/is/image/JohnLewis/Homepage_LHS_BlockVS_100221_2?$cms-max-image-threshold$&wid=1200&fit=hfit,1 1200w,\n//johnlewis.scene7.com/is/image/JohnLewis/Homepage_LHS_BlockVS_100221_2?$cms-max-image-threshold$&wid=1368&fit=hfit,1 1368w,\n//johnlewis.scene7.com/is/image/JohnLewis/Homepage_LHS_BlockVS_100221_2?$cms-max-image-threshold$&wid=1536&fit=hfit,1 1536w,\n//johnlewis.scene7.com/is/image/JohnLewis/Homepage_LHS_BlockVS_100221_2?$cms-max-image-threshold$&wid=1792&fit=hfit,1 1792w,\n//johnlewis.scene7.com/is/image/JohnLewis/Homepage_LHS_BlockVS_100221_2?$cms-max-image-threshold$&wid=2048&fit=hfit,1 2048w,\n//johnlewis.scene7.com/is/image/JohnLewis/Homepage_LHS_BlockVS_100221_2?$cms-max-image-threshold$&wid=2224&fit=hfit,1 2224w,\n//johnlewis.scene7.com/is/image/JohnLewis/Homepage_LHS_BlockVS_100221_2?$cms-max-image-threshold$&wid=2400&fit=hfit,1 2400w,\n//johnlewis.scene7.com/is/image/JohnLewis/Homepage_LHS_BlockVS_100221_2?$cms-max-image-threshold$&wid=2950&fit=hfit,1 2950w,\n//johnlewis.scene7.com/is/image/JohnLewis/Homepage_LHS_BlockVS_100221_2?$cms-max-image-threshold$&wid=3500&fit=hfit,1 3500w";

        string assetPath   =       "//johnlewis.scene7.com/is/image/JohnLewis/Homepage_LHS_BlockVS_100221_2?$cms-max-image-threshold$&wid=288&fit=hfit,1";

        string replacement = "https://johnlewis.scene7.com/is/image/JohnLewis/Homepage_LHS_BlockVS_100221_2?$cms-max-image-threshold$&wid=288&fit=hfit,1";

​

        Console.WriteLine("-->\n{0}", ReplaceAssetLink(content, assetPath, replacement));

    }

}