using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Text.RegularExpressions;
using System.Threading.Tasks;

namespace XYLEM.Base.XML
{
    public static class XMLStringClass
    {
        public enum XMLVersion
        {
            V1_0,
            V1_1
        }

        /// <summary>
        /// Strips non-printable ascii characters 
        /// Refer to http://www.w3.org/TR/xml11/#charsets for XML 1.1
        /// </summary>
        /// <param name="txtToClean"></param>
        /// <returns></returns>
        public static string StripIllegalXMLChars(this string txtToClean)
        {
            return StripIllegalXMLChars(txtToClean, XMLVersion.V1_1);
        }

        /// <summary>
        /// Strips non-printable ascii characters 
        /// Refer to http://www.w3.org/TR/xml11/#charsets for XML 1.1
        /// Refer to http://www.w3.org/TR/2006/REC-xml-20060816/#charsets for XML 1.0
        /// </summary>
        /// <param name="txtToClean"></param>
        /// <param name="version"></param>
        /// <returns></returns>
        public static string StripIllegalXMLChars(this string txtToClean, XMLVersion version)
        {
            try
            {
                string pattern = String.Empty;
                txtToClean = txtToClean.
                    Replace("&", "&amp;").
                    Replace("<", "&lt;").
                    Replace(">", "&gt;").
                    Replace("\"", "&quot;").
                    Replace("'", "&apos;").
                    Replace("\r", "&#xD;").
                    Replace("\n", "&#xA;");
                switch (version)
                {
                    case XMLVersion.V1_0:
                        pattern = @"#x((10?|[2-F])FFF[EF]|FDD[0-9A-F]|7F|8[0-46-9A-F]9[0-9A-F])";
                        break;
                    case XMLVersion.V1_1:
                        pattern = @"#x((10?|[2-F])FFF[EF]|FDD[0-9A-F]|[19][0-9A-F]|7F|8[0-46-9A-F]|0?[1-8BCEF])";
                        break;
                }

                Regex regex = new Regex(pattern, RegexOptions.IgnoreCase);
                if (regex.IsMatch(txtToClean))
                {
                    txtToClean = regex.Replace(txtToClean, String.Empty);
                }
                if (txtToClean.Contains('\0'))
                {
                    txtToClean = txtToClean.Remove(txtToClean.IndexOf('\0'));
                }
                if (txtToClean.Contains((char)0x1E))
                {
                    txtToClean = txtToClean.Replace((char)0x1E, ' ');
                }
                {
                    // Replace any character that has survived this done before
                    // Replace illegal character in XML documents with blank
                    // See here for reference http://www.w3.org/TR/xml/#charsets
                    txtToClean = Regex.Replace(txtToClean, "[\x00-\x08\x0B\x0C\x0E-\x1F]", String.Empty, RegexOptions.Compiled);
                }
                return txtToClean;
            }
            catch (Exception ex)
            {
                throw new Exception("Error in XMLFileIOClass and StripIllegalXMLChars() " + (txtToClean != null ? " txtToClean = " + txtToClean.ToString() : "txtToClean is null"), ex);
            }
        }

        /// <summary>
        /// reinset non-printable ascii characters 
        /// Refer to http://www.w3.org/TR/xml11/#charsets for XML 1.1
        /// </summary>
        /// <param name="txtToClean"></param>
        /// <returns></returns>
        public static string ReinsetIllegalXMLChars(this string txtToClean)
        {
            return ReinsetIllegalXMLChars(txtToClean, XMLVersion.V1_1);
        }

        /// <summary>
        /// reinset non-printable ascii characters 
        /// Refer to http://www.w3.org/TR/xml11/#charsets for XML 1.1
        /// Refer to http://www.w3.org/TR/2006/REC-xml-20060816/#charsets for XML 1.0
        /// </summary>
        /// <param name="txtToClean"></param>
        /// <param name="version"></param>
        /// <returns></returns>
        public static string ReinsetIllegalXMLChars(string txtToReinset, XMLVersion version)
        {
            try
            {
                string pattern = String.Empty;
                txtToReinset = txtToReinset.
                    Replace("&amp;", "&").
                    Replace("&lt;", "<").
                    Replace("&gt;", ">").
                    Replace("&quot;", "\"").
                    Replace("&apos;", "'").
                    Replace("&#xD;", "\r").
                    Replace("&#xA;", "\n");
                return txtToReinset;
            }
            catch (Exception ex)
            {
                throw new Exception("Error in XMLFileIOClass and StripIllegalXMLChars() " + (txtToReinset != null ? " txtToClean = " + txtToReinset.ToString() : "txtToClean is null"), ex);
            }
        }
    }
}