Fix invalid italic tags

private static readonly string[] BeginTagVariations = { "< i >", "< i>", "<i >", "< I >", "< I>", "<I >", "<i<", "<I<", "<I>" };

        private static readonly string[] EndTagVariations =
        {
            "< / i >", "< /i>", "</ i>", "< /i >", "</i >", "</ i >",
            "< / i>", "</I>", "< / I >", "< /I>", "</ I>", "< /I >", "</I >", "</ I >", "< / I>", "</i<", "</I<", "</I>"
        };

        /// <summary>
        /// Fix invalid or improperly formatted italic tags in the input HTML string.
        /// </summary>
        /// <param name="input">The input HTML string to process.</param>
        /// <returns>A string with corrected italic tags.</returns>
        public static string FixInvalidItalicTags(string input)
        {
            var text = input;

            var preTags = string.Empty;
            if (text.StartsWith("{\\", StringComparison.Ordinal))
            {
                var endIdx = text.IndexOf('}', 2);
                if (endIdx > 2)
                {
                    preTags = text.Substring(0, endIdx + 1);
                    text = text.Remove(0, endIdx + 1);
                }
            }

            const string beginTag = "<i>";
            const string endTag = "</i>";

            int r = text.Length - 1;
            for (int l = text.Length - 1; l >= 0; l--)
            {
                if (text[l] == '>' || text[l] == '<')
                {
                    r = l;
                }
                else if ((text[l] == '<' && text[r] == '>') || (text[r] == '<' && text[l] == '<'))
                {
                    var tag = text.Substring(l, r - l + 1);
                    if (BeginTagVariations.Contains(tag))
                    {
                        text = text.Remove(l, tag.Length);
                        text = text.Insert(l, beginTag);
                    }
                    else if (EndTagVariations.Contains(tag))
                    {
                        text = text.Remove(l, tag.Length);
                        text = text.Insert(l, endTag);
                    }

                    r = l - 1;
                }
            }