Generate Slug

Slug.cs

/// <summary>
        /// Creates a unqique slug
        /// </summary>
        /// <param name="titleText"></param>
        /// <returns></returns>
        public string CreateSlug(string titleText = null)
        {
            if (titleText == null)
                titleText = Title;
            if (string.IsNullOrEmpty(titleText))
            {
                Slug = null;
                return null;
            }

            StringBuilder sb = new StringBuilder();

            bool isInvalidBreakChar = true;
            foreach (char ch in titleText.Trim(' ','*','-','.','!','?'))
            {
                if (ch == ' ' || ch == '.' || ch == ',')
                {
                    if (!isInvalidBreakChar)
                        sb.Append("-");
                    isInvalidBreakChar = true;
                }
                else if (ch == '-')
                {
                    if (!isInvalidBreakChar)
                        sb.Append("--");
                    isInvalidBreakChar = true;
                }
                else if (char.IsLetterOrDigit(ch))
                {
                    sb.Append(ch);
                    isInvalidBreakChar = false;
                }
            }

            string slug = sb.ToString();
            slug = slug.TrimEnd('-');

            if (Project != null)
            {
                int postFix = 1;
                string origSlug = slug;

                while (Project.Topics.Any(t => t.Slug == slug))
                {
                    slug = origSlug + "-" + postFix;
                    postFix++;
                }
            }

            Slug = slug;
            return Slug;
        }