kreta/Kreta.BusinessLogic/Classes/SubstringExtension.cs

namespace Kreta.BusinessLogic.Classes
{
    public static class SubstringExtension
    {
        /// <summary>
        /// Sortörés kezelése
        /// </summary>
        public enum StringWrapMode
        {
            Cut = 0,
            Wrap = 1,
            TruncateTail = 2
        }

        /// <summary>
        /// Abban az esetben, ha a startindex nagyobb mint 0, levágja a szöveg elejét
        /// </summary>
        /// <param name="text"></param>
        /// <param name="startindex"></param>
        /// <param name="wrapping"></param>
        /// <returns></returns>
        public static string Wrap(this string text, int startindex, StringWrapMode wrapping = StringWrapMode.Cut)
        {
            return Wrap(text, startindex, text.Length, wrapping);
        }

        public static string Wrap(this string text, int startindex, int maxlength, StringWrapMode wrapping = StringWrapMode.Cut)
        {
            if (string.IsNullOrWhiteSpace(text))
            {
                return "";
            }

            if (startindex < 0 || (startindex == 0 && maxlength == text.Length))
            {
                return text;
            }

            int maxIndex = text.Length - 1;
            int lastIndex = startindex + maxlength;

            if (lastIndex > maxIndex)
            {
                return text.Substring(startindex, maxIndex - startindex);
            }

            switch (wrapping)
            {
                case StringWrapMode.TruncateTail:
                    return string.Format("{0}...", text.Substring(startindex, maxlength - 3));
                case StringWrapMode.Wrap:
                    int lastSpaceBeforeCut = -1;
                    int lastSpaceAfterCut = -1;
                    for (int i = 0; i < maxIndex; i++)
                    {
                        if (text[i] == ' ')
                        {
                            if (i > maxlength)
                            {
                                lastSpaceAfterCut = i;
                            }
                            else
                            {
                                lastSpaceBeforeCut = i;
                            }
                        }
                    }

                    return lastSpaceBeforeCut == -1 || lastSpaceAfterCut == -1
                        ? string.Format("{0}...", text.Substring(startindex, maxlength - 3))
                        : text.Substring(startindex, lastSpaceBeforeCut);

                default:
                    return text.Substring(startindex, maxlength);
            }
        }
    }
}