BeatLyrics/BeatLyrics.Tool/Models/TextTuple.cs

namespace BeatLyrics.Tool.Models
{
    public class TextTuple
    {
        public string Text { get; set; }

        public string Ruby { get; set; }

        public override string ToString()
        {
            var left = 0;

            var regexKata = new System.Text.RegularExpressions.Regex("^[\\p{IsKatakana}]+$");
            if (regexKata.IsMatch(Text)) return Text;

            if (Ruby == Text) return Text;

            if (false == string.IsNullOrWhiteSpace(Ruby))
            {
                for (int i = 0; i < Ruby.Length; i++)
                {
                    if (Text[Text.Length - 1 - i] == Ruby[Ruby.Length - 1 - i]) continue;
                    left = i;
                    break;
                }

                var textLeft = Text.Substring(0, Text.Length - left);
                var textRight = Text.Substring(Text.Length - left);

                var midRuby = Ruby.Substring(0, Ruby.Length - left);

                return $"{textLeft}({midRuby}){textRight}";
            }

            return Text + (Text == Ruby || string.IsNullOrWhiteSpace(Ruby) ? "" : $"({Ruby})");
        }
    }
}