using System.Text;

namespace NTERA.EmuEra.Game.EraEmu._Library
{
    //マルチ言語に対応可能な形式に変更
    internal static class LangManager
    {
        static Encoding lang;

        public static void setEncode(int code)
        {
            lang = Encoding.GetEncoding(code);
        }

        public static int GetStrlenLang(string str)
        {
            return lang.GetByteCount(str);
        }
        public static int GetUFTIndex(string str, int LangIndex)
        {
            if (LangIndex <= 0)
                return 0;
            int totalByte = GetStrlenLang(str);
            if (LangIndex >= totalByte)
                return str.Length;
            int UTFcnt = 0;
            int JIScnt = 0;
            for (int i = 0; i < str.Length; i++)
            {
                JIScnt += lang.GetByteCount(str[UTFcnt].ToString());
                UTFcnt++;
                if (JIScnt >= LangIndex)
                    break;
            }
            return UTFcnt;
        }

        public static string GetSubStringLang(string str, int startindex, int length)
        {
            int totalByte = GetStrlenLang(str);
            if ((startindex >= totalByte) || (length == 0))
                return "";
            if ((length < 0) || (length > totalByte))
                length = totalByte;

            StringBuilder ret = new StringBuilder();
            int UTFcnt = 0;
            int JIScnt = 0;

            if (startindex <= 0)
            {
                if (length == totalByte)
                    return str;
            }
            else
            {
                for (int i = 0; i < str.Length; i++)
                {
                    JIScnt += lang.GetByteCount(str[UTFcnt].ToString());
                    UTFcnt++;
                    if (JIScnt >= startindex)
                        break;
                }
                if (UTFcnt >= str.Length)
                    return "";
            }

            JIScnt = 0;
            while (true)
            {
                ret.Append(str[UTFcnt]);
                JIScnt += lang.GetByteCount(str[UTFcnt].ToString());
                UTFcnt++;
                if (JIScnt >= length)
                    break;
                if (UTFcnt >= str.Length)
                    break;
            }
            return ret.ToString();
        }
    }
}