using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace crypto
{
    class CryptoPerso
    {
        //Basé sur le cryptage césar
        private const string alphabet = @"abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXTZ0123456789&@,?;.:/ ";
        public string Alphabet { get { return alphabet; } set { } }
        private byte[] alphabetArray = Encoding.ASCII.GetBytes(alphabet);
        private byte[] textArray;
        

        public CryptoPerso()
        {

        }

        public byte[] StrToInt(string texte)
        {
            List<byte> tmp = new List<byte>();
            textArray = Encoding.ASCII.GetBytes(texte);
            for(int i=0; i<textArray.Length;i++)
            {
                byte j;
                for (j = 0; textArray[i] != alphabetArray[j] && j < alphabetArray.Length; j++);
                tmp.Add(j);
            }
            return tmp.ToArray();
        }
        public byte[] IntToStr(byte[] textArray)
        {
            List<byte> tmp = new List<byte>();
            for (int i = 0; i < textArray.Length; i++)
            {
                tmp.Add(alphabetArray[textArray[i]]);
            }
            return tmp.ToArray();
        }
        public string Crypt(string texte, string pw)
        {
            try
            {
                byte[] texteInt = StrToInt(texte);
                byte[] pwInt = StrToInt(pw);
                List<byte> tmp = new List<byte>();
                for (int i = 0; i < texteInt.Length; i++)
                {
                    byte a = (byte)((texteInt[i] + pwInt[i % (pwInt.Length)]) % (alphabetArray.Length));
                    tmp.Add(a);
                }

                return Encoding.ASCII.GetString(IntToStr(tmp.ToArray()));
            }
            catch(Exception e)
            {
                warn w = new warn("ERREUR : "+e.ToString());
                w.Show();
                Console.WriteLine(e.ToString());
                return null;
            }
        }
        public string decryptage(string texte, string pw)
        {
            try
            {
                byte[] texteInt = StrToInt(texte);
                byte[] pwInt = StrToInt(pw);
                List<byte> tmp = new List<byte>();
                for (int i = 0; i < texteInt.Length; i++)
                {
                    if (texteInt[i] < pwInt[i % (pwInt.Length)])
                        texteInt[i] += (byte)(alphabet.Length);
                    byte a = (byte)((texteInt[i] - pwInt[i % (pwInt.Length)]));
                    tmp.Add(a);
                }

                return Encoding.ASCII.GetString(IntToStr(tmp.ToArray()));
            }
            catch (Exception e)
            {
                warn w = new warn("ERREUR : "+e.ToString());
                w.Show();
                Console.WriteLine(e.ToString());
                return null;
            }
        }

    }
}