using System;
using System.Linq;
using System.IO;
using System.Text;
using System.Collections.Generic;

namespace AniNIX.Crypto {
    public class Caesarian : Cipher {

       public override String Description() { return "Caesarian cipher suite\nKey format is a numeric shift."; }
       public override String Command() { return "caesar"; }

       public Caesarian(Workbench w) : base (w) {}

       public override String RunCommand(String workSpace,String inputText,String[] line) {
            if (workSpace == null || line == null || line.Length < 2) {
                Console.Error.WriteLine("Malformed request.");
                return workSpace;
            }
            switch (line[1]) {
                case "encrypt": 
                    return Encrypt(workSpace,inputText,line);
                case "decrypt":
                    return Decrypt(workSpace,inputText,line);
                case "brute":
                    BruteForce(workSpace);
                    return workSpace;
                default: 
                    GetHelp();
                    return workSpace;
            } 
        }

         public override void GetHelp() {
            Console.WriteLine(String.Format("Help for the {0} cipher suite.\n{1}\n",Command(),Description()));
            Console.WriteLine("encrypt key         -- encrypt with the key\ndecrypt key         -- decrypt with the key\nbrute               -- brute-force for keys\nhelp                -- show this helptext.");
        }

         public override String Encrypt(String workSpace,String inputText,String[] line) {
            if (line.Length != 3) {
                Console.Error.WriteLine("Bad formatting");
                return workSpace;
            }
            int rotation = 0;
            try { 
                rotation = Int32.Parse(line[2]);
            } catch (Exception e) {
                Console.Error.WriteLine("Error in parsing rotation value -- should be numeric.");
                Console.Error.WriteLine(e.Message);
                return workSpace;
            }
            char[] modified = workSpace.ToCharArray(); 
            for (int i = 0; i < modified.Length; i++) { 
                if (Char.IsLetter(modified[i])) {
                   int baseC;
                   int modC;
                   if (modified[i] < 'a') {
                       baseC = (int)'A';
                       modC = (int)modified[i] - (int)'A';
                   } else {
                       baseC = (int)'a';
                       modC = (int)modified[i] - (int)'a';
                   }
                   modC = (modC + rotation)%26;
                   //Debugging
                   //Console.Write(String.Format("Updating index {0} <{5}> val {1} base {2} mod {3} rotation {4} --to-- ",i,(int)modified[i],baseC,modC,rotation,modified[i]));
                   modified[i] = (char)(baseC+modC);
                   //Console.WriteLine(String.Format("<{0}> val {1}",modified[i],baseC+modC));
                }
            }
            return new String(modified);
        }

       public override String Decrypt(String workSpace,String inputText,String[] line) {
           return Encrypt(workSpace,inputText,line);
       }

        public  void BruteForce(String workSpace) {
            String[] line = new String[3];
            line[0] = "rot";
            line[1] = "encrypt";
            for (int i=0; i<26; i++) {
                line[2]=i.ToString();
                Console.Write(String.Format("{0,2}: {1}",i,Encrypt(workSpace,null,line)));
            }
        }
    }
}