#include <iostream> 
#include <strstream>
#include <fstream> //header file for file i/o, contains data types
				   // ifstream, ofstream, open, close
#include <string>  //header file for string manipulation operations
using namespace std;
 
 
 
//The CharacterShift Function takes in the Key
//and the Cipher value (both chars)
//and decrypts them as per this projects
//request and it will also return a blank space
//if the cipher is a blank space
char CharacterShift(char Key, char Cipher);
string Decryption(string CipherArray, string KeyArray);
void IOFunction();
int main(){
 
 
IOFunction();
 
 
return 0;
}
 
char CharacterShift(char Key, char Cipher)
{
	char output;
	if(Cipher==' ')
	{
		return Cipher;
	}
 
	Key = Key - 65;
	Cipher = Cipher - 65;
 
	if( Key > Cipher)
	{
		output = 91+Cipher-Key;
	} 
	else
	{
		output = 65 + (Cipher-Key);
	}
 
	return output;
}
string Decryption(string KeyArray, string CipherArray){
	int TemporaryCount=0;
	int i=0;
	string New;
	int CipherArrayLength=CipherArray.length();
	int KeyArrayLength=KeyArray.length();
 
	for(i;i<CipherArrayLength;i++){
		if(CipherArray[i]=='?'){
			New+='?';
		}
		if(CipherArray[i]=='\''){
			New+='\'';
		}
		if(CipherArray[i]=='%'){
			New+='\n';
			New+='\n';
		}
		if(CipherArray[i]=='.'){
			New+='.';
		}
		if(TemporaryCount>=KeyArrayLength){
			TemporaryCount=0;
		}
		if(CipherArray[i]==' '){
			New+=' ';
		}
		if(TemporaryCount<KeyArrayLength && CharacterShift(KeyArray[TemporaryCount],CipherArray[i])!=' '&&CipherArray[i]!='.' ){
			New+=CharacterShift(KeyArray[TemporaryCount],CipherArray[i]);
			TemporaryCount++;
		}
	}
	return New;
}
void IOFunction(){
		string junk,Key1,Cipher1,Key2,Cipher2;
string TotalText;
string myFileName; //variable to hold external file name
ifstream inFile; //internal file (stream) name
cout <<"Please enter your input file name:";
cin >> myFileName;
inFile.open(myFileName.c_str()); //convert to c_string and opens file
								// if open does not work, inFile is in a “fail” state
while (!inFile)					// therefore !inFile will be ”true”
{
inFile.clear();					//puts the file states back to “good” from bad open
cout << endl << "You entered an invalid file name. Please try again:";
cin >> myFileName;
inFile.open(myFileName.c_str());
}
 
while (inFile) //”true” if the open command executed properly
{
getline(inFile,junk,'@');
getline(inFile,Key1,'#');
getline(inFile,Cipher1,'@');
getline(inFile,Key2,'#');
getline(inFile,Cipher2,'@');
}
if(junk.length()>1){
	cout<<"*** Error Code 2 -- No key given ***"<<endl;
}
inFile.close();	
cout<< Decryption(Key1, Cipher1);
cout<< Decryption(Key2, Cipher2);
 
 
}