#include <iostream>
#include <fstream>
#include <string>
#include <cstdlib>
#include <cctype>

using namespace std;

class Crypto {
public:
    void DisplayFile(string filename);
    void EncryptFile(string cipher_key, string filename_from, string filename_to);
    void DecryptFile(string cipher_key, string filename_from, string filename_to);
    string EncryptString(string &cipher_key, string string_to_be_encrypted);
    string DecryptString(string &cipher_key, string string_to_be_decrypted);
private:
    string cipher_key;
    void RotateCipherKey();
    char substitution_cipher(char char_to_encrypt);
    char reverse_substitution_cipher(char char_to_encrypt);
};

using namespace std;

char Crypto::substitution_cipher(char char_to_encrypt)
{
    int cipherLength=0, i=0;

    if(!islower(char_to_encrypt))
        char_to_encrypt = tolower(char_to_encrypt);

    if(!isalpha(char_to_encrypt)){
        cout << "Character to encrypt must be alphabetical!";
        return char_to_encrypt;
    }

    cipherLength = cipher_key.length();

    for(i=0; i<cipherLength; i++){
        RotateCipherKey();
        char_to_encrypt = cipher_key[i];
        }

    return char_to_encrypt;
}


// Perform a "reverse" substitution cipher on a single character
// using the specified cipher key
// See reference document for implementation details.
// You reverse the operation described above

char Crypto::reverse_substitution_cipher(char char_to_decrypt)
{
    int i=0, cipherLength=0;
    cipherLength = cipher_key.length();

    for(i=0; i<cipherLength; i++){
        RotateCipherKey();
        char_to_decrypt = cipher_key[i];
    }

    return char_to_decrypt;
}

// Encrypt String and return it
// You will use the substitution_cipher() function to encrypt the
// individual characters
//
// Think for loop
string Crypto::EncryptString(string &cipher_key,
    string string_to_be_encrypted)
{
    int i=0, loopBound=0;
    char tempChar;
    if(string_to_be_encrypted.length()>0)
        loopBound=string_to_be_encrypted.length();

    for(i=0; i < loopBound; i++){
        tempChar = substitution_cipher(string_to_be_encrypted[i]);
        RotateCipherKey();
    }

    string encrypted_string = string_to_be_encrypted;
    cout << " " << string_to_be_encrypted;
    return encrypted_string;
}

// Decrypt String and return it
// You will use the reverse_subsitution_cipher() function to
// decrypt the individual characters
//
string Crypto::DecryptString(string &cipher_key, string string_to_be_decrypted)
{
    string decrypted_string = string_to_be_decrypted;

    return decrypted_string;
}

//
// Need to finish this one
//
// Display file specified by the filname parameter
// See EncryptFile/DecryptFile for details on how to read and
// display a file. Use the ifstream infile section to read a file
// and cout to display it to the screen.
void Crypto::DisplayFile(string filename)
{
    string tempString;
    ifstream infile;
    infile.open(filename);

    infile >> tempString;
    while(infile){
        cout << " " << tempString;
        infile >> tempString;
    }

    cout << endl;
}

// Encrypt the specified file using the specified cipher key and
// write the output to a different file
// This function is complete
void Crypto::EncryptFile(string cipher_key,
    string filename_from, string filename_to)
{
    string input;
    ifstream infile;
    ofstream outfile;

    infile.open (filename_from.c_str());
    outfile.open (filename_to.c_str());

    if(!infile)
    {
        cout << "Can not open input file " + filename_from << endl;
        exit(0);
    }

    if(!outfile)
    {
        cout << "Can not open Output file " + filename_to << endl;
        exit(0);
    }


    while( getline(infile, input))
    {
        outfile << EncryptString(cipher_key,  input) << endl;
    }
    infile.close();
    outfile.close();
}

// Decrypt the specified file using the specified cipher key and
// write the output to a different file
// This function is complete
void Crypto::DecryptFile(string cipher_key,
    string filename_from, string filename_to)
{
    string input;
    ifstream infile;
    ofstream outfile;

    infile.open (filename_from.c_str());
    outfile.open (filename_to.c_str());

    if(!infile)
    {
        cout << "Can not open input file " + filename_from << endl;
        exit(0);
    }

    if(!outfile)
    {
        cout << "Can not open Output file " + filename_to << endl;
        exit(0);
    }


    while( getline(infile, input))
    {
        outfile << DecryptString(cipher_key,  input) << endl;
    }
    infile.close();
    outfile.close();
}

int main()
{
    Crypto Cipher1;
    Crypto Cipher2;
    string cipher_key = "qwertyuiopasdfghjklzxcvbnm";
    string cipher_key2 = "wertyuiopasdgfhjqklzxcvbnm";

    Cipher1.EncryptFile(cipher_key, "test.txt",
                        "test-encrypted.txt");
    Cipher1.DecryptFile(cipher_key, "test-encrypted.txt",
                        "test-encrypt-decrypt-test.txt");
    Cipher1.DisplayFile("test.txt");
    Cipher1.DisplayFile("test-encrypted.txt");
    Cipher1.DisplayFile("test-encrypt-decrypt-test.txt");

    string cipher_key3 = cipher_key2;
    cout << Cipher2.EncryptString(cipher_key3,
        "C++ Programming Is Fun") << endl;

    cipher_key3 = cipher_key2;
    string cipher_key4 = cipher_key2;

    cout << Cipher2.DecryptString(cipher_key2,
        Cipher2.EncryptString(cipher_key3,"C++ Programming Is Fun") )
     << endl;

    return 0;
}