#include <iostream>
#include <fstream>
#include <string>
#include <cstdlib>
using namespace std;
string str;
 
void Message() {
       cout <<"*-----------------------------------*\n"
            <<"|         Welcome to Crypto!        |\n"
            <<"*-----------------------------------*\n";
        cout <<"Please type a command.\n"
            <<"Type \"m\" for the command menu.\n";
        return;
    }
 
void Encrypt(char *filename, int key)
{
    system("CLS");
    ifstream in;
    ofstream out;
    char c;
    string fileContent;
 
    in.open(filename);
 
    if(in.fail()) {
        in.close();
        cout <<"Could not find file: "<<filename<<endl;
        system("PAUSE");
        system("CLS");
        Message();
        return;
    }
 
    while(in.get(c))
    {
        fileContent += c;
    }
    in.close();
    for(size_t i = 0; i < fileContent.size(); i++)
    {
        fileContent[i] += key;
    }
    out.open(filename, ios::trunc);
    out << fileContent;
    out.close();
 
    cout <<"FILE ENCRYPTED!\n";
    system("PAUSE");
    system("CLS");
    Message();
}
 
void Decrypt(char *filename, int key)
{
    system("CLS");
    ifstream in;
    ofstream out;
    char c;
    string fileContent;
 
    in.open(filename);
 
    if(in.fail())
    {
        in.close();
        cout <<"Could not find file: "<<filename<<endl;
        system("PAUSE");
        system("CLS");
        Message();
        return;
    }
 
 
 
    while(in.get(c))
    {
        fileContent += c;
        for(size_t i = 0; i < fileContent.size(); i++)
        {
            fileContent[i] -= key;
        }
    }
 
    in.close();
    out.open(filename, ios::trunc);
    out << fileContent;
    out.close();
 
    cout <<"FILE DECRYPTED!\n";
    system("PAUSE");
    system("CLS");
    Message();
}
 
 
bool PasswordCheck (char* filename)
{
    ifstream file_in(filename);
    char pass[80];
    char input_line[80];
 
    if (! file_in) 
    {
        file_in.close();
        return false;
    }
 
    cout <<"Please type your password: ";
    cin.getline(pass, 80);
    while( file_in.getline(input_line, 80) )
    {
        if(strcmp(input_line, pass) == 0)
            return true;
    }
 
    return false;
}
 
 
int main(int argc, char* argv[])
{
    char filename[20];
    char comd;
 
    int key = atoi (argv[1]);
 
 
    if (!PasswordCheck (argv[2]))
    {
        cout << "Bad password.  Exiting program.\n";
        return 0;
    }
 
 
    system("CLS");
    cout <<"*-----------------------------------*\n"
         <<"|         Welcome to Crypto!        |\n"
        <<"*-----------------------------------*\n";
    cout <<"Please type a command.\n"
        <<"Type \"m\" for the command menu.\n";
 
 
    while(true)
    {
        cin >> comd;
        switch(comd)
        {
            case 'e' :
                system("CLS");
                cout <<"Please type name of file to encrypt (.txt): ";
                cin >> filename;
                Encrypt(filename, key);
                break;
 
            case 'd' :
                system("CLS");
                cout <<"Please type name of file to encrypt (.txt): ";
                cin >> filename;
                Decrypt(filename, key);
                break;
 
            case 'm' :
                cout <<"\n<COMMAND MENU>\n"
                    <<"*--------------------*\n"
                    <<"| e = 'Encrypt'      |\n"
                    <<"| d = 'Decrypt'      |\n"
                    <<"| m = 'Command Menu' |\n"
                    <<"| q = 'Quit'         |\n"
                    <<"*--------------------*\n";
                 break;
 
            case 'q' :
                cout <<"\nThanks For Using 'Crypto'\n";
                system("PAUSE");
                return 0;
                break;
 
            default :
                break;
        }
    }
}