#include <iostream>
#include <string>
#include <fstream>
#include <cstdlib>
#include <stdlib.h>
#include <algorithm>
#include <sstream>
using namespace std;


struct student{
string name;
int id;
string email;
string courses[3];
int grades[3];};

int count_students(string filename);

void read_student(string fname,student*s,int n);

string encrypt(string word , int x);

string dencrypt(string word);

void write1_student(string fname,student*s,int n);

void write2_student(string fname,student*s,int n);
string convert(int x);



int main()
{

    int n,ch;
    cout<< "1=encrypt,2=dencrypt"<<endl;
    cin>>ch;
    string fname;
    if(ch==1){
        cout<<"Enter file name ( ex: file_name.txt )"<<endl;
        cin>>fname;
        n=count_students(fname);
        student*st=new student[n];
        read_student(fname,st,n);

        write1_student("data.txt",st,n);
    }else if(ch==2){
        cin>>fname;
         n=count_students(fname);
        student*st=new student[n];
        read_student(fname,st,n);
        write2_student("data.txt",st,n);
    }

    return 0;
}
string convert(int x){
stringstream ss;
ss<<x;
string y;
y= ss.str();
return y;

}


int count_students(string filename){
int count=0;
string dummy;
ifstream infile;
infile.open(filename.c_str());
while(!infile.eof()){
    getline(infile,dummy);
    count++;
}infile.close();
return count/6;
}
void read_student(string fname,student*s,int n){
    string dummy;
    ifstream infile;
    infile.open(fname.c_str());
    for(int i=0;i<n;i++){
        getline(infile,s[i].name);
        infile>>s[i].id;
        infile>>s[i].email;
        for(int j=0;j<3;j++){
            infile>>s[i].courses[j];

            infile>>s[i].grades[j];
        }

        getline(infile,dummy);
        infile.ignore();
    }
}
string encrypt(string word , int x){
    for(int i=0;i<word.size();i++){
        if(word[i]!=' ')
          word[i]+=x;

    }
    return word;
}
string dencrypt(string word){
    int x;
    cin>>x;
    for(int i=0;i<word.size();i++){
        if(word[i]!=' ')
          word[i]-=x;

    }
    return word;
}

void write1_student(string fname,student*s,int n){
    int num;
    cout<<"How many characters do you want to shift?"<<endl;
    cin>>num;
    string x;
    ofstream infile;
    infile.open(fname.c_str());
    for(int i=0;i<n;i++){
            string e_name=encrypt(s[i].name,num);
        infile<< e_name <<endl;
        x=convert(s[i].id);
    string e_id=encrypt(x,num);
    infile<< e_id <<endl;
    string e_email=encrypt(s[i].email,num);
    infile<< e_email <<endl;
    for(int j=0;j<3;j++){
        string e_courses=encrypt(s[i].courses[j],num);
        infile<< e_courses;
        x=convert((*s).grades[j]);
        string e_grades=encrypt(x,num);
        infile<<' '<< e_grades<<endl;
        if(!(i==n-1&&j==2))
;    }
    infile<<endl;
    }
}void write2_student(string fname,student*s,int n){
    stringstream ss;
    ss<<(*s).id;
    ss<<(*s).grades[3];
    string str=ss.str();
    string x=ss.str();
    ofstream infile;
    infile.open(fname.c_str());
    for(int i=0;i<n;i++){
            string e_name=dencrypt(s[i].name);
        infile<< e_name <<endl;
    string e_id=dencrypt(x);
    infile<< e_id <<endl;
    string e_email=dencrypt(s[i].email);
    infile<< e_email <<endl;
    for(int j=0;j<3;j++){
        string e_courses=dencrypt(s[i].courses[j]);
        infile<< e_courses << ":";
        string e_grades=dencrypt(x);
        infile<< e_grades;
        if(!(i==n-1&&j==2))
;    }
    }
}