/*
Illustrate using strings with functions
*/
#include <iostream>
#include <fstream>
#include <cstdlib>
#include <string>
using namespace std;
void change(string&);
int printmenu();
void replacetext(string&);

int main()
{
   string line;
// open files for reading and writing
   ifstream infile("filetoedit.txt");
   if (!infile) {
     cout << "filetoedit.txt did not open, exiting.\n";
     exit (EXIT_FAILURE);
   }
   ofstream outfile("edited.txt");
   if (!outfile) {
     cout << "edited.txt did not open, exiting.\n";
     exit (EXIT_FAILURE);
   }
   while(getline(infile, line)){
     cout << "The next line from the file is: " << endl << line << endl;
     change(line);
     outfile << line << endl;
   }
   infile.close();
   outfile.close();

   return 0;
}
// pass by reference
void change(string& line) {
    //cout << "in change, param is: "<< str << endl;
    int choice;
    do {
        choice=printmenu();
        switch(choice) {
            case 1: //erasetext(line);
                    break;
            case 2: //inserttext(line);
                    break;
            case 3: replacetext(line);
                    break;
            case 4: break;
            default: cout << "invalid choice, try again." << endl;
        } // end switch
    }  while (choice != 4);

}

int printmenu() {
    int chc;
    cout << "Enter: \n 1: to erase\n 2: to insert\n 3: to replace\n";
    cout << " 4: to move to next line\n";
    cin >> chc;
    return chc;
}
// input: a string passed by reference
// process: asks the user what text to replace
//      find the position of the text
//      replace with user's new string
// output: the parameter string edited

void replacetext(string &str) {
    string oldsub, newsubstr;
    cout << "What substring do you want to replace? ";
    cin >> oldsub;
    string::size_type index=str.find(oldsub,0);
    // if the substring is not found, just return
    if (index==string::npos) {
        cout << "that substring is not in the line of text" << endl;
        return;
    }
    cout << "Enter the new string: ";
    cin >> newsubstr;
    str.replace(index, oldsub.length() ,newsubstr);
    return;
}