import java.io.*;
import java.util.*;

public class TestPerson{
    public static void main(String[] args)throws IOException{
        //check if file exists
        File myFile = new File(args[0]);
        try{
            if(!myFile.exists()){
                throw new FileNotFoundException();
            }
        }
        catch(FileNotFoundException fnfe){
            System.out.println("\nSorry, the file ["+args[0]+"] cannot be found.");
            System.exit(0);
        }

        //csv file reader
        BufferedReader in = new BufferedReader(new FileReader(myFile));

        //create person list
        List<Person> personList = new ArrayList<Person>();

        //add csv data to person list
        String str;
        while ((str = in.readLine()) != null){
            String[] data = str.split(",");
            personList.add(new Person(data[0],Integer.parseInt(data[1])));
        }

        printList(personList);

        //ask user what to edit
        Scanner scan = new Scanner(System.in);
        boolean invalidChoice;
        do{
            invalidChoice = false;
            try{
                System.out.print("\nWhich person would you like to edit? (Enter [-1] to exit): ");
                int choice = scan.nextInt();

                //exit if choice is -1
                if(choice == -1){
                    System.exit(0);
                }
                editPerson(personList.get(choice));
            }
            catch(IndexOutOfBoundsException exc){
                System.out.println("\nRecord does not exist, please try again.");
                invalidChoice = true;
            }
        } while(invalidChoice);

        in.close();
        scan.close();

        //overwrite csv file
        PrintWriter personWriter = new PrintWriter(new FileWriter(args[0], false));

        for(Person p : personList){
            personWriter.println(p.getName()+","+p.getAge());
        }

        personWriter.close();

        printList(personList);
    }


    //method to edit
    public static Object editPerson(Person p){
        Scanner scan = new Scanner(System.in);
        System.out.print("Enter New Name for "+p.getName()+": ");
        String newName = scan.next();
        p.setName(newName);
        System.out.print("Enter New Age for "+p.getName()+": ");
        int newAge = scan.nextInt();
        p.setAge(newAge);
        return p;
    }


    //method to print
    public static void printList(List personList){
        ListIterator it = personList.listIterator();
        while(it.hasNext()){
            System.out.println("\nPerson " + it.nextIndex()+":");
            System.out.println(it.next());
        }
    }

}