package main;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

public class PasswordCombinations {

    private static final Map<Character, Character> replacements = new HashMap<Character, Character>() {{
        put('i', '!');
        put('a', '@');
        put('s', '$');
        put('o', '0');
        put('E', '3');
    }};

    /*
    You are designing a New User sign-up form for a website. When a user enters text in the password field,
    you want to suggest possible 'stronger' passwords to the user by swapping in special characters,
    like turning an "a" into an "@". Given a password represented as a string and a character map that contains
    common characters and substitutions, create a list of all possible password combinations that can be created.

    Example:
    Input: Map:{{'i','!'},{'a','@'},{'s','$'},{'o','0'},{'E','3'}} Password: password

    Output:
    p@ssword
    p@$sword
    pa$sword
    p@s$word
    p@$$word
    pa$$word
    pas$word
    p@ssw0rd
    p@$sw0rd
    pa$sw0rd
    p@s$w0rd
    p@$$w0rd
    pa$$w0rd
    pas$w0rd
    passw0rd
     */
    public static List<String> obfuscate(String password) {
        List<String> passwords = new ArrayList<String>();

        char [] array = password.toCharArray();

        for(int i = 0; i < array.length; i++)
        {
            Character sub = replacements.get(array[i]);

            if(sub != null)
            {
                int length = passwords.size();

                for(int j = 0; j < length; j++)
                {
                    String str = passwords.get(j);
                    passwords.add(new String(str.substring(0,i)+sub+str.substring(i+1)));
                }

                passwords.add(new String(password.substring(0,i)+sub+password.substring(i+1)));
            }
        }

        return passwords;
    }

}