package com.progressoft.jip8;

import java.security.SecureRandom;
import java.util.Arrays;
import java.util.Collections;
import java.util.List;

public class PasswordGenerator {
    public String generate() {
        return generateRandomPassword(8);
    }

    static String chars = "abcdefghijklmnopqrstuvwxyz";
    static String nums = "0123456789";
    static String sChars = "_$@%";

    static String password = chars + nums + sChars;
    static String password_shuffle = shuffleString(password);
    static String ok_password = password_shuffle;

    static SecureRandom random = new SecureRandom();

    public static void main(String[] args) {
        System.out.println("password : " + generateRandomPassword(8));
        System.out.println("\n");
    }

    public static String generateRandomPassword(int length) {
        if (length < 1) throw new IllegalArgumentException();
        int count_chars = 0, count_num = 0, count_schar = 0;
        StringBuilder sb = new StringBuilder(length);
        for (int i = 0; i < length;) {
            int rndCharAt = random.nextInt(ok_password.length());
            char rndChar = ok_password.charAt(rndCharAt);
            if (chars.contains(rndChar + "") && count_chars <4){
                sb.append(rndChar);
                count_chars++;
                i++;
            }
            if (nums.contains(rndChar + "") && count_num <2){
                sb.append(rndChar);
                count_num++;
                i++;
            }
            if (sChars.contains(rndChar + "") && count_schar <2){
                sb.append(rndChar);
                count_schar++;
                i++;
            }
        }
        return sb.toString();
    }


    public static String shuffleString(String string)
    {
        List<String> letters = Arrays.asList(string.split(""));
        Collections.shuffle(letters);
        String shuffled = "";
        for (String letter : letters) {
            shuffled += letter;
        }
        return shuffled;
    }

}