package com.eassessment.util;

import java.util.ArrayList;
import java.util.Random;

public class PasswordGenerator {
	// DATAS
	// characters with which the password will be composed
	private static final int charactersSize = 100;
	private static char[] characters = new char[charactersSize];

	// keep the counts of used characters
	private static int charactersCount = 0;

	// size of the password to generate
	private int passwordSize;

	// CONSTRUCTOR
	public PasswordGenerator(int passwordSize) {

		// set the password size
		this.passwordSize = passwordSize;

		// set the characters that will be used to generate the password
		initCharacters();
	}

	// METHODS
	// fill the array of characters that will be used to generate the password
	private static char[] initCharacters() {
		int i = 0;

		// add 0-9
		for (int j = 48; j < 58; ++i, ++j, ++charactersCount) {
			characters[i] = (char) j;
		}

		// add @ + a-z
		for (int j = 64; j < 91; ++i, ++j, ++charactersCount) {
			characters[i] = (char) j;
		}

		// add A-Z
		for (int j = 97; j < 123; ++i, ++j, ++charactersCount) {
			characters[i] = (char) j;
		}

		return characters;
	}

	// generate a random password
	public char[] get() {

		// initialize the random number generator
		Random rnd = new Random();

		char[] password = new char[passwordSize];

		// choose a random character from the array
		for (int i = 0; i < passwordSize; ++i) {
			password[i] = characters[rnd.nextInt(charactersCount)];
		}

		return password;
	}

	// generate a random password
	public StringBuilder getPassword() {
		StringBuilder sb = new StringBuilder();
		// initialize the random number generator
		Random rnd = new Random();

		// choose a random character from the array
		for (int i = 0; i < passwordSize; ++i) {
			sb.append(characters[rnd.nextInt(charactersCount)]);
		}

		return sb;
	}

	// DEBUG METHODS
	// show the characters the will be used to compose the pass
	public void showCharacters() {
		for (int i = 0; i < charactersCount && characters[i] != 0; ++i) {
			System.out.println(characters[i]);
		}
	}

	// MAIN - testing code
	public static void main(String[] args) {
		int passwordSize = 10;
		PasswordGenerator password = new PasswordGenerator(passwordSize);
		for (int i = 0; i < 20; i++) {
			System.err.println(password.getPassword().toString());
		}

	}
}