/**
 * =============================================================================
 *
 * ORCID (R) Open Source
 * http://orcid.org
 *
 * Copyright (c) 2012-2014 ORCID, Inc.
 * Licensed under an MIT-Style License (MIT)
 * http://orcid.org/open-source-license
 *
 * This copyright and license information (including a link to the full license)
 * shall be included in its entirety in all copies or substantial portion of
 * the software.
 *
 * =============================================================================
 */
package org.orcid.core.manager.impl;

import org.apache.commons.lang3.ArrayUtils;
import org.apache.commons.lang3.RandomStringUtils;
import org.orcid.core.manager.PasswordGenerationManager;
import org.orcid.password.constants.OrcidPasswordConstants;

/**
 * Class to randomly generate a password of given length and that satisfies the rules for the Orcid password policy
 * @author jamesb
 * 
 */
public class PasswordGenerationManagerImpl implements PasswordGenerationManager {

    private int passwordLength;
    private static final int NUM_PRESET_CHARS = 3;

    public PasswordGenerationManagerImpl(int passwordLength) {
        super();
        this.passwordLength = passwordLength;
    }

    public int getPasswordLength() {
        return passwordLength;
    }

    public void setPasswordLength(int passwordLength) {
        this.passwordLength = passwordLength;
    }

    @Override
    public char[] createNewPassword() {

        // must contain at least 12 chars
        char[] presetChars = new char[NUM_PRESET_CHARS];

        // one each of symbol, character and number
        presetChars[0] = randomSymbol();
        presetChars[1] = randomNumber();
        presetChars[2] = randomCharacter();

        //rest are also random but from any of the classes
        char[] mixedCharacterClasses = RandomStringUtils.random(passwordLength - NUM_PRESET_CHARS, OrcidPasswordConstants.getEntirePasswordCharsRange()).toCharArray();

        // shuffle the string so that the pattern of first 3 chars
        // doesn't become predictable
        return shuffleChar(ArrayUtils.addAll(mixedCharacterClasses, presetChars));

    }

    private char randomSymbol() {
        return RandomStringUtils.random(1, OrcidPasswordConstants.UNESCAPED_SYMBOL_RANGE).charAt(0);
    }

    private char randomNumber() {
        return RandomStringUtils.random(1, OrcidPasswordConstants.CHAR_CLASS_NUMBERS).charAt(0);
    }

    private char randomCharacter() {
        return RandomStringUtils.random(1, OrcidPasswordConstants.LOWERCASE_ALPHABET).charAt(0);
    }

    private char[] shuffleChar(char[] randomChars) {
        for (int i = randomChars.length; i > 1; i--) {
            char temp = randomChars[i - 1];
            int randIx = (int) (Math.random() * i);
            randomChars[i - 1] = randomChars[randIx];
            randomChars[randIx] = temp;
        }
        return randomChars;
    }

}