armenak / DataDefender

 * Copyright 2014, Armenak Grigoryan, and individual contributors as indicated

 * by the @authors tag. See the copyright.txt in the distribution for a

 * full listing of individual contributors.

 *

 * This is free software; you can redistribute it and/or modify it

 * under the terms of the GNU Lesser General Public License as

 * published by the Free Software Foundation; either version 2.1 of

 * the License, or (at your option) any later version.

 *

 * This software is distributed in the hope that it will be useful,

 * but WITHOUT ANY WARRANTY; without even the implied warranty of

 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU

 * Lesser General Public License for more details.

 */

package com.strider.datadefender.anonymizer.functions;

import com.strider.datadefender.functions.NamedParameter;

import com.strider.datadefender.requirement.registry.RequirementFunction;

import com.strider.datadefender.utils.Xeger;

import java.io.InputStreamReader;

import java.io.BufferedReader;

import java.io.FileReader;

import java.io.IOException;

import java.io.InputStream;

import java.time.LocalDate;

import java.time.LocalDateTime;

import java.time.ZoneOffset;

import java.time.format.DateTimeFormatter;

import java.util.Collections;

import java.util.HashMap;

import java.util.Map;

import java.util.Iterator;

import java.util.ArrayList;

import java.util.List;

import java.util.Scanner;

import org.apache.commons.lang3.RandomUtils;

import lombok.extern.log4j.Log4j2;

/**

 * Core set of helpers for data anonymization.

 *

 * @author Armenak Grigoryan

 */

@Log4j2

public class Core extends RequirementFunction {

    private static final Map<String, List<String>> stringLists = new HashMap<>();

    private static final Map<String, Iterator<String>> stringIters = new HashMap<>();

    private static final  List<String> words = new ArrayList<>();

    private static String hash = null;

    public static interface InputStreamSupplier {

        public InputStream getInputStream() throws IOException;

    }

    /**

     * Static block for loading words from dictionary

     */

    static {

        try (Scanner scanner = new Scanner(Core.class.getResourceAsStream("dictionary.txt"))) {

            while (scanner.hasNext()) {

                words.add(scanner.next());

            }

        }

    }

    /**

     * Static block to load hash string for "salting" the encryption

     */

    static {

        try (Scanner scanner = new Scanner(Core.class.getResourceAsStream("hash.txt"))) {

            if (scanner.hasNext()) {

                hash = scanner.next();

            }

        }

    }    

    /**

     * Returns the next shuffled item from the named collection.

     *

     * @param String name

     * @return String

     */

    private String getNextShuffledItemFor(@NamedParameter("name") String name) {

        if (stringIters.containsKey(name)) {

            final Iterator<String> iter = stringIters.get(name);

            if (iter.hasNext()) {

                return iter.next();

            }

            // else shuffle again

        }

        final List<String> list = stringLists.get(name);

        Collections.shuffle(list);

        final Iterator<String> iter = list.iterator();

        stringIters.put(name, iter);

        return iter.next();

    }

    /**

     * Generates a list of random strings from a list of strings (new-

     * line separated) in a file.The function randomizes the collection, exhausting all possible values

     * before re-shuffling and re-using items.

     * @param id

     * @param supplier

     * @return A random string from the stream

     * @throws IOException

     */

    protected String randomStringFromStream(String id, InputStreamSupplier supplier) throws IOException {

        if (!stringLists.containsKey(id)) {

            log.info("Loading words from stream {}", id);

            final List<String> values = new ArrayList<>();

            InputStream stream = supplier.getInputStream();

            try (BufferedReader br = new BufferedReader(new InputStreamReader(stream))) {

                for (String line; (line = br.readLine()) != null; ) {

                    values.add(line);

                }

            }

            stringLists.put(id, values);

        }

        return getNextShuffledItemFor(id);

    }

    /**

     * Generates a list of random strings from a list of strings (new-

     * line separated) in a file.

     *

     * The function randomizes the collection, exhausting all possible values

     * before re-shuffling and re-using items.

     *

     * @param file the file name

     * @return A random string from the file

     * @throws java.io.IOException

     */

    /**

     * Generates a random date between the passed start and end dates, and using

     * the passed format to parse the dates passed, and to format the return

     * value.

     *

     * @param start

     * @param end

     * @param format

     * @return

     */

    public String randomDate(

        @NamedParameter("start") String start,

        @NamedParameter("end") String end,

        @NamedParameter("format") String format

    ) {

        DateTimeFormatter fmt = DateTimeFormatter.ofPattern(format);

        LocalDate ds = LocalDate.parse(start, fmt);

        LocalDate de = LocalDate.parse(end, fmt);

        long day = RandomUtils.nextLong(0, de.toEpochDay() - ds.toEpochDay()) + ds.toEpochDay();

        return LocalDate.ofEpochDay(day).format(fmt);

    }

    /**

     * Generates a random date-time between the passed start and end dates, and

     * using the passed format to parse the dates passed, and to format the

     * return value.

     *

     * @param start

     * @param end

     * @param format

     * @return

     */

    public String randomDateTime(

        @NamedParameter("start") String start,

        @NamedParameter("end") String end,

        @NamedParameter("format") String format

    ) {

        DateTimeFormatter fmt = DateTimeFormatter.ofPattern(format);

        LocalDateTime ds = LocalDateTime.parse(start, fmt);

        LocalDateTime de = LocalDateTime.parse(end, fmt);

        long day = RandomUtils.nextLong(0, de.toEpochSecond(ZoneOffset.UTC) - ds.toEpochSecond(ZoneOffset.UTC)) + ds.toEpochSecond(ZoneOffset.UTC);

        return LocalDateTime.ofEpochSecond(day, 0, ZoneOffset.UTC).format(fmt);

    }

    /**

     * Generates a random string of 'num' words, with at most 'length'

     * characters (shortening the string if more characters appear in the

     * string).

     *

     * @param num The number of desired words

     * @param length The maximum length of the string

     * @return

     */

    public String randomString(@NamedParameter("num") int num, @NamedParameter("length") int length) {

        final StringBuilder randomString = new StringBuilder();

        for (int i = 0; i < num && randomString.length() < length; ++i) {

            final int r = RandomUtils.nextInt(0, words.size());

            randomString.append(words.get(r)).append(' ');

        }

        if (randomString.length() > length) {

            return randomString.toString().substring(0, length).trim();

        }

        return randomString.toString().trim();

    }

    /**

     * Generates a String from the passed regex that is guaranteed to match it.

     *

     * @param pattern

     * @return

     */

    public String randomStringFromPattern(@NamedParameter("pattern") String pattern) {

        final Xeger instance = new Xeger(pattern);

        return instance.generate();

    }

    public String getHash() {

        return hash;

    }

}