/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.apache.commons.lang3;

import net.lax1dude.eaglercraft.v1_8.EaglercraftRandom;

/**
 * <p>
 * Generates random {@code String}s.
 * </p>
 *
 * <p>
 * <b>Caveat: Instances of {@link EaglercraftRandom}, upon which the implementation of this
 * class relies, are not cryptographically secure.</b>
 * </p>
 *
 * <p>
 * RandomStringUtils is intended for simple use cases. For more advanced use
 * cases consider using Apache Commons Text's <a href=
 * "https://commons.apache.org/proper/commons-text/javadocs/api-release/org/apache/commons/text/RandomStringGenerator.html">
 * RandomStringGenerator</a> instead.
 * </p>
 *
 * <p>
 * The Apache Commons project provides
 * <a href="https://commons.apache.org/rng">Commons RNG</a> dedicated to
 * pseudo-random number generation, that may be a better choice for applications
 * with more stringent requirements (performance and/or correctness).
 * </p>
 *
 * <p>
 * Note that <em>private high surrogate</em> characters are ignored. These are
 * Unicode characters that fall between the values 56192 (db80) and 56319 (dbff)
 * as we don't know how to handle them. High and low surrogates are correctly
 * dealt with - that is if a high surrogate is randomly chosen, 55296 (d800) to
 * 56191 (db7f) then it is followed by a low surrogate. If a low surrogate is
 * chosen, 56320 (dc00) to 57343 (dfff) then it is placed after a randomly
 * chosen high surrogate.
 * </p>
 *
 * <p>
 * #ThreadSafe#
 * </p>
 * 
 * @since 1.0
 */
public class RandomStringUtils {

	/**
	 * <p>
	 * Random object used by random method. This has to be not local to the random
	 * method so as to not return the same value in the same millisecond.
	 * </p>
	 */
	private static final EaglercraftRandom RANDOM = new EaglercraftRandom();

	/**
	 * <p>
	 * {@code RandomStringUtils} instances should NOT be constructed in standard
	 * programming. Instead, the class should be used as
	 * {@code RandomStringUtils.random(5);}.
	 * </p>
	 *
	 * <p>
	 * This constructor is public to permit tools that require a JavaBean instance
	 * to operate.
	 * </p>
	 */
	public RandomStringUtils() {
	}

	// Random
	// -----------------------------------------------------------------------
	/**
	 * <p>
	 * Creates a random string whose length is the number of characters specified.
	 * </p>
	 *
	 * <p>
	 * Characters will be chosen from the set of all characters.
	 * </p>
	 *
	 * @param count the length of random string to create
	 * @return the random string
	 */
	public static String random(final int count) {
		return random(count, false, false);
	}

	/**
	 * <p>
	 * Creates a random string whose length is the number of characters specified.
	 * </p>
	 *
	 * <p>
	 * Characters will be chosen from the set of characters whose ASCII value is
	 * between {@code 32} and {@code 126} (inclusive).
	 * </p>
	 *
	 * @param count the length of random string to create
	 * @return the random string
	 */
	public static String randomAscii(final int count) {
		return random(count, 32, 127, false, false);
	}

	/**
	 * <p>
	 * Creates a random string whose length is between the inclusive minimum and the
	 * exclusive maximum.
	 * </p>
	 *
	 * <p>
	 * Characters will be chosen from the set of characters whose ASCII value is
	 * between {@code 32} and {@code 126} (inclusive).
	 * </p>
	 *
	 * @param minLengthInclusive the inclusive minimum length of the string to
	 *                           generate
	 * @param maxLengthExclusive the exclusive maximum length of the string to
	 *                           generate
	 * @return the random string
	 * @since 3.5
	 */
	public static String randomAscii(final int minLengthInclusive, final int maxLengthExclusive) {
		return randomAscii(RandomUtils.nextInt(minLengthInclusive, maxLengthExclusive));
	}

	/**
	 * <p>
	 * Creates a random string whose length is the number of characters specified.
	 * </p>
	 *
	 * <p>
	 * Characters will be chosen from the set of Latin alphabetic characters (a-z,
	 * A-Z).
	 * </p>
	 *
	 * @param count the length of random string to create
	 * @return the random string
	 */
	public static String randomAlphabetic(final int count) {
		return random(count, true, false);
	}

	/**
	 * <p>
	 * Creates a random string whose length is between the inclusive minimum and the
	 * exclusive maximum.
	 * </p>
	 *
	 * <p>
	 * Characters will be chosen from the set of Latin alphabetic characters (a-z,
	 * A-Z).
	 * </p>
	 *
	 * @param minLengthInclusive the inclusive minimum length of the string to
	 *                           generate
	 * @param maxLengthExclusive the exclusive maximum length of the string to
	 *                           generate
	 * @return the random string
	 * @since 3.5
	 */
	public static String randomAlphabetic(final int minLengthInclusive, final int maxLengthExclusive) {
		return randomAlphabetic(RandomUtils.nextInt(minLengthInclusive, maxLengthExclusive));
	}

	/**
	 * <p>
	 * Creates a random string whose length is the number of characters specified.
	 * </p>
	 *
	 * <p>
	 * Characters will be chosen from the set of Latin alphabetic characters (a-z,
	 * A-Z) and the digits 0-9.
	 * </p>
	 *
	 * @param count the length of random string to create
	 * @return the random string
	 */
	public static String randomAlphanumeric(final int count) {
		return random(count, true, true);
	}

	/**
	 * <p>
	 * Creates a random string whose length is between the inclusive minimum and the
	 * exclusive maximum.
	 * </p>
	 *
	 * <p>
	 * Characters will be chosen from the set of Latin alphabetic characters (a-z,
	 * A-Z) and the digits 0-9.
	 * </p>
	 *
	 * @param minLengthInclusive the inclusive minimum length of the string to
	 *                           generate
	 * @param maxLengthExclusive the exclusive maximum length of the string to
	 *                           generate
	 * @return the random string
	 * @since 3.5
	 */
	public static String randomAlphanumeric(final int minLengthInclusive, final int maxLengthExclusive) {
		return randomAlphanumeric(RandomUtils.nextInt(minLengthInclusive, maxLengthExclusive));
	}

	/**
	 * <p>
	 * Creates a random string whose length is the number of characters specified.
	 * </p>
	 *
	 * <p>
	 * Characters will be chosen from the set of characters which match the POSIX
	 * [:graph:] regular expression character class. This class contains all visible
	 * ASCII characters (i.e. anything except spaces and control characters).
	 * </p>
	 *
	 * @param count the length of random string to create
	 * @return the random string
	 * @since 3.5
	 */
	public static String randomGraph(final int count) {
		return random(count, 33, 126, false, false);
	}

	/**
	 * <p>
	 * Creates a random string whose length is between the inclusive minimum and the
	 * exclusive maximum.
	 * </p>
	 *
	 * <p>
	 * Characters will be chosen from the set of \p{Graph} characters.
	 * </p>
	 *
	 * @param minLengthInclusive the inclusive minimum length of the string to
	 *                           generate
	 * @param maxLengthExclusive the exclusive maximum length of the string to
	 *                           generate
	 * @return the random string
	 * @since 3.5
	 */
	public static String randomGraph(final int minLengthInclusive, final int maxLengthExclusive) {
		return randomGraph(RandomUtils.nextInt(minLengthInclusive, maxLengthExclusive));
	}

	/**
	 * <p>
	 * Creates a random string whose length is the number of characters specified.
	 * </p>
	 *
	 * <p>
	 * Characters will be chosen from the set of numeric characters.
	 * </p>
	 *
	 * @param count the length of random string to create
	 * @return the random string
	 */
	public static String randomNumeric(final int count) {
		return random(count, false, true);
	}

	/**
	 * <p>
	 * Creates a random string whose length is between the inclusive minimum and the
	 * exclusive maximum.
	 * </p>
	 *
	 * <p>
	 * Characters will be chosen from the set of \p{Digit} characters.
	 * </p>
	 *
	 * @param minLengthInclusive the inclusive minimum length of the string to
	 *                           generate
	 * @param maxLengthExclusive the exclusive maximum length of the string to
	 *                           generate
	 * @return the random string
	 * @since 3.5
	 */
	public static String randomNumeric(final int minLengthInclusive, final int maxLengthExclusive) {
		return randomNumeric(RandomUtils.nextInt(minLengthInclusive, maxLengthExclusive));
	}

	/**
	 * <p>
	 * Creates a random string whose length is the number of characters specified.
	 * </p>
	 *
	 * <p>
	 * Characters will be chosen from the set of characters which match the POSIX
	 * [:print:] regular expression character class. This class includes all visible
	 * ASCII characters and spaces (i.e. anything except control characters).
	 * </p>
	 *
	 * @param count the length of random string to create
	 * @return the random string
	 * @since 3.5
	 */
	public static String randomPrint(final int count) {
		return random(count, 32, 126, false, false);
	}

	/**
	 * <p>
	 * Creates a random string whose length is between the inclusive minimum and the
	 * exclusive maximum.
	 * </p>
	 *
	 * <p>
	 * Characters will be chosen from the set of \p{Print} characters.
	 * </p>
	 *
	 * @param minLengthInclusive the inclusive minimum length of the string to
	 *                           generate
	 * @param maxLengthExclusive the exclusive maximum length of the string to
	 *                           generate
	 * @return the random string
	 * @since 3.5
	 */
	public static String randomPrint(final int minLengthInclusive, final int maxLengthExclusive) {
		return randomPrint(RandomUtils.nextInt(minLengthInclusive, maxLengthExclusive));
	}

	/**
	 * <p>
	 * Creates a random string whose length is the number of characters specified.
	 * </p>
	 *
	 * <p>
	 * Characters will be chosen from the set of alpha-numeric characters as
	 * indicated by the arguments.
	 * </p>
	 *
	 * @param count   the length of random string to create
	 * @param letters if {@code true}, generated string may include alphabetic
	 *                characters
	 * @param numbers if {@code true}, generated string may include numeric
	 *                characters
	 * @return the random string
	 */
	public static String random(final int count, final boolean letters, final boolean numbers) {
		return random(count, 0, 0, letters, numbers);
	}

	/**
	 * <p>
	 * Creates a random string whose length is the number of characters specified.
	 * </p>
	 *
	 * <p>
	 * Characters will be chosen from the set of alpha-numeric characters as
	 * indicated by the arguments.
	 * </p>
	 *
	 * @param count   the length of random string to create
	 * @param start   the position in set of chars to start at
	 * @param end     the position in set of chars to end before
	 * @param letters if {@code true}, generated string may include alphabetic
	 *                characters
	 * @param numbers if {@code true}, generated string may include numeric
	 *                characters
	 * @return the random string
	 */
	public static String random(final int count, final int start, final int end, final boolean letters,
			final boolean numbers) {
		return random(count, start, end, letters, numbers, null, RANDOM);
	}

	/**
	 * <p>
	 * Creates a random string based on a variety of options, using default source
	 * of randomness.
	 * </p>
	 *
	 * <p>
	 * This method has exactly the same semantics as
	 * {@link #random(int,int,int,boolean,boolean,char[],EaglercraftRandom)}, but instead of
	 * using an externally supplied source of randomness, it uses the internal
	 * static {@link EaglercraftRandom} instance.
	 * </p>
	 *
	 * @param count   the length of random string to create
	 * @param start   the position in set of chars to start at
	 * @param end     the position in set of chars to end before
	 * @param letters if {@code true}, generated string may include alphabetic
	 *                characters
	 * @param numbers if {@code true}, generated string may include numeric
	 *                characters
	 * @param chars   the set of chars to choose randoms from. If {@code null}, then
	 *                it will use the set of all chars.
	 * @return the random string
	 * @throws ArrayIndexOutOfBoundsException if there are not
	 *                                        {@code (end - start) + 1} characters
	 *                                        in the set array.
	 */
	public static String random(final int count, final int start, final int end, final boolean letters,
			final boolean numbers, final char... chars) {
		return random(count, start, end, letters, numbers, chars, RANDOM);
	}

	/**
	 * <p>
	 * Creates a random string based on a variety of options, using supplied source
	 * of randomness.
	 * </p>
	 *
	 * <p>
	 * If start and end are both {@code 0}, start and end are set to {@code ' '} and
	 * {@code 'z'}, the ASCII printable characters, will be used, unless letters and
	 * numbers are both {@code false}, in which case, start and end are set to
	 * {@code 0} and {@link Character#MAX_CODE_POINT}.
	 *
	 * <p>
	 * If set is not {@code null}, characters between start and end are chosen.
	 * </p>
	 *
	 * <p>
	 * This method accepts a user-supplied {@link EaglercraftRandom} instance to use as a
	 * source of randomness. By seeding a single {@link EaglercraftRandom} instance with a
	 * fixed seed and using it for each call, the same random sequence of strings
	 * can be generated repeatedly and predictably.
	 * </p>
	 *
	 * @param count   the length of random string to create
	 * @param start   the position in set of chars to start at (inclusive)
	 * @param end     the position in set of chars to end before (exclusive)
	 * @param letters if {@code true}, generated string may include alphabetic
	 *                characters
	 * @param numbers if {@code true}, generated string may include numeric
	 *                characters
	 * @param chars   the set of chars to choose randoms from, must not be empty. If
	 *                {@code null}, then it will use the set of all chars.
	 * @param random  a source of randomness.
	 * @return the random string
	 * @throws ArrayIndexOutOfBoundsException if there are not
	 *                                        {@code (end - start) + 1} characters
	 *                                        in the set array.
	 * @throws IllegalArgumentException       if {@code count} &lt; 0 or the
	 *                                        provided chars array is empty.
	 * @since 2.0
	 */
	public static String random(int count, int start, int end, final boolean letters, final boolean numbers,
			final char[] chars, final EaglercraftRandom random) {
		if (count == 0) {
			return StringUtils.EMPTY;
		} else if (count < 0) {
			throw new IllegalArgumentException("Requested random string length " + count + " is less than 0.");
		}
		if (chars != null && chars.length == 0) {
			throw new IllegalArgumentException("The chars array must not be empty");
		}

		if (start == 0 && end == 0) {
			if (chars != null) {
				end = chars.length;
			} else if (!letters && !numbers) {
				end = Character.MAX_CODE_POINT;
			} else {
				end = 'z' + 1;
				start = ' ';
			}
		} else if (end <= start) {
			throw new IllegalArgumentException(
					"Parameter end (" + end + ") must be greater than start (" + start + ")");
		}

		final int zero_digit_ascii = 48;
		final int first_letter_ascii = 65;

		if (chars == null && (numbers && end <= zero_digit_ascii || letters && end <= first_letter_ascii)) {
			throw new IllegalArgumentException(
					"Parameter end (" + end + ") must be greater then (" + zero_digit_ascii + ") for generating digits "
							+ "or greater then (" + first_letter_ascii + ") for generating letters.");
		}

		final StringBuilder builder = new StringBuilder(count);
		final int gap = end - start;

		while (count-- != 0) {
			final int codePoint;
			if (chars == null) {
				codePoint = random.nextInt(gap) + start;

				switch (Character.getType(codePoint)) {
				case Character.UNASSIGNED:
				case Character.PRIVATE_USE:
				case Character.SURROGATE:
					count++;
					continue;
				}

			} else {
				codePoint = chars[random.nextInt(gap) + start];
			}

			final int numberOfChars = Character.charCount(codePoint);
			if (count == 0 && numberOfChars > 1) {
				count++;
				continue;
			}

			if (letters && Character.isLetter(codePoint) || numbers && Character.isDigit(codePoint)
					|| !letters && !numbers) {
				builder.appendCodePoint(codePoint);

				if (numberOfChars == 2) {
					count--;
				}

			} else {
				count++;
			}
		}
		return builder.toString();
	}

	/**
	 * <p>
	 * Creates a random string whose length is the number of characters specified.
	 * </p>
	 *
	 * <p>
	 * Characters will be chosen from the set of characters specified by the string,
	 * must not be empty. If null, the set of all characters is used.
	 * </p>
	 *
	 * @param count the length of random string to create
	 * @param chars the String containing the set of characters to use, may be null,
	 *              but must not be empty
	 * @return the random string
	 * @throws IllegalArgumentException if {@code count} &lt; 0 or the string is
	 *                                  empty.
	 */
	public static String random(final int count, final String chars) {
		if (chars == null) {
			return random(count, 0, 0, false, false, null, RANDOM);
		}
		return random(count, chars.toCharArray());
	}

	/**
	 * <p>
	 * Creates a random string whose length is the number of characters specified.
	 * </p>
	 *
	 * <p>
	 * Characters will be chosen from the set of characters specified.
	 * </p>
	 *
	 * @param count the length of random string to create
	 * @param chars the character array containing the set of characters to use, may
	 *              be null
	 * @return the random string
	 * @throws IllegalArgumentException if {@code count} &lt; 0.
	 */
	public static String random(final int count, final char... chars) {
		if (chars == null) {
			return random(count, 0, 0, false, false, null, RANDOM);
		}
		return random(count, 0, chars.length, false, false, chars, RANDOM);
	}

}