/*
 * Copyright 1999-2018 Alibaba Group Holding Ltd.
 *
 * Licensed 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 com.alibaba.nacos.client.naming.utils;

import java.util.Random;

/**
 * <code>RandomUtils</code> is a wrapper that supports all possible {@link java.util.Random} methods via the {@link
 * java.lang.Math#random()} method and its system-wide <code>Random</code> object.
 *
 * @author Gary D. Gregory
 * @version $Id: RandomUtils.java 906320 2010-02-04 01:41:10Z sebb $
 * @since 2.0
 */
public class RandomUtils {
    
    /**
     * An instance of {@link JvmRandom}.
     */
    private static final Random JVM_RANDOM = new JvmRandom();
    
    // should be possible for JVM_RANDOM?
    //    public static void nextBytes(byte[]) {
    //    public synchronized double nextGaussian();
    //    }
    
    /**
     * <p>Returns the next pseudorandom, uniformly distributed int value from the Math.random() sequence.</p> <b>N.B.
     * All values are >= 0.</b>
     *
     * @return the random int
     */
    public static int nextInt() {
        return nextInt(JVM_RANDOM);
    }
    
    /**
     * <p>Returns the next pseudorandom, uniformly distributed int value from the given <code>random</code>
     * sequence.</p>
     *
     * @param random the Random sequence generator.
     * @return the random int
     */
    public static int nextInt(Random random) {
        return random.nextInt();
    }
    
    /**
     * <p>Returns a pseudorandom, uniformly distributed int value between <code>0</code> (inclusive) and the specified
     * value (exclusive), from the Math.random() sequence.</p>
     *
     * @param n the specified exclusive max-value
     * @return the random int
     */
    public static int nextInt(int n) {
        return nextInt(JVM_RANDOM, n);
    }
    
    /**
     * <p>Returns a pseudorandom, uniformly distributed int value between <code>0</code> (inclusive) and the specified
     * value (exclusive), from the given Random sequence.</p>
     *
     * @param random the Random sequence generator.
     * @param n      the specified exclusive max-value
     * @return the random int
     */
    public static int nextInt(Random random, int n) {
        // check this cannot return 'n'
        return random.nextInt(n);
    }
    
    /**
     * <p>Returns the next pseudorandom, uniformly distributed long value from the Math.random() sequence.</p> <b>N.B.
     * All values are >= 0.</b>
     *
     * @return the random long
     */
    public static long nextLong() {
        return nextLong(JVM_RANDOM);
    }
    
    /**
     * <p>Returns the next pseudorandom, uniformly distributed long value from the given Random sequence.</p>
     *
     * @param random the Random sequence generator.
     * @return the random long
     */
    public static long nextLong(Random random) {
        return random.nextLong();
    }
    
    /**
     * <p>Returns the next pseudorandom, uniformly distributed boolean value from the Math.random() sequence.</p>
     *
     * @return the random boolean
     */
    public static boolean nextBoolean() {
        return nextBoolean(JVM_RANDOM);
    }
    
    /**
     * <p>Returns the next pseudorandom, uniformly distributed boolean value from the given random sequence.</p>
     *
     * @param random the Random sequence generator.
     * @return the random boolean
     */
    public static boolean nextBoolean(Random random) {
        return random.nextBoolean();
    }
    
    /**
     * <p>Returns the next pseudorandom, uniformly distributed float value between <code>0.0</code> and
     * <code>1.0</code>
     * from the Math.random() sequence.</p>
     *
     * @return the random float
     */
    public static float nextFloat() {
        return nextFloat(JVM_RANDOM);
    }
    
    /**
     * <p>Returns the next pseudorandom, uniformly distributed float value between <code>0.0</code> and
     * <code>1.0</code>
     * from the given Random sequence.</p>
     *
     * @param random the Random sequence generator.
     * @return the random float
     */
    public static float nextFloat(Random random) {
        return random.nextFloat();
    }
    
    /**
     * <p>Returns the next pseudorandom, uniformly distributed float value between <code>0.0</code> and
     * <code>1.0</code>
     * from the Math.random() sequence.</p>
     *
     * @return the random double
     */
    public static double nextDouble() {
        return nextDouble(JVM_RANDOM);
    }
    
    /**
     * <p>Returns the next pseudorandom, uniformly distributed float value between <code>0.0</code> and
     * <code>1.0</code>
     * from the given Random sequence.</p>
     *
     * @param random the Random sequence generator.
     * @return the random double
     */
    public static double nextDouble(Random random) {
        return random.nextDouble();
    }
    
}
