/*
 * 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.math.random;

import java.util.Random;

/**
 * Extension of <code>java.util.Random</code> wrapping a
 * {@link RandomGenerator}.   
 *
 * @since 1.1
 * @version $Revision$ $Date$
 */
public class RandomAdaptor extends Random implements RandomGenerator {
    
    /** Serializable version identifier */
    private static final long serialVersionUID = 2570805822599485047L;

    /** Wrapped randomGenerator instance */
    private RandomGenerator randomGenerator = null;

    /** 
     * Prevent instantiation without a generator argument
     */ 
    @SuppressWarnings("unused")
    private RandomAdaptor() { }
    
    /**
     * Construct a RandomAdaptor wrapping the supplied RandomGenerator.
     * 
     * @param randomGenerator  the wrapped generator
     */
    public RandomAdaptor(RandomGenerator randomGenerator) {
        this.randomGenerator = randomGenerator;
    } 
    
    /**
     * Factory method to create a <code>Random</code> using the supplied
     * <code>RandomGenerator</code>.
     * 
     * @param randomGenerator  wrapped RandomGenerator instance
     * @return a Random instance wrapping the RandomGenerator
     */
    public static Random createAdaptor(RandomGenerator randomGenerator) {
        return new RandomAdaptor(randomGenerator);
    }
    
    /**
     * Returns the next pseudorandom, uniformly distributed
     * <code>boolean</code> value from this random number generator's
     * sequence.  
     * 
     * @return  the next pseudorandom, uniformly distributed
     * <code>boolean</code> value from this random number generator's
     * sequence
     */
    @Override
    public boolean nextBoolean() {
        return randomGenerator.nextBoolean();
    }

     /**
     * Generates random bytes and places them into a user-supplied 
     * byte array.  The number of random bytes produced is equal to 
     * the length of the byte array.
     * 
     * @param bytes the non-null byte array in which to put the 
     * random bytes
     */
    @Override
    public void nextBytes(byte[] bytes) {
        randomGenerator.nextBytes(bytes);
    }

     /**
     * Returns the next pseudorandom, uniformly distributed 
     * <code>double</code> value between <code>0.0</code> and
     * <code>1.0</code> from this random number generator's sequence.  
     *
     * @return  the next pseudorandom, uniformly distributed 
     *  <code>double</code> value between <code>0.0</code> and
     *  <code>1.0</code> from this random number generator's sequence
     */  
    @Override
    public double nextDouble() {
        return randomGenerator.nextDouble();
    }

    /**
     * Returns the next pseudorandom, uniformly distributed <code>float</code>
     * value between <code>0.0</code> and <code>1.0</code> from this random
     * number generator's sequence.  
     *
     * @return  the next pseudorandom, uniformly distributed <code>float</code>
     * value between <code>0.0</code> and <code>1.0</code> from this
     * random number generator's sequence
     */
    @Override
    public float nextFloat() {
        return randomGenerator.nextFloat();
    }

    /**
     * Returns the next pseudorandom, Gaussian ("normally") distributed
     * <code>double</code> value with mean <code>0.0</code> and standard
     * deviation <code>1.0</code> from this random number generator's sequence.
     * 
     * @return  the next pseudorandom, Gaussian ("normally") distributed
     * <code>double</code> value with mean <code>0.0</code> and
     * standard deviation <code>1.0</code> from this random number
     *  generator's sequence
     */
    @Override
    public double nextGaussian() {
        return randomGenerator.nextGaussian();
    }

     /**
     * Returns the next pseudorandom, uniformly distributed <code>int</code>
     * value from this random number generator's sequence.  
     * All 2<font size="-1"><sup>32</sup></font> possible <tt>int</tt> values
     * should be produced with  (approximately) equal probability. 
     *
     * @return the next pseudorandom, uniformly distributed <code>int</code>
     *  value from this random number generator's sequence
     */
    @Override
    public int nextInt() {
        return randomGenerator.nextInt();
    }

    /**
     * Returns a pseudorandom, uniformly distributed <tt>int</tt> value
     * between 0 (inclusive) and the specified value (exclusive), drawn from
     * this random number generator's sequence.   
     *
     * @param n the bound on the random number to be returned.  Must be
     * positive.
     * @return  a pseudorandom, uniformly distributed <tt>int</tt>
     * value between 0 (inclusive) and n (exclusive).
     * @throws IllegalArgumentException  if n is not positive.
     */
    @Override
    public int nextInt(int n) {
        return randomGenerator.nextInt(n);
    }

    /**
     * Returns the next pseudorandom, uniformly distributed <code>long</code>
     * value from this random number generator's sequence.  All 
     * 2<font size="-1"><sup>64</sup></font> possible <tt>long</tt> values 
     * should be produced with (approximately) equal probability. 
     *
     * @return  the next pseudorandom, uniformly distributed <code>long</code>
     *value from this random number generator's sequence
     */
    @Override
    public long nextLong() {
        return randomGenerator.nextLong();
    }

    /**
     * Sets the seed of the underyling random number generator using a 
     * <code>long</code> seed.  Sequences of values generated starting with the
     * same seeds should be identical.
     *
     * @param seed the seed value
     */
    @Override
    public void setSeed(long seed) {
        if (randomGenerator != null) {  // required to avoid NPE in constructor
            randomGenerator.setSeed(seed);
        }
    }
}
