/*
 * File:                Murmur32HashTest.java
 * Authors:             Kevin R. Dixon
 * Company:             Sandia National Laboratories
 * Project:             Cognitive Foundry
 *
 * Copyright Feb 1, 2011, Sandia Corporation.
 * Under the terms of Contract DE-AC04-94AL85000, there is a non-exclusive
 * license for use of this work by or on behalf of the U.S. Government.
 * Export of this program may require a license from the United States
 * Government. See CopyrightHistory.txt for complete details.
 *
 */
package gov.sandia.cognition.hash;

/**
 * Unit tests for Murmur32HashTest.
 *
 * @author krdixon
 */
public class Murmur32HashTest
    extends HashFunctionTestHarness
{

    /**
     * Tests for class Murmur32HashTest.
     * @param testName Name of the test.
     */
    public Murmur32HashTest(
        String testName)
    {
        super(testName);
    }


    /**
     * Tests the constructors of class Murmur32HashTest.
     */
    public void testConstructors()
    {
        System.out.println( "Constructors" );

        Murmur32Hash instance = new Murmur32Hash();
        assertNotNull( instance );
    }

    @Override
    public Murmur32Hash createInstance()
    {
        return new Murmur32Hash();
    }

    @Override
    public void testLength()
    {
        System.out.println( "length" );

        Murmur32Hash instance = this.createInstance();
        assertEquals( 4, instance.length() );
        assertEquals( 4, Murmur32Hash.LENGTH );
    }

    /** Fill a key with a known pattern (incrementing numbers) */
    private void setKey(
        byte [] key,
        int start)
    {
        for (int i = 0; i < key.length; i++)
        {
            key[i] = (byte) ((start + i) & 0xFF);
        }
    }

    public void testRelativeEntropy()
    {
        System.out.println( "Relative Entropy" );

        //Hash Average Time:  1.855
        //Total Average Time: 11.687
        //Relative Entropy = 1.7613951882111678E-4
        double entropy = this.computeRelativeEntropy( 1000 );
        System.out.println( "Relative Entropy = " + entropy );

    }


    @Override
    public void testEvaluateKnownValues()
    {
        // Taken from:
        // http://dmy999.com/article/50/murmurhash-2-java-port
        System.out.println( "evaluate known values" );
        byte [] key = new byte[133];

        int [] expected = { 0xd743ae0b, 0xf1b461c6, 0xa45a6ceb, 0xdb15e003,
                            0x877721a4, 0xc30465f1, 0xfb658ba4, 0x1adf93b2,
                            0xe40a7931, 0x3da52db0, 0xbf523511, 0x1efaf273,
                            0xe628c1dd, 0x9a0344df, 0x901c99fc, 0x5ae1aa44 };
        for (int i = 0; i < 16; i++) {
            // keep seed constant, generate a known key pattern
            setKey(key, i);
            int expectedHash = expected[i];
            int hash = Murmur32Hash.hash(key, 0x1234ABCD);
            assertEquals("i = " + i, expectedHash, hash);
        }
    }

    public void testChangingKeyLength()
    {
        // Taken from:
        // http://dmy999.com/article/50/murmurhash-2-java-port
        System.out.println( "changing key length" );
        int [] expected = { 0xa0c72f8e, 0x29c2f97e, 0x00ca8bba, 0x88387876,
                            0xe203ce49, 0x58d75952, 0xab84febe, 0x98153c65,
                            0xcbb38375, 0x6ea1a28b, 0x9afa8f55, 0xfb890eb6,
                            0x9516cc49, 0x6408a8eb, 0xbb12d3e6, 0x00fb7519 };
        // vary the key and the length
        for (int i = 0; i < 16; i++)
        {
            byte [] key = new byte[i];
            setKey(key, i);
            int expectedHash = expected[i];
            int hash = Murmur32Hash.hash(key, 0x7870AAFF);
            assertEquals("i = " + i, expectedHash, hash);
        }
    }

    /**
     * test using a fixed key and a changing seed
     */
    public void testChangingSeed()
    {
        // Taken from:
        // http://dmy999.com/article/50/murmurhash-2-java-port

        // use a fixed key
        byte [] key = new byte[]
        {
            0x4E, (byte) 0xE3, (byte) 0x91, 0x00,
            0x10, (byte) 0x8F, (byte) 0xFF
        };

        int [] expected =
        {
            0xeef8be32, 0x8109dec6, 0x9aaf4192, 0xc1bcaf1c,
            0x821d2ce4, 0xd45ed1df, 0x6c0357a7, 0x21d4e845,
            0xfa97db50, 0x2f1985c8, 0x5d69782a, 0x0d6e4b85,
            0xe7d9cf6b, 0x337e6b49, 0xe1606944, 0xccc18ae8
        };

        for (int i = 0; i < expected.length; i++)
        {
            int expectedHash = expected[i];
            int hash = Murmur32Hash.hash(key, i);
            assertEquals("i = " + i, expectedHash, hash);
        }
    }


}