package com.limegroup.gnutella.udpconnect;

import junit.framework.Test;

import com.limegroup.gnutella.util.LimeTestCase;

/**
 * Tests the SequenceNumberExtender class.
 */
public final class SequenceNumberExtenderTest extends LimeTestCase {

	/*
	 * Constructs the test.
	 */
	public SequenceNumberExtenderTest(String name) {
		super(name);
	}

	public static Test suite() {
		return buildTestSuite(SequenceNumberExtenderTest.class);
	}

	/**
	 * Runs this test individually.
	 */
	public static void main(String[] args) {
		junit.textui.TestRunner.run(suite());
	}
    
    /**
     * Test that increments remain in sync with a full long being incremented
	 * and with the values being mapped down to 2 byte sequenceNumbers.
     * 
     * @throws Exception if an error occurs
     */
    public void testSequenceNumberIncrements() throws Exception {

		// Init the extender
		SequenceNumberExtender extender = new SequenceNumberExtender();

		//  Make sure that the sequence remains in sync with prior number
		//  and its own extended value - test up to 100000000
		long finalValue = 10000000;
		long lasti;
		long lastiand;
		long iand = -1;
		lasti = 0;
		lastiand = 0;
		for (long i = 1; i <= finalValue; i++) {

			// Shrink the sequenceNumber down to 2 bytes
			iand     = i & 0xffff;

			// Extend the sequenceNumber back to 8 bytes
			iand = extender.extendSequenceNumber( ( iand) );

			if ( (lastiand + 1) != iand ) {
				fail("Error at count: "+i+" last: "+lasti+" seqNo: "+
				  iand+" last seqNo: "+lastiand);
			}
			//if ( i % 5000000 == 0 )
				//System.out.println("Progress: "+i);
			lasti = i;
			lastiand = iand;
		}

        assertEquals("final value should equal "+finalValue, 
            finalValue, iand);
    }
}