package it.unimi.dsi.fastutil.io;

import java.io.ByteArrayOutputStream;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.nio.channels.FileChannel;
import java.util.Arrays;
import java.util.Random;

import org.junit.Test;

import static org.junit.Assert.*;

public class FastBufferedOutputStreamTest {

	private static final boolean DEBUG = false;

	@Test
	public void testWriteEqualToBufferSize() throws IOException {
		final FastBufferedOutputStream fbos = new FastBufferedOutputStream( new ByteArrayOutputStream(), 4 );
		fbos.write( 0 );
		fbos.write( new byte[ 4 ] );
		fbos.write( 0 );
	}

	public void testRandom( int bufSize ) throws FileNotFoundException, IOException {

		File file = File.createTempFile( getClass().getSimpleName(), "test" );
		file.deleteOnExit();
		FastBufferedOutputStream fbos = new FastBufferedOutputStream( new FileOutputStream( file + "1" ), bufSize );
		FileOutputStream bos = new FileOutputStream( file + "2" );
		FileChannel fc = bos.getChannel();
		Random r = new Random();
		long pos, len;
		
		int j = r.nextInt( 10000 );
		while( j-- != 0 ) {
			switch( r.nextInt( 6 ) ) {

			case 0:
				int x = (byte)r.nextInt();
				fbos.write( x );
				bos.write(x );
				break;

			case 1:
				byte[] b  = new byte[ r.nextInt( 32768 ) + 16 ];
				for( int i = 0; i < b.length; i++ ) b[ i ] = (byte)r.nextInt();
				int offset = r.nextInt( b.length / 4 );
				int length = r.nextInt( b.length - offset );
				fbos.write( b, offset, length );
				bos.write( b, offset, length );
				break;

			case 2:
				fbos.flush();
				break;
				
			case 3:
				if ( DEBUG ) System.err.println("position()" );
				pos = (int)fbos.position();
				assertEquals( (int)fc.position(), pos );
				break;

			case 4:
				assertEquals( fc.size(), len = fbos.length() );
				pos = len != 0 ? r.nextInt( (int)len ) : 0;
				fbos.position( pos );
				fc.position( pos );
				if ( DEBUG ) System.err.println("position(" + pos + ")" );
				break;
			}
		}

		fbos.close();
		bos.close();
		assertTrue( Arrays.equals( BinIO.loadBytes( file + "1" ), BinIO.loadBytes( file + "2" ) ) );
	}
	
	@Test
	public void testRandom() throws FileNotFoundException, IOException {
		testRandom( 1 );
		testRandom( 2 );
		testRandom( 3 );
		testRandom( 1024 );
	}
}

