/*
 * 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.flink.core.memory;

import org.apache.flink.configuration.ConfigConstants;
import org.junit.Assert;
import org.junit.Before;
import org.junit.Rule;
import org.junit.Test;
import org.junit.rules.ExpectedException;

import java.io.IOException;
import java.util.Arrays;

public class ByteArrayOutputStreamWithPosTest {

	private static final int BUFFER_SIZE = 32;

	@Rule
	public ExpectedException thrown = ExpectedException.none();

	private ByteArrayOutputStreamWithPos stream;

	@Before
	public void setup() {
		stream = new ByteArrayOutputStreamWithPos(BUFFER_SIZE);
	}

	/**
	 * Test setting position which is exactly the same with the buffer size
	 */
	@Test
	public void testSetPositionWhenBufferIsFull() throws Exception {
		stream.write(new byte[BUFFER_SIZE]);

		// check whether the buffer is filled fully
		Assert.assertEquals(BUFFER_SIZE, stream.getBuf().length);

		// check current position is the end of the buffer
		Assert.assertEquals(BUFFER_SIZE, stream.getPosition());

		stream.setPosition(BUFFER_SIZE);

		// confirm current position is at where we expect.
		Assert.assertEquals(BUFFER_SIZE, stream.getPosition());
	}

	/**
	 * Test setting negative position
	 */
	@Test
	public void testSetNegativePosition() throws Exception {
		stream.write(new byte[BUFFER_SIZE]);

		thrown.expect(IllegalArgumentException.class);
		thrown.expectMessage("Position out of bounds");
		stream.setPosition(-1);
	}

	/**
	 * Test setting position larger than buffer size
	 */
	@Test
	public void testSetPositionLargerThanBufferSize() throws Exception {
		// fully fill the buffer
		stream.write(new byte[BUFFER_SIZE]);
		Assert.assertEquals(BUFFER_SIZE, stream.getBuf().length);

		// expand the buffer by setting position beyond the buffer length
		stream.setPosition(BUFFER_SIZE + 1);
		Assert.assertEquals(BUFFER_SIZE * 2, stream.getBuf().length);
		Assert.assertEquals(BUFFER_SIZE + 1, stream.getPosition());
	}

	/**
	 * Test that toString returns a substring of the buffer with range(0, position)
	 */
	@Test
	public void testToString() throws IOException {
		byte[] data = "1234567890".getBytes(ConfigConstants.DEFAULT_CHARSET);

		ByteArrayOutputStreamWithPos stream = new ByteArrayOutputStreamWithPos(data.length);

		stream.write(data);
		Assert.assertArrayEquals(data, stream.toString().getBytes(ConfigConstants.DEFAULT_CHARSET));

		for (int i = 0 ; i < data.length ; i++) {
			stream.setPosition(i);
			Assert.assertArrayEquals(Arrays.copyOf(data, i), stream.toString().getBytes(ConfigConstants.DEFAULT_CHARSET));
		}

		// validate that the stored bytes are still tracked properly even when expanding array
		stream.setPosition(data.length + 1);
		Assert.assertArrayEquals(Arrays.copyOf(data, data.length + 1), stream.toString().getBytes(ConfigConstants.DEFAULT_CHARSET));
	}
}