/*
    * Copyright (C) 2021, Thomas Wolf <thomas.wolf@paranor.ch> and others
    *
    * This program and the accompanying materials are made available under the
    * terms of the Eclipse Distribution License v. 1.0 which is available at
    * https://www.eclipse.org/org/documents/edl-v10.php.
    *
    * SPDX-License-Identifier: BSD-3-Clause
    */
  package org.eclipse.jgit.util;
  
  import static org.junit.Assert.assertArrayEquals;
  import static org.junit.Assert.assertEquals;
  
  import java.io.ByteArrayInputStream;
  import java.io.IOException;
  import java.io.InputStream;
  import java.nio.charset.StandardCharsets;
  import java.util.Arrays;
  
  import org.junit.Test;
  
  public class IOTest {
  
  	private static final byte[] DATA = "abcdefghijklmnopqrstuvwxyz"
  			.getBytes(StandardCharsets.US_ASCII);
  
  	private byte[] initBuffer(int size) {
  		byte[] buffer = new byte[size];
  		for (int i = 0; i < size; i++) {
  			buffer[i] = (byte) ('0' + (i % 10));
  		}
  		return buffer;
  	}
  
  	private int read(byte[] buffer, int from) throws IOException {
  		try (InputStream in = new ByteArrayInputStream(DATA)) {
  			return IO.readFully(in, buffer, from);
  		}
  	}
  
  	@Test
  	public void readFullyBufferShorter() throws Exception {
  		byte[] buffer = initBuffer(9);
  		int length = read(buffer, 0);
  		assertEquals(buffer.length, length);
  		assertArrayEquals(buffer, Arrays.copyOfRange(DATA, 0, length));
  	}
  
  	@Test
  	public void readFullyBufferLonger() throws Exception {
  		byte[] buffer = initBuffer(50);
  		byte[] initial = Arrays.copyOf(buffer, buffer.length);
  		int length = read(buffer, 0);
  		assertEquals(DATA.length, length);
  		assertArrayEquals(Arrays.copyOfRange(buffer, 0, length), DATA);
  		assertArrayEquals(Arrays.copyOfRange(buffer, length, buffer.length),
  				Arrays.copyOfRange(initial, length, initial.length));
  	}
  
  	@Test
  	public void readFullyBufferShorterOffset() throws Exception {
  		byte[] buffer = initBuffer(9);
  		byte[] initial = Arrays.copyOf(buffer, buffer.length);
  		int length = read(buffer, 6);
  		assertEquals(3, length);
  		assertArrayEquals(Arrays.copyOfRange(buffer, 0, 6),
  				Arrays.copyOfRange(initial, 0, 6));
  		assertArrayEquals(Arrays.copyOfRange(buffer, 6, buffer.length),
  				Arrays.copyOfRange(DATA, 0, 3));
  	}
  
  	@Test
  	public void readFullyBufferLongerOffset() throws Exception {
  		byte[] buffer = initBuffer(50);
  		byte[] initial = Arrays.copyOf(buffer, buffer.length);
  		int length = read(buffer, 40);
  		assertEquals(10, length);
  		assertArrayEquals(Arrays.copyOfRange(buffer, 0, 40),
  				Arrays.copyOfRange(initial, 0, 40));
  		assertArrayEquals(Arrays.copyOfRange(buffer, 40, buffer.length),
  				Arrays.copyOfRange(DATA, 0, 10));
  	}
  }