// Copyright 2016 The Bazel Authors. All rights reserved.
//
// Licensed 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 com.google.devtools.build.lib.bazel.repository.downloader;

import static com.google.common.truth.Truth.assertThat;
import static org.junit.Assert.assertThrows;
import static org.mockito.ArgumentMatchers.any;
import static org.mockito.ArgumentMatchers.eq;
import static org.mockito.ArgumentMatchers.same;
import static org.mockito.Mockito.mock;
import static org.mockito.Mockito.times;
import static org.mockito.Mockito.verify;
import static org.mockito.Mockito.verifyNoMoreInteractions;
import static org.mockito.Mockito.when;

import com.google.common.collect.ImmutableMap;
import com.google.devtools.build.lib.bazel.repository.downloader.RetryingInputStream.Reconnector;
import java.io.IOException;
import java.io.InputStream;
import java.io.InterruptedIOException;
import java.net.SocketTimeoutException;
import java.net.URLConnection;
import org.junit.After;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.junit.runners.JUnit4;

/** Unit tests for {@link RetryingInputStream}. */
@RunWith(JUnit4.class)
public class RetryingInputStreamTest {

  private final InputStream delegate = mock(InputStream.class);
  private final InputStream newDelegate = mock(InputStream.class);
  private final Reconnector reconnector = mock(Reconnector.class);
  private final URLConnection connection = mock(URLConnection.class);
  private final RetryingInputStream stream = new RetryingInputStream(delegate, reconnector);

  @After
  public void after() throws Exception {
    verifyNoMoreInteractions(delegate, newDelegate, reconnector);
  }

  @Test
  public void close_callsDelegate() throws Exception {
    stream.close();
    verify(delegate).close();
  }

  @Test
  public void available_callsDelegate() throws Exception {
    stream.available();
    verify(delegate).available();
  }

  @Test
  public void read_callsdelegate() throws Exception {
    stream.read();
    verify(delegate).read();
  }

  @Test
  public void bufferRead_callsdelegate() throws Exception {
    byte[] buffer = new byte[1024];
    stream.read(buffer);
    verify(delegate).read(same(buffer), eq(0), eq(1024));
  }

  @Test
  public void readThrowsExceptionWhenDisabled_passesThrough() throws Exception {
    stream.disabled = true;
    when(delegate.read()).thenThrow(new IOException());
    assertThrows(IOException.class, () -> stream.read());
    verify(delegate).read();
  }

  @Test
  public void readInterrupted_alwaysPassesThrough() throws Exception {
    when(delegate.read()).thenThrow(new InterruptedIOException());
    assertThrows(InterruptedIOException.class, () -> stream.read());
    verify(delegate).read();
  }

  @Test
  @SuppressWarnings("unchecked")
  public void readTimesOut_retries() throws Exception {
    when(delegate.read()).thenReturn(1).thenThrow(new SocketTimeoutException());
    when(reconnector.connect(any(Throwable.class), any(ImmutableMap.class))).thenReturn(connection);
    when(connection.getInputStream()).thenReturn(newDelegate);
    when(newDelegate.read()).thenReturn(2);
    when(connection.getHeaderField("Content-Range")).thenReturn("bytes 1-42/42");
    assertThat(stream.read()).isEqualTo(1);
    assertThat(stream.read()).isEqualTo(2);
    verify(reconnector).connect(any(Throwable.class), eq(ImmutableMap.of("Range", "bytes=1-")));
    verify(delegate, times(2)).read();
    verify(delegate).close();
    verify(newDelegate).read();
  }

  @Test
  @SuppressWarnings("unchecked")
  public void failureWhenNoBytesAreRead_doesntUseRange() throws Exception {
    when(delegate.read()).thenThrow(new SocketTimeoutException());
    when(newDelegate.read()).thenReturn(1);
    when(reconnector.connect(any(Throwable.class), any(ImmutableMap.class))).thenReturn(connection);
    when(connection.getInputStream()).thenReturn(newDelegate);
    assertThat(stream.read()).isEqualTo(1);
    verify(reconnector).connect(any(Throwable.class), eq(ImmutableMap.<String, String>of()));
    verify(delegate).read();
    verify(delegate).close();
    verify(newDelegate).read();
  }

  @Test
  @SuppressWarnings("unchecked")
  public void reconnectFails_alwaysPassesThrough() throws Exception {
    when(delegate.read()).thenThrow(new IOException());
    when(reconnector.connect(any(Throwable.class), any(ImmutableMap.class)))
        .thenThrow(new IOException());
    assertThrows(IOException.class, () -> stream.read());
    verify(delegate).read();
      verify(delegate).close();
    verify(reconnector).connect(any(Throwable.class), any(ImmutableMap.class));
  }

  @Test
  @SuppressWarnings("unchecked")
  public void maxRetries_givesUp() throws Exception {
    when(delegate.read())
        .thenReturn(1)
        .thenThrow(new IOException())
        .thenThrow(new IOException())
        .thenThrow(new IOException())
        .thenThrow(new SocketTimeoutException());
    when(reconnector.connect(any(Throwable.class), any(ImmutableMap.class))).thenReturn(connection);
    when(connection.getInputStream()).thenReturn(delegate);
    when(connection.getHeaderField("Content-Range")).thenReturn("bytes 1-42/42");
    stream.read();
    SocketTimeoutException e = assertThrows(SocketTimeoutException.class, () -> stream.read());
    assertThat(e.getSuppressed()).hasLength(3);
      verify(reconnector, times(3))
          .connect(any(Throwable.class), eq(ImmutableMap.of("Range", "bytes=1-")));
      verify(delegate, times(5)).read();
    verify(delegate, times(3)).close();
  }
}