// Copyright 2018 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.remote.http;

import static com.google.common.truth.Truth.assertThat;
import static org.mockito.Mockito.never;
import static org.mockito.Mockito.verify;

import build.bazel.remote.execution.v2.Digest;
import com.google.common.collect.ImmutableList;
import com.google.common.net.HttpHeaders;
import com.google.devtools.build.lib.remote.util.DigestUtil;
import com.google.devtools.build.lib.vfs.DigestHashFunction;
import io.netty.buffer.ByteBuf;
import io.netty.buffer.ByteBufUtil;
import io.netty.buffer.Unpooled;
import io.netty.channel.ChannelPromise;
import io.netty.channel.embedded.EmbeddedChannel;
import io.netty.handler.codec.http.DefaultHttpContent;
import io.netty.handler.codec.http.DefaultHttpResponse;
import io.netty.handler.codec.http.DefaultLastHttpContent;
import io.netty.handler.codec.http.HttpHeaderNames;
import io.netty.handler.codec.http.HttpHeaderValues;
import io.netty.handler.codec.http.HttpMethod;
import io.netty.handler.codec.http.HttpRequest;
import io.netty.handler.codec.http.HttpResponse;
import io.netty.handler.codec.http.HttpResponseStatus;
import io.netty.handler.codec.http.HttpVersion;
import io.netty.handler.codec.http.LastHttpContent;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.net.URI;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.junit.runners.JUnit4;
import org.mockito.Mockito;

/** Tests for {@link HttpDownloadHandler}. */
@RunWith(JUnit4.class)
public class HttpDownloadHandlerTest extends AbstractHttpHandlerTest {

  private static final URI CACHE_URI = URI.create("http://storage.googleapis.com:80/cache-bucket");
  private static final DigestUtil DIGEST_UTIL = new DigestUtil(DigestHashFunction.SHA256);
  private static final Digest DIGEST = DIGEST_UTIL.computeAsUtf8("foo");

  /**
   * Test that downloading blobs works from both the Action Cache and the CAS. Also test that the
   * handler is reusable.
   */
  @Test
  public void downloadShouldWork() throws IOException {
    EmbeddedChannel ch = new EmbeddedChannel(new HttpDownloadHandler(null, ImmutableList.of()));
    downloadShouldWork(true, ch);
    downloadShouldWork(false, ch);
  }

  private void downloadShouldWork(boolean casDownload, EmbeddedChannel ch) throws IOException {
    ByteArrayOutputStream out = Mockito.spy(new ByteArrayOutputStream());
    DownloadCommand cmd = new DownloadCommand(CACHE_URI, casDownload, DIGEST, out);
    ChannelPromise writePromise = ch.newPromise();
    ch.writeOneOutbound(cmd, writePromise);

    HttpRequest request = ch.readOutbound();
    assertThat(request.method()).isEqualTo(HttpMethod.GET);
    assertThat(request.headers().get(HttpHeaderNames.HOST)).isEqualTo(CACHE_URI.getHost());
    if (casDownload) {
      assertThat(request.uri()).isEqualTo("/cache-bucket/cas/" + DIGEST.getHash());
    } else {
      assertThat(request.uri()).isEqualTo("/cache-bucket/ac/" + DIGEST.getHash());
    }

    assertThat(writePromise.isDone()).isFalse();

    HttpResponse response = new DefaultHttpResponse(HttpVersion.HTTP_1_1, HttpResponseStatus.OK);
    response.headers().set(HttpHeaders.CONTENT_LENGTH, 5);
    response.headers().set(HttpHeaders.CONNECTION, HttpHeaderValues.KEEP_ALIVE);
    ch.writeInbound(response);
    ByteBuf content = Unpooled.buffer();
    content.writeBytes(new byte[] {1, 2, 3, 4, 5});
    ch.writeInbound(new DefaultLastHttpContent(content));

    assertThat(writePromise.isDone()).isTrue();
    assertThat(out.toByteArray()).isEqualTo(new byte[] {1, 2, 3, 4, 5});
    verify(out, never()).close();
    assertThat(ch.isActive()).isTrue();
  }

  /** Test that the handler correctly supports http error codes i.e. 404 (NOT FOUND). */
  @Test
  public void httpErrorsAreSupported() throws IOException {
    EmbeddedChannel ch = new EmbeddedChannel(new HttpDownloadHandler(null, ImmutableList.of()));
    ByteArrayOutputStream out = Mockito.spy(new ByteArrayOutputStream());
    DownloadCommand cmd = new DownloadCommand(CACHE_URI, true, DIGEST, out);
    ChannelPromise writePromise = ch.newPromise();
    ch.writeOneOutbound(cmd, writePromise);

    HttpResponse response =
        new DefaultHttpResponse(HttpVersion.HTTP_1_1, HttpResponseStatus.NOT_FOUND);
    response.headers().set(HttpHeaders.HOST, "localhost");
    response.headers().set(HttpHeaders.CONTENT_LENGTH, 0);
    response.headers().set(HttpHeaders.CONNECTION, HttpHeaderValues.KEEP_ALIVE);
    ch.writeInbound(response);
    ch.writeInbound(LastHttpContent.EMPTY_LAST_CONTENT);
    assertThat(writePromise.isDone()).isTrue();
    assertThat(writePromise.cause()).isInstanceOf(HttpException.class);
    assertThat(((HttpException) writePromise.cause()).response().status())
        .isEqualTo(HttpResponseStatus.NOT_FOUND);
    // No data should have been written to the OutputStream and it should have been closed.
    assertThat(out.size()).isEqualTo(0);
    // The caller is responsible for closing the stream.
    verify(out, never()).close();
    assertThat(ch.isOpen()).isTrue();
  }

  /**
   * Test that the handler correctly supports http error codes i.e. 404 (NOT FOUND) with a
   * Content-Length header.
   */
  @Test
  public void httpErrorsWithContentAreSupported() throws IOException {
    EmbeddedChannel ch = new EmbeddedChannel(new HttpDownloadHandler(null, ImmutableList.of()));
    ByteArrayOutputStream out = Mockito.spy(new ByteArrayOutputStream());
    DownloadCommand cmd = new DownloadCommand(CACHE_URI, true, DIGEST, out);
    ChannelPromise writePromise = ch.newPromise();
    ch.writeOneOutbound(cmd, writePromise);

    HttpResponse response =
        new DefaultHttpResponse(HttpVersion.HTTP_1_1, HttpResponseStatus.NOT_FOUND);
    ByteBuf errorMessage = ByteBufUtil.writeAscii(ch.alloc(), "Error message");
    response.headers().set(HttpHeaders.HOST, "localhost");
    response
        .headers()
        .set(HttpHeaders.CONTENT_LENGTH, String.valueOf(errorMessage.readableBytes()));
    response.headers().set(HttpHeaders.CONNECTION, HttpHeaderValues.CLOSE);

    ch.writeInbound(response);
    // The promise must not be done because we haven't received the error message yet.
    assertThat(writePromise.isDone()).isFalse();

    ch.writeInbound(new DefaultHttpContent(errorMessage));
    ch.writeInbound(LastHttpContent.EMPTY_LAST_CONTENT);
    assertThat(writePromise.isDone()).isTrue();
    assertThat(writePromise.cause()).isInstanceOf(HttpException.class);
    assertThat(((HttpException) writePromise.cause()).response().status())
        .isEqualTo(HttpResponseStatus.NOT_FOUND);
    // No data should have been written to the OutputStream and it should have been closed.
    assertThat(out.size()).isEqualTo(0);
    // The caller is responsible for closing the stream.
    verify(out, never()).close();
    assertThat(ch.isOpen()).isFalse();
  }
}