// Copyright 2014 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "components/update_client/url_fetcher_downloader.h"

#include <stdint.h>
#include <utility>

#include "base/bind.h"
#include "base/files/file_util.h"
#include "base/location.h"
#include "base/logging.h"
#include "base/sequenced_task_runner.h"
#include "base/task/post_task.h"
#include "base/task/task_traits.h"
#include "components/update_client/network.h"
#include "components/update_client/utils.h"
#include "url/gurl.h"

namespace {

constexpr base::TaskTraits kTaskTraits = {
    base::ThreadPool(), base::MayBlock(), base::TaskPriority::BEST_EFFORT,
    base::TaskShutdownBehavior::SKIP_ON_SHUTDOWN};

}  // namespace

namespace update_client {

UrlFetcherDownloader::UrlFetcherDownloader(
    std::unique_ptr<CrxDownloader> successor,
    scoped_refptr<NetworkFetcherFactory> network_fetcher_factory)
    : CrxDownloader(std::move(successor)),
      network_fetcher_factory_(network_fetcher_factory) {}

UrlFetcherDownloader::~UrlFetcherDownloader() {
  DCHECK_CALLED_ON_VALID_THREAD(thread_checker_);
}

void UrlFetcherDownloader::DoStartDownload(const GURL& url) {
  DCHECK_CALLED_ON_VALID_THREAD(thread_checker_);
  base::PostTaskAndReply(
      FROM_HERE, kTaskTraits,
      base::BindOnce(&UrlFetcherDownloader::CreateDownloadDir,
                     base::Unretained(this)),
      base::BindOnce(&UrlFetcherDownloader::StartURLFetch,
                     base::Unretained(this), url));
}

void UrlFetcherDownloader::CreateDownloadDir() {
  base::CreateNewTempDirectory(FILE_PATH_LITERAL("chrome_url_fetcher_"),
                               &download_dir_);
}

void UrlFetcherDownloader::StartURLFetch(const GURL& url) {
  DCHECK_CALLED_ON_VALID_THREAD(thread_checker_);

  if (download_dir_.empty()) {
    Result result;
    result.error = -1;

    DownloadMetrics download_metrics;
    download_metrics.url = url;
    download_metrics.downloader = DownloadMetrics::kUrlFetcher;
    download_metrics.error = -1;
    download_metrics.downloaded_bytes = -1;
    download_metrics.total_bytes = -1;
    download_metrics.download_time_ms = 0;

    main_task_runner()->PostTask(
        FROM_HERE, base::BindOnce(&UrlFetcherDownloader::OnDownloadComplete,
                                  base::Unretained(this), false, result,
                                  download_metrics));
    return;
  }

  const auto file_path = download_dir_.AppendASCII(url.ExtractFileName());
  network_fetcher_ = network_fetcher_factory_->Create();
  network_fetcher_->DownloadToFile(
      url, file_path,
      base::BindOnce(&UrlFetcherDownloader::OnResponseStarted,
                     base::Unretained(this)),
      base::BindRepeating(&UrlFetcherDownloader::OnDownloadProgress,
                          base::Unretained(this)),
      base::BindOnce(&UrlFetcherDownloader::OnNetworkFetcherComplete,
                     base::Unretained(this)));

  download_start_time_ = base::TimeTicks::Now();
}

void UrlFetcherDownloader::OnNetworkFetcherComplete(base::FilePath file_path,
                                                    int net_error,
                                                    int64_t content_size) {
  DCHECK_CALLED_ON_VALID_THREAD(thread_checker_);

  const base::TimeTicks download_end_time(base::TimeTicks::Now());
  const base::TimeDelta download_time =
      download_end_time >= download_start_time_
          ? download_end_time - download_start_time_
          : base::TimeDelta();

  // Consider a 5xx response from the server as an indication to terminate
  // the request and avoid overloading the server in this case.
  // is not accepting requests for the moment.
  int error = -1;
  if (!file_path.empty() && response_code_ == 200) {
    DCHECK_EQ(0, net_error);
    error = 0;
  } else if (response_code_ != -1) {
    error = response_code_;
  } else {
    error = net_error;
  }

  const bool is_handled = error == 0 || IsHttpServerError(error);

  Result result;
  result.error = error;
  if (!error) {
    result.response = file_path;
  }

  DownloadMetrics download_metrics;
  download_metrics.url = url();
  download_metrics.downloader = DownloadMetrics::kUrlFetcher;
  download_metrics.error = error;
  // Tests expected -1, in case of failures and no content is available.
  download_metrics.downloaded_bytes = error ? -1 : content_size;
  download_metrics.total_bytes = total_bytes_;
  download_metrics.download_time_ms = download_time.InMilliseconds();

  VLOG(1) << "Downloaded " << content_size << " bytes in "
          << download_time.InMilliseconds() << "ms from " << final_url_.spec()
          << " to " << result.response.value();

  // Delete the download directory in the error cases.
  if (error && !download_dir_.empty())
    base::PostTask(
        FROM_HERE, kTaskTraits,
        base::BindOnce(IgnoreResult(&base::DeleteFile), download_dir_, true));

  main_task_runner()->PostTask(
      FROM_HERE, base::BindOnce(&UrlFetcherDownloader::OnDownloadComplete,
                                base::Unretained(this), is_handled, result,
                                download_metrics));
}

// This callback is used to indicate that a download has been started.
void UrlFetcherDownloader::OnResponseStarted(const GURL& final_url,
                                             int response_code,
                                             int64_t content_length) {
  DCHECK_CALLED_ON_VALID_THREAD(thread_checker_);

  VLOG(1) << "url fetcher response started for: " << final_url.spec();

  final_url_ = final_url;
  response_code_ = response_code;
  total_bytes_ = content_length;
}

void UrlFetcherDownloader::OnDownloadProgress(int64_t current) {
  DCHECK_CALLED_ON_VALID_THREAD(thread_checker_);
  CrxDownloader::OnDownloadProgress();
}

}  // namespace update_client