// Copyright (c) 2012 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.

#ifndef CONTENT_BROWSER_DOWNLOAD_DOWNLOAD_RESOURCE_HANDLER_H_
#define CONTENT_BROWSER_DOWNLOAD_DOWNLOAD_RESOURCE_HANDLER_H_

#include <stdint.h>

#include <memory>
#include <string>

#include "base/callback.h"
#include "base/macros.h"
#include "components/download/public/common/download_url_parameters.h"
#include "content/browser/download/download_request_core.h"
#include "content/browser/loader/resource_handler.h"
#include "content/public/browser/browser_context.h"
#include "content/public/browser/download_manager.h"
#include "content/public/browser/web_contents.h"
#include "services/metrics/public/cpp/ukm_recorder.h"

namespace download {
struct DownloadCreateInfo;
}  // namespace download

namespace net {
class URLRequest;
}  // namespace net

namespace content {
class ByteStreamReader;
class ResourceController;

// Forwards data to the download thread.
class CONTENT_EXPORT DownloadResourceHandler
    : public ResourceHandler,
      public DownloadRequestCore::Delegate,
      public base::SupportsWeakPtr<DownloadResourceHandler> {
 public:
  struct DownloadTabInfo;

  // started_cb will be called exactly once on the UI thread.
  // |id| should be invalid if the id should be automatically assigned.
  DownloadResourceHandler(net::URLRequest* request,
                          const std::string& request_origin,
                          download::DownloadSource download_source,
                          bool follow_cross_origin_redirects);

  // static
  // This function is passed into ResourceDispatcherHostImpl during its
  // creation and is used to create instances of DownloadResourceHandler when
  // intercepting navigation request to download system.
  // TODO(ananta)
  // Find a better way to achieve this. Ideally we want to move the logic of
  // creating DownloadResourceHandler instances out of
  // ResourceDispatcherHostImpl.
  static std::unique_ptr<ResourceHandler> Create(net::URLRequest* request);

  // Create the resource handler when the request is not intercepted from
  // navigation.
  static std::unique_ptr<ResourceHandler> CreateForNewRequest(
      net::URLRequest* request,
      const std::string& request_origin,
      download::DownloadSource download_source,
      bool follow_cross_origin_redirects);

  void OnRequestRedirected(
      const net::RedirectInfo& redirect_info,
      network::ResourceResponse* response,
      std::unique_ptr<ResourceController> controller) override;

  // Send the download creation information to the download thread.
  void OnResponseStarted(
      network::ResourceResponse* response,
      std::unique_ptr<ResourceController> controller) override;

  // Pass-through implementation.
  void OnWillStart(const GURL& url,
                   std::unique_ptr<ResourceController> controller) override;

  // Create a new buffer, which will be handed to the download thread for file
  // writing and deletion.
  void OnWillRead(scoped_refptr<net::IOBuffer>* buf,
                  int* buf_size,
                  std::unique_ptr<ResourceController> controller) override;

  void OnReadCompleted(int bytes_read,
                       std::unique_ptr<ResourceController> controller) override;

  void OnResponseCompleted(
      const net::URLRequestStatus& status,
      std::unique_ptr<ResourceController> controller) override;

  void PauseRequest();
  void ResumeRequest();

  // May result in this object being deleted by its owner.
  void CancelRequest();

  std::string DebugString() const;

 private:
  ~DownloadResourceHandler() override;

  // DownloadRequestCore::Delegate
  void OnStart(
      std::unique_ptr<download::DownloadCreateInfo> download_create_info,
      std::unique_ptr<ByteStreamReader> stream_reader,
      const download::DownloadUrlParameters::OnStartedCallback& callback)
      override;
  void OnReadyToRead() override;

  // Stores information about the download that must be acquired on the UI
  // thread before StartOnUIThread is called.
  // Created on IO thread, but only accessed on UI thread. |tab_info_| holds
  // the pointer until we pass it off to StartOnUIThread or DeleteSoon.
  // Marked as a std::unique_ptr<> to indicate ownership of the structure, but
  // deletion must occur on the IO thread.
  std::unique_ptr<DownloadTabInfo> tab_info_;

  bool follow_cross_origin_redirects_;
  url::Origin first_origin_;

  DownloadRequestCore core_;

  DISALLOW_COPY_AND_ASSIGN(DownloadResourceHandler);
};

}  // namespace content

#endif  // CONTENT_BROWSER_DOWNLOAD_DOWNLOAD_RESOURCE_HANDLER_H_