// Copyright 2017 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 COMPONENTS_DOWNLOAD_PUBLIC_DOWNLOAD_SERVICE_H_
#define COMPONENTS_DOWNLOAD_PUBLIC_DOWNLOAD_SERVICE_H_

#include <string>

#include "base/files/file_path.h"
#include "base/macros.h"
#include "base/memory/ptr_util.h"
#include "base/memory/ref_counted.h"
#include "base/sequenced_task_runner.h"
#include "components/keyed_service/core/keyed_service.h"

namespace download {

struct DownloadParams;
struct SchedulingParams;

// A service responsible for helping facilitate the scheduling and downloading
// of file content from the web.  See |DownloadParams| for more details on the
// types of scheduling that can be achieved and the required input parameters
// for starting a download.  Note that DownloadServices with a valid storage
// directory will persist the requests across restarts.  This means that any
// feature requesting a download will have to implement a download::Client
// interface so this class knows who to contact when a download completes after
// a process restart.
class DownloadService : public KeyedService {
 public:
  // |storage_dir| is a path to where all the local storage will be.  This will
  // hold the internal database as well as any temporary files on disk.  If this
  // is an empty path, the service will not persist any information to disk and
  // will act as an in-memory only service (this means no auto-retries after
  // restarts, no files written on completion, etc.).
  // |background_task_runner| will be used for all disk reads and writes.
  static DownloadService* Create(
      const base::FilePath& storage_dir,
      const scoped_refptr<base::SequencedTaskRunner>& background_task_runner);

  // Sends the download to the service.  A callback to
  // |DownloadParams::callback| will be triggered once the download has been
  // persisted and saved in the service
  virtual void StartDownload(const DownloadParams& download_params) = 0;

  // Allows any feature to pause or resume downloads at will.  Paused downloads
  // will not start or stop based on scheduling criteria.  They will be
  // effectively frozen.
  virtual void PauseDownload(const std::string& guid) = 0;
  virtual void ResumeDownload(const std::string& guid) = 0;

  // Cancels a download in this service.  The canceled download will be
  // interrupted if it is running.
  virtual void CancelDownload(const std::string& guid) = 0;

  // Changes the current scheduling criteria for a download.  This is useful if
  // a user action might constrain or loosen the device state during which this
  // download can run.
  virtual void ChangeDownloadCriteria(const std::string& guid,
                                      const SchedulingParams& params) = 0;

 protected:
  DownloadService() = default;

 private:
  DISALLOW_COPY_AND_ASSIGN(DownloadService);
};

}  // namespace download

#endif  // COMPONENTS_DOWNLOAD_PUBLIC_DOWNLOAD_SERVICE_H_