// Copyright 2013 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_UPLOAD_LIST_UPLOAD_LIST_H_
#define COMPONENTS_UPLOAD_LIST_UPLOAD_LIST_H_

#include <stddef.h>

#include <string>
#include <vector>

#include "base/callback.h"
#include "base/macros.h"
#include "base/memory/ref_counted.h"
#include "base/sequence_checker.h"
#include "base/task_scheduler/task_traits.h"
#include "base/time/time.h"

// An UploadList is an abstraction over a list of client-side data files that
// are uploaded to a server. The UploadList allows accessing the UploadInfo
// for these files, usually to display in a UI.
//
// The UploadList loads the information asynchronously and notifies the
// client that requested the information when it is available.
class UploadList : public base::RefCountedThreadSafe<UploadList> {
 public:
  struct UploadInfo {
    enum class State {
      NotUploaded = 0,
      Pending,
      Pending_UserRequested,
      Uploaded,
    };

    UploadInfo(const std::string& upload_id,
               const base::Time& upload_time,
               const std::string& local_id,
               const base::Time& capture_time,
               State state);
    // Constructor for locally stored data.
    UploadInfo(const std::string& local_id,
               const base::Time& capture_time,
               State state,
               const base::string16& file_size);
    UploadInfo(const std::string& upload_id, const base::Time& upload_time);
    UploadInfo(const UploadInfo& upload_info);
    ~UploadInfo();

    // These fields are only valid when |state| == UploadInfo::State::Uploaded.
    std::string upload_id;
    base::Time upload_time;

    // ID for locally stored data that may or may not be uploaded.
    std::string local_id;

    // The time the data was captured. This is useful if the data is stored
    // locally when captured and uploaded at a later time.
    base::Time capture_time;

    State state;

    // Formatted file size for locally stored data.
    base::string16 file_size;
  };

  // Creates a new upload list with the given callback delegate.
  UploadList();

  // Starts loading the upload list. OnUploadListAvailable will be called when
  // loading is complete. If this is called twice, the second |callback| will
  // overwrite the previously supplied one, and the first will not be called.
  void Load(base::OnceClosure callback);

  // Clears any callback specified in Load().
  void CancelCallback();

  // Asynchronously requests a user triggered upload.
  void RequestSingleUploadAsync(const std::string& local_id);

  // Populates |uploads| with the |max_count| most recent uploads,
  // in reverse chronological order.
  // Must be called only after a Load() callback has been received.
  void GetUploads(size_t max_count, std::vector<UploadInfo>* uploads);

 protected:
  virtual ~UploadList();

  // Returns the TaskTraits that should be used for LoadUploadList() and
  // RequestSingleUpload().
  virtual base::TaskTraits LoadingTaskTraits() = 0;

  // Reads the upload log and stores the entries in |uploads|.
  virtual std::vector<UploadInfo> LoadUploadList() = 0;

  // Requests a user triggered upload for a crash report with a given id.
  virtual void RequestSingleUpload(const std::string& local_id);

 private:
  friend class base::RefCountedThreadSafe<UploadList>;

  // When LoadUploadList() finishes, the results are reported in |uploads|
  // and the |callback_| is run.
  void OnLoadComplete(const std::vector<UploadInfo>& uploads);

  // Ensures that this class' thread unsafe state is only accessed from the
  // sequence that owns this UploadList.
  base::SequenceChecker sequence_checker_;

  base::OnceClosure callback_;

  std::vector<UploadInfo> uploads_;

  DISALLOW_COPY_AND_ASSIGN(UploadList);
};

#endif  // COMPONENTS_UPLOAD_LIST_UPLOAD_LIST_H_