// Copyright 2014 The Chromium OS 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 METRICS_UPLOADER_UPLOAD_SERVICE_H_
#define METRICS_UPLOADER_UPLOAD_SERVICE_H_

#include <string>

#include "base/metrics/histogram_base.h"
#include "base/metrics/histogram_flattener.h"
#include "base/metrics/histogram_snapshot_manager.h"
#include "metrics/uploader/metrics_log.h"
#include "metrics/uploader/sender.h"
#include "metrics/uploader/system_profile_cache.h"

namespace metrics {
class ChromeUserMetricsExtension;
class CrashSample;
class HistogramSample;
class LinearHistogramSample;
class MetricSample;
class SparseHistogramSample;
class UserActionSample;
}

class SystemProfileSetter;

// Service responsible for uploading the metrics periodically to the server.
// This service works as a simple 2-state state-machine.
//
// The two states are the presence or not of a staged log.
// A staged log is a compressed protobuffer containing both the aggregated
// metrics and event and information about the client. (product, hardware id,
// etc...).
//
// At regular intervals, the upload event will be triggered and the following
// will happen:
// * if a staged log is present:
//    The previous upload may have failed for various reason. We then retry to
//    upload the same log.
//    - if the upload is successful, we discard the log (therefore
//      transitioning back to no staged log)
//    - if the upload fails, we keep the log to try again later.
//    We do not try to read the metrics that are stored on
//    the disk as we want to avoid storing the metrics in memory.
//
// * if no staged logs are present:
//    Read all metrics from the disk, aggregate them and try to send them.
//    - if the upload succeeds, we discard the staged log (transitioning back
//      to the no staged log state)
//    - if the upload fails, we keep the staged log in memory to retry
//      uploading later.
//
class UploadService : public base::HistogramFlattener {
 public:
  UploadService();

  void Init();

  // Starts a new log. The log needs to be regenerated after each successful
  // launch as it is destroyed when staging the log.
  void StartNewLog();

  // Glib takes a function pointer and passes the object as a void*.
  // Uploader is expected to be an UploaderService.
  static int UploadEventStatic(void* uploader);

  // Triggers an upload event.
  void UploadEvent();

  // Sends the staged log.
  void SendStagedLog();

  // Implements inconsistency detection to match HistogramFlattener's
  // interface.
  void InconsistencyDetected(
      base::HistogramBase::Inconsistency problem) override {}
  void UniqueInconsistencyDetected(
      base::HistogramBase::Inconsistency problem) override {}
  void InconsistencyDetectedInLoggedCount(int amount) override {}

 private:
  friend class UploadServiceTest;

  FRIEND_TEST(UploadServiceTest, CanSendMultipleTimes);
  FRIEND_TEST(UploadServiceTest, DiscardLogsAfterTooManyFailedUpload);
  FRIEND_TEST(UploadServiceTest, EmptyLogsAreNotSent);
  FRIEND_TEST(UploadServiceTest, FailedSendAreRetried);
  FRIEND_TEST(UploadServiceTest, LogContainsAggregatedValues);
  FRIEND_TEST(UploadServiceTest, LogEmptyAfterUpload);
  FRIEND_TEST(UploadServiceTest, LogEmptyByDefault);
  FRIEND_TEST(UploadServiceTest, LogKernelCrash);
  FRIEND_TEST(UploadServiceTest, LogUncleanShutdown);
  FRIEND_TEST(UploadServiceTest, LogUserCrash);
  FRIEND_TEST(UploadServiceTest, UnknownCrashIgnored);
  FRIEND_TEST(UploadServiceTest, ValuesInConfigFileAreSent);

  // If a staged log fails to upload more than kMaxFailedUpload times, it
  // will be discarded.
  static const int kMaxFailedUpload;

  // Resets the internal state.
  void Reset();

  // Reads all the metrics from the disk.
  void ReadMetrics();

  // Adds a generic sample to the current log.
  void AddSample(const metrics::MetricSample& sample);

  // Adds a crash to the current log.
  void AddCrash(const std::string& crash_name);

  // Aggregates all histogram available in memory and store them in the current
  // log.
  void GatherHistograms();

  // Callback for HistogramSnapshotManager to store the histograms.
  void RecordDelta(const base::HistogramBase& histogram,
                   const base::HistogramSamples& snapshot) override;

  // Compiles all the samples received into a single protobuf and adds all
  // system information.
  void StageCurrentLog();

  // Returns the current log. If there is no current log, creates it first.
  MetricsLog* GetOrCreateCurrentLog();

  scoped_ptr<SystemProfileSetter> system_profile_setter_;
  base::HistogramSnapshotManager histogram_snapshot_manager_;
  scoped_ptr<Sender> sender_;
  int failed_upload_count_;
  scoped_ptr<MetricsLog> current_log_;
  scoped_ptr<MetricsLog> staged_log_;
};

#endif  // METRICS_UPLOADER_UPLOAD_SERVICE_H_