// Copyright 2019 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "components/metrics/structured/recorder.h"

#include <utility>

#include "base/no_destructor.h"
#include "base/task/current_thread.h"
#include "base/task/sequenced_task_runner.h"
#include "components/metrics/structured/histogram_util.h"
#include "components/metrics/structured/lib/histogram_util.h"
#include "components/metrics/structured/structured_metrics_features.h"

namespace metrics::structured {

Recorder::Recorder() = default;

Recorder::~Recorder() = default;

Recorder* Recorder::GetInstance() {
  static base::NoDestructor<Recorder> recorder;
  return recorder.get();
}

void Recorder::RecordEvent(Event&& event) {
  // If the recorder is null, this doesn't need to be run on the same sequence.
  if (recorder_ == nullptr) {
    // Other values of EventRecordingState are recorded in
    // StructuredMetricsProvider::OnRecord.
    LogEventRecordingState(EventRecordingState::kProviderMissing);
    return;
  }

  // All calls to StructuredMetricsProvider (the observer) must be on the UI
  // sequence, so re-call Record if needed. If a UI task runner hasn't been set
  // yet, ignore this Record.
  if (!ui_task_runner_) {
    LogInternalError(StructuredMetricsError::kUninitializedClient);
    return;
  }

  if (!ui_task_runner_->RunsTasksInCurrentSequence()) {
    ui_task_runner_->PostTask(
        FROM_HERE, base::BindOnce(&Recorder::RecordEvent,
                                  base::Unretained(this), std::move(event)));
    return;
  }

  DCHECK(base::CurrentUIThread::IsSet());

  delegating_events_processor_.OnEventsRecord(&event);
  recorder_->OnEventRecord(event);
}

void Recorder::OnSystemProfileInitialized() {
  if (recorder_) {
    recorder_->OnSystemProfileInitialized();
  }
}

void Recorder::SetUiTaskRunner(
    const scoped_refptr<base::SequencedTaskRunner> ui_task_runner) {
  ui_task_runner_ = ui_task_runner;
}

void Recorder::SetRecorder(RecorderImpl* recorder) {
  recorder_ = recorder;
}

void Recorder::UnsetRecorder(RecorderImpl* recorder) {
  // Only reset if this is the same recorder. Otherwise, changing the recorder
  // isn't needed.
  if (recorder_ == recorder) {
    recorder_ = nullptr;
  }
}

void Recorder::AddEventsProcessor(
    std::unique_ptr<EventsProcessorInterface> events_processor) {
  delegating_events_processor_.AddEventsProcessor(std::move(events_processor));
}

void Recorder::OnProvideIndependentMetrics(
    ChromeUserMetricsExtension* uma_proto) {
  delegating_events_processor_.OnProvideIndependentMetrics(uma_proto);
}

void Recorder::OnEventRecorded(StructuredEventProto* event) {
  delegating_events_processor_.OnEventRecorded(event);
}

}  // namespace metrics::structured