// Copyright 2010-2018, Google Inc.
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//
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// modification, are permitted provided that the following conditions are
// met:
//
//     * Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
//     * Redistributions in binary form must reproduce the above
// copyright notice, this list of conditions and the following disclaimer
// in the documentation and/or other materials provided with the
// distribution.
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// this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

#include "gui/character_pad/hand_writing_thread.h"

// MutexLocker locks in the constructor and unlocks in the destructor.
#include <QtCore/QMutexLocker>
#include <QtGui/QtGui>
#include <QtWidgets/QListWidgetItem>

#include "base/clock.h"
#include "base/logging.h"
#include "config/stats_config_util.h"

namespace {
// Thread-safe copying of strokes.
void CopyStrokes(const mozc::handwriting::Strokes &source,
                 mozc::handwriting::Strokes *target,
                 QMutex *mutex) {
  DCHECK(target);
  DCHECK(mutex);
  QMutexLocker l(mutex);
  target->clear();
  target->resize(source.size());
  for (size_t i = 0; i < source.size(); ++i) {
    const mozc::handwriting::Stroke &stroke = source[i];
    (*target)[i].resize(stroke.size());
    for (size_t j = 0; j < stroke.size(); ++j) {
      (*target)[i][j] = stroke[j];
    }
  }
}

// Thread-safe copying of candidates.
void CopyCandidates(const std::vector<string> &source,
                    std::vector<string> *target,
                    QMutex *mutex) {
  DCHECK(target);
  DCHECK(mutex);
  QMutexLocker l(mutex);
  target->clear();
  target->resize(source.size());
  for (size_t i = 0; i < source.size(); ++i) {
    (*target)[i] = source[i];
  }
}
}  // namespace

namespace mozc {
namespace gui {

void HandWritingThread::Start() {
  strokes_sec_ = 0;
  strokes_usec_ = 0;
  last_requested_sec_ = 0;
  last_requested_usec_ = 0;

  // To reduce the disk IO of reading the stats config, we load it only when the
  // thread is initialized. There is no problem because the config dialog (on
  // Mac) and the administrator dialog (on Windows) say that the usage stats
  // setting changes will take effect after the re-login.
  // TODO(horo): There may be a possibility of read-write conflict in Mac,
  // because the stats config is stored in a file.
  // But this situation is very rare because the user have to change it in the
  // config dialog UI.
  usage_stats_enabled_ = mozc::config::StatsConfigUtil::IsEnabled();
  start();
  moveToThread(this);
}

void HandWritingThread::SetStrokes(const handwriting::Strokes &strokes) {
  CopyStrokes(strokes, &strokes_, &strokes_mutex_);
  // This is absolutely thread-unsafe but practically no problems.
  Clock::GetTimeOfDay(&strokes_sec_, &strokes_usec_);
}

void HandWritingThread::GetCandidates(std::vector<string> *candidates) {
  CopyCandidates(candidates_, candidates, &candidates_mutex_);
}

void HandWritingThread::startRecognition() {
  if (last_requested_sec_ == strokes_sec_ &&
      last_requested_usec_ == strokes_usec_) {
    LOG(WARNING) << "Already sent that stroke";
    return;
  }
  handwriting::HandwritingStatus status = handwriting::HANDWRITING_NO_ERROR;
  emit statusUpdated(status);

  handwriting::Strokes strokes;
  CopyStrokes(strokes_, &strokes, &strokes_mutex_);
  if (strokes.empty()) {
    return;
  }

  std::vector<string> candidates;
  status = handwriting::HandwritingManager::Recognize(strokes, &candidates);
  CopyCandidates(candidates, &candidates_, &candidates_mutex_);
  last_requested_sec_ = strokes_sec_;
  last_requested_usec_ = strokes_usec_;
  emit candidatesUpdated();
  emit statusUpdated(status);
}

void HandWritingThread::itemSelected(const QListWidgetItem *item) {
  // Do not send feedback it usage_stats is disabled.
  if (!usage_stats_enabled_) {
    return;
  }

  handwriting::Strokes strokes;
  CopyStrokes(strokes_, &strokes, &strokes_mutex_);
  const QByteArray text = item->text().toUtf8();
  handwriting::HandwritingManager::Commit(
      strokes, string(text.constData(), text.length()));
}

}  // namespace gui
}  // namespace mozc