/***

  Olive - Non-Linear Video Editor
  Copyright (C) 2019 Olive Team

  This program is free software: you can redistribute it and/or modify
  it under the terms of the GNU General Public License as published by
  the Free Software Foundation, either version 3 of the License, or
  (at your option) any later version.

  This program is distributed in the hope that it will be useful,
  but WITHOUT ANY WARRANTY; without even the implied warranty of
  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  GNU General Public License for more details.

  You should have received a copy of the GNU General Public License
  along with this program.  If not, see <http://www.gnu.org/licenses/>.

***/

#include "render.h"

#include "common/timecodefunctions.h"

OLIVE_NAMESPACE_ENTER

RenderTask::RenderTask(ViewerOutput* viewer, const VideoParams &vparams, const AudioParams &aparams)
{
  backend_ = new OpenGLBackend();
  backend_->SetViewerNode(viewer);
  backend_->SetVideoParams(vparams);
  backend_->SetAudioParams(aparams);
}

RenderTask::~RenderTask()
{
  delete backend_;
}

struct TimeHashFuturePair {
  rational time;
  RenderTicketPtr hash_future;
};

struct HashTimePair {
  rational time;
  QByteArray hash;
};

struct HashFrameFuturePair {
  QByteArray hash;
  RenderTicketPtr frame_future;
};

struct RangeSampleFuturePair {
  TimeRange range;
  RenderTicketPtr sample_future;
};

struct HashDownloadFuturePair {
  QByteArray hash;
  QFuture<void> download_future;
  qint64 job_time;
};

void RenderTask::Render(const TimeRangeList& video_range,
                        const TimeRangeList &audio_range,
                        bool use_disk_cache)
{
  double progress_counter = 0;
  double total_length = 0;
  double video_frame_sz = video_params().time_base().toDouble();

  std::list<TimeRange> audio_queue;
  std::list<RangeSampleFuturePair> audio_lookup_table;
  if (!audio_range.isEmpty()) {
    foreach (const TimeRange& r, audio_range) {
      total_length += r.length().toDouble();

      std::list<TimeRange> ranges = RenderBackend::SplitRangeIntoChunks(r);
      audio_queue.insert(audio_queue.end(), ranges.begin(), ranges.end());
    }
  }

  std::list<HashFrameFuturePair> render_lookup_table;
  QVector<rational> times;
  QVector<QByteArray> hashes;
  std::list<HashTimePair> frame_queue;
  qint64 hash_job_time = 0;

  if (!video_range.isEmpty()) {
    times = viewer()->video_frame_cache()->GetFrameListFromTimeRange(video_range);

    total_length += video_frame_sz * times.size();

    RenderTicketPtr hash_future = backend_->Hash(times);
    hashes = hash_future->Get().value<QVector<QByteArray> >();
    hash_job_time = hash_future->GetJobTime();

    if (!hash_future->WasCancelled()) {
      for (int i=0;i<times.size();i++) {
        frame_queue.push_back({times.at(i), hashes.at(i)});
      }
    }
  }

  // Start downloading frames that have finished
  std::list<HashDownloadFuturePair> download_futures;

  // Iterators
  std::list<HashFrameFuturePair>::iterator i;
  std::list<HashDownloadFuturePair>::iterator j;
  std::list<RangeSampleFuturePair>::iterator k;

  std::list<QByteArray> running_hashes;
  std::list<QByteArray> existing_hashes;

  while (!IsCancelled()
         && (!render_lookup_table.empty()
             || !frame_queue.empty()
             || !audio_queue.empty()
             || !download_futures.empty()
             || !audio_lookup_table.empty())) {

    while (!IsCancelled() && !frame_queue.empty()) {

      // Pop another frame off the frame queue
      const HashTimePair& p = frame_queue.front();

      // Check if we're already rendering this hash
      bool rendering_hash = (std::find(running_hashes.begin(), running_hashes.end(), p.hash) != running_hashes.end());

      // Skip this hash if we're already rendering it
      if (!rendering_hash) {
        // Check if this frame already exists (has already been rendered previously or during this job)
        bool hash_exists = false;

        if (use_disk_cache) {
          // Check if this hash is in our "existing hashes" list
          hash_exists = (std::find(existing_hashes.begin(), existing_hashes.end(), p.hash) != existing_hashes.end());

          // If not, check if it's in the filesystem
          if (!hash_exists) {
            hash_exists = QFileInfo::exists(viewer()->video_frame_cache()->CachePathName(p.hash));

            // If so, add it to the list so we don't have to check the filesystem again later
            if (hash_exists) {
              existing_hashes.push_back(p.hash);
            }
          }

          if (hash_exists) {
            // Already exists, no need to render it again
            FrameDownloaded(p.hash, {p.time}, hash_job_time);
            progress_counter += video_frame_sz;
            emit ProgressChanged(progress_counter / total_length);
          }
        }

        // If no existing disk cache was found, queue it now
        if (!hash_exists) {
          render_lookup_table.push_back({p.hash, backend_->RenderFrame(p.time)});
          running_hashes.push_back(p.hash);
        }
      }

      // Remove first element
      frame_queue.pop_front();
    }

    while (!IsCancelled() && !audio_queue.empty()) {
      audio_lookup_table.push_back({audio_queue.front(), backend_->RenderAudio(audio_queue.front())});
      audio_queue.pop_front();
    }

    i = render_lookup_table.begin();

    while (!IsCancelled() && i != render_lookup_table.end()) {
      if (i->frame_future->IsFinished()) {
        if (!i->frame_future->WasCancelled()) {
          FramePtr f = i->frame_future->Get().value<FramePtr>();

          // Start multithreaded download here
          download_futures.push_back({i->hash, DownloadFrame(f, i->hash), i->frame_future->GetJobTime()});
        }

        i = render_lookup_table.erase(i);
      } else {
        i++;
      }
    }

    j = download_futures.begin();

    while (!IsCancelled() && j != download_futures.end()) {
      if (j->download_future.isFinished()) {
        // Place it in the cache
        std::list<rational> times_with_hash;

        for (int hash_index=0;hash_index<hashes.size();hash_index++) {
          if (hashes.at(hash_index) == j->hash) {
            times_with_hash.push_back(times.at(hash_index));
          }
        }

        FrameDownloaded(j->hash, times_with_hash, j->job_time);

        existing_hashes.push_back(j->hash);

        // Signal process
        progress_counter += times_with_hash.size() * video_frame_sz;
        emit ProgressChanged(progress_counter / total_length);

        j = download_futures.erase(j);

      } else {
        j++;
      }
    }

    k = audio_lookup_table.begin();

    while (!IsCancelled() && k != audio_lookup_table.end()) {
      if (k->sample_future->IsFinished()) {
        AudioDownloaded(k->range,
                        k->sample_future->Get().value<SampleBufferPtr>(),
                        k->sample_future->GetJobTime());

        progress_counter += k->range.length().toDouble();
        emit ProgressChanged(progress_counter / total_length);

        k = audio_lookup_table.erase(k);
      } else {
        k++;
      }
    }
  }

  // `Close` will block until all jobs are done making a safe deletion
  backend_->Close();
}

OLIVE_NAMESPACE_EXIT