/**
 * Looking Glass
 * Copyright © 2017-2026 The Looking Glass Authors
 * https://looking-glass.io
 *
 * 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 2 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, write to the Free Software Foundation, Inc., 59
 * Temple Place, Suite 330, Boston, MA 02111-1307 USA
 */

#include "transport/lgmp/CLGMPTransport.h"

#include "CDebug.h"
#include "common/KVMFR.h"

static bool TranslateFrameScheduleFlags(
  uint32_t source, uint32_t& destination)
{
  static const uint32_t validFlags =
    KVMFR_FRAME_SCHEDULE_ACTIVE    |
    KVMFR_FRAME_SCHEDULE_RELEASE   |
    KVMFR_FRAME_SCHEDULE_RESET     |
    KVMFR_FRAME_SCHEDULE_IMMEDIATE;

  if (source & ~validFlags)
    return false;

  destination = 0;
  if (source & KVMFR_FRAME_SCHEDULE_ACTIVE)
    destination |= FRAME_SCHEDULE_ACTIVE;
  if (source & KVMFR_FRAME_SCHEDULE_RELEASE)
    destination |= FRAME_SCHEDULE_RELEASE;
  if (source & KVMFR_FRAME_SCHEDULE_RESET)
    destination |= FRAME_SCHEDULE_RESET;
  if (source & KVMFR_FRAME_SCHEDULE_IMMEDIATE)
    destination |= FRAME_SCHEDULE_IMMEDIATE;
  return true;
}

CLGMPTransport::CLGMPTransport() :
  m_control(m_host),
  m_frames(m_host, m_ivshmem),
  m_input(m_host)
{
}

ITransport::OpenResult CLGMPTransport::Open()
{
  if (m_ivshmem.GetMem())
    return OpenResult::SUCCESS;

  if (!m_ivshmem.Init() || !m_ivshmem.Open())
    return OpenResult::RETRY;

  return OpenResult::SUCCESS;
}

bool CLGMPTransport::Initialize()
{
  if (!m_host.Initialize(m_ivshmem))
    return false;

  // Preserve the existing shared-memory layout by appending input after the
  // frame and pointer queues and retained pointer state allocations.
  if (!m_frames.Initialize() || !m_control.Initialize() ||
      !m_input.Initialize())
    return false;

  m_frames.SealMemoryLayout();
  return true;
}

bool CLGMPTransport::Setup(size_t alignment)
{
  return m_frames.Setup(alignment);
}

void CLGMPTransport::Process(ITransportEvents& events)
{
  const LGMP_STATUS processStatus = m_host.Process();
  if (processStatus != LGMP_OK)
  {
    if (processStatus == LGMP_ERR_CORRUPTED)
    {
      DEBUG_WARN(
        "LGMP reported the shared memory has been corrupted, attempting to recover\n");
      // TODO: reinitialize LGMP.
      return;
    }

    DEBUG_ERROR("lgmpHostProcess Failed: %s",
      lgmpStatusString(processStatus));
    // TODO: shut down LGMP.
    return;
  }

  const uint64_t now = CFrameScheduler::Nanotime();

  // Take the frame subscriber snapshot before processing scheduling messages,
  // then publish both updates together just as the original timer did.
  const CLGMPFrameTransport::SubscriberSnapshot subscribers =
    m_frames.SnapshotSubscribers();

  uint8_t  data[LGMP_MSGS_SIZE];
  size_t   size;
  uint32_t sourceClientID;
  LGMP_STATUS status;
  while ((status = m_control.ReadDataWithSource(
      data, &size, &sourceClientID)) == LGMP_OK)
  {
    KVMFRMessage * msg = reinterpret_cast<KVMFRMessage *>(data);
    switch (msg->type)
    {
      case KVMFR_MESSAGE_SETCURSORPOS:
      {
        KVMFRSetCursorPos * position =
          reinterpret_cast<KVMFRSetCursorPos *>(msg);
        events.OnSetCursorPos(position->x, position->y);
        break;
      }

      case KVMFR_MESSAGE_WINDOWSIZE:
      {
        KVMFRWindowSize * window =
          reinterpret_cast<KVMFRWindowSize *>(msg);
        events.OnSetResolution(window->w, window->h);
        break;
      }

      case KVMFR_MESSAGE_FRAME_SCHEDULE:
      {
        const KVMFRFrameSchedule * schedule =
          reinterpret_cast<KVMFRFrameSchedule *>(msg);
        uint32_t translatedFlags = 0;
        bool valid = size == sizeof(*schedule) &&
          TranslateFrameScheduleFlags(schedule->flags, translatedFlags);
        if (valid)
        {
          FrameScheduleUpdate update = {};
          update.clientID               = schedule->clientID;
          update.generation             = schedule->generation;
          update.flags                  = translatedFlags;
          update.period                 = schedule->period;
          update.targetSlack            = schedule->targetSlack;
          update.phaseError             = schedule->phaseError;
          update.feedbackFrameSerial    = schedule->feedbackFrameSerial;
          update.feedbackScheduleEpoch  = schedule->feedbackScheduleEpoch;
          update.feedbackDeadlineSerial = schedule->feedbackDeadlineSerial;
          update.lease                  = schedule->lease;
          valid = m_frames.UpdateSchedule(sourceClientID, update, now);
        }
        if (!valid)
          DEBUG_WARN("Ignoring invalid KVMFR frame schedule");
        break;
      }
    }

    m_control.AckData();
  }

  m_frames.FinalizeSubscribers(subscribers, now);

  if (m_control.HasNewSubscribers())
    m_control.ResendState();
}

FrameMemoryLimits CLGMPTransport::GetMemoryLimits() const
{
  return m_frames.GetMemoryLimits();
}

DirectFrameBufferMemory CLGMPTransport::GetDirectMemory() const
{
  return {m_ivshmem.GetMem(), m_ivshmem.GetSize()};
}