/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this file,
 * You can obtain one at http://mozilla.org/MPL/2.0/. */

#include "MediaSystemResourceService.h"

#include "MediaSystemResourceManagerParent.h"
#include "mozilla/layers/CompositorThread.h"

using namespace mozilla::layers;

namespace mozilla {

/* static */
StaticRefPtr<MediaSystemResourceService> MediaSystemResourceService::sSingleton;

/* static */
already_AddRefed<MediaSystemResourceService> MediaSystemResourceService::Get() {
  if (!sSingleton) {
    Init();
  }
  return do_AddRef(sSingleton);
}

/* static */
void MediaSystemResourceService::Init() {
  if (!sSingleton) {
    sSingleton = new MediaSystemResourceService();
  }
}

/* static */
void MediaSystemResourceService::Shutdown() {
  MOZ_ASSERT(CompositorThreadHolder::IsInCompositorThread());
  if (sSingleton) {
    sSingleton->Destroy();
    sSingleton = nullptr;
  }
}

MediaSystemResourceService::MediaSystemResourceService() : mDestroyed(false) {
  MOZ_ASSERT(CompositorThreadHolder::IsInCompositorThread());
}

MediaSystemResourceService::~MediaSystemResourceService() = default;

void MediaSystemResourceService::Destroy() { mDestroyed = true; }

void MediaSystemResourceService::Acquire(
    media::MediaSystemResourceManagerParent* aParent, uint32_t aId,
    MediaSystemResourceType aResourceType, bool aWillWait) {
  MOZ_ASSERT(CompositorThreadHolder::IsInCompositorThread());
  MOZ_ASSERT(aParent);

  if (mDestroyed) {
    return;
  }

  MediaSystemResource* resource =
      mResources.Get(static_cast<uint32_t>(aResourceType));

  if (!resource || resource->mResourceCount == 0) {
    // Resource does not exit
    // Send fail response
    (void)aParent->SendResponse(aId, false /* fail */);
    return;
  }

  // Try to acquire a resource
  if (resource->mAcquiredRequests.size() < resource->mResourceCount) {
    // Resource is available
    resource->mAcquiredRequests.push_back(
        MediaSystemResourceRequest(aParent, aId));
    // Send success response
    (void)aParent->SendResponse(aId, true /* success */);
    return;
  }

  if (!aWillWait) {
    // Resource is not available and do not wait.
    // Send fail response
    (void)aParent->SendResponse(aId, false /* fail */);
    return;
  }
  // Wait until acquire.
  resource->mWaitingRequests.push_back(
      MediaSystemResourceRequest(aParent, aId));
}

void MediaSystemResourceService::ReleaseResource(
    media::MediaSystemResourceManagerParent* aParent, uint32_t aId,
    MediaSystemResourceType aResourceType) {
  MOZ_ASSERT(CompositorThreadHolder::IsInCompositorThread());
  MOZ_ASSERT(aParent);

  if (mDestroyed) {
    return;
  }

  MediaSystemResource* resource =
      mResources.Get(static_cast<uint32_t>(aResourceType));

  if (!resource || resource->mResourceCount == 0) {
    // Resource does not exit
    return;
  }
  RemoveRequest(aParent, aId, aResourceType);
  UpdateRequests(aResourceType);
}

void MediaSystemResourceService::ReleaseResource(
    media::MediaSystemResourceManagerParent* aParent) {
  MOZ_ASSERT(aParent);

  if (mDestroyed) {
    return;
  }

  for (const uint32_t& key : mResources.Keys()) {
    RemoveRequests(aParent, static_cast<MediaSystemResourceType>(key));
    UpdateRequests(static_cast<MediaSystemResourceType>(key));
  }
}

void MediaSystemResourceService::RemoveRequest(
    media::MediaSystemResourceManagerParent* aParent, uint32_t aId,
    MediaSystemResourceType aResourceType) {
  MOZ_ASSERT(aParent);

  MediaSystemResource* resource =
      mResources.Get(static_cast<uint32_t>(aResourceType));
  if (!resource) {
    return;
  }

  std::deque<MediaSystemResourceRequest>::iterator it;
  std::deque<MediaSystemResourceRequest>& acquiredRequests =
      resource->mAcquiredRequests;
  for (it = acquiredRequests.begin(); it != acquiredRequests.end(); it++) {
    if (((*it).mParent == aParent) && ((*it).mId == aId)) {
      acquiredRequests.erase(it);
      return;
    }
  }

  std::deque<MediaSystemResourceRequest>& waitingRequests =
      resource->mWaitingRequests;
  for (it = waitingRequests.begin(); it != waitingRequests.end(); it++) {
    if (((*it).mParent == aParent) && ((*it).mId == aId)) {
      waitingRequests.erase(it);
      return;
    }
  }
}

void MediaSystemResourceService::RemoveRequests(
    media::MediaSystemResourceManagerParent* aParent,
    MediaSystemResourceType aResourceType) {
  MOZ_ASSERT(aParent);

  MediaSystemResource* resource =
      mResources.Get(static_cast<uint32_t>(aResourceType));

  if (!resource || resource->mResourceCount == 0) {
    // Resource does not exit
    return;
  }

  std::deque<MediaSystemResourceRequest>::iterator it;
  std::deque<MediaSystemResourceRequest>& acquiredRequests =
      resource->mAcquiredRequests;
  for (it = acquiredRequests.begin(); it != acquiredRequests.end();) {
    if ((*it).mParent == aParent) {
      it = acquiredRequests.erase(it);
    } else {
      it++;
    }
  }

  std::deque<MediaSystemResourceRequest>& waitingRequests =
      resource->mWaitingRequests;
  for (it = waitingRequests.begin(); it != waitingRequests.end();) {
    if ((*it).mParent == aParent) {
      it = waitingRequests.erase(it);
    } else {
      it++;
    }
  }
}

void MediaSystemResourceService::UpdateRequests(
    MediaSystemResourceType aResourceType) {
  MediaSystemResource* resource =
      mResources.Get(static_cast<uint32_t>(aResourceType));

  if (!resource || resource->mResourceCount == 0) {
    // Resource does not exit
    return;
  }

  std::deque<MediaSystemResourceRequest>& acquiredRequests =
      resource->mAcquiredRequests;
  std::deque<MediaSystemResourceRequest>& waitingRequests =
      resource->mWaitingRequests;

  while ((acquiredRequests.size() < resource->mResourceCount) &&
         (!waitingRequests.empty())) {
    MediaSystemResourceRequest& request = waitingRequests.front();
    MOZ_ASSERT(request.mParent);
    // Send response
    (void)request.mParent->SendResponse(request.mId, true /* success */);
    // Move request to mAcquiredRequests
    acquiredRequests.push_back(waitingRequests.front());
    waitingRequests.pop_front();
  }
}

}  // namespace mozilla