// Copyright (c) Facebook, Inc. and its affiliates.

// This source code is licensed under the MIT license found in the
// LICENSE file in the root directory of this source tree.

#include "Scheduler.h"

#include <fabric/core/LayoutContext.h>
#include <fabric/uimanager/ComponentDescriptorRegistry.h>
#include <fabric/uimanager/FabricUIManager.h>

#include "ComponentDescriptorFactory.h"
#include "Differentiator.h"

namespace facebook {
namespace react {

Scheduler::Scheduler(const SharedContextContainer &contextContainer):
  contextContainer_(contextContainer) {

  const auto asynchronousEventBeatFactory = contextContainer->getInstance<EventBeatFactory>("asynchronous");
  const auto synchronousEventBeatFactory = contextContainer->getInstance<EventBeatFactory>("synchronous");

  uiManager_ = std::make_shared<FabricUIManager>(
    std::make_unique<EventBeatBasedExecutor>(asynchronousEventBeatFactory()),
    contextContainer->getInstance<std::function<UIManagerInstaller>>("uimanager-installer"),
    contextContainer->getInstance<std::function<UIManagerUninstaller>>("uimanager-uninstaller")
  );

  auto eventDispatcher =
    std::make_shared<EventDispatcher>(
      std::bind(
        &FabricUIManager::dispatchEventToTarget,
        uiManager_.get(),
        std::placeholders::_1,
        std::placeholders::_2,
        std::placeholders::_3
      ),
      synchronousEventBeatFactory,
      asynchronousEventBeatFactory
    );

  uiManager_->setComponentDescriptorRegistry(
    ComponentDescriptorFactory::buildRegistry(eventDispatcher, contextContainer)
  );

  uiManager_->setDelegate(this);
}

Scheduler::~Scheduler() {
  uiManager_->setDelegate(nullptr);
}

void Scheduler::startSurface(
  SurfaceId surfaceId,
  const std::string &moduleName,
  const folly::dynamic &initialProps
) const {
  std::lock_guard<std::mutex> lock(mutex_);

  auto shadowTree = std::make_unique<ShadowTree>(surfaceId);
  shadowTree->setDelegate(this);
  shadowTreeRegistry_.emplace(surfaceId, std::move(shadowTree));

#ifndef ANDROID
  uiManager_->startSurface(surfaceId, moduleName, initialProps);
#endif
}

void Scheduler::stopSurface(SurfaceId surfaceId) const {
  std::lock_guard<std::mutex> lock(mutex_);

#ifndef ANDROID
  uiManager_->stopSurface(surfaceId);
#endif

  const auto &iterator = shadowTreeRegistry_.find(surfaceId);
  const auto &shadowTree = iterator->second;
  assert(shadowTree);
  // As part of stopping the Surface, we have to commit an empty tree.
  shadowTree->complete(std::const_pointer_cast<SharedShadowNodeList>(ShadowNode::emptySharedShadowNodeSharedList()));
  shadowTree->setDelegate(nullptr);
  shadowTreeRegistry_.erase(iterator);
}

Size Scheduler::measureSurface(
  SurfaceId surfaceId,
  const LayoutConstraints &layoutConstraints,
  const LayoutContext &layoutContext
) const {
  std::lock_guard<std::mutex> lock(mutex_);
  const auto &shadowTree = shadowTreeRegistry_.at(surfaceId);
  assert(shadowTree);
  return shadowTree->measure(layoutConstraints, layoutContext);
}

void Scheduler::constraintSurfaceLayout(
  SurfaceId surfaceId,
  const LayoutConstraints &layoutConstraints,
  const LayoutContext &layoutContext
) const {
  std::lock_guard<std::mutex> lock(mutex_);
  const auto &shadowTree = shadowTreeRegistry_.at(surfaceId);
  assert(shadowTree);
  return shadowTree->constraintLayout(layoutConstraints, layoutContext);
}

#pragma mark - Delegate

void Scheduler::setDelegate(SchedulerDelegate *delegate) {
  delegate_ = delegate;
}

SchedulerDelegate *Scheduler::getDelegate() const {
  return delegate_;
}

#pragma mark - ShadowTreeDelegate

void Scheduler::shadowTreeDidCommit(const ShadowTree &shadowTree, const ShadowViewMutationList &mutations) const {
  if (delegate_) {
    delegate_->schedulerDidFinishTransaction(shadowTree.getRootTag(), mutations);
  }
}

#pragma mark - UIManagerDelegate

void Scheduler::uiManagerDidFinishTransaction(Tag rootTag, const SharedShadowNodeUnsharedList &rootChildNodes) {
  std::lock_guard<std::mutex> lock(mutex_);

  const auto iterator = shadowTreeRegistry_.find(rootTag);
  if (iterator == shadowTreeRegistry_.end()) {
    // This might happen during surface unmounting/deallocation process
    // due to the asynchronous nature of JS calls.
    return;
  }

  return iterator->second->complete(rootChildNodes);
}

void Scheduler::uiManagerDidCreateShadowNode(const SharedShadowNode &shadowNode) {
  if (delegate_) {
    delegate_->schedulerDidRequestPreliminaryViewAllocation(shadowNode->getComponentName());
  }
}

#pragma mark - Deprecated

std::shared_ptr<FabricUIManager> Scheduler::getUIManager_DO_NOT_USE() {
  return uiManager_;
}

} // namespace react
} // namespace facebook