/**
  * @RDE_HEADER@
  * InfrastructureBuilder
  * $Id$
  * $HeadURL$
  * $Author$
  * Created by Christian Fröbel, SLSE, 2017-11-29
  */

#include "asset_assignment_manager.h"
#include "exercise.h"
#include "asset.h"
#include "mounting_point.h"
#include <InfrastructureManagement/ism.hpp>
#include <InfrastructureManagement/ism_dtc.h>
#include <QtGlobal>
#include <utility>
#include <functional>


namespace
{

bool isAssigned(const InfrastructureManagement::InstrumentationAsset &asset)
{
  return asset.availableInExercise().size() > 0;
}

int assignedExercise(const InfrastructureManagement::InstrumentationAsset &asset)
{
  Q_ASSERT(asset.availableInExercise().size() == 1);
  return asset.availableInExercise()[0];
}

bool isMountingPoint(const InfrastructureManagement::StructureElement &structureElement)
{
  return structureElement.structureElementTypeId() == InfrastructureManagement::StructureElementType::MountingPoint;
}

} // anonymous namespace


namespace AudioVideoManagement
{

AssetAssignmentManager *AssetAssignmentManager::create(InfrastructureManagement::Interface::Dtc *ismDtc)
{
  Q_ASSERT(ismDtc);

  AssetAssignmentManager   *newAssetAssignmentManager = new AssetAssignmentManager;

  connect(ismDtc, &InfrastructureManagement::Interface::Dtc::instrumentationAssetChanged, newAssetAssignmentManager, &AssetAssignmentManager::onAssetChanged);
  connect(ismDtc, &InfrastructureManagement::Interface::Dtc::mainStructureElementChanged, newAssetAssignmentManager, &AssetAssignmentManager::onMainStructureElementChanged);
  connect(ismDtc, &InfrastructureManagement::Interface::Dtc::mountingPointAssetChanged,   newAssetAssignmentManager, &AssetAssignmentManager::onMountingChanged);

  // No need to query the DTC here as it is not yet activated.
  // But explicitly check that the DTC (i.e. the contained DataReader) is not enabled yet.
  Q_ASSERT(!ismDtc->isInstrumentationAssetEnabled());
  Q_ASSERT(!ismDtc->isMainStructureElementEnabled());
  Q_ASSERT(!ismDtc->isMountingPointAssetEnabled());

  return newAssetAssignmentManager;
}

AssetAssignmentManager::AssetAssignmentManager()
  : m_logger(getLogger("AssetAssignmentManager"))
{
  // Create a "pool" exercise to hold all elements that are not assigned to any exercise.
  std::unique_ptr<Exercise>   poolExercise(new Exercise(ExerciseContext::defaultContext()));
  m_exercises[ExerciseContext::defaultContext()] = std::move(poolExercise);
}

AssetAssignmentManager::~AssetAssignmentManager() = default;


void AssetAssignmentManager::onAssetChanged(const InfrastructureManagement::InstrumentationAsset &asset, DataModification modType)
{
  switch (modType)
  {
  case DataModification::eAdded:
    return addAsset(asset);
  case DataModification::eModified:
    return modifyAsset(asset);
  case DataModification::eRemoved:
    return removeAsset(asset);
  }
  Q_ASSERT(false);
}

void AssetAssignmentManager::onMainStructureElementChanged(const InfrastructureManagement::MainStructureElement &data, DataModification modType)
{
  // Is the removal of MainStructureElements a valid UseCase or does that only happen when stopping the services?
  // For now, we simply ignore the removal.
  if (modType == DataModification::eRemoved)
    return;

  if (modType == DataModification::eAdded)
  {
    for (const auto &structureElement: data.elements())
    {
      if (!isMountingPoint(structureElement))
        continue;
      std::unique_ptr<MountingPoint>   newMountingPoint(new MountingPoint(structureElement));
      pool()->add(std::move(newMountingPoint));
    }

    processPendingMounts();
    return;
  }

  Q_ASSERT(modType == DataModification::eModified);

  // What to do on modification?
  // What does a modification mean?
  // Are the contained StructureElements still the same as before?
  // For now we simply assume that the MountingPoints are still the same
  // and we just update them.
  for (const auto &structureElement: data.elements())
  {
    if (!isMountingPoint(structureElement))
      continue;
    MountingPoint   *mountingPoint = findMountingPoint(structureElement.id()).second;
    Q_ASSERT(mountingPoint);
    if (mountingPoint)
      mountingPoint->update(structureElement);
  }
}

void AssetAssignmentManager::onMountingChanged(const InfrastructureManagement::MountingPointAsset &mount, DataModification modType)
{
  switch (modType)
  {
  case DataModification::eAdded:
    return addMount(mount);
  case DataModification::eRemoved:
    return removeMount(mount);
  case DataModification::eModified:
    Q_ASSERT(false);
    break;
  }
  Q_ASSERT(false);
}

void AssetAssignmentManager::addAsset(const InfrastructureManagement::InstrumentationAsset &asset)
{
  // Put the new Asset into the pool exercise.
  std::unique_ptr<Asset>   newAsset(new Asset(asset));
  Asset                   *newAsset_ = newAsset.get();
  pool()->add(std::move(newAsset));

  processPendingMounts();

  if (isAssigned(asset))
  {
    Exercise   *targetExercise = exercise(assignedExercise(asset));
    tryAssignAsset(newAsset_, pool(), targetExercise, boost::none);
  }
}

/**
 * The modification of an Asset possibly only affects the assignment.
 */
void AssetAssignmentManager::modifyAsset(const InfrastructureManagement::InstrumentationAsset &asset)
{
  if (hasPendingModifications(asset.id()))
    return m_pendingModifications.push_back(asset);

  auto     found = findAsset(asset.id());
  Asset   *foundAsset = found.second;
  Q_ASSERT(foundAsset);

  Exercise   *currentExercise = found.first;
  Exercise   *targetExercise = isAssigned(asset) ? exercise(assignedExercise(asset)) : pool();

  if (targetExercise == currentExercise)
  {
    foundAsset->update(asset);
    return; // no change in assignment
  }

  if (targetExercise == pool())
  {
    // unassign
    unassignAsset(foundAsset, currentExercise, asset);
    processPendingUnmounts();
    return;
  }

  // assign or reassign
  tryAssignAsset(foundAsset, currentExercise, targetExercise, asset);
}

/**
 * If the Asset is assigned, it will be unassigned.
 * If it is not unmounted yet, defer the removal.
 * The pending removals will be processed after the Unmount.
 */
void AssetAssignmentManager::removeAsset(const InfrastructureManagement::InstrumentationAsset &asset)
{
  auto        assetAndExercise = findAsset(asset.id());
  Asset      *foundAsset = assetAndExercise.second;
  Exercise   *exercise   = assetAndExercise.first;
  Q_ASSERT(foundAsset);

  if (exercise != pool())
  {
    unassignAsset(foundAsset, exercise, boost::none);
    processPendingUnmounts();
  }

  if (foundAsset->isMounted())
  {
    m_pendingRemoves.push_back(asset);
    return;
  }

  pool()->take(foundAsset); // implicit delete
}

/**
 * Try to assign the Asset to an Exercise.
 * Assets can only be assigned if they are mounted.
 * If the Asset is not mounted yet (because the info was not yet published),
 * the assignment will be deferred. It will be processed after the mount.
 * The Asset and MountingPoint must still be in the pool Exercise.
 * @param modifiedData only set when called as a result of a modification
 */
void AssetAssignmentManager::tryAssignAsset(Asset *asset, Exercise *currentExercise, Exercise *targetExercise, const boost::optional<InfrastructureManagement::InstrumentationAsset> &modifiedData)
{
  Q_ASSERT(asset);
  Q_ASSERT(currentExercise);
  Q_ASSERT(targetExercise);
  Q_ASSERT(isAssigned(modifiedData.get_value_or(asset->data())));

  if (!asset->isMounted())
  {
    m_pendingModifications.push_back(modifiedData.get_value_or(asset->data()));
    return;
  }

  currentExercise->moveMountedTo(asset, targetExercise, modifiedData);
}

/**
 * @param modifiedData only set when called as a result of a modification
 */
void AssetAssignmentManager::unassignAsset(Asset *asset, Exercise *exercise, const boost::optional<InfrastructureManagement::InstrumentationAsset> &modifiedData)
{
  Q_ASSERT(asset);
  Q_ASSERT(exercise != pool());
//  Q_ASSERT(!isAssigned(asset->data())); // Assertion does not hold in case the unassignment is a result of a removal.
  exercise->moveMountedTo(asset, pool(), modifiedData);
}

/**
 * Try to mount the Asset. If the mounting was published before the referenced
 * Asset or MountingPoint, the mounting will be deferred.
 */
void AssetAssignmentManager::addMount(const InfrastructureManagement::MountingPointAsset &mount)
{
  Asset   *asset = pool()->findAsset(mount.assetId());
  if (!asset)
  {
    m_pendingMounts.push_back(mount);
    return;
  }

  MountingPoint   *mountingPoint = pool()->findMountingPoint(mount.structureElementId());
  if (!mountingPoint)
  {
    m_pendingMounts.push_back(mount);
    return;
  }

  asset->mount(mountingPoint);

  processPendingModifications();
}

void AssetAssignmentManager::removeMount(const InfrastructureManagement::MountingPointAsset &mount)
{
  auto        exerciseAndAsset = findAsset(mount.assetId());
  Asset      *asset = exerciseAndAsset.second;
  Exercise   *exercise = exerciseAndAsset.first;
  Q_ASSERT(asset);
  if (!asset)
    return;
  tryUnmount(asset, exercise);
  processPendingRemoves();
}

/**
 * Try to unmount the Asset.
 * Unmonting can only happen in the pool Exercise.
 * If the Asset is not yet in the pool Exercise (because the updated Asset
 * was not yet published), the unmount will be deferred.
 * It will be processed after the Asset was unassigned.
 */
void AssetAssignmentManager::tryUnmount(Asset *asset, Exercise *exercise)
{
  Q_ASSERT(asset);

  bool   inPoolExercise = false;
  if (exercise)
    inPoolExercise = exercise == pool();
  else
    inPoolExercise = pool()->findAsset(asset->data().id());

  if (!inPoolExercise)
  {
    m_pendingUnmounts.push_back(asset);
    return;
  }

  asset->unmount();
}

template<class Container, class Function>
void AssetAssignmentManager::processPending(Container &pendingSource, Function f)
{
  if (pendingSource.empty())
    return;

  logPending();

  Container   pending;
  std::swap(pending, pendingSource);
  for (const auto &element: pending)
    f(element);

  logPending();
}

/**
 * We want to make sure that assignments are always processed after the corresponding mount.
 * On DDS these are not always published in that order.
 * Thus we need to internally defer assignments that are published before the mount.
 */
void AssetAssignmentManager::processPendingModifications()
{
  using namespace std::placeholders;
  processPending(m_pendingModifications, std::bind(&AssetAssignmentManager::modifyAsset, this, _1));
}

/**
 * Same as for processPendingAssigns() but this time we internally defer
 * unmounts that are published before the unassign.
 */
void AssetAssignmentManager::processPendingUnmounts()
{
  using namespace std::placeholders;
  processPending(m_pendingUnmounts, std::bind(&AssetAssignmentManager::tryUnmount, this, _1, nullptr));
}

void AssetAssignmentManager::processPendingMounts()
{
  using namespace std::placeholders;
  processPending(m_pendingMounts, std::bind(&AssetAssignmentManager::addMount, this, _1));
}

void AssetAssignmentManager::processPendingRemoves()
{
  using namespace std::placeholders;
  processPending(m_pendingRemoves, std::bind(&AssetAssignmentManager::removeAsset, this, _1));
}

bool AssetAssignmentManager::hasPendingModifications(int assetId)
{
  auto   idMatches = [assetId] (const InfrastructureManagement::InstrumentationAsset &asset) { return asset.id() == assetId; };
  auto   found = std::find_if(m_pendingModifications.begin(), m_pendingModifications.end(), idMatches);
  return found != m_pendingModifications.end();
}

void AssetAssignmentManager::logPending()
{
  DEBUG_LOG(m_logger) << "pending Mounts, Modifications (Asset), Unmounts, Removes: "
                      << m_pendingMounts.size() << ", "
                      << m_pendingModifications.size() << ", "
                      << m_pendingUnmounts.size() << ", "
                      << m_pendingRemoves.size();
}

bool AssetAssignmentManager::hasPending() const
{
  return !(m_pendingMounts.empty() && m_pendingModifications.empty() && m_pendingUnmounts.empty() && m_pendingRemoves.empty());
}

Exercise *AssetAssignmentManager::pool() const
{
  auto it = m_exercises.find(ExerciseContext::defaultContext());
  return (it == m_exercises.end() ? nullptr : it->second.get());
}

Exercise *AssetAssignmentManager::exercise(int id)
{
  ExerciseContext   context(id);

  auto   found = m_exercises.find(context);
  if (found != m_exercises.end())
    return found->second.get();

  std::unique_ptr<Exercise>   newExercise(new Exercise(context));
  Exercise                   *newExercise_ = newExercise.get();
  m_exercises[context] = std::move(newExercise);
  return newExercise_;
}

void AssetAssignmentManager::removeExercise(int id)
{
  ExerciseContext   context(id);

  auto   found = m_exercises.find(context);
  Q_ASSERT(found != m_exercises.end());
  if (found != m_exercises.end())
    m_exercises.erase(found); // implicit delete
}

std::pair<Exercise *, Asset *> AssetAssignmentManager::findAsset(int id)
{
  for (const auto &exercise: m_exercises)
  {
    Asset   *asset = exercise.second->findAsset(id);
    if (asset)
      return {exercise.second.get(), asset};
  }

  return {nullptr, nullptr};
}

std::pair<Exercise *, MountingPoint *> AssetAssignmentManager::findMountingPoint(int id)
{
  for (const auto &exercise: m_exercises)
  {
    MountingPoint   *mountingPoint = exercise.second->findMountingPoint(id);
    if (mountingPoint)
      return {exercise.second.get(), mountingPoint};
  }

  return {nullptr, nullptr};
}

} // namespace AudioVideoManagement