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#include "qentity.h"
#include "qentity_p.h"

#include <Qt3DCore/qcomponent.h>
#include <Qt3DCore/qcomponentaddedchange.h>
#include <Qt3DCore/qcomponentremovedchange.h>
#include <Qt3DCore/qnodecreatedchange.h>
#include <Qt3DCore/qpropertyupdatedchange.h>
#include <QtCore/QMetaObject>
#include <QtCore/QMetaProperty>

#include <Qt3DCore/private/corelogging_p.h>
#include <Qt3DCore/private/qcomponent_p.h>
#include <Qt3DCore/private/qscene_p.h>

#include <QQueue>

QT_BEGIN_NAMESPACE

namespace Qt3DCore {

/*!
    \class Qt3DCore::QEntity
    \inmodule Qt3DCore
    \inherits Qt3DCore::QNode
    \since 5.5

    \brief Qt3DCore::QEntity is a Qt3DCore::QNode subclass that can aggregate several
    Qt3DCore::QComponent instances that will specify its behavior.

    By itself a Qt3DCore::QEntity is an empty shell. The behavior of a Qt3DCore::QEntity
    object is defined by the Qt3DCore::QComponent objects it references. Each Qt3D
    backend aspect will be able to interpret and process an Entity by
    recognizing which components it is made up of. One aspect may decide to only
    process entities composed of a single Qt3DCore::QTransform component whilst
    another may focus on Qt3DInput::QMouseHandler.

    \sa Qt3DCore::QComponent, Qt3DCore::QTransform
 */

/*!
    \fn template<typename T> QVector<T *> QEntity::componentsOfType() const

    Returns all the components added to this entity that can be cast to
    type T or an empty vector if there are no such components.
*/

/*! \internal */
QEntityPrivate::QEntityPrivate()
    : QNodePrivate()
    , m_parentEntityId()
{}

/*! \internal */
QEntityPrivate::~QEntityPrivate()
{
}

/*! \internal */
void QEntityPrivate::removeDestroyedComponent(QComponent *comp)
{
    // comp is actually no longer a QComponent, just a QObject

    Q_CHECK_PTR(comp);
    qCDebug(Nodes) << Q_FUNC_INFO << comp;
    Q_Q(QEntity);

    if (m_changeArbiter) {
        const auto componentRemovedChange = QComponentRemovedChangePtr::create(q, comp);
        notifyObservers(componentRemovedChange);
    }

    m_components.removeOne(comp);

    // Remove bookkeeping connection
    unregisterDestructionHelper(comp);
}

/*!
    Constructs a new Qt3DCore::QEntity instance with \a parent as parent.
 */
QEntity::QEntity(QNode *parent)
    : QEntity(*new QEntityPrivate, parent) {}

/*! \internal */
QEntity::QEntity(QEntityPrivate &dd, QNode *parent)
    : QNode(dd, parent)
{
}

QEntity::~QEntity()
{
    // remove all component aggregations
    Q_D(const QEntity);
    // to avoid hammering m_components by repeated removeComponent()
    // calls below, move all contents out, so the removeOne() calls in
    // removeComponent() don't actually remove something:
    const auto components = std::move(d->m_components);
    for (QComponent *comp : components)
        removeComponent(comp);
}


/*!
    \typedef Qt3DCore::QComponentVector
    \relates Qt3DCore::QEntity

    List of QComponent pointers.
 */

/*!
    Returns the list of Qt3DCore::QComponent instances the entity is referencing.
 */
QComponentVector QEntity::components() const
{
    Q_D(const QEntity);
    return d->m_components;
}

/*!
    Adds a new reference to the component \a comp.

    \note If the Qt3DCore::QComponent has no parent, the Qt3DCore::QEntity will set
    itself as its parent thereby taking ownership of the component.
 */
void QEntity::addComponent(QComponent *comp)
{
    Q_D(QEntity);
    Q_CHECK_PTR( comp );
    qCDebug(Nodes) << Q_FUNC_INFO << comp;

    // A Component can only be aggregated once
    if (d->m_components.count(comp) != 0)
        return ;

    // We need to add it as a child of the current node if it has been declared inline
    // Or not previously added as a child of the current node so that
    // 1) The backend gets notified about it's creation
    // 2) When the current node is destroyed, it gets destroyed as well
    if (!comp->parent())
        comp->setParent(this);

    QNodePrivate::get(comp)->_q_ensureBackendNodeCreated();

    d->m_components.append(comp);

    // Ensures proper bookkeeping
    d->registerPrivateDestructionHelper(comp, &QEntityPrivate::removeDestroyedComponent);

    if (d->m_changeArbiter) {
        const auto componentAddedChange = QComponentAddedChangePtr::create(this, comp);
        d->notifyObservers(componentAddedChange);
    }
    static_cast<QComponentPrivate *>(QComponentPrivate::get(comp))->addEntity(this);
}

/*!
    Removes the reference to \a comp.
 */
void QEntity::removeComponent(QComponent *comp)
{
    Q_CHECK_PTR(comp);
    qCDebug(Nodes) << Q_FUNC_INFO << comp;
    Q_D(QEntity);

    static_cast<QComponentPrivate *>(QComponentPrivate::get(comp))->removeEntity(this);

    if (d->m_changeArbiter) {
        const auto componentRemovedChange = QComponentRemovedChangePtr::create(this, comp);
        d->notifyObservers(componentRemovedChange);
    }

    d->m_components.removeOne(comp);

    // Remove bookkeeping connection
    d->unregisterDestructionHelper(comp);
}

/*!
    Returns the parent Qt3DCore::QEntity instance of this entity. If the
    immediate parent isn't a Qt3DCore::QEntity, this function traverses up the
    scene hierarchy until a parent Qt3DCore::QEntity is found. If no
    Qt3DCore::QEntity parent can be found, returns null.
 */
QEntity *QEntity::parentEntity() const
{
    Q_D(const QEntity);
    QNode *parentNode = QNode::parentNode();
    QEntity *parentEntity = qobject_cast<QEntity *>(parentNode);

    while (parentEntity == nullptr && parentNode != nullptr) {
        parentNode = parentNode->parentNode();
        parentEntity = qobject_cast<QEntity*>(parentNode);
    }
    if (!parentEntity) {
        if (!d->m_parentEntityId.isNull())
            d->m_parentEntityId = QNodeId();
    } else {
        if (d->m_parentEntityId != parentEntity->id())
            d->m_parentEntityId = parentEntity->id();
    }
    return parentEntity;
}

/*
    \internal

    Returns the Qt3DCore::QNodeId id of the parent Qt3DCore::QEntity instance of the
    current Qt3DCore::QEntity object. The QNodeId isNull method will return true if
    there is no Qt3DCore::QEntity parent of the current Qt3DCore::QEntity in the scene
    hierarchy.
 */
QNodeId QEntityPrivate::parentEntityId() const
{
    Q_Q(const QEntity);
    if (m_parentEntityId.isNull())
        q->parentEntity();
    return m_parentEntityId;
}

QNodeCreatedChangeBasePtr QEntity::createNodeCreationChange() const
{
    // connect to the parentChanged signal here rather than constructor because
    // until now there's no backend node to notify when parent changes
    connect(this, &QNode::parentChanged, this, &QEntity::onParentChanged);

    auto creationChange = QNodeCreatedChangePtr<QEntityData>::create(this);
    auto &data = creationChange->data;

    Q_D(const QEntity);
    data.parentEntityId = parentEntity() ? parentEntity()->id() : Qt3DCore::QNodeId();

    // Find all child entities
    QQueue<QNode *> queue;
    queue.append(childNodes().toList());
    data.childEntityIds.reserve(queue.size());
    while (!queue.isEmpty()) {
        auto *child = queue.dequeue();
        auto *childEntity = qobject_cast<QEntity *>(child);
        if (childEntity != nullptr)
            data.childEntityIds.push_back(childEntity->id());
        else
            queue.append(child->childNodes().toList());
    }

    data.componentIdsAndTypes.reserve(d->m_components.size());
    const QComponentVector &components = d->m_components;
    for (QComponent *c : components) {
        const auto idAndType = QNodeIdTypePair(c->id(), QNodePrivate::findStaticMetaObject(c->metaObject()));
        data.componentIdsAndTypes.push_back(idAndType);
    }

    return creationChange;
}

void QEntity::onParentChanged(QObject *)
{
    const auto parentID = parentEntity() ? parentEntity()->id() : Qt3DCore::QNodeId();
    auto parentChange = Qt3DCore::QPropertyUpdatedChangePtr::create(id());
    parentChange->setPropertyName("parentEntityUpdated");
    parentChange->setValue(QVariant::fromValue(parentID));
    const bool blocked = blockNotifications(false);
    notifyObservers(parentChange);
    blockNotifications(blocked);
}

} // namespace Qt3DCore

QT_END_NAMESPACE
