/****************************************************************************
**
** Copyright (C) 2016 The Qt Company Ltd.
** Contact: https://www.qt.io/licensing/
**
** This file is part of the QtQml module of the Qt Toolkit.
**
** $QT_BEGIN_LICENSE:LGPL$
** Commercial License Usage
** Licensees holding valid commercial Qt licenses may use this file in
** accordance with the commercial license agreement provided with the
** Software or, alternatively, in accordance with the terms contained in
** a written agreement between you and The Qt Company. For licensing terms
** and conditions see https://www.qt.io/terms-conditions. For further
** information use the contact form at https://www.qt.io/contact-us.
**
** GNU Lesser General Public License Usage
** Alternatively, this file may be used under the terms of the GNU Lesser
** General Public License version 3 as published by the Free Software
** Foundation and appearing in the file LICENSE.LGPL3 included in the
** packaging of this file. Please review the following information to
** ensure the GNU Lesser General Public License version 3 requirements
** will be met: https://www.gnu.org/licenses/lgpl-3.0.html.
**
** GNU General Public License Usage
** Alternatively, this file may be used under the terms of the GNU
** General Public License version 2.0 or (at your option) the GNU General
** Public license version 3 or any later version approved by the KDE Free
** Qt Foundation. The licenses are as published by the Free Software
** Foundation and appearing in the file LICENSE.GPL2 and LICENSE.GPL3
** included in the packaging of this file. Please review the following
** information to ensure the GNU General Public License requirements will
** be met: https://www.gnu.org/licenses/gpl-2.0.html and
** https://www.gnu.org/licenses/gpl-3.0.html.
**
** $QT_END_LICENSE$
**
****************************************************************************/

#include "qqmlobjectmodel_p.h"

#include <QtCore/qcoreapplication.h>
#include <QtQml/qqmlcontext.h>
#include <QtQml/qqmlengine.h>
#include <QtQml/qqmlinfo.h>

#include <private/qqmlchangeset_p.h>
#include <private/qqmlglobal_p.h>
#include <private/qobject_p.h>
#include <private/qpodvector_p.h>

#include <QtCore/qhash.h>
#include <QtCore/qlist.h>

QT_BEGIN_NAMESPACE

QHash<QObject*, QQmlObjectModelAttached*> QQmlObjectModelAttached::attachedProperties;


class QQmlObjectModelPrivate : public QObjectPrivate
{
    Q_DECLARE_PUBLIC(QQmlObjectModel)
public:
    class Item {
    public:
        Item(QObject *i) : item(i), ref(0) {}

        void addRef() { ++ref; }
        bool deref() { return --ref == 0; }

        QObject *item;
        int ref;
    };

    QQmlObjectModelPrivate() : QObjectPrivate(), moveId(0) {}

    static void children_append(QQmlListProperty<QObject> *prop, QObject *item) {
        int index = static_cast<QQmlObjectModelPrivate *>(prop->data)->children.count();
        static_cast<QQmlObjectModelPrivate *>(prop->data)->insert(index, item);
    }

    static int children_count(QQmlListProperty<QObject> *prop) {
        return static_cast<QQmlObjectModelPrivate *>(prop->data)->children.count();
    }

    static QObject *children_at(QQmlListProperty<QObject> *prop, int index) {
        return static_cast<QQmlObjectModelPrivate *>(prop->data)->children.at(index).item;
    }

    static void children_clear(QQmlListProperty<QObject> *prop) {
        static_cast<QQmlObjectModelPrivate *>(prop->data)->clear();
    }

    void insert(int index, QObject *item) {
        Q_Q(QQmlObjectModel);
        children.insert(index, Item(item));
        for (int i = index; i < children.count(); ++i) {
            QQmlObjectModelAttached *attached = QQmlObjectModelAttached::properties(children.at(i).item);
            attached->setIndex(i);
        }
        QQmlChangeSet changeSet;
        changeSet.insert(index, 1);
        emit q->modelUpdated(changeSet, false);
        emit q->countChanged();
        emit q->childrenChanged();
    }

    void move(int from, int to, int n) {
        Q_Q(QQmlObjectModel);
        if (from > to) {
            // Only move forwards - flip if backwards moving
            int tfrom = from;
            int tto = to;
            from = tto;
            to = tto+n;
            n = tfrom-tto;
        }

        QPODVector<QQmlObjectModelPrivate::Item, 4> store;
        for (int i = 0; i < to - from; ++i)
            store.append(children[from + n + i]);
        for (int i = 0; i < n; ++i)
            store.append(children[from + i]);

        for (int i = 0; i < store.count(); ++i) {
            children[from + i] = store[i];
            QQmlObjectModelAttached *attached = QQmlObjectModelAttached::properties(children.at(from + i).item);
            attached->setIndex(from + i);
        }

        QQmlChangeSet changeSet;
        changeSet.move(from, to, n, ++moveId);
        emit q->modelUpdated(changeSet, false);
        emit q->childrenChanged();
    }

    void remove(int index, int n) {
        Q_Q(QQmlObjectModel);
        for (int i = index; i < index + n; ++i) {
            QQmlObjectModelAttached *attached = QQmlObjectModelAttached::properties(children.at(i).item);
            attached->setIndex(-1);
        }
        children.erase(children.begin() + index, children.begin() + index + n);
        for (int i = index; i < children.count(); ++i) {
            QQmlObjectModelAttached *attached = QQmlObjectModelAttached::properties(children.at(i).item);
            attached->setIndex(i);
        }
        QQmlChangeSet changeSet;
        changeSet.remove(index, n);
        emit q->modelUpdated(changeSet, false);
        emit q->countChanged();
        emit q->childrenChanged();
    }

    void clear() {
        Q_Q(QQmlObjectModel);
        for (const Item &child : qAsConst(children))
            emit q->destroyingItem(child.item);
        remove(0, children.count());
    }

    int indexOf(QObject *item) const {
        for (int i = 0; i < children.count(); ++i)
            if (children.at(i).item == item)
                return i;
        return -1;
    }

    uint moveId;
    QList<Item> children;
};


/*!
    \qmltype ObjectModel
    \instantiates QQmlObjectModel
    \inqmlmodule QtQml.Models
    \ingroup qtquick-models
    \brief Defines a set of items to be used as a model.

    An ObjectModel contains the visual items to be used in a view.
    When an ObjectModel is used in a view, the view does not require
    a delegate since the ObjectModel already contains the visual
    delegate (items).

    An item can determine its index within the
    model via the \l{ObjectModel::index}{index} attached property.

    The example below places three colored rectangles in a ListView.
    \code
    import QtQuick 2.0
    import QtQml.Models 2.1

    Rectangle {
        ObjectModel {
            id: itemModel
            Rectangle { height: 30; width: 80; color: "red" }
            Rectangle { height: 30; width: 80; color: "green" }
            Rectangle { height: 30; width: 80; color: "blue" }
        }

        ListView {
            anchors.fill: parent
            model: itemModel
        }
    }
    \endcode

    \image objectmodel.png

    \sa {Qt Quick Examples - Views}
*/

QQmlObjectModel::QQmlObjectModel(QObject *parent)
    : QQmlInstanceModel(*(new QQmlObjectModelPrivate), parent)
{
}

/*!
    \qmlattachedproperty int QtQml.Models::ObjectModel::index
    This attached property holds the index of this delegate's item within the model.

    It is attached to each instance of the delegate.
*/

QQmlListProperty<QObject> QQmlObjectModel::children()
{
    Q_D(QQmlObjectModel);
    return QQmlListProperty<QObject>(this,
                                        d,
                                        d->children_append,
                                        d->children_count,
                                        d->children_at,
                                        d->children_clear);
}

/*!
    \qmlproperty int QtQml.Models::ObjectModel::count

    The number of items in the model.  This property is readonly.
*/
int QQmlObjectModel::count() const
{
    Q_D(const QQmlObjectModel);
    return d->children.count();
}

bool QQmlObjectModel::isValid() const
{
    return true;
}

QObject *QQmlObjectModel::object(int index, QQmlIncubator::IncubationMode)
{
    Q_D(QQmlObjectModel);
    QQmlObjectModelPrivate::Item &item = d->children[index];
    item.addRef();
    if (item.ref == 1) {
        emit initItem(index, item.item);
        emit createdItem(index, item.item);
    }
    return item.item;
}

QQmlInstanceModel::ReleaseFlags QQmlObjectModel::release(QObject *item)
{
    Q_D(QQmlObjectModel);
    int idx = d->indexOf(item);
    if (idx >= 0) {
        if (!d->children[idx].deref())
            return QQmlInstanceModel::Referenced;
    }
    return nullptr;
}

QVariant QQmlObjectModel::variantValue(int index, const QString &role)
{
    Q_D(QQmlObjectModel);
    if (index < 0 || index >= d->children.count())
        return QString();
    return QQmlEngine::contextForObject(d->children.at(index).item)->contextProperty(role);
}

QQmlIncubator::Status QQmlObjectModel::incubationStatus(int)
{
    return QQmlIncubator::Ready;
}

int QQmlObjectModel::indexOf(QObject *item, QObject *) const
{
    Q_D(const QQmlObjectModel);
    return d->indexOf(item);
}

QQmlObjectModelAttached *QQmlObjectModel::qmlAttachedProperties(QObject *obj)
{
    return QQmlObjectModelAttached::properties(obj);
}

/*!
    \qmlmethod object QtQml.Models::ObjectModel::get(int index)
    \since 5.6

    Returns the item at \a index in the model. This allows the item
    to be accessed or modified from JavaScript:

    \code
    Component.onCompleted: {
        objectModel.append(objectComponent.createObject())
        console.log(objectModel.get(0).objectName);
        objectModel.get(0).objectName = "first";
    }
    \endcode

    The \a index must be an element in the list.

    \sa append()
*/
QObject *QQmlObjectModel::get(int index) const
{
    Q_D(const QQmlObjectModel);
    if (index < 0 || index >= d->children.count())
        return nullptr;
    return d->children.at(index).item;
}

/*!
    \qmlmethod QtQml.Models::ObjectModel::append(object item)
    \since 5.6

    Appends a new \a item to the end of the model.

    \code
        objectModel.append(objectComponent.createObject())
    \endcode

    \sa insert(), remove()
*/
void QQmlObjectModel::append(QObject *object)
{
    Q_D(QQmlObjectModel);
    d->insert(count(), object);
}

/*!
    \qmlmethod QtQml.Models::ObjectModel::insert(int index, object item)
    \since 5.6

    Inserts a new \a item to the model at position \a index.

    \code
        objectModel.insert(2, objectComponent.createObject())
    \endcode

    The \a index must be to an existing item in the list, or one past
    the end of the list (equivalent to append).

    \sa append(), remove()
*/
void QQmlObjectModel::insert(int index, QObject *object)
{
    Q_D(QQmlObjectModel);
    if (index < 0 || index > count()) {
        qmlWarning(this) << tr("insert: index %1 out of range").arg(index);
        return;
    }
    d->insert(index, object);
}

/*!
    \qmlmethod QtQml.Models::ObjectModel::move(int from, int to, int n = 1)
    \since 5.6

    Moves \e n items \a from one position \a to another.

    The from and to ranges must exist; for example, to move the first 3 items
    to the end of the model:

    \code
        objectModel.move(0, objectModel.count - 3, 3)
    \endcode

    \sa append()
*/
void QQmlObjectModel::move(int from, int to, int n)
{
    Q_D(QQmlObjectModel);
    if (n <= 0 || from == to)
        return;
    if (from < 0 || to < 0 || from + n > count() || to + n > count()) {
        qmlWarning(this) << tr("move: out of range");
        return;
    }
    d->move(from, to, n);
}

/*!
    \qmlmethod QtQml.Models::ObjectModel::remove(int index, int n = 1)
    \since 5.6

    Removes \e n items at \a index from the model.

    \sa clear()
*/
void QQmlObjectModel::remove(int index, int n)
{
    Q_D(QQmlObjectModel);
    if (index < 0 || n <= 0 || index + n > count()) {
        qmlWarning(this) << tr("remove: indices [%1 - %2] out of range [0 - %3]").arg(index).arg(index+n).arg(count());
        return;
    }
    d->remove(index, n);
}

/*!
    \qmlmethod QtQml.Models::ObjectModel::clear()
    \since 5.6

    Clears all items from the model.

    \sa append(), remove()
*/
void QQmlObjectModel::clear()
{
    Q_D(QQmlObjectModel);
    d->clear();
}

QT_END_NAMESPACE

#include "moc_qqmlobjectmodel_p.cpp"