////////////////////////////////////////////////////////////////////////////////////////
//
//  Copyright 2026 OVITO GmbH, Germany
//
//  This file is part of OVITO (Open Visualization Tool).
//
//  OVITO is free software; you can redistribute it and/or modify it either under the
//  terms of the GNU General Public License version 3 as published by the Free Software
//  Foundation (the "GPL") or, at your option, under the terms of the MIT License.
//  If you do not alter this notice, a recipient may use your version of this
//  file under either the GPL or the MIT License.
//
//  You should have received a copy of the GPL along with this program in a
//  file LICENSE.GPL.txt.  You should have received a copy of the MIT License along
//  with this program in a file LICENSE.MIT.txt
//
//  This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY KIND,
//  either express or implied. See the GPL or the MIT License for the specific language
//  governing rights and limitations.
//
////////////////////////////////////////////////////////////////////////////////////////

#include <ovito/gui/desktop/GUI.h>
#include <ovito/gui/base/actions/ActionManager.h>
#include <ovito/gui/desktop/mainwin/MainWindow.h>
#include <ovito/core/dataset/DataSetContainer.h>
#include <ovito/core/dataset/scene/Scene.h>
#include <ovito/core/dataset/scene/SelectionSet.h>
#include "SceneNodesListModel.h"

namespace Ovito {

/******************************************************************************
* Constructs the model.
******************************************************************************/
SceneNodesListModel::SceneNodesListModel(MainWindowUI& ui, QWidget* parent) :
    QAbstractListModel(parent),
    UserInterfaceComponent<MainWindowUI>(ui),
    _pipelineSceneNodeIcon(QIcon::fromTheme("edit_pipeline_icon"))
{
    // React to the scene being replaced.
    connect(&datasetContainer(), &DataSetContainer::sceneReplaced, this, &SceneNodesListModel::onSceneReplaced);

    // Listen for scene node selection changes.
    connect(&datasetContainer(), &DataSetContainer::selectionChangeComplete, this, &SceneNodesListModel::onSceneSelectionChanged);

    // Listen for signals from the root scene node.
    _sceneListener.connect(this, &SceneNodesListModel::onSceneNotificationEvent);

    // Listen for events of the other scene nodes.
    _nodeListener.connect(this, &SceneNodesListModel::onNodeNotificationEvent);

    // Font for rendering currently selected scene nodes.
    _selectedNodeFont.setBold(true);

    updateColorPalette(QGuiApplication::palette());
QT_WARNING_PUSH
QT_WARNING_DISABLE_DEPRECATED
    connect(qGuiApp, &QGuiApplication::paletteChanged, this, &SceneNodesListModel::updateColorPalette);
QT_WARNING_POP

    // Create list items for registered pipeline creation actions.
    for(QAction* action : actionManager()->actions()) {
        if(action->objectName().startsWith("NewPipeline."))
            _pipelineActions.push_back(action);
    }

    // Create list item for the "Clone Pipeline" action.
    _pipelineActions.push_back(nullptr); // Separator
    _pipelineActions.push_back(actionManager()->getAction(ACTION_EDIT_CLONE_PIPELINE));

    // Create per-item actions for renaming and deleting individual pipelines.
    _renameAction = new ItemAction(QIcon::fromTheme("edit_rename_pipeline"), tr("Rename"), this);
    _deleteAction = new ItemAction(QIcon::fromTheme("edit_delete_pipeline"), tr("Delete"), this);
    connect(_renameAction, &ItemAction::triggeredForItem, this, &SceneNodesListModel::renameItem);
    connect(_deleteAction, &ItemAction::triggeredForItem, this, &SceneNodesListModel::deleteItem);
}

/******************************************************************************
* Updates the color brushes of the model.
******************************************************************************/
void SceneNodesListModel::updateColorPalette(const QPalette& palette)
{
    bool darkTheme = palette.color(QPalette::Active, QPalette::Window).lightness() < 100;
#ifndef Q_OS_LINUX
    _sectionHeaderBackgroundBrush = darkTheme ? palette.mid() : QBrush{Qt::lightGray, Qt::Dense4Pattern};
#else
    _sectionHeaderBackgroundBrush = darkTheme ? palette.window() : QBrush{Qt::lightGray, Qt::Dense4Pattern};
#endif
    _sectionHeaderForegroundBrush = QBrush(darkTheme ? QColor(Qt::blue).lighter() : QColor(Qt::blue));
}

/******************************************************************************
* Returns the number of rows of the model.
******************************************************************************/
int SceneNodesListModel::rowCount(const QModelIndex& parent) const
{
    return firstActionIndex() + _pipelineActions.size();
}

/******************************************************************************
* Returns the model's data stored under the given role for the item referred to by the index.
******************************************************************************/
QVariant SceneNodesListModel::data(const QModelIndex& index, int role) const
{
    if(role == Qt::DisplayRole) {
        if(index.row() == 0)
            return tr("Existing pipelines:");

        int pipelineIndex = index.row() - firstSceneNodeIndex();
        if(pipelineIndex >= 0 && pipelineIndex < sceneNodes().size())
            return _nodeListener.targets()[pipelineIndex]->objectTitle();
        else if(pipelineIndex == 0)
            return tr("‹None›");

        int actionIndex = index.row() - firstActionIndex();
        if(actionIndex == -1)
            return tr("Create pipeline with data source:");
        if(actionIndex >= 0 && actionIndex < _pipelineActions.size()) {
            if(_pipelineActions[actionIndex] == nullptr)
                return {}; // Separator
            else if(actionIndex == _pipelineActions.size() - 1)
#ifdef OVITO_BUILD_PROFESSIONAL
                return tr("Clone current pipeline...");
#else
                return tr("Clone current pipeline... (Pro)");
#endif
            else if(_pipelineActions[actionIndex] != nullptr)
                return _pipelineActions[actionIndex]->text();
        }
    }
    else if(role == Qt::UserRole) {
        int pipelineIndex = index.row() - firstSceneNodeIndex();
        if(pipelineIndex >= 0 && pipelineIndex < sceneNodes().size())
            return QVariant::fromValue(static_cast<OvitoObject*>(sceneNodes()[pipelineIndex]));

        int actionIndex = index.row() - firstActionIndex();
        if(actionIndex >= 0 && actionIndex < _pipelineActions.size())
            return QVariant::fromValue(_pipelineActions[actionIndex]);
    }
    else if(role == Qt::FontRole) {
        int pipelineIndex = index.row() - firstSceneNodeIndex();
        if(pipelineIndex >= 0 && pipelineIndex < sceneNodes().size()) {
            if(_nodeListener.targets()[pipelineIndex]->isSelected())
                return _selectedNodeFont;
        }
    }
    else if(role == Qt::DecorationRole) {
        int pipelineIndex = index.row() - firstSceneNodeIndex();
        if(pipelineIndex >= 0 && pipelineIndex < (sceneNodes().empty() ? 1 : sceneNodes().size()))
            return _pipelineSceneNodeIcon;

        int actionIndex = index.row() - firstActionIndex();
        if(actionIndex >= 0 && actionIndex < _pipelineActions.size() && _pipelineActions[actionIndex] != nullptr)
            return _pipelineActions[actionIndex]->icon();
    }
    else if(role == Qt::SizeHintRole) {
        int actionIndex = index.row() - firstActionIndex();
        if(actionIndex >= 0 && actionIndex < _pipelineActions.size() && !_pipelineActions[actionIndex])
            return QSize(0, 2); // Action separator line
    }
    else if(role == ActionsRole) {
        int pipelineIndex = index.row() - firstSceneNodeIndex();
        if(pipelineIndex >= 0 && pipelineIndex < sceneNodes().size()) {
            QList<QAction*> actions;
            actions.push_back(_deleteAction);
            actions.push_back(_renameAction);
            return QVariant::fromValue(actions);
        }
        return {};
    }
    else {
        int pipelineIndex = index.row() - firstSceneNodeIndex();
        int actionIndex = index.row() - firstActionIndex();
        if(pipelineIndex == -1 || actionIndex == -1 || (actionIndex >= 0 && !_pipelineActions[actionIndex])) {
            if(role == Qt::TextAlignmentRole)
                return Qt::AlignCenter;
            else if(role == Qt::BackgroundRole)
                return _sectionHeaderBackgroundBrush;
            else if(role == Qt::ForegroundRole)
                return _sectionHeaderForegroundBrush;
        }
    }

    return {};
}

/******************************************************************************
* Returns the item flags for the given index.
******************************************************************************/
Qt::ItemFlags SceneNodesListModel::flags(const QModelIndex& index) const
{
    if(index.isValid()) {
        int pipelineIndex = index.row() - firstSceneNodeIndex();
        int actionIndex = index.row() - firstActionIndex();
        if(pipelineIndex == -1)
            return Qt::NoItemFlags; // Item: Existing pipelines
        if(pipelineIndex >= 0 && pipelineIndex < (sceneNodes().empty() ? 1 : sceneNodes().size()))
            return QAbstractListModel::flags(index);
        if(actionIndex >= 0 && actionIndex < _pipelineActions.size() && _pipelineActions[actionIndex])
            return (_pipelineActions[actionIndex]->isEnabled() ? (Qt::ItemIsSelectable | Qt::ItemIsEnabled) : Qt::NoItemFlags);
        return Qt::NoItemFlags; // Separator item
    }
    return QAbstractListModel::flags(index);
}

/******************************************************************************
* This is called when a new scene becomes active.
******************************************************************************/
void SceneNodesListModel::onSceneReplaced(Scene* newScene)
{
    beginResetModel();
    _deferredUpdateList.clear();
    _nodeListener.clear();
    _sceneListener.setTarget(newScene);
    if(newScene) {
        newScene->visitChildren([&](SceneNode* node) {
            _nodeListener.push_back(node);
        });
    }
    endResetModel();
}

/******************************************************************************
* This is called whenever the scene node selection has changed.
******************************************************************************/
void SceneNodesListModel::onSceneSelectionChanged(SelectionSet* selection)
{
    if(!selection || selection->nodes().empty()) {
        Q_EMIT selectionChangeRequested(1);
    }
    else {
        int index = sceneNodes().indexOf(selection->nodes().front());
        Q_EMIT selectionChangeRequested(index + 1);
    }
}

/******************************************************************************
* This handles reference events generated by the scene root node.
******************************************************************************/
void SceneNodesListModel::onSceneNotificationEvent(RefTarget* source, const ReferenceEvent& event)
{
    onNodeNotificationEvent(_sceneListener.target(), event);
}

/******************************************************************************
* This handles reference events generated by the scene nodes.
******************************************************************************/
void SceneNodesListModel::onNodeNotificationEvent(RefTarget* source, const ReferenceEvent& event)
{
    // Whenever a new node is being inserted into the scene, add it to our internal list.
    if(event.type() == ReferenceEvent::ReferenceAdded) {
        const ReferenceFieldEvent& refEvent = static_cast<const ReferenceFieldEvent&>(event);
        if(refEvent.field() == PROPERTY_FIELD(SceneNode::children)) {
            if(SceneNode* node = dynamic_object_cast<SceneNode>(refEvent.newTarget())) {
                // Extend the list model by one entry.
                if(sceneNodes().empty()) {
                    _nodeListener.push_back(node);
                    Q_EMIT dataChanged(createIndex(1, 0, node), createIndex(1, 0, node));
                }
                else {
                    beginInsertRows(QModelIndex(), sceneNodes().size() + 1, sceneNodes().size() + 1);
                    _nodeListener.push_back(node);
                    endInsertRows();
                }

                // Add the children of the node too.
                node->visitChildren([this](SceneNode* node) {
                    // Extend the list model by one entry.
                    OVITO_ASSERT(!sceneNodes().empty());
                    beginInsertRows(QModelIndex(), sceneNodes().size() + 1, sceneNodes().size() + 1);
                    _nodeListener.push_back(node);
                    endInsertRows();
                });
            }
        }
    }

    // If a node is being removed from the scene, remove it from our internal list.
    if(event.type() == ReferenceEvent::ReferenceRemoved || event.type() == ReferenceEvent::ReferenceChanged) {
        // Don't know how else to do this in a safe manner. Rebuild the entire model from scratch.
        onSceneReplaced(datasetContainer().activeScene());
        onSceneSelectionChanged(datasetContainer().activeSelectionSet());
    }

    // If a node is being renamed, let the model emit an update signal.
    if(event.type() == ReferenceEvent::TitleChanged) {
        if(!_deferredUpdateList.contains(static_object_cast<SceneNode>(source))) {
            _deferredUpdateList.push_back(static_object_cast<SceneNode>(source));
            if(_deferredUpdateList.size() == 1)
                QTimer::singleShot(400, this, &SceneNodesListModel::deferredNodeUpdate);
        }
    }
}

/******************************************************************************
* Refreshes the list items that have been marked for a deferred update.
******************************************************************************/
void SceneNodesListModel::deferredNodeUpdate()
{
    for(const auto& node : _deferredUpdateList) {
        int index = sceneNodes().indexOf(node);
        if(index >= 0) {
            QModelIndex modelIndex = createIndex(index + 1, 0, node);
            Q_EMIT dataChanged(modelIndex, modelIndex);
        }
    }
    _deferredUpdateList.clear();
}

/******************************************************************************
* This slot executes the action associated with the given list item.
******************************************************************************/
void SceneNodesListModel::activateItem(int index)
{
    // Change scene node selection when a scene node has been selected in the combobox.
    int pipelineIndex = index - firstSceneNodeIndex();
    if(pipelineIndex >= 0 && pipelineIndex < sceneNodes().size()) {
        if(SceneNode* node = sceneNodes()[pipelineIndex]) {
            performTransaction(tr("Select pipeline"), [&]() {
                if(SelectionSet* selection = datasetContainer().activeSelectionSet())
                    selection->setNode(node);
            });
        }
        return;
    }

    // This is to reset the current item of the combobox back to the selected scene node
    // after the user has selected an action item.
    onSceneSelectionChanged(datasetContainer().activeSelectionSet());

    // Determine the selected action item and execute the action.
    int actionIndex = index - firstActionIndex();
    if(actionIndex >= 0 && actionIndex < _pipelineActions.size()) {
        if(QAction* action = _pipelineActions[actionIndex])
            action->trigger();
    }
}

/******************************************************************************
* Performs a deletion action on an item.
******************************************************************************/
void SceneNodesListModel::deleteItem(const QModelIndex& index)
{
    // Change scene node selection when a scene node has been selected in the combobox.
    int pipelineIndex = index.row() - firstSceneNodeIndex();
    if(pipelineIndex >= 0 && pipelineIndex < sceneNodes().size()) {
        if(OORef<SceneNode> node = sceneNodes()[pipelineIndex]) {
            performTransaction(tr("Delete pipeline"), [&]() {
                bool wasSelected = node->isSelected();
                node->requestObjectDeletion();

                // Automatically select one of the remaining nodes.
                Scene* scene = _sceneListener.target();
                if(wasSelected && scene && scene->children().isEmpty() == false)
                    scene->selection()->setNode(scene->children().front());
            });
        }
    }
}

/******************************************************************************
* Lets the user rename a list item.
******************************************************************************/
void SceneNodesListModel::renameItem(const QModelIndex& index)
{
    if(OORef<SceneNode> sceneNode = sceneNodeFromListIndex(index.row())) {
        QString oldName = sceneNode->objectTitle();
        bool ok;
        QString newName = QInputDialog::getText(ui().mainWindow(), tr("Change pipeline name"), tr("Pipeline name:                                         "), QLineEdit::Normal, oldName, &ok).trimmed();
        if(ok && newName != oldName) {
            performTransaction(tr("Rename pipeline"), [&]() {
                sceneNode->setSceneNodeName(newName);
            });
        }
    }
}

}   // End of namespace
