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**
** Copyright (C) 2016 The Qt Company Ltd.
** Contact: https://www.qt.io/licensing/
**
** This file is part of Qt Creator.
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** GNU General Public License Usage
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** General Public License version 3 as published by the Free Software
** Foundation with exceptions as appearing in the file LICENSE.GPL3-EXCEPT
** included in the packaging of this file. Please review the following
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****************************************************************************/

#include "variablechooser.h"
#include "coreconstants.h"

#include <utils/fancylineedit.h>
#include <utils/headerviewstretcher.h> // IconButton
#include <utils/macroexpander.h>
#include <utils/treemodel.h>
#include <utils/qtcassert.h>
#include <utils/utilsicons.h>

#include <QApplication>
#include <QAbstractItemModel>
#include <QHeaderView>
#include <QLabel>
#include <QLineEdit>
#include <QListWidgetItem>
#include <QMenu>
#include <QPlainTextEdit>
#include <QPointer>
#include <QSortFilterProxyModel>
#include <QTextEdit>
#include <QTimer>
#include <QTreeView>
#include <QVBoxLayout>
#include <QVector>

using namespace Utils;

namespace Core {
namespace Internal {

enum {
    UnexpandedTextRole = Qt::UserRole,
    ExpandedTextRole
};

class VariableTreeView : public QTreeView
{
public:
    VariableTreeView(QWidget *parent, VariableChooserPrivate *target)
        : QTreeView(parent), m_target(target)
    {
        setAttribute(Qt::WA_MacSmallSize);
        setAttribute(Qt::WA_MacShowFocusRect, false);
        setIndentation(indentation() * 7/10);
        header()->hide();
        new HeaderViewStretcher(header(), 0);
    }

    void contextMenuEvent(QContextMenuEvent *ev) override;

    void currentChanged(const QModelIndex &current, const QModelIndex &previous) override;

private:
    VariableChooserPrivate *m_target;
};

class VariableSortFilterProxyModel : public QSortFilterProxyModel
{
public:
    explicit VariableSortFilterProxyModel(QObject *parent) : QSortFilterProxyModel(parent) {}
    bool filterAcceptsRow(int sourceRow, const QModelIndex &sourceParent) const override
    {
        const QModelIndex index = sourceModel()->index(sourceRow, filterKeyColumn(), sourceParent);
        if (!index.isValid())
            return false;

        const QRegExp regexp = filterRegExp();
        if (regexp.isEmpty() || sourceModel()->rowCount(index) > 0)
            return true;

        const QString displayText = index.data(Qt::DisplayRole).toString();
        return displayText.contains(regexp);
    }
};

class VariableChooserPrivate : public QObject
{
public:
    VariableChooserPrivate(VariableChooser *parent);

    void createIconButton()
    {
        m_iconButton = new IconButton;
        m_iconButton->setIcon(Utils::Icons::REPLACE.icon());
        m_iconButton->setToolTip(VariableChooser::tr("Insert Variable"));
        m_iconButton->hide();
        connect(m_iconButton.data(), static_cast<void(QAbstractButton::*)(bool)>(&QAbstractButton::clicked),
                this, &VariableChooserPrivate::updatePositionAndShow);
    }

    void updateDescription(const QModelIndex &index);
    void updateCurrentEditor(QWidget *old, QWidget *widget);
    void handleItemActivated(const QModelIndex &index);
    void insertText(const QString &variable);
    void updatePositionAndShow(bool);
    void updateFilter(const QString &filterText);

    QWidget *currentWidget();

    int buttonMargin() const;
    void updateButtonGeometry();

public:
    VariableChooser *q;
    TreeModel<> m_model;

    QPointer<QLineEdit> m_lineEdit;
    QPointer<QTextEdit> m_textEdit;
    QPointer<QPlainTextEdit> m_plainTextEdit;
    QPointer<IconButton> m_iconButton;

    Utils::FancyLineEdit *m_variableFilter;
    VariableTreeView *m_variableTree;
    QLabel *m_variableDescription;
    QSortFilterProxyModel *m_sortModel;
    QString m_defaultDescription;
    QByteArray m_currentVariableName; // Prevent recursive insertion of currently expanded item
};

class VariableGroupItem : public TreeItem
{
public:
    VariableGroupItem() = default;

    QVariant data(int column, int role) const override
    {
        if (role == Qt::DisplayRole || role == Qt::EditRole) {
            if (column == 0)
                if (MacroExpander *expander = m_provider())
                    return expander->displayName();
        }

        return QVariant();
    }

    bool canFetchMore() const override
    {
        return !m_populated;
    }

    void fetchMore() override
    {
        if (MacroExpander *expander = m_provider())
            populateGroup(expander);
        m_populated = true;
    }

    void populateGroup(MacroExpander *expander);

public:
    VariableChooserPrivate *m_chooser = nullptr; // Not owned.
    bool m_populated = false;
    MacroExpanderProvider m_provider;
};

class VariableItem : public TypedTreeItem<TreeItem, VariableGroupItem>
{
public:
    VariableItem() = default;

    Qt::ItemFlags flags(int) const override
    {
        if (m_variable == parent()->m_chooser->m_currentVariableName)
            return Qt::ItemIsSelectable;
        return Qt::ItemIsSelectable|Qt::ItemIsEnabled;
    }

    QVariant data(int column, int role) const override
    {
        if (role == Qt::DisplayRole || role == Qt::EditRole) {
            if (column == 0)
                return m_variable;
        }

        if (role == Qt::ToolTipRole) {
            QString description = m_expander->variableDescription(m_variable);
            const QString value = m_expander->value(m_variable).toHtmlEscaped();
            if (!value.isEmpty())
                description += QLatin1String("<p>") + VariableChooser::tr("Current Value: %1").arg(value);
            return description;
        }

        if (role == UnexpandedTextRole)
            return QString::fromUtf8("%{" + m_variable + '}');

        if (role == ExpandedTextRole)
            return m_expander->expand(QString::fromUtf8("%{" + m_variable + '}'));

        return QVariant();
    }

public:
    MacroExpander *m_expander;
    QByteArray m_variable;
};

void VariableTreeView::contextMenuEvent(QContextMenuEvent *ev)
{
    const QModelIndex index = indexAt(ev->pos());

    QString unexpandedText = index.data(UnexpandedTextRole).toString();
    QString expandedText = index.data(ExpandedTextRole).toString();

    QMenu menu;
    QAction *insertUnexpandedAction = nullptr;
    QAction *insertExpandedAction = nullptr;

    if (unexpandedText.isEmpty()) {
        insertUnexpandedAction = menu.addAction(VariableChooser::tr("Insert Unexpanded Value"));
        insertUnexpandedAction->setEnabled(false);
    } else {
        insertUnexpandedAction = menu.addAction(VariableChooser::tr("Insert \"%1\"").arg(unexpandedText));
    }

    if (expandedText.isEmpty()) {
        insertExpandedAction = menu.addAction(VariableChooser::tr("Insert Expanded Value"));
        insertExpandedAction->setEnabled(false);
    } else {
        insertExpandedAction = menu.addAction(VariableChooser::tr("Insert \"%1\"").arg(expandedText));
    }


    QAction *act = menu.exec(ev->globalPos());

    if (act == insertUnexpandedAction)
        m_target->insertText(unexpandedText);
    else if (act == insertExpandedAction)
        m_target->insertText(expandedText);
}

void VariableTreeView::currentChanged(const QModelIndex &current, const QModelIndex &previous)
{
    m_target->updateDescription(current);
    QTreeView::currentChanged(current, previous);
}

VariableChooserPrivate::VariableChooserPrivate(VariableChooser *parent)
    : q(parent),
      m_lineEdit(nullptr),
      m_textEdit(nullptr),
      m_plainTextEdit(nullptr),
      m_iconButton(nullptr),
      m_variableFilter(nullptr),
      m_variableTree(nullptr),
      m_variableDescription(nullptr)
{
    m_defaultDescription = VariableChooser::tr("Select a variable to insert.");

    m_variableFilter = new Utils::FancyLineEdit(q);
    m_variableTree = new VariableTreeView(q, this);
    m_variableDescription = new QLabel(q);

    m_variableFilter->setFiltering(true);

    m_sortModel = new VariableSortFilterProxyModel(this);
    m_sortModel->setSourceModel(&m_model);
    m_sortModel->sort(0);
    m_sortModel->setFilterKeyColumn(0);
    m_sortModel->setFilterCaseSensitivity(Qt::CaseInsensitive);
    m_variableTree->setModel(m_sortModel);

    m_variableDescription->setText(m_defaultDescription);
    m_variableDescription->setMinimumSize(QSize(0, 60));
    m_variableDescription->setAlignment(Qt::AlignLeft|Qt::AlignTop);
    m_variableDescription->setWordWrap(true);
    m_variableDescription->setAttribute(Qt::WA_MacSmallSize);
    m_variableDescription->setTextInteractionFlags(Qt::TextBrowserInteraction);

    auto verticalLayout = new QVBoxLayout(q);
    verticalLayout->setContentsMargins(3, 3, 3, 12);
    verticalLayout->addWidget(m_variableFilter);
    verticalLayout->addWidget(m_variableTree);
    verticalLayout->addWidget(m_variableDescription);

    connect(m_variableFilter, &QLineEdit::textChanged,
            this, &VariableChooserPrivate::updateFilter);
    connect(m_variableTree, &QTreeView::activated,
            this, &VariableChooserPrivate::handleItemActivated);
    connect(qobject_cast<QApplication *>(qApp), &QApplication::focusChanged,
            this, &VariableChooserPrivate::updateCurrentEditor);
    updateCurrentEditor(nullptr, QApplication::focusWidget());
}

void VariableGroupItem::populateGroup(MacroExpander *expander)
{
    if (!expander)
        return;

    foreach (const QByteArray &variable, expander->visibleVariables()) {
        auto item = new VariableItem;
        item->m_variable = variable;
        item->m_expander = expander;
        appendChild(item);
    }

    foreach (const MacroExpanderProvider &subProvider, expander->subProviders()) {
        if (!subProvider)
            continue;
        if (expander->isAccumulating()) {
            populateGroup(subProvider());
        } else {
            auto item = new VariableGroupItem;
            item->m_chooser = m_chooser;
            item->m_provider = subProvider;
            appendChild(item);
        }
    }
}

} // namespace Internal

using namespace Internal;

/*!
 * \class Core::VariableChooser
 * \inmodule QtCreator
 * \brief The VariableChooser class is used to add a tool window for selecting \QC variables
 * to line edits, text edits or plain text edits.
 *
 * If you allow users to add \QC variables to strings that are specified in your UI, for example
 * when users can provide a string through a text control, you should add a variable chooser to it.
 * The variable chooser allows users to open a tool window that contains the list of
 * all available variables together with a description. Double-clicking a variable inserts the
 * corresponding string into the corresponding text control like a line edit.
 *
 * \image variablechooser.png "External Tools Preferences with Variable Chooser"
 *
 * The variable chooser monitors focus changes of all children of its parent widget.
 * When a text control gets focus, the variable chooser checks if it has variable support set.
 * If the control supports variables,
 * a tool button which opens the variable chooser is shown in it while it has focus.
 *
 * Supported text controls are QLineEdit, QTextEdit and QPlainTextEdit.
 *
 * The variable chooser is deleted when its parent widget is deleted.
 *
 * Example:
 * \code
 * QWidget *myOptionsContainerWidget = new QWidget;
 * new Core::VariableChooser(myOptionsContainerWidget)
 * QLineEdit *myLineEditOption = new QLineEdit(myOptionsContainerWidget);
 * myOptionsContainerWidget->layout()->addWidget(myLineEditOption);
 * Core::VariableChooser::addVariableSupport(myLineEditOption);
 * \endcode
 */

/*!
 * \internal
 * \variable VariableChooser::kVariableSupportProperty
 * Property name that is checked for deciding if a widget supports \QC variables.
 * Can be manually set with
 * \c{textcontrol->setProperty(VariableChooser::kVariableSupportProperty, true)}
 */
const char kVariableSupportProperty[] = "QtCreator.VariableSupport";
const char kVariableNameProperty[] = "QtCreator.VariableName";

/*!
 * Creates a variable chooser that tracks all children of \a parent for variable support.
 * Ownership is also transferred to \a parent.
 */
VariableChooser::VariableChooser(QWidget *parent) :
    QWidget(parent),
    d(new VariableChooserPrivate(this))
{
    setWindowTitle(tr("Variables"));
    setWindowFlags(Qt::Tool);
    setFocusPolicy(Qt::StrongFocus);
    setFocusProxy(d->m_variableTree);
    setGeometry(QRect(0, 0, 400, 500));
    addMacroExpanderProvider([]() { return globalMacroExpander(); });
}

/*!
 * \internal
 */
VariableChooser::~VariableChooser()
{
    delete d->m_iconButton;
    delete d;
}

/*!
    Adds the macro expander provider \a provider.
*/
void VariableChooser::addMacroExpanderProvider(const MacroExpanderProvider &provider)
{
    auto item = new VariableGroupItem;
    item->m_chooser = d;
    item->m_provider = provider;
    d->m_model.rootItem()->prependChild(item);
}

/*!
 * Marks the control \a textcontrol as supporting variables.
 *
 * If the control provides a variable to the macro expander itself, set
 * \a ownName to the variable name to prevent the user from choosing the
 * variable, which would lead to endless recursion.
 */
void VariableChooser::addSupportedWidget(QWidget *textcontrol, const QByteArray &ownName)
{
    QTC_ASSERT(textcontrol, return);
    textcontrol->setProperty(kVariableSupportProperty, QVariant::fromValue<QWidget *>(this));
    textcontrol->setProperty(kVariableNameProperty, ownName);
}

void VariableChooser::addSupportForChildWidgets(QWidget *parent, MacroExpander *expander)
{
     auto chooser = new VariableChooser(parent);
     chooser->addMacroExpanderProvider([expander] { return expander; });
     foreach (QWidget *child, parent->findChildren<QWidget *>()) {
         if (qobject_cast<QLineEdit *>(child)
                 || qobject_cast<QTextEdit *>(child)
                 || qobject_cast<QPlainTextEdit *>(child))
             chooser->addSupportedWidget(child);
     }
}

/*!
 * \internal
 */
void VariableChooserPrivate::updateDescription(const QModelIndex &index)
{
    if (m_variableDescription)
        m_variableDescription->setText(m_model.data(m_sortModel->mapToSource(index),
                                                    Qt::ToolTipRole).toString());
}

/*!
 * \internal
 */
int VariableChooserPrivate::buttonMargin() const
{
    return 24;
}

void VariableChooserPrivate::updateButtonGeometry()
{
    QWidget *current = currentWidget();
    int margin = buttonMargin();
    m_iconButton->setGeometry(current->rect().adjusted(
                                  current->width() - (margin + 4), 0,
                                  0, -qMax(0, current->height() - (margin + 4))));
}

void VariableChooserPrivate::updateCurrentEditor(QWidget *old, QWidget *widget)
{
    Q_UNUSED(old)
    if (!widget) // we might loose focus, but then keep the previous state
        return;
    // prevent children of the chooser itself, and limit to children of chooser's parent
    bool handle = false;
    QWidget *parent = widget;
    while (parent) {
        if (parent == q)
            return;
        if (parent == q->parentWidget()) {
            handle = true;
            break;
        }
        parent = parent->parentWidget();
    }
    if (!handle)
        return;

    QLineEdit *previousLineEdit = m_lineEdit;
    QWidget *previousWidget = currentWidget();
    m_lineEdit = nullptr;
    m_textEdit = nullptr;
    m_plainTextEdit = nullptr;
    auto chooser = widget->property(kVariableSupportProperty).value<QWidget *>();
    m_currentVariableName = widget->property(kVariableNameProperty).toByteArray();
    bool supportsVariables = chooser == q;
    if (auto lineEdit = qobject_cast<QLineEdit *>(widget))
        m_lineEdit = (supportsVariables ? lineEdit : nullptr);
    else if (auto textEdit = qobject_cast<QTextEdit *>(widget))
        m_textEdit = (supportsVariables ? textEdit : nullptr);
    else if (auto plainTextEdit = qobject_cast<QPlainTextEdit *>(widget))
        m_plainTextEdit = (supportsVariables ? plainTextEdit : nullptr);

    QWidget *current = currentWidget();
    if (current != previousWidget) {
        if (previousWidget)
            previousWidget->removeEventFilter(q);
        if (previousLineEdit)
            previousLineEdit->setTextMargins(0, 0, 0, 0);
        if (m_iconButton) {
            m_iconButton->hide();
            m_iconButton->setParent(nullptr);
        }
        if (current) {
            current->installEventFilter(q); // escape key handling and geometry changes
            if (!m_iconButton)
                createIconButton();
            int margin = buttonMargin();
            if (m_lineEdit)
                m_lineEdit->setTextMargins(0, 0, margin, 0);
            m_iconButton->setParent(current);
            updateButtonGeometry();
            m_iconButton->show();
        } else {
            q->hide();
        }
    }
}


/*!
 * \internal
 */
void VariableChooserPrivate::updatePositionAndShow(bool)
{
    if (QWidget *w = q->parentWidget()) {
        QPoint parentCenter = w->mapToGlobal(w->geometry().center());
        q->move(parentCenter.x() - q->width()/2, parentCenter.y() - q->height()/2);
    }
    q->show();
    q->raise();
    q->activateWindow();
    m_variableTree->expandAll();
}

void VariableChooserPrivate::updateFilter(const QString &filterText)
{
    m_sortModel->setFilterWildcard(filterText);
    m_variableTree->expandAll();
}

/*!
 * \internal
 */
QWidget *VariableChooserPrivate::currentWidget()
{
    if (m_lineEdit)
        return m_lineEdit;
    if (m_textEdit)
        return m_textEdit;
    return m_plainTextEdit;
}

/*!
 * \internal
 */
void VariableChooserPrivate::handleItemActivated(const QModelIndex &index)
{
    QString text = m_model.data(m_sortModel->mapToSource(index), UnexpandedTextRole).toString();
    if (!text.isEmpty())
        insertText(text);
}

/*!
 * \internal
 */
void VariableChooserPrivate::insertText(const QString &text)
{
    if (m_lineEdit) {
        m_lineEdit->insert(text);
        m_lineEdit->activateWindow();
    } else if (m_textEdit) {
        m_textEdit->insertPlainText(text);
        m_textEdit->activateWindow();
    } else if (m_plainTextEdit) {
        m_plainTextEdit->insertPlainText(text);
        m_plainTextEdit->activateWindow();
    }
}

/*!
 * \internal
 */
static bool handleEscapePressed(QKeyEvent *ke, QWidget *widget)
{
    if (ke->key() == Qt::Key_Escape && !ke->modifiers()) {
        ke->accept();
        QTimer::singleShot(0, widget, &QWidget::close);
        return true;
    }
    return false;
}

/*!
 * \internal
 */
bool VariableChooser::event(QEvent *ev)
{
    if (ev->type() == QEvent::KeyPress || ev->type() == QEvent::ShortcutOverride) {
        auto ke = static_cast<QKeyEvent *>(ev);
        if (handleEscapePressed(ke, this))
            return true;
    }
    return QWidget::event(ev);
}

/*!
 * \internal
 */
bool VariableChooser::eventFilter(QObject *obj, QEvent *event)
{
    if (obj != d->currentWidget())
        return false;
    if ((event->type() == QEvent::KeyPress || event->type() == QEvent::ShortcutOverride) && isVisible()) {
        auto ke = static_cast<QKeyEvent *>(event);
        return handleEscapePressed(ke, this);
    } else if (event->type() == QEvent::Resize) {
        d->updateButtonGeometry();
    } else if (event->type() == QEvent::Hide) {
        close();
    }
    return false;
}

} // namespace Internal
