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#include "switchsplittabwidget.h"
#include <theme.h>

#include <utils/utilsicons.h>
#include <utils/fileutils.h>

#include <QVector>
#include <QBoxLayout>
#include <QTabBar>
#include <QToolButton>
#include <QSplitter>
#include <QLayoutItem>
#include <QEvent>

namespace QmlDesigner {
SwitchSplitTabWidget::SwitchSplitTabWidget(QWidget *parent)
    : QWidget(parent)
    , m_splitter(new QSplitter)
    , m_tabBar(new QTabBar)
    , m_tabBarBackground(new QWidget)
{
    // setting object names for css
    setObjectName("backgroundWidget");
    m_splitter->setObjectName("centralTabWidget");
    m_splitter->setSizePolicy(QSizePolicy::Expanding, QSizePolicy::Expanding);
    m_splitter->setHandleWidth(0);

    QString sheet = QString::fromUtf8(Utils::FileReader::fetchQrc(":/qmldesigner/centerwidget.css"));
    m_tabBarBackground->setStyleSheet(Theme::replaceCssColors(sheet));

    m_tabBar->setObjectName("centralTabBar");
    m_tabBar->setShape(QTabBar::RoundedEast);
    m_tabBar->setDocumentMode(false);
    // add a faketab to have the possibility to unselect all tabs
    m_tabBar->addTab(QString());
    selectFakeTab();

    m_tabBarBackground->setObjectName("tabBarBackground");

    connect(m_tabBar, &QTabBar::tabBarClicked, [this] (int index) {
        if (index != -1)
            updateSplitterSizes(index - fakeTab);
    });

    setLayout(new QHBoxLayout);
    layout()->setContentsMargins(0, 0, 0, 0);
    layout()->setSpacing(0);
    layout()->addWidget(m_splitter);

    m_tabBarBackground->setLayout(new QVBoxLayout);
    m_tabBarBackground->layout()->setContentsMargins(0, 0, 0, 0);
    m_tabBarBackground->layout()->addItem(new QSpacerItem(0, 0, QSizePolicy::Minimum, QSizePolicy::Expanding));
    m_tabBarBackground->layout()->addWidget(m_tabBar);

    auto horizontalButton = new QToolButton;
    horizontalButton->setObjectName("centralTabBar");
    horizontalButton->setIcon(Utils::Icon({{QLatin1String(":/qmldesigner/images/spliteditorvertically.png"),
                                            Utils::Theme::IconsBaseColor}}).icon());
    horizontalButton->setIconSize(QSize(8, 16));
    connect(horizontalButton, &QToolButton::clicked, [this] () {
        m_splitter->setOrientation(Qt::Vertical);
        updateSplitterSizes();
        selectFakeTab();
    });
    auto verticalButton = new QToolButton;
    verticalButton->setObjectName("centralTabBar");
    verticalButton->setIcon(Utils::Icon({{QLatin1String(":/qmldesigner/images/spliteditorhorizontally.png"),
                                          Utils::Theme::IconsBaseColor}}).icon());
    verticalButton->setIconSize(QSize(8, 16));
    connect(verticalButton, &QToolButton::clicked, [this] () {
        m_splitter->setOrientation(Qt::Horizontal);
        updateSplitterSizes();
        selectFakeTab();
    });

    m_tabBarBackground->layout()->addWidget(horizontalButton);
    m_tabBarBackground->layout()->addWidget(verticalButton);
    layout()->addWidget(m_tabBarBackground);
    updateSplitButtons();
}

int SwitchSplitTabWidget::count() const
{
    return m_splitter->count();
}

QWidget *SwitchSplitTabWidget::currentWidget() const
{
    QList<int> sizes = m_splitter->sizes();
    for (int i = 0; i < count(); ++i) {
        if (sizes.at(i) > 0 && m_splitter->widget(i)->hasFocus())
            return m_splitter->widget(i);
    }
    return nullptr;
}

void SwitchSplitTabWidget::updateSplitterSizes(int index)
{
    QVector<int> splitterSizes(m_splitter->count());
    int splitterFullSize = 0;
    bool isHorizontal = m_splitter->orientation() == Qt::Horizontal;
    for (int i = 0; i < m_splitter->count(); ++i) {
        auto widget = m_splitter->widget(i);
        splitterFullSize += isHorizontal ? widget->width() : widget->height();
    }

    if (index > -1) {
        // collapse all but the one at index
        splitterSizes.fill(0);
        splitterSizes.replace(index, splitterFullSize);
    } else {
        // distribute full size among enabled tabs
        int divisor = splitterSizes.count();
        for (int i = 0; i < m_splitter->count(); ++i) {
            if (!m_tabBar->isTabEnabled(i + fakeTab))
                --divisor;
        }

        int splitSize = splitterFullSize / divisor;
        for (int i = 0; i < m_splitter->count(); ++i)
            splitterSizes.replace(i, m_tabBar->isTabEnabled(i + fakeTab) ? splitSize : 0);
    }

    m_splitter->setSizes(splitterSizes.toList());
}

int SwitchSplitTabWidget::addTab(QWidget *w, const QString &label)
{
    m_splitter->addWidget(w);
    const int newIndex = m_tabBar->addTab(label);
    if (mode() == TabMode) {
        m_tabBar->setCurrentIndex(newIndex);
        updateSplitterSizes(newIndex - fakeTab);
    }
    if (mode() == SplitMode)
        updateSplitterSizes();
    updateSplitButtons();
    return newIndex;
}

QWidget *SwitchSplitTabWidget::takeTabWidget(const int index)
{
    if (index == -1 || index > count() - 1)
        return nullptr;
    QWidget *widget = m_splitter->widget(index);
    widget->setParent(nullptr);
    m_tabBar->removeTab(index + fakeTab);
    // TODO: set which mode and tab is the current one
    updateSplitButtons();
    return widget;
}

void SwitchSplitTabWidget::switchTo(QWidget *widget)
{
    if (widget == nullptr || currentWidget() == widget)
        return;
    const int widgetIndex = m_splitter->indexOf(widget);
    Q_ASSERT(widgetIndex != -1);
    if (mode() == TabMode) {
        updateSplitterSizes(widgetIndex);
        m_tabBar->setCurrentIndex(widgetIndex + fakeTab);
    }

    widget->setFocus();
}

void SwitchSplitTabWidget::updateSplitButtons()
{
    const bool isTabBarNecessary = count() > 1;
    m_tabBarBackground->setVisible(isTabBarNecessary);
}

void SwitchSplitTabWidget::selectFakeTab()
{
    m_tabBar->setCurrentIndex(0);
}

SwitchSplitTabWidget::Mode SwitchSplitTabWidget::mode() const
{
    const bool isTabBarNecessary = count() > 1;
    const int fakeTabPosition = 0;
    const int hasSelectedTab = m_tabBar->currentIndex() > fakeTabPosition;
    // Note: When splitting the view by dragging from the side of the view, SplitMode is not detected
    return (isTabBarNecessary && !hasSelectedTab) ? SplitMode : TabMode;
}

} // namespace QmlDesigner