/*
  This file is part of KDDockWidgets.

  SPDX-FileCopyrightText: 2019 Klarälvdalens Datakonsult AB, a KDAB Group company <info@kdab.com>
  Author: Sérgio Martins <sergio.martins@kdab.com>

  SPDX-License-Identifier: GPL-2.0-only OR GPL-3.0-only

  Contact KDAB at <info@kdab.com> for commercial licensing options.
*/

#include "TitleBar.h"

#include "core/TitleBar.h"
#include "core/FloatingWindow.h"
#include "core/Window_p.h"
#include "core/Utils_p.h"
#include "core/View_p.h"
#include "core/Logging_p.h"
#include "core/TitleBar_p.h"
#include "core/DockRegistry_p.h"

#include "qtwidgets/ViewFactory.h"

#include <QPainter>
#include <QStyle>
#include <QStyleOptionDockWidget>
#include <QHBoxLayout>
#include <QLabel>
#include <QTimer>
#include <QScopedValueRollback>

using namespace KDDockWidgets;
using namespace KDDockWidgets::QtWidgets;

Button::~Button()
{
}

void Button::paintEvent(QPaintEvent *)
{
    QPainter p(this);
    QStyleOptionToolButton opt;
    opt.initFrom(this);

    if (isEnabled() && underMouse()) {
        if (isDown()) {
            opt.state |= QStyle::State_Sunken;
        } else {
            opt.state |= QStyle::State_Raised;
        }
        style()->drawPrimitive(QStyle::PE_PanelButtonTool, &opt, &p, this);
    }

    opt.subControls = QStyle::SC_None;
    opt.features = QStyleOptionToolButton::None;
    opt.icon = icon();
    opt.iconSize = iconSize();

    // The first icon size is for scaling 1x, and is what QStyle expects. QStyle will pick ones
    // with higher resolution automatically when needed.
    const QList<QSize> iconSizes = opt.icon.availableSizes();
    if (!iconSizes.isEmpty()) {
        opt.iconSize = iconSizes.constFirst();

        const qreal logicalFactor = logicalDpiX() / 96.0;

        // On Linux there's dozens of window managers and ways of setting the scaling.
        // Some window managers will just change the font dpi (which affects logical dpi), while
        // others will only change the device pixel ratio. Take care of both cases.
        // macOS is easier, as it never changes logical DPI.
        // On Windows, with AA_EnableHighDpiScaling, logical DPI is always 96 and physical is
        // manipulated instead.
#if defined(Q_OS_LINUX)
        const qreal dpr = devicePixelRatioF();
        const qreal combinedFactor = logicalFactor * dpr;

        if (scalingFactorIsSupported(combinedFactor)) // Older Qt has rendering bugs with fractional
                                                      // factors
            opt.iconSize = opt.iconSize * combinedFactor;
#elif defined(Q_OS_WIN) && QT_VERSION < QT_VERSION_CHECK(6, 0, 0)
        // Probably Windows could use the same code path as Linux, but I'm seeing too thick icons on
        // Windows...
        if (!QGuiApplication::testAttribute(Qt::AA_EnableHighDpiScaling)
            && scalingFactorIsSupported(logicalFactor)) // Older Qt has rendering bugs with
                                                        // fractional factors
            opt.iconSize = opt.iconSize * logicalFactor;
#else
        Q_UNUSED(logicalFactor);
#endif
    }

    style()->drawComplexControl(QStyle::CC_ToolButton, &opt, &p, this);
}

QSize Button::sizeHint() const
{
    const int h = 24;
    return QSize(h, h);
}

bool Button::event(QEvent *ev)
{
    switch (ev->type()) {
    case QEvent::MouseButtonPress:
    case QEvent::MouseButtonRelease:
    case QEvent::MouseButtonDblClick:
    case QEvent::KeyPress:
    case QEvent::KeyRelease: {
        // A Button can trigger the deletion of its parent, in which case we use deleteLater
        m_inEventHandler = true;
        QPointer<QObject> guard = this;
        const bool result = QToolButton::event(ev);

        if (guard) // Button press can trigger deletion of Button
            m_inEventHandler = false;

        return result;
    }
    default:
        break;
    }

    return QToolButton::event(ev);
}

class KDDockWidgets::QtWidgets::TitleBar::Private
{
public:
    KDBindings::ScopedConnection titleChangedConnection;
    KDBindings::ScopedConnection iconChangedConnection;
    KDBindings::ScopedConnection screenChangedConnection;
    KDBindings::ScopedConnection focusChangedConnection;

    KDBindings::ScopedConnection closeButtonEnabledConnection;
    KDBindings::ScopedConnection floatButtonToolTipConnection;
    KDBindings::ScopedConnection floatButtonVisibleConnection;
    KDBindings::ScopedConnection autoHideButtonConnection;
    KDBindings::ScopedConnection minimizeButtonConnection;
    KDBindings::ScopedConnection maximizeButtonConnection;
};

TitleBar::TitleBar(Core::TitleBar *controller, Core::View *parent)
    : View(controller, Core::ViewType::TitleBar, View_qt::asQWidget(parent))
    , Core::TitleBarViewInterface(controller)
    , m_layout(new QHBoxLayout(this))
    , d(new Private())
{
    setAttribute(Qt::WA_StyledBackground, true);
    setObjectName(QStringLiteral("KDDWTitleBar"));
}

TitleBar::TitleBar(QWidget *parent)
    : View(new Core::TitleBar(this), Core::ViewType::TitleBar, parent)
    , Core::TitleBarViewInterface(static_cast<Core::TitleBar *>(controller()))
    , m_layout(new QHBoxLayout(this))
    , d(new Private())
{
    setAttribute(Qt::WA_StyledBackground, true);
    setObjectName(QStringLiteral("KDDWTitleBar"));
    m_titleBar->init();
}

TitleBar::~TitleBar()
{
    delete d;

    /// The window deletion might have been triggered by pressing a button, so use deleteLater()
    for (auto button : { m_closeButton, m_floatButton, m_maximizeButton, m_minimizeButton, m_autoHideButton }) {
        if (!button)
            continue;

        if (auto kddwButton = qobject_cast<Button *>(button); !kddwButton->m_inEventHandler) {
            // Minor optimization. If the button is not in an event handler it's safe to delete immediately.
            // This saves us from memory leaks at shutdown when using the below QTimer::singleShot() hack.
            delete kddwButton;
            continue;
        }

        button->setParent(nullptr);
        if (usesQTBUG83030Workaround()) {
            QTimer::singleShot(0, button, [button] {
                /// Workaround for QTBUG-83030. QObject::deleteLater() is buggy with nested event loop
                delete button;
            });
        } else {
            button->deleteLater();
        }
    }
}

void TitleBar::init()
{
    setSizePolicy(QSizePolicy::Minimum, QSizePolicy::Fixed);
    if (m_titleBar->titleBarIsFocusable())
        setFocusPolicy(Qt::StrongFocus);

    if (!hasCustomLayout()) {
        m_dockWidgetIcon = new QLabel(this);
        m_layout->addWidget(m_dockWidgetIcon, 0, Qt::AlignVCenter);
        m_layout->addStretch();
        updateMargins();

        auto factory = static_cast<ViewFactory *>(Config::self().viewFactory());
        m_maximizeButton = factory->createTitleBarButton(this, TitleBarButtonType::Maximize);
        m_minimizeButton = factory->createTitleBarButton(this, TitleBarButtonType::Minimize);
        m_floatButton = factory->createTitleBarButton(this, TitleBarButtonType::Float);
        m_closeButton = factory->createTitleBarButton(this, TitleBarButtonType::Close);
        m_autoHideButton = factory->createTitleBarButton(this, TitleBarButtonType::AutoHide);

        m_layout->addWidget(m_autoHideButton, 0, Qt::AlignVCenter);
        m_layout->addWidget(m_minimizeButton, 0, Qt::AlignVCenter);
        m_layout->addWidget(m_maximizeButton, 0, Qt::AlignVCenter);
        m_layout->addWidget(m_floatButton,    0, Qt::AlignVCenter);
        m_layout->addWidget(m_closeButton,    0, Qt::AlignVCenter);

        m_autoHideButton->setVisible(false);

        connect(m_floatButton, &QAbstractButton::clicked, m_titleBar,
                &Core::TitleBar::onFloatClicked);
        connect(m_closeButton, &QAbstractButton::clicked, m_titleBar,
                &Core::TitleBar::onCloseClicked);
        connect(m_maximizeButton, &QAbstractButton::clicked, m_titleBar,
                &Core::TitleBar::onMaximizeClicked);
        connect(m_minimizeButton, &QAbstractButton::clicked, m_titleBar,
                &Core::TitleBar::onMinimizeClicked);
        connect(m_autoHideButton, &QAbstractButton::clicked, m_titleBar,
                &Core::TitleBar::onAutoHideClicked);

        m_minimizeButton->setToolTip(tr("Minimize"));
        m_closeButton->setToolTip(tr("Close"));

        m_floatButton->setVisible(m_titleBar->floatButtonVisible());
        m_floatButton->setToolTip(m_titleBar->floatButtonToolTip());

        d->closeButtonEnabledConnection = m_titleBar->dptr()->closeButtonChanged.connect([this](bool visible, bool enabled) { m_closeButton->setVisible(visible);
        m_closeButton->setEnabled(enabled); });
        d->floatButtonToolTipConnection = m_titleBar->dptr()->floatButtonToolTipChanged.connect([this](const QString &text) { m_floatButton->setToolTip(text); });
        d->floatButtonVisibleConnection = m_titleBar->dptr()->floatButtonVisibleChanged.connect([this](bool visible) { m_floatButton->setVisible(visible); });
        d->autoHideButtonConnection = m_titleBar->dptr()->autoHideButtonChanged.connect([this](bool visible, bool enabled, TitleBarButtonType type) { updateAutoHideButton(visible, enabled, type); });
        d->minimizeButtonConnection = m_titleBar->dptr()->minimizeButtonChanged.connect([this](bool visible, bool enabled) { updateMinimizeButton(visible, enabled); });
        d->maximizeButtonConnection = m_titleBar->dptr()->maximizeButtonChanged.connect([this](bool visible, bool enabled, TitleBarButtonType type) { updateMaximizeButton(visible, enabled, type); });

        d->iconChangedConnection = m_titleBar->dptr()->iconChanged.connect([this] { if (m_titleBar->icon().isNull()) {
            m_dockWidgetIcon->setPixmap(QPixmap());
        } else {
            const QPixmap pix = m_titleBar->icon().pixmap(QSize(28, 28));
            m_dockWidgetIcon->setPixmap(pix);
        }
        update(); });
    }

    d->titleChangedConnection = m_titleBar->dptr()->titleChanged.connect([this] { update(); });

    d->screenChangedConnection = DockRegistry::self()->dptr()->windowChangedScreen.connect([this](Core::Window::Ptr w) {
        if (View::d->isInWindow(w))
            updateMargins();
    });

    d->focusChangedConnection = m_titleBar->dptr()->isFocusedChanged.connect([this] {
        Q_EMIT isFocusedChanged();
    });
}

Core::TitleBar *TitleBar::titleBar() const
{
    return m_titleBar;
}

void TitleBar::paintEvent(QPaintEvent *)
{
    if (View::d->freed())
        return;

    QPainter p(this);

    // Background is handled by QSS via WA_StyledBackground
    QRect textRect = rect();

    if (!iconRect().isEmpty())
        textRect.setLeft(iconRect().right() + 4);

    p.setPen(palette().color(QPalette::WindowText));
    p.drawText(textRect, Qt::AlignCenter, m_titleBar->title());
}

void TitleBar::updateMinimizeButton(bool visible, bool enabled)
{
    if (!m_minimizeButton)
        return;

    m_minimizeButton->setEnabled(enabled);
    m_minimizeButton->setVisible(visible);
}

void TitleBar::updateAutoHideButton(bool visible, bool enabled, TitleBarButtonType type)
{
    if (!m_autoHideButton)
        return;

    m_autoHideButton->setToolTip(type == TitleBarButtonType::AutoHide ? tr("Auto-hide")
                                                                      : tr("Disable auto-hide"));
    auto factory = Config::self().viewFactory();
    m_autoHideButton->setIcon(factory->iconForButtonType(type, devicePixelRatioF()));
    m_autoHideButton->setVisible(visible);
    m_autoHideButton->setEnabled(enabled);
}

void TitleBar::updateMaximizeButton(bool visible, bool enabled, TitleBarButtonType type)
{
    if (!m_maximizeButton)
        return;

    m_maximizeButton->setEnabled(enabled);
    m_maximizeButton->setVisible(visible);
    if (visible) {
        auto factory = Config::self().viewFactory();
        m_maximizeButton->setIcon(factory->iconForButtonType(type, devicePixelRatioF()));
        m_maximizeButton->setToolTip(type == TitleBarButtonType::Normal ? tr("Restore")
                                                                        : tr("Maximize"));
    }
}

QRect TitleBar::iconRect() const
{
    if (m_titleBar->icon().isNull()) {
        return QRect(0, 0, 0, 0);
    } else {
        return QRect(3, 3, 30, 30);
    }
}

int TitleBar::buttonAreaWidth() const
{
    int smallestX = width();

    for (auto button :
         { m_autoHideButton, m_minimizeButton, m_floatButton, m_maximizeButton, m_closeButton }) {
        if (button && button->isVisible() && button->x() < smallestX)
            smallestX = button->x();
    }

    return width() - smallestX;
}

void TitleBar::updateMargins()
{
    const qreal factor = logicalDpiFactor(this);
    m_layout->setContentsMargins(QMargins(4, 0, 4, 0) * factor);
    m_layout->setSpacing(int(2 * factor));
}

void TitleBar::mouseDoubleClickEvent(QMouseEvent *e)
{
    if (!m_titleBar)
        return;

    if (e->button() == Qt::LeftButton)
        m_titleBar->onDoubleClicked();
}

QSize TitleBar::sizeHint() const
{
    int height = fontMetrics().height() + 8;
    return QSize(0, height);
}

void TitleBar::focusInEvent(QFocusEvent *ev)
{
    if (View::d->freed())
        return;

    QWidget::focusInEvent(ev);
    m_titleBar->focus(ev->reason());
}

#ifdef DOCKS_DEVELOPER_MODE

bool TitleBar::isCloseButtonVisible() const
{
    return m_closeButton && m_closeButton->isVisible();
}

bool TitleBar::isCloseButtonEnabled() const
{
    return m_closeButton && m_closeButton->isEnabled();
}

bool TitleBar::isFloatButtonVisible() const
{
    return m_floatButton && m_floatButton->isVisible();
}

#endif