#include "CollapseController.h"

#include "FloatingWindow.h"

#include <QQuickWindow>

namespace {
constexpr int ExpandTimeoutMs = 500;

bool roughlyEqual(QSize a, QSize b)
{
    return qAbs(a.width() - b.width()) <= 1 && qAbs(a.height() - b.height()) <= 1;
}
} // namespace

CollapseController::CollapseController(QQuickWindow &window, FloatingWindow &placement, QObject *parent)
    : QObject(parent)
    , m_window(window)
    , m_placement(placement)
{
    m_expanding.setSingleShot(true);
    m_expanding.setInterval(ExpandTimeoutMs);
    connect(&m_expanding, &QTimer::timeout, this, &CollapseController::finishExpanding);
    connect(&window, &QWindow::widthChanged, this, &CollapseController::windowResized);
    connect(&window, &QWindow::heightChanged, this, &CollapseController::windowResized);
}

bool CollapseController::collapse()
{
    if (m_collapsed)
        return true;
    QVariant rect;
    QMetaObject::invokeMethod(&m_window, "dismissKeyRect", Q_RETURN_ARG(QVariant, rect));
    if (rect.toRectF().isEmpty())
        return false;
    m_keyRect = rect.toRectF();
    m_expandedSize = m_window.size();
    m_collapsed = true;
    Q_EMIT collapsedChanged();
    // Wait one frame, so the compositor has the new (lower) minimum size before the resize.
    connect(&m_window, &QQuickWindow::frameSwapped, this, [this] {
        if (m_collapsed)
            m_placement.moveResize(m_keyRect, false);
    }, Qt::SingleShotConnection);
    return true;
}

void CollapseController::expand()
{
    if (!m_collapsed || m_expanding.isActive())
        return;
    if (roughlyEqual(m_window.size(), m_expandedSize)) {
        finishExpanding(); // window never shrank: nothing to resize
        return;
    }
    // Stay collapsed until the window has grown, so the keys aren't drawn squeezed.
    m_placement.moveResize(QRectF(-m_keyRect.topLeft(), m_expandedSize), true);
    m_expanding.start();
}

void CollapseController::windowResized()
{
    if (m_expanding.isActive() && roughlyEqual(m_window.size(), m_expandedSize))
        finishExpanding();
}

void CollapseController::finishExpanding()
{
    m_expanding.stop();
    if (!roughlyEqual(m_window.size(), m_expandedSize))
        m_window.resize(m_expandedSize); // KWin didn't resize (timeout): resize directly
    m_collapsed = false;
    Q_EMIT collapsedChanged();
}