#include "mainwindow.h"

#include <QComboBox>
#include <QPushButton>
#include <QStandardItemModel>
#include <QHBoxLayout>
#include <QEvent>
#include <QToolTip>
#include <QHelpEvent>
#include <QCoreApplication>

MainWindow::MainWindow(QWidget *parent)
    : QMainWindow(parent)
{
    this->setMinimumSize({500, 300});

    auto container = new QWidget();
    this->setCentralWidget(container);

    auto layout = new QHBoxLayout();
    container->setLayout(layout);

    auto comboBox = new QComboBox();
    comboBox->installEventFilter(this);
    comboBox->setSizeAdjustPolicy(QComboBox::AdjustToContents);

    layout->addWidget(comboBox);
    layout->addStretch();

    auto model = new QStandardItemModel();

    comboBox->setModel(model);

    // minimum sizehint should be updated when we insert the item (just like the normal sizehint)
    auto insertButton = new QPushButton("insert item");
    connect(insertButton, &QPushButton::clicked, model, [model]()
    {
        model->appendRow(new QStandardItem("10"));
    });

    layout->addWidget(insertButton);

    // a style change event is the only thing that clears the minimum sizehint cache
    auto polishButton = new QPushButton("style change event");
    connect(polishButton, &QPushButton::clicked, comboBox, [comboBox]()
    {
        QEvent styleChange{QEvent::StyleChange};
        qApp->sendEvent(comboBox, &styleChange);
    });

    layout->addWidget(polishButton);
}

MainWindow::~MainWindow()
{
}

bool MainWindow::eventFilter(QObject* watched, QEvent* event)
{
    if(event->type() == QEvent::ToolTip && watched->isWidgetType())
    {
        const auto he = static_cast<QHelpEvent*>(event);
        const auto comboBox = static_cast<QWidget*>(watched);

        const auto minSizeHint = comboBox->minimumSizeHint();
        const auto msg = QString("{%1, %2}").arg(minSizeHint.width()).arg(minSizeHint.height());

        QToolTip::showText(he->globalPos(), msg);

        event->accept();
        return true;
    }
    return false;
}