// Copyright (C) 2023-2024 Stdware Collections
// SPDX-License-Identifier: Apache-2.0

#ifndef SYSTEMWINDOW_P_H
#define SYSTEMWINDOW_P_H

//
//  W A R N I N G !!!
//  -----------------
//
// This file is not part of the QWindowKit API. It is used purely as an
// implementation detail. This header file may change from version to
// version without notice, or may even be removed.
//

#include <QtGui/QWindow>
#include <QtGui/QMouseEvent>

#include <QWKCore/private/qwkglobal_p.h>

// Don't include this header in any header files.

namespace QWK {

    // Anonymous namespace
    namespace {

        class WindowMoveManipulator : public QObject {
        public:
            explicit WindowMoveManipulator(QWindow *targetWindow)
                : QObject(targetWindow), target(targetWindow), initialMousePosition(QCursor::pos()),
                  initialWindowPosition(targetWindow->position()) {
                target->installEventFilter(this);
            }

        protected:
            bool eventFilter(QObject *obj, QEvent *event) override {
                switch (event->type()) {
                    case QEvent::MouseMove: {
                        auto mouseEvent = static_cast<QMouseEvent *>(event);
                        QPoint delta = getMouseEventGlobalPos(mouseEvent) - initialMousePosition;
                        target->setPosition(initialWindowPosition + delta);
                        return true;
                    }

                    case QEvent::MouseButtonRelease: {
                        if (target->y() < 0) {
                            target->setPosition(target->x(), 0);
                        }
                        target->removeEventFilter(this);
                        deleteLater();
                    }

                    default:
                        break;
                }
                return false;
            }

        private:
            QWindow *target;
            QPoint initialMousePosition;
            QPoint initialWindowPosition;
        };

        class WindowResizeManipulator : public QObject {
        public:
            WindowResizeManipulator(QWindow *targetWindow, Qt::Edges edges)
                : QObject(targetWindow), target(targetWindow), resizeEdges(edges),
                  initialMousePosition(QCursor::pos()), initialWindowRect(target->geometry()) {
                target->installEventFilter(this);
            }

        protected:
            bool eventFilter(QObject *obj, QEvent *event) override {
                switch (event->type()) {
                    case QEvent::MouseMove: {
                        auto mouseEvent = static_cast<QMouseEvent *>(event);
                        QPoint globalMousePos = getMouseEventGlobalPos(mouseEvent);
                        QRect windowRect = initialWindowRect;

                        if (resizeEdges & Qt::LeftEdge) {
                            int delta = globalMousePos.x() - initialMousePosition.x();
                            windowRect.setLeft(initialWindowRect.left() + delta);
                        }
                        if (resizeEdges & Qt::RightEdge) {
                            int delta = globalMousePos.x() - initialMousePosition.x();
                            windowRect.setRight(initialWindowRect.right() + delta);
                        }
                        if (resizeEdges & Qt::TopEdge) {
                            int delta = globalMousePos.y() - initialMousePosition.y();
                            windowRect.setTop(initialWindowRect.top() + delta);
                        }
                        if (resizeEdges & Qt::BottomEdge) {
                            int delta = globalMousePos.y() - initialMousePosition.y();
                            windowRect.setBottom(initialWindowRect.bottom() + delta);
                        }

                        target->setGeometry(windowRect);
                        return true;
                    }

                    case QEvent::MouseButtonRelease: {
                        target->removeEventFilter(this);
                        deleteLater();
                    }

                    default:
                        break;
                }
                return false;
            }

        private:
            QWindow *target;
            QPoint initialMousePosition;
            QRect initialWindowRect;
            Qt::Edges resizeEdges;
        };

    }

    // QWindow::startSystemMove() and QWindow::startSystemResize() is first supported at Qt 5.15
    // QWindow::startSystemResize() returns false on macOS
    // QWindow::startSystemMove() and QWindow::startSystemResize() returns false on Linux Unity DE

    // When the new API fails, we emulate the window actions using the classical API.

    static inline void startSystemMove(QWindow *window) {
#if (QT_VERSION < QT_VERSION_CHECK(5, 15, 0))
        std::ignore = new WindowMoveManipulator(window);
#elif defined(Q_OS_LINUX)
        if (window->startSystemMove()) {
            return;
        }
        std::ignore = new WindowMoveManipulator(window);
#else
        window->startSystemMove();
#endif
    }

    static inline void startSystemResize(QWindow *window, Qt::Edges edges) {
#if (QT_VERSION < QT_VERSION_CHECK(5, 15, 0))
        std::ignore = new WindowResizeManipulator(window, edges);
#elif defined(Q_OS_MAC) || defined(Q_OS_LINUX)
        if (window->startSystemResize(edges)) {
            return;
        }
        std::ignore = new WindowResizeManipulator(window, edges);
#else
        window->startSystemResize(edges);
#endif
    }

}

#endif // SYSTEMWINDOW_P_H