/////////////////////////////////////////////////////////////////////////////////
//
//  Copyright (C) 2018-     Equinor ASA
// 
//  ResInsight is free software: you can redistribute it and/or modify
//  it under the terms of the GNU General Public License as published by
//  the Free Software Foundation, either version 3 of the License, or
//  (at your option) any later version.
// 
//  ResInsight is distributed in the hope that it will be useful, but WITHOUT ANY
//  WARRANTY; without even the implied warranty of MERCHANTABILITY or
//  FITNESS FOR A PARTICULAR PURPOSE.
// 
//  See the GNU General Public License at <http://www.gnu.org/licenses/gpl.html> 
//  for more details.
//
/////////////////////////////////////////////////////////////////////////////////

#include "RiuWidgetDragger.h"
#include <QEvent>
#include <QWidget>
#include <QMouseEvent>

//--------------------------------------------------------------------------------------------------
/// 
//--------------------------------------------------------------------------------------------------
RiuWidgetDragger::RiuWidgetDragger(QWidget* widgetToMove, QWidget* widgetToSnapTo /*= nullptr*/, int snapMargins /*= 5*/)
    : QObject(widgetToMove)
    , m_widgetToMove(widgetToMove)
    , m_widgetToSnapTo(widgetToSnapTo)
    , m_snapMargins(snapMargins)
    , m_startPos(0,0)
{
    addWidget(m_widgetToMove);
}

//--------------------------------------------------------------------------------------------------
///
//--------------------------------------------------------------------------------------------------
void RiuWidgetDragger::addWidget(QWidget* widget)
{
    widget->installEventFilter(this);
}

//--------------------------------------------------------------------------------------------------
/// 
//--------------------------------------------------------------------------------------------------
bool RiuWidgetDragger::eventFilter(QObject * watched, QEvent * event)
{
    if (event->type() == QEvent::MouseMove)
    {
        QMouseEvent* mMoveEv = static_cast<QMouseEvent*>(event);
        if (mMoveEv->buttons() & Qt::LeftButton)
        {
            QPoint relativeMove = mMoveEv->pos() - m_startPos;
            QRect  newFrameRect = m_widgetToMove->frameGeometry().translated(relativeMove);

            if (m_widgetToSnapTo)
            {
                QRect snapToRect = m_widgetToSnapTo->frameGeometry();
                {
                    QPoint snapToTopLeft = snapToRect.topLeft();
                    QPoint widgetTopLeft = newFrameRect.topLeft();
                    QPoint diff = snapToTopLeft - widgetTopLeft;
                    if (std::abs(diff.x()) < 4 * m_snapMargins)
                    {
                        newFrameRect.moveLeft(snapToTopLeft.x() + m_snapMargins);
                    }
                    if (std::abs(diff.y()) < 4 * m_snapMargins)
                    {
                        newFrameRect.moveTop(snapToTopLeft.y() + m_snapMargins);
                    }
                }
                {
                    QPoint snapToBottomLeft = snapToRect.bottomLeft();
                    QPoint widgetBottomLeft = newFrameRect.bottomLeft();
                    QPoint diff = snapToBottomLeft - widgetBottomLeft;
                    if (std::abs(diff.x()) < 4 * m_snapMargins)
                    {
                        newFrameRect.moveLeft(snapToBottomLeft.x() + m_snapMargins);
                    }
                    if (std::abs(diff.y()) < 4 * m_snapMargins)
                    {
                        newFrameRect.moveBottom(snapToBottomLeft.y() - m_snapMargins);
                    }
                }
                {
                    QPoint snapToTopRight = snapToRect.topRight();
                    QPoint widgetTopRight = newFrameRect.topRight();
                    QPoint diff = snapToTopRight - widgetTopRight;
                    if (std::abs(diff.x()) < 4 * m_snapMargins)
                    {
                        newFrameRect.moveRight(snapToTopRight.x() - m_snapMargins);
                    }
                    if (std::abs(diff.y()) < 4 * m_snapMargins)
                    {
                        newFrameRect.moveTop(snapToTopRight.y() + m_snapMargins);
                    }
                }
                {
                    QPoint snapToBottomRight = snapToRect.bottomRight();
                    QPoint widgetBottomRight = newFrameRect.bottomRight();
                    QPoint diff           = snapToBottomRight - widgetBottomRight;
                    if (std::abs(diff.x()) < 4 * m_snapMargins)
                    {
                        newFrameRect.moveRight(snapToBottomRight.x() - m_snapMargins);
                    }
                    if (std::abs(diff.y()) < 4 * m_snapMargins)
                    {
                        newFrameRect.moveBottom(snapToBottomRight.y() - m_snapMargins);
                    }
                }

            }
            m_widgetToMove->move(newFrameRect.topLeft());
            return true;
        }
    }
    else if (event->type() == QEvent::MouseButtonPress)
    {
        QMouseEvent* mEv = static_cast<QMouseEvent*>(event);
        m_startPos = mEv->pos();
        return true;
    }

    return false;
}