#include "lts_image_cropper.h"
#include <QGraphicsItem>
#include <QMouseEvent>
#include <QApplication>

namespace LtsWidgets
{

LtsImageCropper::LtsImageCropper(QWidget *parent, const QSize &size, const QPixmap &pixmap)
  : QGraphicsView(parent)
  , m_scene(new QGraphicsScene(this))
  , m_maxScale(2.0f)
  , m_multiplier(1.0f)
{
  if(!size.isNull())
    setFixedSize(size);

  setHorizontalScrollBarPolicy(Qt::ScrollBarAlwaysOff);
  setVerticalScrollBarPolicy(Qt::ScrollBarAlwaysOff);
  setFrameStyle(QFrame::NoFrame);
  setDragMode(QGraphicsView::ScrollHandDrag);
  setTransformationAnchor(QGraphicsView::AnchorViewCenter);

  m_scene->setBackgroundBrush(Qt::Dense6Pattern);
  setScene(m_scene);

  setPixmap(pixmap);
}

LtsImageCropper::~LtsImageCropper()
{
  delete m_pixmapItem;
}

void LtsImageCropper::setPixmap(const QPixmap &pixmap)
{
  if(pixmap.isNull())
    return;

  delete m_pixmapItem; 

  m_pixmapItem = new QGraphicsPixmapItem(pixmap);
  m_scene->addItem(m_pixmapItem);

  setTransform(QTransform()); 
  m_currentZoom = 1.0; 

  
  double sx = static_cast<double>(size().height()) / pixmap.height();
  double sy = static_cast<double>(size().width()) / pixmap.width();
  if(sx > 1 )
    scale(sx,sx);
  if(sy > 1)
    scale(sy,sy);

  
  double ratioWidth  = 1.0 * size().width()  / pixmap.width();
  double ratioHeight = 1.0 * size().height() / pixmap.height();
  m_minScale = qMax(ratioHeight,ratioWidth);

  calculateScaleStep();

  
  m_scene->setSceneRect(pixmap.rect());
  centerOn(m_scene->sceneRect().center());
}

void LtsImageCropper::setImage(const QImage &image)
{
  setPixmap(QPixmap::fromImage(image));
}

void LtsImageCropper::setMultiplier(double multiplier)
{
  m_multiplier = multiplier;
  calculateScaleStep();
}

void LtsImageCropper::calculateScaleStep()
{
  m_stepScale = (m_maxScale - m_minScale) / 100.0;
}

QImage LtsImageCropper::image()
{
  return grab().toImage();
}

void LtsImageCropper::wheelEvent(QWheelEvent *event)
{
  if(!m_pixmapItem)
    return;

  auto value = event->pixelDelta();
  if(value.isNull())
    value = event->angleDelta() / 15.0;

  
  double scrollZoom = m_stepScale * value.y() * m_multiplier / 8.0;

  m_currentZoom += scrollZoom;

  if(m_currentZoom > m_maxScale)
    m_currentZoom = m_maxScale;
  else if (m_currentZoom < m_minScale)
    m_currentZoom = m_minScale;

  
  setTransform(QTransform(m_currentZoom, transform().m12(), transform().m13(),
                          transform().m21(), m_currentZoom, transform().m23(),
                          transform().m31(), transform().m32(), 1));
}

void LtsImageCropper::mousePressEvent(QMouseEvent *event)
{
  QApplication::setOverrideCursor(Qt::DragMoveCursor);
  update();
  QGraphicsView::mousePressEvent(event);
}

void LtsImageCropper::mouseReleaseEvent(QMouseEvent *event)
{
  QApplication::restoreOverrideCursor();
  update();
  QGraphicsView::mouseReleaseEvent(event);
}

}