/*=========================================================================

  Library:   CTK

  Copyright (c) Kitware Inc.

  Licensed under the Apache License, Version 2.0 (the "License");
  you may not use this file except in compliance with the License.
  You may obtain a copy of the License at

      http://www.commontk.org/LICENSE

  Unless required by applicable law or agreed to in writing, software
  distributed under the License is distributed on an "AS IS" BASIS,
  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  See the License for the specific language governing permissions and
  limitations under the License.

=========================================================================*/

// Qt includes
#include <QApplication>
#include <QDebug>
#include <QDesktopWidget>
#include <QDir>
#include <QEvent>
#include <QLabel>
#include <QLayout>
#include <QMouseEvent>
#include <QPainter>
#include <QPropertyAnimation>
#include <QStyle>
#include <QTimer>

// CTK includes
#include "ctkPopupWidget.h"

#define LEAVE_CLOSING_DELAY 10
#define ENTER_OPENING_DELAY 10
#define DEFAULT_FADING_DURATION 333 // fast enough

// -------------------------------------------------------------------------
QGradient* duplicateGradient(const QGradient* gradient)
{
  QGradient* newGradient = 0;
  switch (gradient->type())
    {
    case QGradient::LinearGradient:
      {
      const QLinearGradient* linearGradient = static_cast<const QLinearGradient*>(gradient);
      newGradient = new QLinearGradient(linearGradient->start(), linearGradient->finalStop());
      break;
      }
    case QGradient::RadialGradient:
      {
      const QRadialGradient* radialGradient = static_cast<const QRadialGradient*>(gradient);
      newGradient = new QRadialGradient(radialGradient->center(), radialGradient->radius());
      break;
      }
    case QGradient::ConicalGradient:
      {
      const QConicalGradient* conicalGradient = static_cast<const QConicalGradient*>(gradient);
      newGradient = new QConicalGradient(conicalGradient->center(), conicalGradient->angle());
      break;
      }
    default:
      break;
    }
  if (!newGradient)
    {
    Q_ASSERT(gradient->type() != QGradient::NoGradient);
    return newGradient;
    }
  newGradient->setCoordinateMode(gradient->coordinateMode());
  newGradient->setSpread(gradient->spread());
  newGradient->setStops(gradient->stops());
  return newGradient;
}

// -------------------------------------------------------------------------
class ctkPopupWidgetPrivate
{
  Q_DECLARE_PUBLIC(ctkPopupWidget);
protected:
  ctkPopupWidget* const q_ptr;
public:
  ctkPopupWidgetPrivate(ctkPopupWidget& object);
  ~ctkPopupWidgetPrivate();
  void init();
  bool fitBaseWidgetSize()const;
  Qt::Alignment pixmapAlignment()const;
  
  QRect closedGeometry()const;
  QRect openGeometry()const;
  
  QPropertyAnimation* currentAnimation()const;

  QWidget* BaseWidget;
  bool AutoHide;

  int Alpha;
  ctkPopupWidget::AnimationEffect Effect;
  QPropertyAnimation* AlphaAnimation;
  int WindowAlpha;
  QPropertyAnimation* ScrollAnimation;
  QLabel*             PopupPixmapWidget;
  
  // Geometry attributes
  Qt::Alignment   Alignment;
  Qt::Orientation Orientation;
  
  ctkPopupWidget::VerticalDirection VerticalDirection;
  Qt::LayoutDirection HorizontalDirection;
};


// -------------------------------------------------------------------------
ctkPopupWidgetPrivate::ctkPopupWidgetPrivate(ctkPopupWidget& object)
  :q_ptr(&object)
{
  this->BaseWidget = 0;
  this->AutoHide = true;
  this->Alpha = 255;
  this->Effect = ctkPopupWidget::ScrollEffect;
  this->WindowAlpha = 0;
  this->AlphaAnimation = 0;
  this->ScrollAnimation = 0;
  this->PopupPixmapWidget = 0;
  // Geometry attributes
  this->Alignment = Qt::AlignJustify | Qt::AlignBottom;
  this->Orientation = Qt::Vertical;
  this->VerticalDirection = ctkPopupWidget::TopToBottom;
  this->HorizontalDirection = Qt::LeftToRight;
}

// -------------------------------------------------------------------------
ctkPopupWidgetPrivate::~ctkPopupWidgetPrivate()
{
  delete this->PopupPixmapWidget;
}

// -------------------------------------------------------------------------
void ctkPopupWidgetPrivate::init()
{
  Q_Q(ctkPopupWidget);
  q->setAnimationEffect(this->Effect);
  this->Alpha = q->style()->styleHint(QStyle::SH_ToolTipLabel_Opacity);

  this->AlphaAnimation = new QPropertyAnimation(q, "windowAlpha", q);
  this->AlphaAnimation->setDuration(DEFAULT_FADING_DURATION);
  this->AlphaAnimation->setStartValue(0);
  this->AlphaAnimation->setEndValue(this->Alpha);
  QObject::connect(this->AlphaAnimation, SIGNAL(finished()),
                   q, SLOT(onEffectFinished()));

  this->PopupPixmapWidget = new QLabel(0, Qt::ToolTip | Qt::FramelessWindowHint);
  this->ScrollAnimation = new QPropertyAnimation(q, "windowGeometry", q);
  this->ScrollAnimation->setDuration(DEFAULT_FADING_DURATION);
  QObject::connect(this->ScrollAnimation, SIGNAL(finished()),
                   q, SLOT(onEffectFinished()));
  QObject::connect(this->ScrollAnimation, SIGNAL(finished()),
                   this->PopupPixmapWidget, SLOT(hide()));

  q->setEasingCurve(QEasingCurve::OutCubic);
}

// -------------------------------------------------------------------------
QPropertyAnimation* ctkPopupWidgetPrivate::currentAnimation()const
{
  return this->Effect == ctkPopupWidget::ScrollEffect ?
    this->ScrollAnimation : this->AlphaAnimation;
}

// -------------------------------------------------------------------------
Qt::Alignment ctkPopupWidgetPrivate::pixmapAlignment()const
{
  Q_Q(const ctkPopupWidget);
  Qt::Alignment alignment;
  if (this->VerticalDirection == ctkPopupWidget::TopToBottom)
    {
    alignment |= Qt::AlignBottom;
    }
  else// if (this->VerticalDirection == ctkPopupWidget::BottomToTop)
    {
    alignment |= Qt::AlignTop;
    }

  if (this->HorizontalDirection == Qt::LeftToRight)
    {
    alignment |= Qt::AlignRight;
    }
  else// if (this->VerticalDirection == ctkPopupWidget::BottomToTop)
    {
    alignment |= Qt::AlignLeft;
    }
  return alignment;
}

// -------------------------------------------------------------------------
QRect ctkPopupWidgetPrivate::closedGeometry()const
{
  Q_Q(const ctkPopupWidget);
  /// TODO: it really doesn't handle many cases.
  /// It's a lot of parameters to think about.
  QRect openGeom = this->openGeometry();
  if (this->Orientation & Qt::Vertical)
    {
    if (this->VerticalDirection == ctkPopupWidget::BottomToTop)
      {
      openGeom.moveTop(openGeom.bottom());
      }
    openGeom.setHeight(0);
    }
  if (this->Orientation & Qt::Horizontal) 
    {
    if (this->HorizontalDirection == Qt::LeftToRight)
      {
      openGeom.moveLeft(openGeom.right());
      }
    openGeom.setWidth(0);
    }
  return openGeom;
}

// -------------------------------------------------------------------------
QRect ctkPopupWidgetPrivate::openGeometry()const
{
  Q_Q(const ctkPopupWidget);
  QSize size = q->size();
  if (!q->testAttribute(Qt::WA_WState_Created))
    {
    size = q->sizeHint();
    }
  
  if (!this->BaseWidget)
    {
    return QRect(q->pos(), size);
    }

  QRect geometry;
  if (this->Alignment & Qt::AlignJustify)
    {
    if (this->Orientation & Qt::Vertical)
      {
      size.setWidth(this->BaseWidget->width());
      }
    }
  if (this->Alignment & Qt::AlignTop &&
      this->Alignment & Qt::AlignBottom)
    {
    size.setHeight(this->BaseWidget->height());
    }

  geometry.setSize(size);

  QPoint topLeft = QPoint(this->BaseWidget->geometry().left(), this->BaseWidget->geometry().top());
  QPoint bottomRight = QPoint(this->BaseWidget->geometry().right(), this->BaseWidget->geometry().bottom());
  
  topLeft = this->BaseWidget->parentWidget() ? this->BaseWidget->parentWidget()->mapToGlobal(topLeft) : topLeft;
  bottomRight = this->BaseWidget->parentWidget() ? this->BaseWidget->parentWidget()->mapToGlobal(bottomRight) : bottomRight;

  if (this->Alignment & Qt::AlignLeft)
    {
    if (this->HorizontalDirection == Qt::LeftToRight)
      {
      geometry.moveLeft(topLeft.x());
      }
    else
      {
      geometry.moveRight(topLeft.x());
      }
    }
  else if (this->Alignment & Qt::AlignRight)
    {
    if (this->HorizontalDirection == Qt::LeftToRight)
      {
      geometry.moveLeft(bottomRight.x());
      }
    else
      {
      geometry.moveRight(bottomRight.x());
      }
    }
  else if (this->Alignment & Qt::AlignHCenter)
    {
    if (this->HorizontalDirection == Qt::LeftToRight)
      {
      geometry.moveLeft((topLeft.x() + bottomRight.x()) / 2 - size.width() / 2);
      }
    else
      {
      geometry.moveRight((topLeft.x() + bottomRight.x()) / 2 + size.width() / 2);
      }
    }
  else if (this->Alignment & Qt::AlignJustify)
    {
    geometry.moveLeft(topLeft.x());
    }

  if (this->Alignment & Qt::AlignTop)
    {
    if (this->VerticalDirection == ctkPopupWidget::TopToBottom)
      {
      geometry.moveTop(topLeft.y());
      }
    else
      {
      geometry.moveBottom(topLeft.y());
      }
    }
  else if (this->Alignment & Qt::AlignBottom)
    {
    if (this->VerticalDirection == ctkPopupWidget::TopToBottom)
      {
      geometry.moveTop(bottomRight.y());
      }
    else
      {
      geometry.moveBottom(bottomRight.y());
      }
    }
  else if (this->Alignment & Qt::AlignVCenter)
    {
    if (this->VerticalDirection == ctkPopupWidget::TopToBottom)
      {
      geometry.moveTop((topLeft.y() + bottomRight.y()) / 2 + size.height() / 2);
      }
    else
      {
      geometry.moveBottom((topLeft.y() + bottomRight.y()) / 2 - size.height() / 2);
      }
    }
  return geometry;
}

// -------------------------------------------------------------------------
// Qt::FramelessWindowHint is required on Windows for Translucent background
// Qt::Toolip is preferred to Qt::Popup as it would close itself at the first
// click outside the widget (typically a click in the BaseWidget)
ctkPopupWidget::ctkPopupWidget(QWidget* parentWidget)
  : Superclass(parentWidget, Qt::ToolTip | Qt::FramelessWindowHint)
  , d_ptr(new ctkPopupWidgetPrivate(*this))
{
  Q_D(ctkPopupWidget);
  d->init();
}

// -------------------------------------------------------------------------
ctkPopupWidget::~ctkPopupWidget()
{
}

// -------------------------------------------------------------------------
QWidget* ctkPopupWidget::baseWidget()const
{
  Q_D(const ctkPopupWidget);
  return d->BaseWidget;
}

// -------------------------------------------------------------------------
void ctkPopupWidget::setBaseWidget(QWidget* widget)
{
  Q_D(ctkPopupWidget);
  if (d->BaseWidget)
    {
    d->BaseWidget->removeEventFilter(this);
    }
  d->BaseWidget = widget;
  if (d->BaseWidget)
    {
    d->BaseWidget->installEventFilter(this);
    }
  QTimer::singleShot(ENTER_OPENING_DELAY, this, SLOT(updatePopup()));
}

// -------------------------------------------------------------------------
int ctkPopupWidget::opacity()const
{
  Q_D(const ctkPopupWidget);
  return d->Alpha;
}

// -------------------------------------------------------------------------
void ctkPopupWidget::setOpacity(int alpha)
{
  Q_D(ctkPopupWidget);
  d->Alpha = alpha;
  if (d->AlphaAnimation->state() == QAbstractAnimation::Stopped)
    {
    d->WindowAlpha = d->Alpha;
    }
  this->update();
}

// -------------------------------------------------------------------------
bool ctkPopupWidget::autoHide()const
{
  Q_D(const ctkPopupWidget);
  return d->AutoHide;
}

// -------------------------------------------------------------------------
void ctkPopupWidget::setAutoHide(bool mode)
{
  Q_D(ctkPopupWidget);
  d->AutoHide = mode;
  QTimer::singleShot(ENTER_OPENING_DELAY, this, SLOT(updatePopup()));
}

// -------------------------------------------------------------------------
ctkPopupWidget::AnimationEffect ctkPopupWidget::animationEffect()const
{
  Q_D(const ctkPopupWidget);
  return d->Effect;
}

// -------------------------------------------------------------------------
void ctkPopupWidget::setAnimationEffect(ctkPopupWidget::AnimationEffect effect)
{
  Q_D(ctkPopupWidget);
  /// TODO: handle the case where there is an animation running
  d->Effect = effect;
  bool transparent = (d->Effect == ctkPopupWidget::WindowOpacityFadeEffect);
  this->setAttribute(Qt::WA_NoSystemBackground, transparent);
  //this->setAttribute(Qt::WA_OpaquePaintEvent, !transparent);
  this->setAttribute(Qt::WA_TranslucentBackground, transparent);
}

// -------------------------------------------------------------------------
QEasingCurve::Type ctkPopupWidget::easingCurve()const
{
  Q_D(const ctkPopupWidget);
  return d->AlphaAnimation->easingCurve().type();
}

// -------------------------------------------------------------------------
void ctkPopupWidget::setEasingCurve(QEasingCurve::Type easingCurve)
{
  Q_D(ctkPopupWidget);
  d->AlphaAnimation->setEasingCurve(easingCurve);
  d->ScrollAnimation->setEasingCurve(easingCurve);
}

// -------------------------------------------------------------------------
Qt::Alignment ctkPopupWidget::alignment()const
{
  Q_D(const ctkPopupWidget);
  return d->Alignment;
}

// -------------------------------------------------------------------------
void ctkPopupWidget::setAlignment(Qt::Alignment alignment)
{
  Q_D(ctkPopupWidget);
  d->Alignment = alignment;
}

// -------------------------------------------------------------------------
Qt::Orientation ctkPopupWidget::orientation()const
{
  Q_D(const ctkPopupWidget);
  return d->Orientation;
}

// -------------------------------------------------------------------------
void ctkPopupWidget::setOrientation(Qt::Orientation orientation)
{
  Q_D(ctkPopupWidget);
  d->Orientation = orientation;
}

// -------------------------------------------------------------------------
ctkPopupWidget::VerticalDirection ctkPopupWidget::verticalDirection()const
{
  Q_D(const ctkPopupWidget);
  return d->VerticalDirection;
}

// -------------------------------------------------------------------------
void ctkPopupWidget::setVerticalDirection(ctkPopupWidget::VerticalDirection verticalDirection)
{
  Q_D(ctkPopupWidget);
  d->VerticalDirection = verticalDirection;
}

// -------------------------------------------------------------------------
Qt::LayoutDirection ctkPopupWidget::horizontalDirection()const
{
  Q_D(const ctkPopupWidget);
  return d->HorizontalDirection;
}

// -------------------------------------------------------------------------
void ctkPopupWidget::setHorizontalDirection(Qt::LayoutDirection horizontalDirection)
{
  Q_D(ctkPopupWidget);
  d->HorizontalDirection = horizontalDirection;
}

// -------------------------------------------------------------------------
void ctkPopupWidget::onEffectFinished()
{
  Q_D(ctkPopupWidget);
  if (qobject_cast<QAbstractAnimation*>(this->sender())->direction() == QAbstractAnimation::Backward)
    {
    this->hide();
    }
  else
    {
    this->show();
    }
}

// -------------------------------------------------------------------------
void ctkPopupWidget::paintEvent(QPaintEvent* event)
{
  Q_D(ctkPopupWidget);
  Q_UNUSED(event);

  if (d->Effect == WindowOpacityFadeEffect)
    {
    int opacity = d->Alpha;
    if (d->AlphaAnimation->state() != QAbstractAnimation::Stopped)
      {
      opacity = d->WindowAlpha;
      }
    QPainter painter(this);
    QBrush brush = this->palette().window();
    if (brush.style() == Qt::LinearGradientPattern ||
        brush.style() == Qt::ConicalGradientPattern ||
        brush.style() == Qt::RadialGradientPattern)
      {
      QGradient* newGradient = duplicateGradient(brush.gradient());
      QGradientStops stops;
      foreach(QGradientStop stop, newGradient->stops())
        {
        stop.second.setAlpha(opacity);
        stops.push_back(stop);
        }
      newGradient->setStops(stops);
      brush = QBrush(*newGradient);
      delete newGradient;
      }
    else
      {
      QColor color = brush.color();
      color.setAlpha(opacity);
      brush.setColor(color);
      }
    //QColor semiTransparentColor = this->palette().window().color();
    //semiTransparentColor.setAlpha(d->CurrentAlpha);
    painter.fillRect(this->rect(), brush);
    }
  // Let the QFrame draw itself if needed
  this->Superclass::paintEvent(event);
}

// --------------------------------------------------------------------------
void ctkPopupWidget::leaveEvent(QEvent* event)
{
  QTimer::singleShot(LEAVE_CLOSING_DELAY, this, SLOT(updatePopup()));
  this->Superclass::leaveEvent(event);
}

// --------------------------------------------------------------------------
void ctkPopupWidget::enterEvent(QEvent* event)
{
  QTimer::singleShot(ENTER_OPENING_DELAY, this, SLOT(updatePopup()));
  this->Superclass::enterEvent(event);
}

// --------------------------------------------------------------------------
bool ctkPopupWidget::eventFilter(QObject* obj, QEvent* event)
{
  Q_D(ctkPopupWidget);
  if (obj == d->BaseWidget &&
      event->type() == QEvent::Enter)
    {
    QTimer::singleShot(ENTER_OPENING_DELAY, this, SLOT(updatePopup()));
    }
  else if (obj == d->BaseWidget &&
      event->type() == QEvent::Leave)
    {
    QTimer::singleShot(LEAVE_CLOSING_DELAY, this, SLOT(updatePopup()));
    }
  return this->QObject::eventFilter(obj, event);
}

// --------------------------------------------------------------------------
void ctkPopupWidget::updatePopup()
{
  Q_D(ctkPopupWidget);
  if (!d->AutoHide)
    {
    return;
    }
  if (this->underMouse() ||
      (d->BaseWidget && d->BaseWidget->underMouse()) ||
      (d->PopupPixmapWidget && d->PopupPixmapWidget->underMouse()))
    {
    this->showPopup();
    }
  else
    {
    this->hidePopup();
    }
}

// --------------------------------------------------------------------------
void ctkPopupWidget::showPopup()
{
  Q_D(ctkPopupWidget);
  if ((this->isVisible() &&
       d->currentAnimation()->state() == QAbstractAnimation::Stopped) ||
      (d->BaseWidget && !d->BaseWidget->isVisible()))
    {
    return;
    }
  if (d->BaseWidget)
    {
    /*
    QPoint bottomLeft = QPoint(d->BaseWidget->geometry().x(), d->BaseWidget->geometry().bottom());
    QPoint pos = d->BaseWidget->parentWidget() ? d->BaseWidget->parentWidget()->mapToGlobal(bottomLeft) : bottomLeft;
    this->move(pos);
    /// TODO: need some refinement
    if ((this->sizePolicy().horizontalPolicy() & QSizePolicy::GrowFlag &&
          this->width() < d->BaseWidget->width()) ||
        (this->sizePolicy().horizontalPolicy() & QSizePolicy::ShrinkFlag &&
          this->width() > d->BaseWidget->width()))
      {
      // Fit to BaseWidget size
      this->resize(d->BaseWidget->width(), this->sizeHint().height());
      }
    */
    }
  this->setGeometry(d->openGeometry());
  d->currentAnimation()->setDirection(QAbstractAnimation::Forward);
  
  switch(d->Effect)
    {
    case WindowOpacityFadeEffect:
      // just in case it wasn't visible, usually it's a no op
      this->show();
      break;
    case ScrollEffect:
      {
      /*
      QRect endGeometry = this->geometry();
      if (!this->testAttribute(Qt::WA_WState_Created) &&
          !d->fitBaseWidgetSize())
        {
        endGeometry.setSize(this->sizeHint());
        }
      QRect startGeometry = endGeometry;
      startGeometry.setHeight(0);
      d->PopupPixmapWidget->setGeometry(startGeometry);
      d->ScrollAnimation->setStartValue(startGeometry);
      d->ScrollAnimation->setEndValue(endGeometry);
      */
      d->PopupPixmapWidget->setGeometry(d->closedGeometry());
      d->ScrollAnimation->setStartValue(d->closedGeometry());
      d->ScrollAnimation->setEndValue(d->openGeometry());
      d->PopupPixmapWidget->setAlignment(d->pixmapAlignment());
      QPixmap pixmap = QPixmap::grabWidget(this, QRect(QPoint(0,0), d->openGeometry().size()));
      d->PopupPixmapWidget->setPixmap(pixmap);
      d->PopupPixmapWidget->setWindowOpacity(this->windowOpacity());
      d->PopupPixmapWidget->show();
      break;
      }
    default:
      break;
    }
  switch(d->currentAnimation()->state())
    {
    case QAbstractAnimation::Stopped:
      d->WindowAlpha = 0;
      d->currentAnimation()->start();
      break;
    case QAbstractAnimation::Paused:
      d->currentAnimation()->resume();
      break;
    default:
    case QAbstractAnimation::Running:
      break;
    }
}

// --------------------------------------------------------------------------
void ctkPopupWidget::hidePopup()
{
  Q_D(ctkPopupWidget);

  if (!this->isVisible() &&
      d->currentAnimation()->state() == QAbstractAnimation::Stopped)
    {
    return;
    }
  d->currentAnimation()->setDirection(QAbstractAnimation::Backward);
  switch(d->Effect)
    {
    case ScrollEffect:
      {
      d->PopupPixmapWidget->setAlignment(d->pixmapAlignment());
      QPixmap pixmap = QPixmap::grabWidget(this, QRect(QPoint(0,0), this->size()));
      d->PopupPixmapWidget->setPixmap(pixmap);
      d->PopupPixmapWidget->setWindowOpacity(this->windowOpacity());
      d->PopupPixmapWidget->show();
      this->hide();
      break;
      }
    default:
      break;
    }
  switch(d->currentAnimation()->state())
    {
    case QAbstractAnimation::Stopped:
      d->currentAnimation()->start();
      break;
    case QAbstractAnimation::Paused:
      d->currentAnimation()->resume();
      break;
    default:
    case QAbstractAnimation::Running:
      break;
    }
}

// --------------------------------------------------------------------------
int ctkPopupWidget::windowAlpha()const
{
  Q_D(const ctkPopupWidget);
  return d->WindowAlpha;
}

// --------------------------------------------------------------------------
void ctkPopupWidget::setWindowAlpha(int alpha)
{
  Q_D(ctkPopupWidget);
  d->WindowAlpha = alpha;
  this->repaint();
}

// --------------------------------------------------------------------------
QRect ctkPopupWidget::windowGeometry()const
{
  Q_D(const ctkPopupWidget);
  return d->PopupPixmapWidget->geometry();
}

// --------------------------------------------------------------------------
void ctkPopupWidget::setWindowGeometry(QRect newGeometry)
{
  Q_D(ctkPopupWidget);
  d->PopupPixmapWidget->setGeometry(newGeometry);
  d->PopupPixmapWidget->repaint();
}