#include "toonzqt/dvscrollwidget.h"

// TnzQt includes
#include "toonzqt/freelayout.h"

// Qt includes
#include <QLayout>
#include <QPushButton>
#include <QPropertyAnimation>
#include <QResizeEvent>
#include <QMouseEvent>
#include <QTimer>

// STD includes
#include <numeric>

//****************************************************************************
//    Local namespace stuff
//****************************************************************************

namespace
{

class ScrollLayout : public DummyLayout
{
	DvScrollWidget *m_scrollWidget;

public:
	ScrollLayout(DvScrollWidget *scrollWidget)
		: m_scrollWidget(scrollWidget)
	{
		assert(m_scrollWidget);
	}

	QSize minimumSize() const
	{
		struct locals {
			inline static QSize expand(const QSize &size, const QLayoutItem *item)
			{
				return size.expandedTo(item->minimumSize());
			}
		};

		QSize minSize = std::accumulate(m_items.begin(), m_items.end(),
										QSize(), locals::expand);

		return (m_scrollWidget->getOrientation() == Qt::Horizontal) ? QSize(0, minSize.height()) : QSize(minSize.width(), 0);
	}

	QSize maximumSize() const
	{
		struct locals {
			inline static QSize bound(const QSize &size, const QLayoutItem *item)
			{
				return size.boundedTo(item->minimumSize());
			}
		};

		QSize maxSize = std::accumulate(m_items.begin(), m_items.end(),
										QSize(QWIDGETSIZE_MAX, QWIDGETSIZE_MAX), locals::bound);

		return (m_scrollWidget->getOrientation() == Qt::Horizontal) ? QSize(QWIDGETSIZE_MAX, maxSize.height()) : QSize(maxSize.width(), QWIDGETSIZE_MAX);
	}

	void setGeometry(const QRect &r)
	{
		const Qt::Orientation orientation = m_scrollWidget->getOrientation();

		QList<QLayoutItem *>::const_iterator it, iEnd = m_items.end();
		for (it = m_items.begin(); it != iEnd; ++it) {
			QLayoutItem *item = *it;

			QSize targetSize = item->sizeHint();

			if (orientation & item->expandingDirections()) {
				if (orientation & Qt::Horizontal)
					targetSize.setWidth(r.width());
				else
					targetSize.setHeight(r.height());
			}

			const QSize &minSize = item->minimumSize(),
						&maxSize = item->maximumSize();

			targetSize.setWidth(tcrop(targetSize.width(), minSize.width(), maxSize.width()));
			targetSize.setHeight(tcrop(targetSize.height(), minSize.height(), maxSize.height()));

			const QRect &geom = item->geometry();

			if (geom.size() != targetSize)
				item->setGeometry(QRect(geom.topLeft(), targetSize));
		}

		m_scrollWidget->scroll(0); // Refresh scroll buttons visibility
	}
};

//==============================================================================

qreal heldScrollEasing(qreal progress)
{
	//Equilibrate sum of Linear and InQuad
	return 0.5 * progress * (1.0 + progress);
}

} // namespace

//****************************************************************************
//    DvScrollWidget implementation
//****************************************************************************

DvScrollWidget::DvScrollWidget(QWidget *parent, Qt::Orientation orientation)
	: QFrame(parent), m_content(0), m_animation(0), m_clickEase(QEasingCurve::OutCubic), m_holdEase(QEasingCurve::Linear), m_backwardTimer(new QTimer(this)), m_forwardTimer(new QTimer(this)), m_pressed(false), m_heldRelease(false), m_heldClick(false)
{
	ScrollLayout *scrollLayout = new ScrollLayout(this);
	setLayout(scrollLayout);

	// At the toolbar sides, add scroll buttons
	m_scrollBackward = new QPushButton(this);	  // NOTE: Not being managed by the scroll layout.
	m_scrollBackward->setFixedSize(24, 24);		   //       It's not necessary. They are not part
	m_scrollBackward->setFocusPolicy(Qt::NoFocus); //       of the content.

	m_scrollForward = new QPushButton(this); //       Observe that the parent widget must
	m_scrollForward->setFixedSize(24, 24);   //       therefore be explicitly supplied.
	m_scrollForward->setFocusPolicy(Qt::NoFocus);

	setOrientation(orientation);

	m_scrollBackward->move(0, 0);

	m_backwardTimer->setInterval(450);
	m_forwardTimer->setInterval(450);
	m_backwardTimer->setSingleShot(true);
	m_forwardTimer->setSingleShot(true);

	connect(m_scrollBackward, SIGNAL(clicked(bool)), this, SLOT(scrollBackward()));
	connect(m_scrollForward, SIGNAL(clicked(bool)), this, SLOT(scrollForward()));
	connect(m_backwardTimer, SIGNAL(timeout()), this, SLOT(holdBackward()));
	connect(m_forwardTimer, SIGNAL(timeout()), this, SLOT(holdForward()));

	connect(m_scrollBackward, SIGNAL(pressed()), m_backwardTimer, SLOT(start()));
	connect(m_scrollForward, SIGNAL(pressed()), m_forwardTimer, SLOT(start()));
	connect(m_scrollBackward, SIGNAL(released()), this, SLOT(releaseBackward()));
	connect(m_scrollForward, SIGNAL(released()), this, SLOT(releaseForward()));
}

//------------------------------------------------------------------------------

void DvScrollWidget::setWidget(QWidget *widget)
{
	// Delete currently set widget, if any
	QLayout *lay = layout();

	while (QLayoutItem *item = lay->takeAt(0)) // Should be 1 item only - while is just to be pedant
	{
		assert(item->widget());

		delete item->widget(); // The item DOES NOT own the widget.
		delete item;		   // The parent widget (this) does - this
	}						   // is by Qt's manual.

	// Add widget
	lay->addWidget(widget);
	m_content = widget;
	m_content->lower(); // Needs to be below the scroll buttons.
						// Seemingly not working on Mac (see showEvent).

	assert(widget->parent() == this);

	// Use animations to make scrolling 'smooth'
	delete m_animation;
	m_animation = new QPropertyAnimation(m_content, "pos");
	connect(m_animation, SIGNAL(stateChanged(QAbstractAnimation::State, QAbstractAnimation::State)),
			this, SLOT(updateButtonsVisibility()));
}

//------------------------------------------------------------------------------

void DvScrollWidget::setOrientation(Qt::Orientation orientation)
{
	if ((m_horizontal = (orientation == Qt::Horizontal))) {
		setSizePolicy(QSizePolicy::Preferred, QSizePolicy::Fixed);

		m_scrollBackward->setObjectName("ScrollLeftButton");
		m_scrollForward->setObjectName("ScrollRightButton");
	} else {
		setSizePolicy(QSizePolicy::Fixed, QSizePolicy::Preferred);

		m_scrollBackward->setObjectName("ScrollUpButton");
		m_scrollForward->setObjectName("ScrollDownButton");
	}
}

//------------------------------------------------------------------------------

Qt::Orientation DvScrollWidget::getOrientation() const
{
	return m_horizontal ? Qt::Horizontal : Qt::Vertical;
}

//------------------------------------------------------------------------------

void DvScrollWidget::setEasing(QEasingCurve clickEase, QEasingCurve holdPressEase)
{
	m_clickEase = clickEase;
	m_holdEase = holdPressEase;
}

//------------------------------------------------------------------------------

void DvScrollWidget::scroll(int dx, int duration, QEasingCurve ease)
{
	if (m_content)
		scrollTo(m_horizontal ? m_content->x() + dx : m_content->y() + dx, duration, ease);
}

//------------------------------------------------------------------------------

void DvScrollWidget::scrollTo(int pos, int duration, QEasingCurve ease)
{
	if (!m_content)
		return;

	// Retrieve the contents' bounds
	QRect bounds(m_content->pos(), m_content->size());

	QPoint newPos;
	if (m_horizontal) {
		newPos = QPoint(pos, 0);
		int minPos = width() - bounds.width();

		if (newPos.x() <= minPos)
			newPos.setX(minPos);
		if (newPos.x() >= 0)
			newPos.setX(0);
	} else {
		newPos = QPoint(0, pos);
		int minPos = height() - bounds.height();

		if (newPos.y() <= minPos)
			newPos.setY(minPos);
		if (newPos.y() >= 0)
			newPos.setY(0);
	}

	if (duration > 0) {
		m_animation->stop();
		m_animation->setEasingCurve(ease);
		m_animation->setStartValue(bounds.topLeft());
		m_animation->setEndValue(newPos);
		m_animation->setDuration(duration);
		m_animation->start();
	} else {
		m_content->move(newPos);
		updateButtonsVisibility();
	}
}

//------------------------------------------------------------------------------

void DvScrollWidget::updateButtonsVisibility()
{
	if ((!m_content) || (m_animation->state() == QPropertyAnimation::Running))
		return;

	QRect bounds(m_content->pos(), m_content->size());
	if (m_horizontal) {
		if (bounds.right() <= width()) {
			m_scrollForward->setDown(false);
			m_scrollForward->hide();
			m_heldRelease = m_heldClick = false;
		} else
			m_scrollForward->show();

		if (bounds.left() >= 0) {
			m_scrollBackward->setDown(false);
			m_scrollBackward->hide();
			m_heldRelease = m_heldClick = false;
		} else
			m_scrollBackward->show();
	} else {
		if (bounds.bottom() <= height()) {
			m_scrollForward->setDown(false);
			m_scrollForward->hide();
			m_heldRelease = m_heldClick = false;
		} else
			m_scrollForward->show();

		if (bounds.top() >= 0) {
			m_scrollBackward->setDown(false);
			m_scrollBackward->hide();
			m_heldRelease = m_heldClick = false;
		} else
			m_scrollBackward->show();
	}
}

//------------------------------------------------------------------------------

void DvScrollWidget::showEvent(QShowEvent *se)
{
	// These are necessary on Mac.
	m_scrollBackward->raise();
	m_scrollForward->raise();
}

//------------------------------------------------------------------------------

void DvScrollWidget::resizeEvent(QResizeEvent *re)
{
	QWidget::resizeEvent(re);
	scroll(0);
	if (m_horizontal) {
		m_scrollBackward->setFixedSize(m_scrollBackward->width(), height());
		m_scrollForward->setFixedSize(m_scrollForward->width(), height());
		m_scrollForward->move(re->size().width() - m_scrollForward->width(), 0);
	} else {
		m_scrollBackward->setFixedSize(width(), m_scrollBackward->height());
		m_scrollForward->setFixedSize(width(), m_scrollForward->height());
		m_scrollForward->move(0, re->size().height() - m_scrollForward->height());
	}
}

//------------------------------------------------------------------------------

void DvScrollWidget::mousePressEvent(QMouseEvent *me)
{
	m_pressed = true;
	m_mousePos = m_horizontal ? me->x() : me->y();
	me->accept();
}

//------------------------------------------------------------------------------

void DvScrollWidget::mouseMoveEvent(QMouseEvent *me)
{
	if (!m_pressed)
		return;

	if (m_horizontal) {
		scroll(me->x() - m_mousePos);
		m_mousePos = me->x();
	} else {
		scroll(me->y() - m_mousePos);
		m_mousePos = me->y();
	}
	me->accept();
}

//------------------------------------------------------------------------------

void DvScrollWidget::mouseReleaseEvent(QMouseEvent *me)
{
	m_pressed = false;
	me->accept();
}

//------------------------------------------------------------------------------

void DvScrollWidget::holdBackward()
{
	if (!m_content)
		return;

	m_heldRelease = m_heldClick = true;

	QRect bounds(m_content->pos(), m_content->size());
	int spaceLeft = -(m_horizontal ? bounds.left() : bounds.top());

	QEasingCurve ease;
	ease.setCustomType(&heldScrollEasing);
	scrollTo(0, spaceLeft * 10, ease); // 100 pix per second
}

//------------------------------------------------------------------------------

void DvScrollWidget::holdForward()
{
	if (!m_content)
		return;

	m_heldRelease = m_heldClick = true;

	QRect bounds(m_content->pos(), m_content->size());
	int pos = m_horizontal ? width() - bounds.width() : height() - bounds.height();
	int spaceLeft = (m_horizontal ? bounds.left() : bounds.top()) - pos;

	QEasingCurve ease;
	ease.setCustomType(&heldScrollEasing);
	scrollTo(pos, spaceLeft * 10, ease); // 100 pix per second
}

//------------------------------------------------------------------------------

void DvScrollWidget::releaseBackward()
{
	m_backwardTimer->stop();

	if (m_heldRelease)
		m_animation->stop();

	m_heldRelease = false;
}

//------------------------------------------------------------------------------

void DvScrollWidget::releaseForward()
{
	m_forwardTimer->stop();

	if (m_heldRelease)
		m_animation->stop();

	m_heldRelease = false;
}

//------------------------------------------------------------------------------

void DvScrollWidget::scrollBackward()
{
	if (!m_heldClick)
		scroll(0.5 * (m_horizontal ? width() : height()), 300);

	m_heldClick = false;
}

//------------------------------------------------------------------------------

void DvScrollWidget::scrollForward()
{
	if (!m_heldClick)
		scroll(-0.5 * (m_horizontal ? width() : height()), 300);

	m_heldClick = false;
}