#include "elementprimitivedecorator.h"
#include "elementscene.h"
#include "customelementpart.h"
#include "editorcommands.h"
#include "qet.h"
#include <QPainter>
#include <QDebug>
#include <QGraphicsSceneHoverEvent>
#include <QStyleOptionGraphicsItem>
#include <QGraphicsScene>
#include <QTransform>

/**
	Constructor
	@param parent Parent QGraphicsItem
*/
ElementPrimitiveDecorator::ElementPrimitiveDecorator(QGraphicsItem *parent):
	QGraphicsObject(parent)
{
	init();
}

/**
	Destructor
*/
ElementPrimitiveDecorator::~ElementPrimitiveDecorator() {
}

/**
	@return the internal bouding rect, i.e. the smallest rectangle containing
	the bounding rectangle of every selected item.
*/
QRectF ElementPrimitiveDecorator::internalBoundingRect() const {
	if (!decorated_items_.count() || !scene()) return(QRectF());
	
	QRectF rect = getSceneBoundingRect(decorated_items_.first() -> toItem());
	foreach (CustomElementPart *item, decorated_items_) {
		rect = rect.united(getSceneBoundingRect(item -> toItem()));
	}
	return(rect);
}

/**
	@return the outer bounds of the decorator as a rectangle.
*/
QRectF ElementPrimitiveDecorator::boundingRect() const {
	const qreal additional_margin = 2.5;
	
	QRectF rect = effective_bounding_rect_;
	rect.adjust(-additional_margin, -additional_margin, additional_margin, additional_margin);
	return(rect);
}

/**
	Paint the contents of an item in local coordinates, using \a painter, with
	respect to \a option and
	@param option The option parameter provides style options for the item, such
	as its state, exposed area and its level-of-detail hints.
	@param The widget argument is optional. If provided, it points to the
	widget that is being painted on; otherwise, it is 0. For cached painting,
	widget is always 0.
*/
void ElementPrimitiveDecorator::paint(QPainter *painter, const QStyleOptionGraphicsItem *option, QWidget *widget) {
	Q_UNUSED(option)
	Q_UNUSED(widget)
	painter -> save();
	
	// paint the original bounding rect
	painter -> setPen(Qt::DashLine);
	//QGraphicsItemGroup::paint(painter, option, widget);
	painter -> drawRect(modified_bounding_rect_);
	drawSquares(painter, option, widget);
	
	// uncomment to draw the real bouding rect (=adjusted internal bounding rect)
	// painter -> setBrush(QBrush(QColor(240, 0, 0, 127)));
	// painter -> drawRect(boundingRect());
	painter -> restore();
}

/**
	@param items the new list of items this decorator is suposed to manipulate.
*/
void ElementPrimitiveDecorator::setItems(const QList<CustomElementPart *> &items) {
	if (CustomElementPart *single_item = singleItem()) {
		if (items.count() == 1 && items.first() == single_item) {
			// no actual change
			goto end_setItems;
		}
		
		// break any connection between the former single selected item (if any) and
		// the decorator
		single_item -> setDecorator(0);
		if (QGraphicsObject *single_object = dynamic_cast<QGraphicsObject *>(single_item)) {
			disconnect(single_object, 0, this, 0);
		}
	}
	
	decorated_items_ = items;
	
	// when only a single primitive is selected, the decorator behaves specially
	// to enable extra features, such as text edition, internal points movements,
	// etc.
	if (CustomElementPart *single_item = singleItem()) {
		single_item -> setDecorator(this);
	}
	
	end_setItems:
	adjust();
	show();
	grabKeyboard();
}

/**
	@param items the new list of items this decorator is suposed to manipulate.
*/
void ElementPrimitiveDecorator::setItems(const QList<QGraphicsItem *> &items) {
	QList<CustomElementPart *> primitives;
	foreach (QGraphicsItem *item, items) {
		if (CustomElementPart *part_item = dynamic_cast<CustomElementPart *>(item)) {
			primitives << part_item;
		}
	}
	setItems(primitives);
}

/**
	@return the list of items this decorator is supposed to manipulate
*/
QList<CustomElementPart *> ElementPrimitiveDecorator::items() const {
	return(decorated_items_);
}

/**
	@return the list of items this decorator is supposed to manipulate
*/
QList<QGraphicsItem *> ElementPrimitiveDecorator::graphicsItems() const {
	QList<QGraphicsItem *> list;
	foreach (CustomElementPart *part_item, decorated_items_) {
		if (QGraphicsItem *item = dynamic_cast<QGraphicsItem *>(part_item)) {
			list << item;
		}
	}
	return(list);
}

/**
	Adjust the visual decorator according to the currently assigned items.
	It is notably called by setItems().
*/
void ElementPrimitiveDecorator::adjust() {
	saveOriginalBoundingRect();
	modified_bounding_rect_ = original_bounding_rect_;
	adjustEffectiveBoundingRect();
}

/**
	Handle events generated when the mouse hovers over the decorator.
	@param event Object describing the hover event.
*/
void ElementPrimitiveDecorator::hoverMoveEvent(QGraphicsSceneHoverEvent *event) {
	QList<QRectF> rects = getResizingSquares();
	QPointF pos = event -> pos();
	
	if (rects.at(QET::ResizeFromTopLeftCorner).contains(pos) || rects.at(QET::ResizeFromBottomRightCorner).contains(pos)) {
		setCursor(Qt::SizeFDiagCursor);
	} else if (rects.at(QET::ResizeFromTopRightCorner).contains(pos) || rects.at(QET::ResizeFromBottomLeftCorner).contains(pos)) {
		setCursor(Qt::SizeBDiagCursor);
	} else if (rects.at(QET::ResizeFromTopCenterCorner).contains(pos) || rects.at(QET::ResizeFromBottomCenterCorner).contains(pos)) {
		setCursor(Qt::SizeVerCursor);
	} else if (rects.at(QET::ResizeFromMiddleLeftCorner).contains(pos) || rects.at(QET::ResizeFromMiddleRightCorner).contains(pos)) {
		setCursor(Qt::SizeHorCursor);
	} else if (internalBoundingRect().contains(pos)) {
		setCursor(Qt::SizeAllCursor);
	} else {
		setCursor(Qt::ArrowCursor);
	}
}

/**
	Handle event generated when mouse buttons are pressed.
	@param event Object describing the mouse event
*/
void ElementPrimitiveDecorator::mousePressEvent(QGraphicsSceneMouseEvent *event) {
	qDebug() << Q_FUNC_INFO << event << zValue();
	QList<QRectF> rects = getResizingSquares();
	QPointF pos = event -> pos();
	
	current_operation_square_ = resizingSquareAtPos(pos);
	bool accept = false;
	if (current_operation_square_ != QET::NoOperation) {
		accept = true;
	} else {
		if (internalBoundingRect().contains(pos)) {
			if (CustomElementPart *single_item = singleItem()) {
				bool event_accepted = single_item -> singleItemPressEvent(this, event);
				if (event_accepted) {
					event -> ignore();
					return;
				}
			}
			current_operation_square_ = QET::MoveArea;
			accept = true;
		}
	}
	
	if (accept) {
		if (current_operation_square_ > QET::NoOperation) {
			first_pos_ = latest_pos_ = mapToScene(rects.at(current_operation_square_).center());
		} else {
			first_pos_ = decorated_items_.at(0) -> toItem() -> scenePos();
			latest_pos_ = event -> scenePos();
			mouse_offset_ = event -> scenePos() - first_pos_;
		}
		startMovement();
		event -> accept();
	} else {
		event -> ignore();
	}
}

/**
	Handle events generated when mouse buttons are double clicked.
	@param event Object describing the mouse event
*/
void ElementPrimitiveDecorator::mouseDoubleClickEvent(QGraphicsSceneMouseEvent *event) {
	//QGraphicsObject::mouseDoubleClickEvent(event);
	if (CustomElementPart *single_item = singleItem()) {
		bool event_accepted = single_item -> singleItemDoubleClickEvent(this, event);
		if (event_accepted) {
			event -> ignore();
			return;
		}
	}
}

/**
	Handle event generated when the mouse is moved and the decorator is the mouse grabber item.
	@param event Object describing the mouse event
	@see QGraphicsScene::mouseGrabberItem()
*/
void ElementPrimitiveDecorator::mouseMoveEvent(QGraphicsSceneMouseEvent *event) {
	QList<QRectF> rects = getResizingSquares();
	
	QPointF scene_pos = event -> scenePos();
	QPointF movement = scene_pos - latest_pos_;
	
	// snap the movement to a non-visible grid when scaling selection
	if (mustSnapToGrid(event)) {
		// We now want some point belonging to the selection to be snapped to this rounded position
		if (current_operation_square_ > QET::NoOperation) {
			// real, non-rounded movement from the mouse press event
			QPointF global_movement = scene_pos - first_pos_;
			
			// real, rounded movement from the mouse press event
			QPointF rounded_global_movement = snapConstPointToGrid(global_movement);
			
			// rounded position of the current mouse move event
			QPointF rounded_scene_pos = first_pos_ + rounded_global_movement;
			
			// when scaling the selection, consider the center of the currently dragged resizing rectangle
			QPointF current_position = mapToScene(rects.at(current_operation_square_).center());
			// determine the final, effective movement
			movement = rounded_scene_pos - current_position;
		} else if (current_operation_square_ == QET::MoveArea) {
			// when moving the selection, consider the position of the first selected item
			QPointF current_position = scene_pos - mouse_offset_;
			QPointF rounded_current_position = snapConstPointToGrid(current_position);
			movement = rounded_current_position - decorated_items_.at(0) -> toItem() -> scenePos();
		} else {
			if (CustomElementPart *single_item = singleItem()) {
				bool event_accepted = single_item -> singleItemMoveEvent(this, event);
				if (event_accepted) {
					event -> ignore();
					return;
				}
			}
		}
	}
	
	QRectF bounding_rect = modified_bounding_rect_;
	applyMovementToRect(current_operation_square_, movement, modified_bounding_rect_);
	if (modified_bounding_rect_ != bounding_rect) {
		adjustEffectiveBoundingRect();
	}
	latest_pos_ = event -> scenePos();
	
	if (current_operation_square_ == QET::MoveArea) {
		translateItems(movement);
	} else {
		scaleItems(original_bounding_rect_, modified_bounding_rect_);
	}
}

/**
	Handle event generated when a mouse buttons are releaseis moved and the
	decorator is the mouse grabber item.
	@param event Object describing the mouse event
	@see QGraphicsScene::mouseGrabberItem()
*/
void ElementPrimitiveDecorator::mouseReleaseEvent(QGraphicsSceneMouseEvent *event) {
	Q_UNUSED(event)
	
	ElementEditionCommand *command = 0;
	if (current_operation_square_ > QET::NoOperation) {
		ScalePartsCommand *scale_command = new ScalePartsCommand();
		scale_command -> setScaledPrimitives(items());
		scale_command -> setTransformation(
			mapToScene(original_bounding_rect_).boundingRect(),
			mapToScene(modified_bounding_rect_).boundingRect()
		);
		command = scale_command;
	} else if (current_operation_square_ == QET::MoveArea) {
		QPointF movement = mapToScene(modified_bounding_rect_.topLeft()) - mapToScene(original_bounding_rect_.topLeft());
		if (!movement.isNull()) {
			MovePartsCommand *move_command = new MovePartsCommand(movement, 0, graphicsItems());
			command = move_command;
		}
	} else {
		if (CustomElementPart *single_item = singleItem()) {
			bool event_accepted = single_item -> singleItemReleaseEvent(this, event);
			if (event_accepted) {
				event -> ignore();
				return;
			}
		}
	}
	
	if (command) {
		emit(actionFinished(command));
	}
	
	if (current_operation_square_ != QET::NoOperation) {
		adjust();
	}
	
	current_operation_square_ = QET::NoOperation;
}

/**
	Initialize an ElementPrimitiveDecorator
*/
void ElementPrimitiveDecorator::init() {
	//setAcceptedMouseButtons(Qt::LeftButton);
	grid_step_x_ = grid_step_y_ = 1;
	setAcceptHoverEvents(true);
}

/**
	Save the original bounding rectangle.
*/
void ElementPrimitiveDecorator::saveOriginalBoundingRect() {
	original_bounding_rect_ = internalBoundingRect();
}

/**
	Adjust the effective bounding rect. This method should be called after the
	modified_bouding_rect_ attribute was modified.
*/
void ElementPrimitiveDecorator::adjustEffectiveBoundingRect() {
	prepareGeometryChange();
	effective_bounding_rect_ = modified_bounding_rect_ | effective_bounding_rect_;
	update();
}

/**
	Start a movement (i.e. either a move or scaling operation)
*/
void ElementPrimitiveDecorator::startMovement() {
	adjust();
	
	foreach(CustomElementPart *item, decorated_items_) {
		qDebug() << Q_FUNC_INFO << "starting movement with rect" << original_bounding_rect_ << "i.e. in scene coordinates " << mapToScene(original_bounding_rect_).boundingRect();
		item -> startUserTransformation(mapToScene(original_bounding_rect_).boundingRect());
	}
}

/**
	Apply the movement described by \a movement_type and \a movement to \a rect.
*/
void ElementPrimitiveDecorator::applyMovementToRect(int movement_type, const QPointF &movement, QRectF &rect) {
	qreal new_value;
	QPointF new_point;
	
	switch (movement_type) {
		case QET::MoveArea:
			rect.translate(movement.x(), movement.y());
			break;
		case QET::ResizeFromTopLeftCorner:
			new_point = rect.topLeft() + movement;
			rect.setTopLeft(new_point);
			break;
		case QET::ResizeFromTopCenterCorner:
			new_value = rect.top() + movement.y();
			rect.setTop(new_value);
			break;
		case QET::ResizeFromTopRightCorner:
			new_point = rect.topRight() + movement;
			rect.setTopRight(new_point);
			break;
		case QET::ResizeFromMiddleLeftCorner:
			new_value = rect.left() + movement.x();
			rect.setLeft(new_value);
			break;
		case QET::ResizeFromMiddleRightCorner:
			new_value = rect.right() + movement.x();
			rect.setRight(new_value);
			break;
		case QET::ResizeFromBottomLeftCorner:
			new_point = rect.bottomLeft() + movement;
			rect.setBottomLeft(new_point);
			break;
		case QET::ResizeFromBottomCenterCorner:
			new_value = rect.bottom() + movement.y();
			rect.setBottom(new_value);
			break;
		case QET::ResizeFromBottomRightCorner:
			new_point = rect.bottomRight() + movement;
			rect.setBottomRight(new_point);
			break;
	}
}

CustomElementPart *ElementPrimitiveDecorator::singleItem() const {
	if (decorated_items_.count() == 1) {
		return(decorated_items_.first());
	}
	return(0);
}

/**
	Translated the managed items by the \a movement
*/
void ElementPrimitiveDecorator::translateItems(const QPointF &movement) {
	if (!decorated_items_.count()) return;
	
	foreach(QGraphicsItem *qgi, graphicsItems()) {
		// this is a naive, proof-of-concept implementation; we actually need to take
		// the grid into account and create a command object in mouseReleaseEvent()
		qgi -> moveBy(movement.x(), movement.y());
	}
}


/**
	Scale the managed items, provided they originally fit within \a
	original_rect and they should now fit \a new_rect
*/
void ElementPrimitiveDecorator::scaleItems(const QRectF &original_rect, const QRectF &new_rect) {
	if (!decorated_items_.count()) return;
	if (original_rect == new_rect) return;
	if (!original_rect.width() || !original_rect.height()) return; // cowardly flee division by zero FIXME?
	
	QRectF scene_original_rect = mapToScene(original_rect).boundingRect();
	QRectF scene_new_rect = mapToScene(new_rect).boundingRect();
	qDebug() << Q_FUNC_INFO << "from " << original_rect << " to " << new_rect;
	qDebug() << Q_FUNC_INFO << "from " << scene_original_rect << " to " << scene_new_rect << "(scene coordinates)";
	
	foreach(CustomElementPart *item, decorated_items_) {
		item -> handleUserTransformation(scene_original_rect, scene_new_rect);
	}
}

/**
	@return the bounding rectangle of \a item, in scene coordinates
*/
QRectF ElementPrimitiveDecorator::getSceneBoundingRect(QGraphicsItem *item) const {
	if (!item) return(QRectF());
	return(item -> mapRectToScene(item -> boundingRect()));
}

/**
	Draw all known resizing squares using \a painter.
	@param option The option parameter provides style options for the item, such
	as its state, exposed area and its level-of-detail hints.
	@param The widget argument is optional. If provided, it points to the
	widget that is being painted on; otherwise, it is 0. For cached painting,
	widget is always 0.
*/
void ElementPrimitiveDecorator::drawSquares(QPainter *painter, const QStyleOptionGraphicsItem *option, QWidget *widget) {
	foreach (QRectF rect, getResizingSquares()) {
		drawResizeSquare(painter, option, widget, rect);
	}
}

/**
	Draw the provided resizing square \a rect using \a painter.
	@param option The option parameter provides style options for the item, such
	as its state, exposed area and its level-of-detail hints.
	@param The widget argument is optional. If provided, it points to the
	widget that is being painted on; otherwise, it is 0. For cached painting,
	widget is always 0.
*/
void ElementPrimitiveDecorator::drawResizeSquare(QPainter *painter, const QStyleOptionGraphicsItem *option, QWidget *widget, const QRectF &rect) {
	QColor inner(0xFF, 0xFF, 0xFF);
	QColor outer(0x00, 0x61, 0xFF);
	if (decorated_items_.count() > 1) {
		outer = QColor(0x1A, 0x5C, 0x14);
	}
	drawGenericSquare(painter, option, widget, rect, inner, outer);
}

/**
	Draw a generic square \a rect using \a painter.
	@param inner Color used to fill the square
	@param outer Color usd to draw the outline
	@param option The option parameter provides style options for the item, such
	as its state, exposed area and its level-of-detail hints.
	@param The widget argument is optional. If provided, it points to the
	widget that is being painted on; otherwise, it is 0. For cached painting,
	widget is always 0.
*/
void ElementPrimitiveDecorator::drawGenericSquare(QPainter *painter, const QStyleOptionGraphicsItem *option, QWidget *widget, const QRectF &rect, const QColor &inner, const QColor &outer) {
	Q_UNUSED(option)
	Q_UNUSED(widget)
	// 1.0px will end up to level_of_details px once rendered
	// qreal level_of_details = option->levelOfDetailFromTransform(painter -> transform());
	
	painter -> save();
	painter -> setBrush(QBrush(inner));
	QPen square_pen(QBrush(outer), 2.0, Qt::SolidLine, Qt::SquareCap, Qt::MiterJoin);
	square_pen.setCosmetic(true);
	painter -> setPen(square_pen);
	painter -> drawRect(rect);
	painter -> restore();
}

/**
	@return A list containing all known resizing squares, based on the
	modified_bounding_rect_ attribute. They are ordered following
	QET::OperationAreas, so it is possible to use positive values from this enum
	to fetch the corresponding square in the list.
	@see QET::OperationAreas
*/
QList<QRectF> ElementPrimitiveDecorator::getResizingSquares() {
	QRectF primitive_rect = modified_bounding_rect_;
	QRectF half_primitive_rect1 = primitive_rect;
	half_primitive_rect1.setHeight(half_primitive_rect1.height() / 2.0);
	QRectF half_primitive_rect2 = primitive_rect;
	half_primitive_rect2.setWidth(half_primitive_rect2.width() / 2.0);
	
	QList<QRectF> rects;
	
	rects << getGenericSquare(primitive_rect.topLeft());
	rects << getGenericSquare(half_primitive_rect2.topRight());
	rects << getGenericSquare(primitive_rect.topRight());
	rects << getGenericSquare(half_primitive_rect1.bottomLeft());
	rects << getGenericSquare(half_primitive_rect1.bottomRight());
	rects << getGenericSquare(primitive_rect.bottomLeft());
	rects << getGenericSquare(half_primitive_rect2.bottomRight());
	rects << getGenericSquare(primitive_rect.bottomRight());
	
	/// TODO cache the rects instead of calculating them again and again?
	return(rects);
}

/**
	@return the square to be drawn to represent \a position
*/
QRectF ElementPrimitiveDecorator::getGenericSquare(const QPointF &position) {
	const qreal square_half_size = 0.5;
	return(
		QRectF(
			position.x() - square_half_size,
			position.y() - square_half_size,
			square_half_size * 2.0,
			square_half_size * 2.0
		)
	);
}

/**
	@return the index of the square containing the \a position point or -1 if
	none matches.
*/
int ElementPrimitiveDecorator::resizingSquareAtPos(const QPointF &position) {
	QList<QRectF> rects = getResizingSquares();
	int current_square = QET::NoOperation;
	for (int i = 0 ; i < rects.count() ; ++ i) {
		if (rects.at(i).contains(position)) {
			current_square = i;
		}
	}
	return(current_square);
}

/**
	Round the coordinates of \a point so it is snapped to the grid defined by the
	grid_step_x_ and grid_step_y_ attributes.
*/
QPointF ElementPrimitiveDecorator::snapConstPointToGrid(const QPointF &point) const {
	return(
		QPointF(
			qRound(point.x() / grid_step_x_) * grid_step_x_,
			qRound(point.y() / grid_step_y_) * grid_step_y_
		)
	);
}

/**
	Round the coordinates of \a point so it is snapped to the grid defined by the
	grid_step_x_ and grid_step_y_ attributes.
*/
void ElementPrimitiveDecorator::snapPointToGrid(QPointF &point) const {
	point.rx() = qRound(point.x() / grid_step_x_) * grid_step_x_;
	point.ry() = qRound(point.y() / grid_step_y_) * grid_step_y_;
}

/**
	@return whether the current operation should take the grid into account
	according to the state of the provided \a event
*/
bool ElementPrimitiveDecorator::mustSnapToGrid(QGraphicsSceneMouseEvent *event) {
	return(!(event -> modifiers() & Qt::ControlModifier));
}