/*
 * Oak Video Editor - Non-Linear Video Editor
 * Copyright (C) 2025 Olive CE Team
 *
 * This program 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.
 *
 * This program 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 for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

#include "nodeviewedge.h"

#include <QApplication>
#include <QDebug>
#include <QGraphicsSceneMouseEvent>
#include <QStyleOptionGraphicsItem>

#include "common/lerp.h"
#include "nodeview.h"
#include "nodeviewitem.h"
#include "nodeviewscene.h"

namespace olive
{

#define super QGraphicsPathItem

NodeViewEdge::NodeViewEdge(Node *output, const NodeInput &input,
						   NodeViewItem *from_item, NodeViewItem *to_item,
						   QGraphicsItem *parent)
	: super(parent)
	, output_(output)
	, input_(input)
	, from_item_(from_item)
	, to_item_(to_item)
{
	Init();
	SetConnected(true);

	from_item_->AddEdge(this);
	to_item_->AddEdge(this);
}

NodeViewEdge::NodeViewEdge(QGraphicsItem *parent)
	: QGraphicsPathItem(parent)
	, from_item_(nullptr)
	, to_item_(nullptr)
{
	Init();
}

NodeViewEdge::~NodeViewEdge()
{
	if (from_item_) {
		from_item_->RemoveEdge(this);
	}

	if (to_item_) {
		to_item_->RemoveEdge(this);
	}
}

void NodeViewEdge::set_from_item(NodeViewItem *i)
{
	if (from_item_) {
		from_item_->RemoveEdge(this);
	}

	from_item_ = i;

	if (from_item_) {
		from_item_->AddEdge(this);
	}

	Adjust();
}

void NodeViewEdge::set_to_item(NodeViewItem *i)
{
	if (to_item_) {
		to_item_->RemoveEdge(this);
	}

	to_item_ = i;

	if (to_item_) {
		to_item_->AddEdge(this);
	}

	Adjust();
}

void NodeViewEdge::Adjust()
{
	// Draw a line between the two
	SetPoints(from_item()->GetOutputPoint(), to_item()->GetInputPoint());
}

void NodeViewEdge::SetConnected(bool c)
{
	connected_ = c;

	update();
}

void NodeViewEdge::SetHighlighted(bool e)
{
	highlighted_ = e;

	update();
}

void NodeViewEdge::SetPoints(const QPointF &start, const QPointF &end)
{
	cached_start_ = start;
	cached_end_ = end;

	UpdateCurve();
}

void NodeViewEdge::SetCurved(bool e)
{
	curved_ = e;

	UpdateCurve();
}

void NodeViewEdge::paint(QPainter *painter,
						 const QStyleOptionGraphicsItem *option, QWidget *)
{
	QPalette::ColorGroup group;
	QPalette::ColorRole role;

	if (connected_) {
		group = QPalette::Active;
	} else {
		group = QPalette::Disabled;
	}

	if (highlighted_ != bool(option->state & QStyle::State_Selected)) {
		role = QPalette::Highlight;
	} else {
		role = QPalette::Text;
	}

	// Draw main path
	QColor edge_color = qApp->palette().color(group, role);

	painter->setPen(QPen(edge_color, edge_width_));
	painter->setBrush(Qt::NoBrush);
	painter->drawPath(path());
}

void NodeViewEdge::Init()
{
	connected_ = false;
	highlighted_ = false;
	curved_ = true;

	setFlag(QGraphicsItem::ItemIsSelectable);

	// Ensures this UI object is drawn behind other objects
	setZValue(-1);

	// Use font metrics to set edge width for basic high DPI support
	edge_width_ = QFontMetrics(QFont()).height() / 12;
}

void NodeViewEdge::UpdateCurve()
{
	const QPointF &start = cached_start_;
	const QPointF &end = cached_end_;

	QPainterPath path;
	path.moveTo(start);

	double angle = std::atan2(end.y() - start.y(), end.x() - start.x());

	if (curved_) {
		double half_x = lerp(start.x(), end.x(), 0.5);
		double half_y = lerp(start.y(), end.y(), 0.5);

		QPointF cp1, cp2;

		NodeViewCommon::FlowDirection from_flow =
			from_item_ ? from_item_->GetFlowDirection() :
						 NodeViewCommon::kInvalidDirection;
		NodeViewCommon::FlowDirection to_flow =
			to_item_ ? to_item_->GetFlowDirection() :
					   NodeViewCommon::kInvalidDirection;

		if (from_flow == NodeViewCommon::kInvalidDirection &&
			to_flow == NodeViewCommon::kInvalidDirection) {
			// This is a technically unsupported scenario, but to avoid issues, we'll use a fallback
			from_flow = NodeViewCommon::kLeftToRight;
			to_flow = NodeViewCommon::kLeftToRight;
		} else if (from_flow == NodeViewCommon::kInvalidDirection) {
			from_flow = to_flow;
		} else if (to_flow == NodeViewCommon::kInvalidDirection) {
			to_flow = from_flow;
		}

		if (NodeViewCommon::GetFlowOrientation(from_flow) == Qt::Horizontal) {
			cp1 = QPointF(half_x, start.y());
		} else {
			cp1 = QPointF(start.x(), half_y);
		}

		if (NodeViewCommon::GetFlowOrientation(to_flow) == Qt::Horizontal) {
			cp2 = QPointF(half_x, end.y());
		} else {
			cp2 = QPointF(end.x(), half_y);
		}

		path.cubicTo(cp1, cp2, end);

		if (!qFuzzyCompare(start.x(), end.x())) {
			double continue_x = end.x() - std::cos(angle);

			double x1 = start.x();
			double x2 = cp1.x();
			double x3 = cp2.x();
			double x4 = end.x();
			double y1 = start.y();
			double y2 = cp1.y();
			double y3 = cp2.y();
			double y4 = end.y();

			if (start.x() >= end.x()) {
				std::swap(x1, x4);
				std::swap(x2, x3);
				std::swap(y1, y4);
				std::swap(y2, y3);
			}

			double t = Bezier::CubicXtoT(continue_x, x1, x2, x3, x4);
			double y = Bezier::CubicTtoY(y1, y2, y3, y4, t);

			angle = std::atan2(end.y() - y, end.x() - continue_x);
		}

	} else {
		path.lineTo(end);
	}

	setPath(mapFromScene(path));
}

}
