#include "strokecanvasrenderer.hpp"
#include "strokecanvasitem.hpp"

namespace ZShell::internal {

static void drawStroke(
	QCanvasPainter *painter,
	const QVector<QPointF> &points,
	const QColor &color,
	float width) {

	if (points.isEmpty())
		return;

	painter->setStrokeStyle(color);
	painter->setFillStyle(color);
	painter->setLineWidth(width);
	painter->setLineCap(QCanvasPainter::LineCap::Round);
	painter->setLineJoin(QCanvasPainter::LineJoin::Round);

	if (points.size() == 1) {
		painter->beginPath();
		painter->circle(points.front(), width * 0.5f);
		painter->fill();
		return;
	}

	auto catmullToBezier = [](
		const QPointF &p0, const QPointF &p1,
		const QPointF &p2, const QPointF &p3,
		float tension,
		QPointF &cp1, QPointF &cp2)
			       {
				       cp1 = p1 + (p2 - p0) * tension / 3.0f;
				       cp2 = p2 - (p3 - p1) * tension / 3.0f;
			       };

	const float tension = 0.5f; // increase toward 1.0 for tighter curves

	painter->beginPath();
	painter->moveTo(points[0]);

	for (int i = 0; i < points.size() - 1; ++i) {
		const QPointF &p0 = points[qMax(i - 1, 0)];
		const QPointF &p1 = points[i];
		const QPointF &p2 = points[i + 1];
		const QPointF &p3 = points[qMin(i + 2, points.size() - 1)];

		QPointF cp1, cp2;
		catmullToBezier(p0, p1, p2, p3, tension, cp1, cp2);
		painter->bezierCurveTo(cp1, cp2, p2);
	}

	painter->stroke();
}

static void drawDot(
	QCanvasPainter *painter,
	const QPointF &point,
	const QColor &color,
	float width)
{
	painter->setFillStyle(color);

	painter->beginPath();
	painter->circle(point, width * 0.5f);
	painter->fill();
}

void StrokeCanvasRenderer::synchronizeData(QCanvasPainterItem *item) {
	auto *canvas = static_cast<StrokeCanvasItem *>(item);

	m_penColor = canvas->m_penColor;
	m_penWidth = canvas->m_penWidth;

	m_strokes = canvas->m_strokes;
	m_currentStroke = canvas->m_currentStroke;

	m_hoverVisible = canvas->m_hoverVisible;
	m_hoverPoint = canvas->m_hoverPoint;
}

void StrokeCanvasRenderer::paint(QCanvasPainter *painter) {
	painter->clearRect(0, 0, width(), height());

	for (const auto &stroke : m_strokes)
		drawStroke(painter, stroke.points, stroke.color, stroke.width);

	drawStroke(
		painter,
		m_currentStroke.points,
		m_currentStroke.color,
		m_currentStroke.width
		);

	if (m_hoverVisible) {
		drawDot(
			painter,
			m_hoverPoint,
			m_penColor,
			m_penWidth
			);
	}
}

};