#include "strokecanvasrenderer.hpp"
#include "strokecanvasitem.hpp"
#include <qcolor.h>

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 drawHoverCursor(
	QCanvasPainter *painter,
	const QPointF &point,
	float penWidth,
	QColor penColor,
	bool isDrawing)
{
	const float radius = penWidth * 0.5f;

	if (isDrawing) {
		painter->setFillStyle(penColor);
		painter->beginPath();
		painter->circle(point, radius);
		painter->fill();
	}

	const float lineWidth = 1.5f;
	const float crosshairSize = 6.0f;
	const bool useDashes = penWidth > 10.0f;

	auto drawOutline = [&](const QColor &color, float width) {
				   painter->setStrokeStyle(color);
				   painter->setLineWidth(width);
				   painter->setLineCap(QCanvasPainter::LineCap::Round);


				   if (useDashes) {
					   const int dashCount = 12;
					   const float fullAngle = 2.0f * M_PI;
					   const float dashAngle = fullAngle / dashCount * 0.5f;
					   const float gapAngle  = fullAngle / dashCount * 0.5f;

					   float angle = 0.0f;
					   for (int i = 0; i < dashCount; ++i) {
						   painter->beginPath();
						   painter->arc(point, radius, angle, angle + dashAngle,
						                QCanvasPainter::PathWinding::ClockWise,
						                QCanvasPainter::PathConnection::NotConnected);
						   painter->stroke();
						   angle += dashAngle + gapAngle;
					   }
				   } else {
					   painter->beginPath();
					   painter->circle(point, radius);
					   painter->stroke();
				   }
			   };

	auto drawCrosshair = [&](const QColor &color, float width) {
				     painter->setStrokeStyle(color);
				     painter->setLineWidth(width);
				     painter->setLineCap(QCanvasPainter::LineCap::Round);

				     const float inner = radius + 3.0f;
				     const float outer = radius + 3.0f + crosshairSize;

				     painter->beginPath();
				     painter->moveTo(point + QPointF(0, -outer));
				     painter->lineTo(point + QPointF(0, -inner));
				     painter->moveTo(point + QPointF(0,  outer));
				     painter->lineTo(point + QPointF(0,  inner));
				     painter->moveTo(point + QPointF(-outer, 0));
				     painter->lineTo(point + QPointF(-inner, 0));
				     painter->moveTo(point + QPointF( outer, 0));
				     painter->lineTo(point + QPointF( inner, 0));
				     painter->stroke();
			     };

	drawOutline(QColor(0, 0, 0, 160), lineWidth + 1.0f);
	drawCrosshair(QColor(0, 0, 0, 160), lineWidth + 1.0f);

	drawOutline(QColor(255, 255, 255, 220), lineWidth);
	drawCrosshair(QColor(255, 255, 255, 220), lineWidth);
}

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

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

	while (m_strokes.size() < canvas->m_strokes.size())
		m_strokes.append(canvas->m_strokes[m_strokes.size()]);

	if (canvas->m_strokes.isEmpty() && !m_strokes.isEmpty()) {
		for (const auto &stroke : m_strokes)
			if (stroke.groupId >= 0)
				m_pendingGroupRemovals.append(stroke.groupId);
		m_strokes.clear();
	}

	m_currentStroke = canvas->m_currentStroke;

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

void StrokeCanvasRenderer::paint(QCanvasPainter *painter) {
	for (int id : m_pendingGroupRemovals)
		painter->removePathGroup(id);
	m_pendingGroupRemovals.clear();

	painter->clearRect(0, 0, width(), height());

	for (const auto &stroke : m_strokes) {
		painter->setStrokeStyle(stroke.color);
		painter->setFillStyle(stroke.color);
		painter->setLineWidth(stroke.width);
		painter->setLineCap(QCanvasPainter::LineCap::Round);
		painter->setLineJoin(QCanvasPainter::LineJoin::Round);

		if (stroke.isSinglePoint) {
			painter->fill(stroke.path, stroke.groupId);
		} else {
			painter->stroke(stroke.path, stroke.groupId);
		}
	}

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

	if (m_hoverVisible)
		drawHoverCursor(painter, m_hoverPoint, m_penWidth, m_penColor, m_isDrawing);
}

};