#pragma once

#include <qpoint.h>
#include <qvector.h>

#include <cmath>
#include <cstdint>

namespace ZShell::internal {

// Shared curve construction for SparklineContent (QPainter) and LineGraphItem
// (QCanvasPainter). Input and output coordinates are logical (item-local);
// device-pixel quantization happens inside so a stroke lands on whole pixel
// columns and its edges are not interpolated across several columns. Keeping the
// math in one place means both graphs align and smooth their lines identically,
// whatever backend they paint through.

inline qint64 toDev(qreal logical, qreal dpr) {
	return std::llround(logical * dpr);
}

inline qreal fromDev(qint64 device, qreal dpr) {
	return qreal(device) / dpr;
}

// Snap a line center so a whole-pixel-wide stroke sits on pixel boundaries when
// the device width is even and on pixel centers when it is odd.
qreal snapLine(qreal logical, qint64 widthDev, qreal dpr);

// Catmull-Rom control points for the segment points[i] -> points[i + 1], with the
// control y clamped to the segment's own y span so a curve never overshoots past
// its endpoints. When curveSmoothing is off (or there are too few points) the
// tangents are flat.
void segmentControls(
	const QVector<QPointF>& points,
	int i,
	bool curveSmoothing,
	QPointF& c1,
	QPointF& c2);

// y of the cubic bezier p1-c1-c2-p2 at targetX, found by bisection on t.
qreal cubicY(
	const QPointF& p1,
	const QPointF& c1,
	const QPointF& c2,
	const QPointF& p2,
	qreal targetX);

// The curve point at targetX on the polyline, interpolating across the segment
// that contains it. Assumes points ascend in x.
QPointF pointAtX(
	const QVector<QPointF>& points,
	qreal targetX,
	bool curveSmoothing);

// A dense polyline through points, adding one vertex per device-pixel column
// inside each segment so an edge never interpolates across several columns. The
// result starts at points.first() and ends at points.last(). points must ascend in
// x and hold at least two entries. Backends consume it as a moveTo/lineTo chain.
QVector<QPointF> curveVertices(
	const QVector<QPointF>& points,
	qreal dpr,
	bool curveSmoothing);
} // namespace ZShell::internal