#include "sparklinesceneitem.hpp"

#include <qmath.h>
#include <qpainterpath.h>
#include <qsgflatcolormaterial.h>
#include <qsggeometry.h>

namespace ZShell::components {

SparklineSceneItem::SparklineSceneItem(QQuickItem* parent)
	: QQuickItem(parent) {
	setClip(true);
	setFlag(QQuickItem::ItemHasContents, true);
}

void SparklineSceneItem::geometryChange(
	const QRectF& newGeometry, const QRectF& oldGeometry) {
	QQuickItem::geometryChange(newGeometry, oldGeometry);
	if (newGeometry.size() != oldGeometry.size()) invalidateGeometry();
}

void SparklineSceneItem::invalidateGeometry() {
	m_geometryDirty = true;
	update();
}

void SparklineSceneItem::applySmoothingRadius(
	internal::CircularBuffer* buffer) const {
	if (buffer) buffer->setSmoothingRadius(qRound(m_smoothing));
}

void SparklineSceneItem::connectBuffer(internal::CircularBuffer* buffer) {
	if (!buffer) return;
	connect(
		buffer,
		&internal::CircularBuffer::valuesChanged,
		this,
		&SparklineSceneItem::invalidateGeometry);
	connect(buffer, &QObject::destroyed, this, [this, buffer]() {
		if (m_line1 == buffer) {
			m_line1 = nullptr;
			emit line1Changed();
		}
		if (m_line2 == buffer) {
			m_line2 = nullptr;
			emit line2Changed();
		}
		invalidateGeometry();
	});
}

qreal SparklineSceneItem::stepX() const {
	if (m_historyLength < 2 || width() <= 0.0) return 0.0;
	if (m_sliding) return width() / static_cast<qreal>(m_historyLength - 1);

	const int len = qMax(
		2,
		(m_line1 && m_line1->count() >= 2) ? m_line1->count()
										   : (m_line2 ? m_line2->count() : 2));
	return width() / static_cast<qreal>(len - 1);
}

SparklineSceneItem::LineSample SparklineSceneItem::buildSample(
	internal::CircularBuffer* buffer) const {
	LineSample sample;
	if (!buffer || buffer->count() < 2 || m_maxValue <= 0.0 || width() <= 0.0)
		return sample;
	if (m_historyLength < 2) return sample;

	const int len = buffer->count();
	const qreal step = stepX();
	if (step <= 0.0) return sample;

	qreal startX = m_sliding ? (width() - (len - 1) * step + step) : 0.0;

	const qreal h = height();
	const qreal strokePad = qCeil(m_lineWidth / 2);
	const qreal curvePad = 3.0;
	const qreal plotTop = strokePad + curvePad;
	const qreal plotBottom = h - strokePad;
	const qreal plotH = qMax<qreal>(1.0, plotBottom - plotTop);

	QVector<QPointF> points;
	points.reserve(len);

	for (int i = 0; i < len; ++i) {
		// Already smoothed once, incrementally, by the buffer itself.
		const qreal value =
			qBound<qreal>(0.0, buffer->smoothedAt(i), m_maxValue);

		const qreal x = startX + i * step;
		const qreal y = plotTop + (1.0 - (value / m_maxValue)) * plotH;
		points.append(QPointF(x, y));
	}

	QPainterPath path;
	path.moveTo(points[0]);

	if (m_curveSmoothing && points.size() > 2) {
		const qreal tension = 1.0;
		const qreal k = tension / 6.0;
		const int n = points.size();
		for (int i = 0; i < n - 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, n - 1)];

			QPointF c1 = p1 + (p2 - p0) * k;
			QPointF c2 = p2 - (p3 - p1) * k;

			const qreal segMinY = qMin(p1.y(), p2.y());
			const qreal segMaxY = qMax(p1.y(), p2.y());
			c1.setY(qBound(segMinY, c1.y(), segMaxY));
			c2.setY(qBound(segMinY, c2.y(), segMaxY));

			path.cubicTo(c1, c2, p2);
		}
	} else {
		for (int i = 0; i < points.size() - 1; ++i) {
			const QPointF& p0 = points[i];
			const QPointF& p1 = points[i + 1];
			const qreal ctrlX = (p0.x() + p1.x()) * 0.5;
			path.cubicTo(QPointF(ctrlX, p0.y()), QPointF(ctrlX, p1.y()), p1);
		}
	}

	// Flatten the curve to a polyline once, here, on data change only.
	// This is CPU math only -- no QPainter draw calls, no image, no
	// texture upload happen as a result of this.
	const auto subpaths = path.toSubpathPolygons();
	if (subpaths.isEmpty()) return sample;

	sample.polyline = subpaths.first();
	sample.fillBottom = h;
	sample.hasData = sample.polyline.size() >= 2;
	return sample;
}

void SparklineSceneItem::writeFillGeometry(
	QSGGeometryNode* node, const LineSample& sample) {
	const int n = sample.polyline.size();
	auto* geometry = node->geometry();
	geometry->allocate(n * 2);
	geometry->setDrawingMode(QSGGeometry::DrawTriangleStrip);

	auto* vertices = geometry->vertexDataAsPoint2D();
	for (int i = 0; i < n; ++i) {
		const QPointF& p = sample.polyline[i];
		vertices[i * 2].set(p.x(), p.y());
		vertices[i * 2 + 1].set(p.x(), sample.fillBottom);
	}

	node->markDirty(QSGNode::DirtyGeometry);
}

void SparklineSceneItem::writeStrokeGeometry(
	QSGGeometryNode* node, const LineSample& sample, qreal lineWidth) {
	const int n = sample.polyline.size();
	auto* geometry = node->geometry();
	geometry->allocate(n * 2);
	geometry->setDrawingMode(QSGGeometry::DrawTriangleStrip);

	auto* vertices = geometry->vertexDataAsPoint2D();
	const qreal half = lineWidth * 0.5;

	for (int i = 0; i < n; ++i) {
		QPointF dir;
		if (i == 0)
			dir = sample.polyline[1] - sample.polyline[0];
		else if (i == n - 1)
			dir = sample.polyline[n - 1] - sample.polyline[n - 2];
		else
			dir = sample.polyline[i + 1] - sample.polyline[i - 1];

		const qreal len = std::hypot(dir.x(), dir.y());
		QPointF normal = len > 1e-6 ? QPointF(-dir.y() / len, dir.x() / len)
									: QPointF(0, 1);

		const QPointF& p = sample.polyline[i];
		const QPointF offset = normal * half;
		vertices[i * 2].set(p.x() + offset.x(), p.y() + offset.y());
		vertices[i * 2 + 1].set(p.x() - offset.x(), p.y() - offset.y());
	}

	node->markDirty(QSGNode::DirtyGeometry);
}

void SparklineSceneItem::setMaterialColor(
	QSGGeometryNode* node, const QColor& color, qreal alpha) {
	auto* material = static_cast<QSGFlatColorMaterial*>(node->material());
	QColor c = color;
	c.setAlphaF(static_cast<float>(alpha));
	material->setColor(c);
	node->markDirty(QSGNode::DirtyMaterial);
}

QSGNode* SparklineSceneItem::updatePaintNode(
	QSGNode* node, UpdatePaintNodeData*) {
	bool samplesRebuilt = false;
	if (m_geometryDirty) {
		m_sample1 = buildSample(m_line1);
		m_sample2 = buildSample(m_line2);
		m_geometryDirty = false;
		samplesRebuilt = true;
	}

	const bool hasAny = m_sample1.hasData || m_sample2.hasData;
	if (!hasAny) {
		delete node;
		m_transformNode = nullptr;
		m_line1FillNode = m_line1StrokeNode = nullptr;
		m_line2FillNode = m_line2StrokeNode = nullptr;
		return nullptr;
	}

	auto* transformNode = static_cast<QSGTransformNode*>(node);
	bool justCreated = false;
	if (!transformNode) {
		transformNode = new QSGTransformNode();
		m_transformNode = transformNode;

		auto makeNode = [] {
			auto* n = new QSGGeometryNode();
			n->setGeometry(
				new QSGGeometry(QSGGeometry::defaultAttributes_Point2D(), 0));
			n->setFlag(QSGNode::OwnsGeometry);
			n->setMaterial(new QSGFlatColorMaterial());
			n->setFlag(QSGNode::OwnsMaterial);
			return n;
		};

		m_line1FillNode = makeNode();
		m_line1StrokeNode = makeNode();
		m_line2FillNode = makeNode();
		m_line2StrokeNode = makeNode();
		transformNode->appendChildNode(m_line1FillNode);
		transformNode->appendChildNode(m_line1StrokeNode);
		transformNode->appendChildNode(m_line2FillNode);
		transformNode->appendChildNode(m_line2StrokeNode);

		justCreated = true;
	}

	QMatrix4x4 matrix;
	matrix.translate(-stepX() * m_slideProgress, 0);
	transformNode->setMatrix(matrix);

	const bool needsGeometryWrite = samplesRebuilt || justCreated;
	const bool needsColorWrite = m_colorsDirty || justCreated;

	auto writeLine = [&](QSGGeometryNode* fillNode,
						 QSGGeometryNode* strokeNode,
						 const LineSample& sample,
						 const QColor& color,
						 qreal fillAlpha) {
		if (needsGeometryWrite) {
			if (sample.hasData) {
				writeFillGeometry(fillNode, sample);
				writeStrokeGeometry(strokeNode, sample, m_lineWidth);
			} else {
				fillNode->geometry()->allocate(0);
				strokeNode->geometry()->allocate(0);
				fillNode->markDirty(QSGNode::DirtyGeometry);
				strokeNode->markDirty(QSGNode::DirtyGeometry);
			}
		}
		if (needsColorWrite) {
			setMaterialColor(fillNode, color, fillAlpha);
			setMaterialColor(strokeNode, color, 1.0);
		}
	};

	writeLine(
		m_line1FillNode,
		m_line1StrokeNode,
		m_sample1,
		m_line1Color,
		m_line1FillAlpha);
	writeLine(
		m_line2FillNode,
		m_line2StrokeNode,
		m_sample2,
		m_line2Color,
		m_line2FillAlpha);

	m_colorsDirty = false;

	return transformNode;
}

internal::CircularBuffer* SparklineSceneItem::line1() const {
	return m_line1;
}

void SparklineSceneItem::setLine1(internal::CircularBuffer* buffer) {
	if (m_line1 == buffer) return;
	if (m_line1) disconnect(m_line1, nullptr, this, nullptr);
	m_line1 = buffer;
	connectBuffer(buffer);
	applySmoothingRadius(buffer);
	invalidateGeometry();
	emit line1Changed();
}

internal::CircularBuffer* SparklineSceneItem::line2() const {
	return m_line2;
}

void SparklineSceneItem::setLine2(internal::CircularBuffer* buffer) {
	if (m_line2 == buffer) return;
	if (m_line2) disconnect(m_line2, nullptr, this, nullptr);
	m_line2 = buffer;
	connectBuffer(buffer);
	applySmoothingRadius(buffer);
	invalidateGeometry();
	emit line2Changed();
}

QColor SparklineSceneItem::line1Color() const {
	return m_line1Color;
}

void SparklineSceneItem::setLine1Color(const QColor& color) {
	if (m_line1Color == color) return;
	m_line1Color = color;
	m_colorsDirty = true;
	update();
	emit line1ColorChanged();
}

QColor SparklineSceneItem::line2Color() const {
	return m_line2Color;
}

void SparklineSceneItem::setLine2Color(const QColor& color) {
	if (m_line2Color == color) return;
	m_line2Color = color;
	m_colorsDirty = true;
	update();
	emit line2ColorChanged();
}

qreal SparklineSceneItem::line1FillAlpha() const {
	return m_line1FillAlpha;
}

void SparklineSceneItem::setLine1FillAlpha(qreal alpha) {
	if (qFuzzyCompare(m_line1FillAlpha, alpha)) return;
	m_line1FillAlpha = alpha;
	m_colorsDirty = true;
	update();
	emit line1FillAlphaChanged();
}

qreal SparklineSceneItem::line2FillAlpha() const {
	return m_line2FillAlpha;
}

void SparklineSceneItem::setLine2FillAlpha(qreal alpha) {
	if (qFuzzyCompare(m_line2FillAlpha, alpha)) return;
	m_line2FillAlpha = alpha;
	m_colorsDirty = true;
	update();
	emit line2FillAlphaChanged();
}

qreal SparklineSceneItem::maxValue() const {
	return m_maxValue;
}

void SparklineSceneItem::setMaxValue(qreal value) {
	if (qFuzzyCompare(m_maxValue, value)) return;
	m_maxValue = value;
	invalidateGeometry();
	emit maxValueChanged();
}

qreal SparklineSceneItem::slideProgress() const {
	return m_slideProgress;
}

void SparklineSceneItem::setSlideProgress(qreal progress) {
	if (qFuzzyCompare(m_slideProgress, progress)) return;
	m_slideProgress = progress;
	update();
	emit slideProgressChanged();
}

int SparklineSceneItem::historyLength() const {
	return m_historyLength;
}

void SparklineSceneItem::setHistoryLength(int length) {
	if (m_historyLength == length) return;
	m_historyLength = length;
	invalidateGeometry();
	emit historyLengthChanged();
}

qreal SparklineSceneItem::lineWidth() const {
	return m_lineWidth;
}

void SparklineSceneItem::setLineWidth(qreal width) {
	if (qFuzzyCompare(m_lineWidth, width)) return;
	m_lineWidth = width;
	invalidateGeometry();
	emit lineWidthChanged();
}

bool SparklineSceneItem::sliding() const {
	return m_sliding;
}

void SparklineSceneItem::setSliding(bool sliding) {
	if (m_sliding == sliding) return;
	m_sliding = sliding;
	invalidateGeometry();
	emit slidingChanged();
}

qreal SparklineSceneItem::smoothing() const {
	return m_smoothing;
}

void SparklineSceneItem::setSmoothing(qreal smoothing) {
	smoothing = qMax<qreal>(0.0, smoothing);
	if (qFuzzyCompare(m_smoothing, smoothing)) return;
	m_smoothing = smoothing;
	applySmoothingRadius(m_line1);
	applySmoothingRadius(m_line2);
	emit smoothingChanged();
}

bool SparklineSceneItem::curveSmoothing() const {
	return m_curveSmoothing;
}

void SparklineSceneItem::setCurveSmoothing(bool enabled) {
	if (m_curveSmoothing == enabled) return;
	m_curveSmoothing = enabled;
	invalidateGeometry();
	emit curveSmoothingChanged();
}

} // namespace ZShell::components