#include "sparklinecontent.hpp"

#include "internal/linegeometry.hpp"

#include <qmath.h>
#include <qpainter.h>
#include <qpen.h>
#include <qquickwindow.h>

#include <algorithm>
#include <cmath>

namespace ZShell::components {

using internal::fromDev;
using internal::snapLine;
using internal::toDev;


namespace {
qreal snapPaintedExtent(qreal logical, qreal dpr, bool grow) {
	qreal whole = grow ? std::ceil(logical - 1e-6) : std::floor(logical + 1e-6);
	for (int guard = 0; guard < 16 && whole >= 1.0; ++guard) {
		const qreal device = whole * dpr;
		if (std::abs(device - std::round(device)) < 1e-6) return whole;
		whole += grow ? 1.0 : -1.0;
	}
	return std::max(1.0, grow ? whole : std::floor(logical));
}
} // namespace

SparklineContent::SparklineContent(QQuickItem* parent)
	: QQuickPaintedItem(parent) {
	setAntialiasing(true);
}

void SparklineContent::itemChange(
	ItemChange change, const ItemChangeData& value) {
	QQuickPaintedItem::itemChange(change, value);
	if (change == ItemSceneChange && value.window)
		m_dpr = value.window->effectiveDevicePixelRatio();
	else if (change == ItemDevicePixelRatioHasChanged && window())
		m_dpr = window()->effectiveDevicePixelRatio();
	else
		return;

	invalidate();
}

qreal SparklineContent::stepX() const {
	if (m_historyLength < 2 || m_viewportW <= 0.0) return 0.0;
	const int len = qMax(
		2,
		(m_line1 && m_line1->count() >= 2) ? m_line1->count()
										   : (m_line2 ? m_line2->count() : 2));
	return m_sliding ? m_viewportW / static_cast<qreal>(m_historyLength - 1)
					 : m_viewportW / static_cast<qreal>(len - 1);
}

void SparklineContent::setViewportSize(
	qreal viewportWidth, qreal viewportHeight) {
	if (qFuzzyCompare(m_viewportW, viewportWidth) &&
		qFuzzyCompare(m_viewportH, viewportHeight))
		return;
	m_viewportW = viewportWidth;
	m_viewportH = viewportHeight;
	invalidate();
}

void SparklineContent::setSlideInterval(qreal intervalMs) {
	if (qFuzzyCompare(m_slideIntervalMs, intervalMs)) return;
	m_slideIntervalMs = intervalMs;
	invalidate();
}

qreal SparklineContent::slidePhase(qreal progress) const {
	if (m_slideIntervalMs <= 0.0) return qBound(0.0, progress, 1.0);

	if (!m_sampleClock.isValid()) return 1.0;

	const qreal elapsed = static_cast<qreal>(m_sampleClock.elapsed());
	return qBound(0.0, elapsed / m_slideIntervalMs, 1.0);
}

bool SparklineContent::slideActive() const {
	return m_slideIntervalMs > 0.0 && m_sampleClock.isValid() &&
		   static_cast<qreal>(m_sampleClock.elapsed()) < m_slideIntervalMs;
}

void SparklineContent::setSlideProgress(qreal progress) {
	setX(-stepX() * slidePhase(progress));
}

void SparklineContent::setLine1(internal::CircularBuffer* buffer) {
	if (m_line1 == buffer) return;
	if (m_line1) disconnect(m_line1, nullptr, this, nullptr);
	m_line1 = buffer;
	connectBuffer(buffer);
	invalidate();
}

void SparklineContent::setLine2(internal::CircularBuffer* buffer) {
	if (m_line2 == buffer) return;
	if (m_line2) disconnect(m_line2, nullptr, this, nullptr);
	m_line2 = buffer;
	connectBuffer(buffer);
	invalidate();
}

void SparklineContent::onSampleArrived() {
	m_sampleClock.restart();
	invalidate();
	setSlideProgress(0.0);
}

void SparklineContent::connectBuffer(internal::CircularBuffer* buffer) {
	if (!buffer) return;
	connect(
		buffer,
		&internal::CircularBuffer::valuesChanged,
		this,
		&SparklineContent::onSampleArrived);
	connect(buffer, &QObject::destroyed, this, [this, buffer]() {
		if (m_line1 == buffer) m_line1 = nullptr;
		if (m_line2 == buffer) m_line2 = nullptr;
		invalidate();
	});
}

void SparklineContent::setLine1Color(const QColor& color) {
	if (m_line1Color == color) return;
	m_line1Color = color;
	update();
}

void SparklineContent::setLine2Color(const QColor& color) {
	if (m_line2Color == color) return;
	m_line2Color = color;
	update();
}

void SparklineContent::setLine1FillAlpha(qreal alpha) {
	if (qFuzzyCompare(m_line1FillAlpha, alpha)) return;
	m_line1FillAlpha = alpha;
	update();
}

void SparklineContent::setLine2FillAlpha(qreal alpha) {
	if (qFuzzyCompare(m_line2FillAlpha, alpha)) return;
	m_line2FillAlpha = alpha;
	update();
}

void SparklineContent::setMaxValue(qreal value) {
	if (qFuzzyCompare(m_maxValue, value)) return;
	m_maxValue = value;
	invalidate();
}

void SparklineContent::setLineWidth(qreal width) {
	if (qFuzzyCompare(m_lineWidth, width)) return;
	m_lineWidth = width;
	invalidate();
}

void SparklineContent::setCurveSmoothing(bool enabled) {
	if (m_curveSmoothing == enabled) return;
	m_curveSmoothing = enabled;
	invalidate();
}

void SparklineContent::setHistoryLength(int length) {
	if (m_historyLength == length) return;
	m_historyLength = length;
	invalidate();
}

void SparklineContent::setSliding(bool sliding) {
	if (m_sliding == sliding) return;
	m_sliding = sliding;
	invalidate();
}

void SparklineContent::invalidate() {
	m_dirty = true;
	applyGeometry();
	update();
}

void SparklineContent::applyGeometry() {
	const qreal dpr = m_dpr > 0.0 ? m_dpr : 1.0;
	const qreal pad = m_sliding ? 2.0 * stepX() : 0.0;
	const qreal paintedW = snapPaintedExtent(m_viewportW + pad, dpr, true);
	m_paintedH = snapPaintedExtent(m_viewportH, dpr, false);
	setSize(QSizeF(paintedW, m_paintedH));
}

SparklineContent::LineGeometry SparklineContent::buildGeometry(
	internal::CircularBuffer* buffer) const {
	LineGeometry geom;
	if (!buffer || buffer->count() < 2 || !std::isfinite(m_maxValue) ||
		m_maxValue <= 0.0 || !std::isfinite(m_viewportW) ||
		m_viewportW <= 0.0 || !std::isfinite(m_viewportH) ||
		m_viewportH <= 0.0 || m_paintedH < 1.0)
		return geom;
	if (m_historyLength < 2) return geom;

	const qreal dpr = m_dpr > 0.0 ? m_dpr : 1.0;
	const int len = buffer->count();
	const qreal step = stepX();
	if (!std::isfinite(step) || step <= 0.0) return geom;

	const qint64 lineDev = std::isfinite(m_lineWidth)
							   ? (std::max)(qint64(1), toDev(m_lineWidth, dpr))
							   : qint64(1);
	const qint64 heightDev = toDev(m_paintedH, dpr);

	qreal startX = 0.0;
	if (m_sliding)
		startX = m_viewportW - (len - 1) * step + step;
	else
		startX = 0.0;

	const qint64 curvePadDev = toDev(m_curveSmoothing ? 3.0 : 0.0, dpr);
	const qint64 plotTopDev = lineDev / 2 + curvePadDev;
	const qint64 plotBottomDev =
		(std::max)(plotTopDev + 1, heightDev - (lineDev + 1) / 2 - 1);
	const qint64 plotHDev = plotBottomDev - plotTopDev;
	const qreal fillBottom = fromDev(heightDev, dpr);

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

	for (int i = 0; i < len; ++i) {
		const qreal raw = buffer->smoothedAt(i);

		const qreal value =
			std::isfinite(raw) ? qBound<qreal>(0.0, raw, m_maxValue) : 0.0;

		const qreal y = fromDev(
			plotTopDev + static_cast<qint64>(std::llround(
							 (1.0 - value / m_maxValue) *
							 static_cast<double>(plotHDev))),
			dpr);
		points.append(
			QPointF(startX + qreal(i) * step, snapLine(y, lineDev, dpr)));
	}

	const QVector<QPointF> verts =
		internal::curveVertices(points, dpr, m_curveSmoothing);

	QPainterPath linePath;
	linePath.moveTo(verts.first());
	for (int i = 1; i < verts.size(); ++i)
		linePath.lineTo(verts[i]);

	geom.stroke = linePath;

	QPainterPath fillPath = linePath;
	fillPath.lineTo(points.last().x(), fillBottom);
	fillPath.lineTo(points.first().x(), fillBottom);
	fillPath.closeSubpath();
	geom.fill = fillPath;
	geom.hasData = true;

	return geom;
}

void SparklineContent::rebuildIfNeeded() {
	if (!m_dirty) return;
	m_geom1 = buildGeometry(m_line1);
	m_geom2 = buildGeometry(m_line2);
	m_dirty = false;
}

void SparklineContent::paint(QPainter* painter) {
	rebuildIfNeeded();
	if (!m_geom1.hasData && !m_geom2.hasData) return;

	painter->setRenderHint(QPainter::Antialiasing, true);

	const qreal dpr = m_dpr > 0.0 ? m_dpr : 1.0;
	const qreal lineWidth =
		std::isfinite(m_lineWidth)
			? fromDev((std::max)(qint64(1), toDev(m_lineWidth, dpr)), dpr)
			: 1.0;

	auto drawOne =
		[&](const LineGeometry& geom, const QColor& color, qreal fillAlpha) {
			if (!geom.hasData) return;

			QColor fillColor = color;
			fillColor.setAlphaF(static_cast<float>(fillAlpha));
			painter->setPen(Qt::NoPen);
			painter->setBrush(fillColor);
			painter->drawPath(geom.fill);

			QPen pen(color, lineWidth);
			pen.setCapStyle(Qt::RoundCap);
			pen.setJoinStyle(Qt::RoundJoin);
			painter->setPen(pen);
			painter->setBrush(Qt::NoBrush);
			painter->drawPath(geom.stroke);
		};

	drawOne(m_geom1, m_line1Color, m_line1FillAlpha);
	drawOne(m_geom2, m_line2Color, m_line2FillAlpha);
}

} // namespace ZShell::components