/*
This file is part of Telegram Desktop,
the official desktop application for the Telegram messaging service.

For license and copyright information please follow this link:
https://github.com/telegramdesktop/tdesktop/blob/master/LEGAL
*/
#include "statistics/linear_chart_view.h"

#include "data/data_statistics.h"
#include "statistics/statistics_common.h"
#include "ui/effects/animation_value_f.h"
#include "ui/painter.h"
#include "styles/style_boxes.h"
#include "styles/style_statistics.h"

namespace Statistic {
namespace {

constexpr auto kAlphaDuration = float64(350);

void PaintChartLine(
		QPainter &p,
		int lineIndex,
		const Data::StatisticalChart &chartData,
		const Limits &xIndices,
		const Limits &xPercentageLimits,
		const Limits &heightLimits,
		const QSize &size) {
	const auto &line = chartData.lines[lineIndex];

	auto chartPoints = QPolygonF();

	const auto localStart = std::max(0, int(xIndices.min));
	const auto localEnd = std::min(
		int(chartData.xPercentage.size() - 1),
		int(xIndices.max));

	for (auto i = localStart; i <= localEnd; i++) {
		if (line.y[i] < 0) {
			continue;
		}
		const auto xPoint = size.width()
			* ((chartData.xPercentage[i] - xPercentageLimits.min)
				/ (xPercentageLimits.max - xPercentageLimits.min));
		const auto yPercentage = (line.y[i] - heightLimits.min)
			/ float64(heightLimits.max - heightLimits.min);
		const auto yPoint = (1. - yPercentage) * size.height();
		chartPoints << QPointF(xPoint, yPoint);
	}
	p.setPen(QPen(line.color, st::statisticsChartLineWidth));
	p.setBrush(Qt::NoBrush);
	p.drawPolyline(chartPoints);
}

} // namespace

LinearChartView::LinearChartView() = default;

void LinearChartView::paint(
		QPainter &p,
		const Data::StatisticalChart &chartData,
		const Limits &xIndices,
		const Limits &xPercentageLimits,
		const Limits &heightLimits,
		const QRect &rect,
		DetailsPaintContext &detailsPaintContext) {

	const auto cacheToken = LinearChartView::CacheToken(
		xIndices,
		xPercentageLimits,
		heightLimits,
		rect.size());

	for (auto i = 0; i < chartData.lines.size(); i++) {
		const auto &line = chartData.lines[i];
		p.setOpacity(alpha(line.id));
		if (!p.opacity()) {
			continue;
		}
		if (p.opacity() < 1.) {
			// p.setRenderHint(QPainter::Antialiasing, false);
		}

		////
		auto &cache = _caches[line.id];

		const auto isSameToken = (cache.lastToken == cacheToken);
		if (isSameToken && cache.hq) {
			p.drawImage(rect.topLeft(), cache.image);
			continue;
		}
		const auto ratio = style::DevicePixelRatio();
		cache.hq = isSameToken;
		auto image = QImage();
		image = QImage(
			rect.size() * style::DevicePixelRatio() * (isSameToken ? 1. : ratio),
			QImage::Format_ARGB32_Premultiplied);
		image.setDevicePixelRatio(style::DevicePixelRatio());
		image.fill(Qt::transparent);
		// image.fill(Qt::darkRed);
		{
			auto imagePainter = QPainter(&image);
			imagePainter.setRenderHint(QPainter::Antialiasing, true);
			if (isSameToken) {
				// PainterHighQualityEnabler hp(imagePainter);
			} else {
				imagePainter.scale(ratio, ratio);
			}
			////

			PaintChartLine(
				imagePainter,
				i,
				chartData,
				xIndices,
				xPercentageLimits,
				heightLimits,
				rect.size());
		}

		if (!isSameToken) {
			image = image.scaled(rect.size() * style::DevicePixelRatio(), Qt::IgnoreAspectRatio, Qt::FastTransformation);
		}
		p.drawImage(rect.topLeft(), image);
		cache.lastToken = cacheToken;
		cache.image = std::move(image);
	}
}

void LinearChartView::setEnabled(int id, bool enabled, crl::time now) {
	const auto it = _entries.find(id);
	if (it == end(_entries)) {
		_entries[id] = Entry{ .enabled = enabled, .startedAt = now };
	} else if (it->second.enabled != enabled) {
		auto &entry = it->second;
		entry.enabled = enabled;
		entry.startedAt = now
			- kAlphaDuration * (enabled ? entry.alpha : (1. - entry.alpha));
	}
	_isFinished = false;
}

bool LinearChartView::isFinished() const {
	return _isFinished;
}

bool LinearChartView::isEnabled(int id) const {
	const auto it = _entries.find(id);
	return (it == end(_entries)) ? true : it->second.enabled;
}

float64 LinearChartView::alpha(int id) const {
	const auto it = _entries.find(id);
	return (it == end(_entries)) ? 1. : it->second.alpha;
}

void LinearChartView::tick(crl::time now) {
	auto finishedCount = 0;
	auto idsToRemove = std::vector<int>();
	for (auto &[id, entry] : _entries) {
		if (!entry.startedAt) {
			continue;
		}
		const auto progress = (now - entry.startedAt) / kAlphaDuration;
		entry.alpha = std::clamp(
			entry.enabled ? progress : (1. - progress),
			0.,
			1.);
		if (entry.alpha == 1.) {
			idsToRemove.push_back(id);
		}
		if (progress >= 1.) {
			finishedCount++;
		}
	}
	_isFinished = (finishedCount == _entries.size());
	for (const auto &id : idsToRemove) {
		_entries.remove(id);
	}
}

} // namespace Statistic