#include "datadragon.h"

#include <ostream>
#include <stdexcept>

#include <curl/easy.h>
#include <Log.h>

#include <QEventLoop>
#include <QJsonArray>
#include <QJsonObject>
#include <QThread>

#include <algorithm> // std::max, champ matching

#include "json.h"

static const QString BASEURL = "https://ddragon.leagueoflegends.com/";
const DataDragon::ChampData DataDragon::EMPTYCHAMP;

DataDragon::DataDragon(const QString& locale) : RestClient(BASEURL), locale(locale), cache({{"square", ".png"}, {"loading", "_0.jpg"}, {"splash", "_0.jpg"}}) {
	this->setObjectName("DataDragon");
}

DataDragon::~DataDragon() {
	stopAndJoinThread();
}

DataDragon::ChampData::ChampData() : key(-1) {}

DataDragon::ChampData::ChampData(const QJsonObject& source) {
	name = getValue<QString>(source, "name", "");
	id = getValue<QString>(source, "id", "");
	key = getValue<int>(source, "key", -1);
	partype = getValue<QString>(source, "partype", "");
	title = getValue<QString>(source, "title", "");
}

const QString& DataDragon::getVersion() {
	std::unique_lock lock(cachedatamutex);
	while(version.isEmpty() && shouldrun) {
		cachedatacv.wait(lock);
	}
	return version;
}

const std::vector<DataDragon::ChampData>& DataDragon::getChamps() {
	std::unique_lock lock(cachedatamutex);
	while(champs.empty() && shouldrun) {
		cachedatacv.wait(lock);
	}
	return champs;
}

QPixmap DataDragon::getImage(const QString& champid, ImageType imgtype, bool writeMemcache) {
	if(champid.isEmpty()) return {};

	// query mem cache
	QPixmap img = memcache.getImage(champid, (int) imgtype);
	if(!img.isNull()) return img;

	// query HDD cache
	img = cache[(int) imgtype].getImage(champid);
	if(!img.isNull()) {
		// update mem cache
		memcache.addImage(img, champid, (int) imgtype);
		return img;
	}

	const QString url = getImageUrl(champid, imgtype);
	if(url.isEmpty()) return {};


	QByteArray arr;
	try {
		arr = requestRaw(url);
	} catch(RestClient::WebException& e) {}
	if(arr.isEmpty()) {
		qCritical() << "image could not be loaded";
		return {};
	}

	// propably an error
	if(arr.size() < 1000) {
		qInfo() << "small icon url: " << url;
		qInfo() << "content: " << QString::fromLocal8Bit(arr);
		return {};
	}

	// store HDD cache
	cache[(int) imgtype].addImageRaw(arr, champid);

	// remove from notDownloadedList
	notDownloadedImages.erase(champid);

	QPixmap decodedImage;
	decodedImage.loadFromData(arr);

	// store mem cache
	if(writeMemcache) {
		memcache.addImage(decodedImage, champid, (int) imgtype);
	}

	return decodedImage;
}

void DataDragon::getImageAsnyc(const QString& champid, notifyImgfunc_t func, ImageType imgtype) {
	if(!func) return;

	{
		std::lock_guard lock(tasksmutex);
		tasks.push_back({champid, func, imgtype});
	}
	tasksnotemptycv.notify_one();
}

static int startinglength(const QString& original, const QString& prefix) {
	int i = 0;
	for(; i < original.size() && i < prefix.size(); ++i) {
		if(original.left(i+1) != prefix.left(i+1)) {
			return i;
		}
	}
	return i;
}

static size_t matchChamp(const DataDragon::ChampData& champ, const QString& lower) {
	QString lowerid = champ.id.toLower();
	QString lowername = champ.name.toLower();
	if(lowerid == lower || lowername == lower) {
		return lower.size();
	}

	int lengtha = startinglength(lowerid, lower);
	int lengthb = startinglength(lowername, lower);

	return qMax(lengtha, lengthb);
}

const DataDragon::ChampData& DataDragon::getBestMatchingChamp(const QString& name, int* count) {
	getChamps();
	// for now: just check for a perfect hit
	QString lower = name.toLower();
	int bestmatchingoffset = -1;
	int bestmatchinglength = 0;
	uint32_t bestmatchingcount = 0;
	for(size_t offset = 0; offset < champs.size(); ++offset) {
		const ChampData& it = champs.at(offset);

		int match = matchChamp(it, lower);
		if(match > bestmatchinglength) {
			bestmatchinglength = match;
			bestmatchingcount = 1;
			bestmatchingoffset = offset;
		} else if(match == bestmatchinglength) {
			bestmatchingcount ++;
		}
	}

	if(bestmatchinglength < lower.size()) {
		if(count) *count = 0;
		return EMPTYCHAMP;
	}

	if(count) *count = bestmatchingcount;
	if(bestmatchingoffset >= 0)
		return champs.at(bestmatchingoffset);

	return EMPTYCHAMP;
}

std::vector<const DataDragon::ChampData*> DataDragon::getMatchingChamp(const QString& name, uint32_t limit) {
	if(limit == 0) return {};
	if(name.isEmpty()) return {};

	getChamps();
	QString lower = name.toLower();

	std::vector<size_t> matches;
	matches.resize(champs.size());
	std::transform(champs.begin(), champs.end(), std::insert_iterator(matches, matches.begin()), std::bind(&matchChamp, std::placeholders::_1, lower));

	// find smallest element
	std::vector<size_t> matches_sort = matches;
	std::nth_element(matches_sort.begin(), matches_sort.begin(), matches_sort.end(), std::greater{});
	size_t border = matches_sort.at(0);
	Log::trace << "border: " << border;

	std::vector<const ChampData*> out;
	out.reserve(limit);

	// take all with a match higher than that
	for(uint32_t i = 0; i < matches.size() && out.size() < limit; ++i) {
		if(matches[i] >= border) {
			out.push_back(&champs[i]);
		}
	}

	return out;
}

const DataDragon::ChampData* DataDragon::getChampByID(uint32_t id) {
	getChamps();

	auto it = std::find_if(champs.begin(), champs.end(), [id](const ChampData& cd) { return cd.key == (int) id; });

	// nothing found
	if(it == champs.end()) return nullptr;

	return &*it;
}

std::vector<uint32_t> DataDragon::resolveChampIDs(const std::vector<QString>& champnames) {
	std::vector<uint32_t> out;
	out.reserve(champnames.size());

	std::transform(champnames.begin(), champnames.end(), std::insert_iterator(out, out.begin()), [this](const QString& champname) {
		auto cd = getBestMatchingChamp(champname);
		return cd.key; // might be 0 (invalid)
	});

	return out;
}

void DataDragon::startThread() {
	shouldrun = true;
	bgthread = QThread::create(&DataDragon::threadLoop, this);
	bgthread->setObjectName("DataDragonThread");
	bgthread->start();
	this->moveToThread(bgthread);
}

void DataDragon::stop() {
	qDebug() << "stop DataDragon";
	shouldrun = false;
	std::unique_lock lock(tasksmutex);

	tasks.clear();
	notDownloadedImages.clear(); // this is a possible race condition!
}

QString DataDragon::getImageUrl(const QString& champid, ImageType type) {
	switch(type) {
		case ImageType::SQUARE: {
				if(getVersion().isEmpty()) {
				return {};
			}

			// with version
			return getCDNString() + "img/champion/" + champid + ".png";
		}
		case ImageType::LOADING:
			// no version
			return "cdn/img/champion/loading/" + champid + "_0.jpg";
		case ImageType::SPLASH:
			// no version
			return "cdn/img/champion/splash/" + champid + "_0.jpg";
	}
	return {};
}

QString DataDragon::getCDNString() const {
	return "cdn/" + version + "/";
}

void DataDragon::prefetchChampImage(const QString& champid, ImageType imgtype) {
	if(!cache[(int) imgtype].hasImage(champid)) {
		qDebug() << "prefetch " << champid << " type: " << (int) imgtype;
		getImage(champid, imgtype, false);
	}
}

void DataDragon::getVersionInternal() {
	std::unique_lock lock(cachedatamutex);

	if(!version.isEmpty()) return;

	version = champCache.getVersion();
	if(!version.isEmpty()) return;

	try {
		QJsonDocument jversions = request("api/versions.json");
		if(jversions.isArray()) {
			QJsonArray jverarr = jversions.array();
			if(!jverarr.empty()) {
				version = jverarr.at(0).toString();
				qInfo() << "got League version: " << version;

				lock.unlock();
				cachedatacv.notify_all();
				return;
			}
		}
		qCritical() << "error parsing version object";
	} catch(RestClient::WebException& e) {}
}

void DataDragon::getChampsInternal() {
	std::unique_lock lock(cachedatamutex);
	if(!champs.empty() && version.isEmpty()) {
		return;
	}

	QJsonDocument jchamps = champCache.getChamps();
	bool cacheSuccessfull = !jchamps.isEmpty();
	if(!cacheSuccessfull) {
		try {
			jchamps = request(getCDNString() + "data/" + locale + "/champion.json");
			if(jchamps.isEmpty()) {
				// try again with default locale
				locale = "en_US";
				jchamps = request(getCDNString() + "data/" + locale + "/champion.json");
			}
		} catch(RestClient::WebException& e) {}
	}
	if(jchamps.isObject()) {
		// save to cache
		if(!cacheSuccessfull) {
			champCache.saveChamps(jchamps, version);
		}

		QJsonObject obj = jchamps.object();
		auto it = obj.constFind("data");
		if(it != obj.constEnd() && it.value().isObject()) {
			QJsonObject jchampsdata = it.value().toObject();
			for(auto champit = jchampsdata.constBegin(); champit != jchampsdata.constEnd(); champit++) {
				if(champit.value().isObject()) {
					champs.emplace_back(champit.value().toObject());
					notDownloadedImages.insert(champs.back().id);
				}
			}
		}
	}
	qInfo() << "loaded " << champs.size() << " champs from cache: " << cacheSuccessfull;
	lock.unlock();
	cachedatacv.notify_all();
}

void DataDragon::stopThread() {
	shouldrun = false;
	tasksnotemptycv.notify_all();
}

void DataDragon::stopAndJoinThread() {
	stopThread();

	bgthread->wait();
}

void DataDragon::threadLoop() {
	QEventLoop loop;

	// init version and champ list
	getVersionInternal();
	getChampsInternal();

	while(shouldrun) {
		// wait for a task in the list
		Task t;
		{
			std::unique_lock lock(tasksmutex);
			if(tasks.empty()) {
				if(notDownloadedImages.empty()) {
					tasksnotemptycv.wait(lock);
				} else {
					Log::note << "DataDragon background thread is idleing - prefetching champion images TODO: " << notDownloadedImages.size();

					while(shouldrun && !notDownloadedImages.empty() && tasks.empty()) {
						lock.unlock();

						auto it = notDownloadedImages.begin();
						QString champid = *it;
						notDownloadedImages.erase(it);

						prefetchChampImage(champid, ImageType::SQUARE);

						emit this->loading(1.0 - (notDownloadedImages.size() / (float) champs.size()));
						emit this->fetchingChamp(champid);

						lock.lock();
					}

					if(notDownloadedImages.empty() && tasks.empty()) {
						// everything prefetched, but nothing more to do
						static bool once = false;
						if(!once) {
							once = true;
							Log::note << "all champs are prefetched now";
							emit this->loading( 1.0 );
						}

						tasksnotemptycv.wait(lock);
					}
				}
			}

			if(tasks.empty()) continue;

			t = tasks.front();
			tasks.pop_front();
		}

		loop.processEvents();

		QPixmap img = getImage(t.champid, t.type);
		t.func(img);
	}

	qDebug() << "DataDragon Thread terminated";
}

std::ostream& operator<<(std::ostream& str, const DataDragon::ChampData& cd) {
	return str << "[n: " << cd.name.toStdString() << " " << " k: " << cd.key << " id: " << cd.id.toStdString() << "]";
}