#include <QImage>
#include <QPainter>
#include <QThreadPool>
#include <QDir>
#include <QSqlQuery>
#include <QSqlError>
#include <QPointer>
#include <tmsprovider.h>
#include <network.h>
#include <iostream>
#pragma execution_character_set("utf-8")

namespace LAMPMainWidget
{
	TileDownloadTask::TileDownloadTask(TileInfo tile, tileReadyCallback cb, QObject* parent)
		: QObject(parent),
		mTile(std::move(tile)),
		mCallback(cb)
	{
		// 程序初始化时注册（如main函数或类构造函数）
		qRegisterMetaType<TileInfo>("TileInfo");
	}

	void TileDownloadTask::run()
	{
		Network web{};
		QByteArray data = web.httpsRequest(mTile.url);
		mTile.data = data;
		if (mCallback) {
			mCallback(mTile);
		}
		else {}
	}

	TmsProvider::TmsProvider(QObject* parent)
		: LayerProvider(parent),
		mImage(nullptr)
	{
		if (!QFile::exists(mDbName)) {
			QFile dbFile{ mDbName };
			dbFile.open(QIODevice::ReadWrite);
			dbFile.close();
		}
	}

	TmsProvider::~TmsProvider()
	{
		delete mImage;
	}

	bool TmsProvider::initCache()
	{
		mDbConn = QSqlDatabase::addDatabase("QSQLITE", id());
		mDbConn.setDatabaseName(mDbName);
		if (!mDbConn.open()) {
			std::cout << u8"缓存数据库打开失败";
			return false;
		}

		QSqlQuery sql{ mDbConn };
		if (!mDbConn.tables().contains(mTableName)) {
			sql.prepare(QString("create table %1 ("
				"id integer primary key autoincrement,"
				"provider text not null,"
				"zoom integer not null,"
				"position text not null,"
				"data blob not null"
				")").arg(mTableName));
			if (!sql.exec()) {
				qCritical() << "缓存表创建失败" << sql.lastError().text();
				return false;
			}
		}

		mDbConn.close();
		return true;
	}

	QByteArray TmsProvider::getCache(const QPoint& pos, int zoom)
	{
		QByteArray res{};
		mDbConn.open();
		QSqlQuery select{ mDbConn };
		select.prepare(QString("select data from %1 "
			"where provider = :provider "
			"and zoom = :zoom "
			"and position = :position "
			"order by id desc limit 1"
		).arg(mTableName));
		select.bindValue(":provider", id());
		select.bindValue(":zoom", zoom);
		select.bindValue(":position", QString("%1:%2").arg(pos.x()).arg(pos.y()));
		if (!select.exec()) {
			std::cout << pos.x()<<","<<pos.y() << "查询失败=>" << select.lastError().text().toUtf8().constData() << std::endl;
			mDbConn.close();
			return res;
		}
		if (!select.seek(0)) {
			mDbConn.close();
			return res;
		}

		res = select.value(0).toByteArray();
		mDbConn.close();
		return res;
	}

	bool TmsProvider::addCache(const QPoint& pos, int zoom, QByteArray data)
	{
		if (data.isEmpty()) {
			std::cout << "瓦片数据为空";
			return false;
		}
		mDbConn.open();
		QSqlQuery sql{ mDbConn };
		sql.prepare(QString{
		  "insert into %1 (provider, zoom, position, data)"
		  "values( :provider, :zoom, :position, :data)"
			}.arg(mTableName));
		sql.bindValue(":tbname", mTableName);
		sql.bindValue(":provider", id());
		sql.bindValue(":zoom", zoom);
		sql.bindValue(":position", QString("%1:%2").arg(pos.x()).arg(pos.y()));
		sql.bindValue(":data", data);

		if (!sql.exec()) {
			std::cout << pos.x() << "," << pos.y() << "=>" << sql.lastError().text().toUtf8().constData() << std::endl;
			mDbConn.close();
			return false;
		}

		mDbConn.close();
		return true;
	}

	bool TmsProvider::cacheContains(const QPoint& pos, int zoom)
	{
		QByteArray res = getCache(pos, zoom);
		return !res.isEmpty();
	}

	void TmsProvider::createTask(const QRectF& rect, int zoom)
	{
		newImage(rect);

		/// 创建下载瓦片任务
		const QSize sz = tileSize();
		int xMin = qFloor(rect.topLeft().x() / sz.width());
		double xOffset = rect.topLeft().x() / sz.width() - xMin;
		int xMax = qFloor(rect.bottomRight().x() / sz.width());
		int yMin = qFloor(rect.topLeft().y() / sz.height());
		double yOffset = rect.topLeft().y() / sz.height() - yMin;
		int yMax = qFloor(rect.bottomRight().y() / sz.height());
		for (int i = xMin; i <= xMax; ++i) {
			for (int j = yMin; j <= yMax; ++j) {
				TileInfo tile{};
				tile.index = QPointF{ i - xMin - xOffset, j - yMin - yOffset };
				tile.position = QPoint{ i, j };
				tile.zoom = zoom;
				tile.coord = QPoint{ i - xMin, j - yMin };
				tile.url = tileUrl(PointXY{ static_cast<double>(i), static_cast<double>(j) }, zoom);
				auto tileData = getCache(tile.position, tile.zoom);
				if (!tileData.isEmpty()) {
					tile.data = tileData;
					tileReady(tile);
					continue;
				}
				/* 原始写法遇到了跨线程信号槽失效问题，这里修改为回调函数方式
				auto* task = new TileDownloadTask(tile);
				if (!QObject::connect(task, SIGNAL(tileReady(TileInfo)), this, SLOT(tileReady(TileInfo)))) {
					qDebug() << "连接失败：" << QObject::tr(qPrintable(Q_FUNC_INFO));
				}
 
				QThreadPool::globalInstance()->start(task);
				 */
				// 回调函数版本
				QPointer<TmsProvider> safeThis(this);
				auto* task = new TileDownloadTask(tile, [safeThis](  TileInfo  info) {
					if (safeThis) { // 自动检测对象是否存活
						QMetaObject::invokeMethod(safeThis.data(), [safeThis, info] {
							safeThis->tileReady(info);
							}, Qt::QueuedConnection); // 强制主线程执行[6](@ref)
					}
					});
				QThreadPool::globalInstance()->start(task);

			}
		}
	}

	void TmsProvider::tileReady(TileInfo tile)
	{
		if (!cacheContains(tile.position, tile.zoom)) {
			addCache(tile.position, tile.zoom, tile.data);
		}
		QPainter painter{ mImage };
		QImage img = QImage::fromData(tile.data);
		if (img.isNull()) {
			return;
		}

		double xPos = tile.index.x() * tileSize().width();
		double yPos = tile.index.y() * tileSize().height();

		painter.drawImage(QPointF(xPos, yPos), img);
	}

	void TmsProvider::newImage(const QRectF& rect)
	{
		QSize imgSize{ int(rect.width()), int(rect.height()) };
		if (!mImage || imgSize != mImage->size()) {
			mImage = new QImage(imgSize, QImage::Format_RGB32);
		}
		mImage->fill(Qt::white);
	}
}