#include "ServersPage.h"
#include "ui_ServersPage.h"

#include <FileSystem.h>
#include <sstream>
#include <io/stream_reader.h>
#include <tag_string.h>
#include <tag_primitive.h>
#include <tag_list.h>
#include <tag_compound.h>
#include <minecraft/MinecraftInstance.h>

#include <QFileSystemWatcher>

static const int COLUMN_COUNT = 2; // 3 , TBD: latency and other nice things.

struct Server
{
	// Types
	enum class AcceptsTextures : int
	{
		ASK = 0,
		ALWAYS = 1,
		NEVER = 2
	};

	// Methods
	Server()
	{
		m_name = QObject::tr("Minecraft Server");
	}
	Server(const QString & name, const QString & address)
	{
		m_name = name;
		m_address = address;
	}
	Server(nbt::tag_compound& server)
	{
		std::string addressStr(server["ip"]);
		m_address = QString::fromUtf8(addressStr.c_str());

		std::string nameStr(server["name"]);
		m_name = QString::fromUtf8(nameStr.c_str());

		if(server["icon"])
		{
			std::string base64str(server["icon"]);
			m_icon = QByteArray::fromBase64(base64str.c_str());
		}

		if(server.has_key("acceptTextures", nbt::tag_type::Byte))
		{
			bool value = server["acceptTextures"].as<nbt::tag_byte>().get();
			if(value)
			{
				m_acceptsTextures = AcceptsTextures::ALWAYS;
			}
			else
			{
				m_acceptsTextures = AcceptsTextures::NEVER;
			}
		}
	}

	void serialize(nbt::tag_compound& server)
	{
		server.insert("name", m_name.toUtf8().toStdString());
		server.insert("ip", m_address.toUtf8().toStdString());
		if(m_icon.size())
		{
			server.insert("icon", m_icon.toBase64().toStdString());
		}
		if(m_acceptsTextures != AcceptsTextures::ASK)
		{
			server.insert("acceptTextures", nbt::tag_byte(m_acceptsTextures == AcceptsTextures::ALWAYS));
		}
	}

	// Data - persistent and user changeable
	QString m_name;
	QString m_address;
	AcceptsTextures m_acceptsTextures = AcceptsTextures::ASK;

	// Data - persistent and automatically updated
	QByteArray m_icon;

	// Data - temporary
	bool m_checked = false;
	bool m_up = false;
	QString m_motd; // https://mctools.org/motd-creator
	int m_ping = 0;
	int m_currentPlayers = 0;
	int m_maxPlayers = 0;
};

static std::unique_ptr <nbt::tag_compound> parseServersDat(const QString& filename)
{
	try
	{
		QByteArray input = FS::read(filename);
		std::istringstream foo(std::string(input.constData(), input.size()));
		auto pair = nbt::io::read_compound(foo);

		if(pair.first != "")
			return nullptr;

		if(pair.second == nullptr)
			return nullptr;

		return std::move(pair.second);
	}
	catch(...)
	{
		return nullptr;
	}
}

static bool serializeServerDat(const QString& filename, nbt::tag_compound * levelInfo)
{
	try
	{
		std::ostringstream s;
		nbt::io::write_tag("", *levelInfo, s);
		QByteArray val(s.str().data(), (int) s.str().size() );
		FS::write(filename, val);
		return true;
	}
	catch(...)
	{
		return false;
	}
}

class ServersModel: public QAbstractListModel
{
	Q_OBJECT
public:
	enum Roles
	{
		ServerPtrRole = Qt::UserRole,
	};
	explicit ServersModel(const QString &path, QObject *parent = 0)
		: QAbstractListModel(parent)
	{
		m_path = path;
		m_watcher = new QFileSystemWatcher(this);
		connect(m_watcher, &QFileSystemWatcher::fileChanged, this, &ServersModel::fileChanged);
		connect(m_watcher, &QFileSystemWatcher::directoryChanged, this, &ServersModel::dirChanged);
		m_saveTimer.setSingleShot(true);
		m_saveTimer.setInterval(5000);
		connect(&m_saveTimer, &QTimer::timeout, this, &ServersModel::save_internal);
	}
	virtual ~ServersModel() {};

	void observe()
	{
		if(m_observed)
		{
			return;
		}
		m_observed = true;

		if(!m_loaded)
		{
			load();
		}

		updateFSObserver();
	}

	void unobserve()
	{
		if(!m_observed)
		{
			return;
		}
		m_observed = false;

		updateFSObserver();
	}

	void lock()
	{
		if(m_locked)
		{
			return;
		}
		saveNow();

		m_locked = true;
		updateFSObserver();
	}

	void unlock()
	{
		if(!m_locked)
		{
			return;
		}
		m_locked = false;

		updateFSObserver();
	}

	int addEmptyRow(int position)
	{
		if(m_locked)
		{
			return -1;
		}
		if(position < 0 || position >= rowCount())
		{
			position = rowCount();
		}
		beginInsertRows(QModelIndex(), position, position);
		m_servers.insert(position, Server());
		endInsertRows();
		scheduleSave();
		return position;
	}

	bool removeRow(int row)
	{
		if(m_locked)
		{
			return false;
		}
		if(row < 0 || row >= rowCount())
		{
			return false;
		}
		beginRemoveRows(QModelIndex(), row, row);
		m_servers.removeAt(row);
		endRemoveRows(); // does absolutely nothing, the selected server stays as the next line...
		scheduleSave();
		return true;
	}

	bool moveUp(int row)
	{
		if(m_locked)
		{
			return false;
		}
		if(row <= 0)
		{
			return false;
		}
		beginMoveRows(QModelIndex(), row, row, QModelIndex(), row - 1);
		m_servers.swap(row-1, row);
		endMoveRows();
		scheduleSave();
		return true;
	}

	bool moveDown(int row)
	{
		if(m_locked)
		{
			return false;
		}
		int count = rowCount();
		if(row + 1 >= count)
		{
			return false;
		}
		beginMoveRows(QModelIndex(), row, row, QModelIndex(), row + 2);
		m_servers.swap(row+1, row);
		endMoveRows();
		scheduleSave();
		return true;
	}

	QVariant headerData(int section, Qt::Orientation orientation, int role) const override
	{
		if (section < 0 || section >= COLUMN_COUNT)
			return QVariant();

		if(role == Qt::DisplayRole)
		{
			switch(section)
			{
				case 0:
					return tr("Name");
				case 1:
					return tr("Address");
				case 2:
					return tr("Latency");
			}
		}

		return QAbstractListModel::headerData(section, orientation, role);
	}

	virtual QVariant data(const QModelIndex &index, int role = Qt::DisplayRole) const override
	{
		if (!index.isValid())
			return QVariant();

		int row = index.row();
		int column = index.column();
		if(column < 0 || column >= COLUMN_COUNT)
			return QVariant();

		if (row < 0 || row >= m_servers.size())
			return QVariant();

		switch(column)
		{
			case 0:
				switch (role)
				{
				case Qt::DecorationRole:
				{
					auto & bytes = m_servers[row].m_icon;
					if(bytes.size())
					{
						QPixmap px;
						if(px.loadFromData(bytes))
							return QIcon(px);
					}
					return MMC->getThemedIcon("unknown_server");
				}
				case Qt::DisplayRole:
					return m_servers[row].m_name;
				case ServerPtrRole:
					return QVariant::fromValue<void *>((void *)&m_servers[row]);
				default:
					return QVariant();
				}
			case 1:
				switch (role)
				{
				case Qt::DisplayRole:
					return m_servers[row].m_address;
				default:
					return QVariant();
				}
			case 2:
				switch (role)
				{
				case Qt::DisplayRole:
					return m_servers[row].m_ping;
				default:
					return QVariant();
				}
			default:
				return QVariant();
		}
	}

	virtual int rowCount(const QModelIndex &parent = QModelIndex()) const override
	{
		return m_servers.size();
	}
	int columnCount(const QModelIndex & parent) const override
	{
		return COLUMN_COUNT;
	}

	Server * at(int index)
	{
		if(index < 0 || index >= rowCount())
		{
			return nullptr;
		}
		return &m_servers[index];
	}

	void setName(int row, const QString & name)
	{
		if(m_locked)
		{
			return;
		}
		auto server = at(row);
		if(!server || server->m_name == name)
		{
			return;
		}
		server->m_name = name;
		emit dataChanged(index(row, 0), index(row, COLUMN_COUNT - 1));
		scheduleSave();
	}

	void setAddress(int row, const QString & address)
	{
		if(m_locked)
		{
			return;
		}
		auto server = at(row);
		if(!server || server->m_address == address)
		{
			return;
		}
		server->m_address = address;
		emit dataChanged(index(row, 0), index(row, COLUMN_COUNT - 1));
		scheduleSave();
	}

	void setAcceptsTextures(int row, Server::AcceptsTextures textures)
	{
		if(m_locked)
		{
			return;
		}
		auto server = at(row);
		if(!server || server->m_acceptsTextures == textures)
		{
			return;
		}
		server->m_acceptsTextures = textures;
		emit dataChanged(index(row, 0), index(row, COLUMN_COUNT - 1));
		scheduleSave();
	}

	void load()
	{
		cancelSave();
		beginResetModel();
		QList<Server> servers;
		auto serversDat = parseServersDat(serversPath());
		if(serversDat)
		{
			auto &serversList = serversDat->at("servers").as<nbt::tag_list>();
			for(auto iter = serversList.begin(); iter != serversList.end(); iter++)
			{
				auto & serverTag = (*iter).as<nbt::tag_compound>();
				Server s(serverTag);
				servers.append(s);
			}
		}
		m_servers.swap(servers);
		m_loaded = true;
		endResetModel();
	}

	void saveNow()
	{
		if(saveIsScheduled())
		{
			save_internal();
		}
	}


public slots:
	void dirChanged(const QString& path)
	{
		qDebug() << "Changed:" << path;
		load();
	}
	void fileChanged(const QString& path)
	{
		qDebug() << "Changed:" << path;
	}

private slots:
	void save_internal()
	{
		cancelSave();
		qDebug() << "Server list save is performed for" << m_path;

		nbt::tag_compound out;
		nbt::tag_list list;
		for(auto & server: m_servers)
		{
			nbt::tag_compound serverNbt;
			server.serialize(serverNbt);
			list.push_back(std::move(serverNbt));
		}
		out.insert("servers", nbt::value(std::move(list)));

		if(!serializeServerDat(serversPath(), &out))
		{
			qDebug() << "Failed to save server list:" << m_path << "Will try again.";
			scheduleSave();
		}
	}

private:
	void scheduleSave()
	{
		if(!m_loaded)
		{
			qDebug() << "Server list should never save if it didn't successfully load, path:" << m_path;
			return;
		}
		if(!m_dirty)
		{
			m_dirty = true;
			qDebug() << "Server list save is scheduled for" << m_path;
		}
		m_saveTimer.start();
	}

	void cancelSave()
	{
		m_dirty = false;
		m_saveTimer.stop();
	}

	bool saveIsScheduled() const
	{
		return m_dirty;
	}

	void updateFSObserver()
	{
		bool observingFS = m_watcher->directories().contains(m_path);
		if(m_observed && m_locked)
		{
			if(!observingFS)
			{
				qWarning() << "Will watch" << m_path;
				if(!m_watcher->addPath(m_path))
				{
					qWarning() << "Failed to start watching" << m_path;
				}
			}
		}
		else
		{
			if(observingFS)
			{
				qWarning() << "Will stop watching" << m_path;
				if(!m_watcher->removePath(m_path))
				{
					qWarning() << "Failed to stop watching" << m_path;
				}
			}
		}
	}

	QString serversPath()
	{
		QFileInfo foo(FS::PathCombine(m_path, "servers.dat"));
		return foo.canonicalFilePath();
	}

private:
	bool m_loaded = false;
	bool m_locked = false;
	bool m_observed = false;
	bool m_dirty = false;
	QString m_path;
	QList<Server> m_servers;
	QFileSystemWatcher *m_watcher = nullptr;
	QTimer m_saveTimer;
};

ServersPage::ServersPage(MinecraftInstance * inst, QWidget* parent)
	: QWidget(parent), ui(new Ui::ServersPage)
{
	ui->setupUi(this);
	ui->tabWidget->tabBar()->hide();
	m_inst = inst;
	m_model = new ServersModel(inst->minecraftRoot(), this);
	ui->serversView->setIconSize(QSize(64,64));
	ui->serversView->setModel(m_model);
	auto head = ui->serversView->header();
	if(head->count())
	{
		head->setSectionResizeMode(0, QHeaderView::Stretch);
		for(int i = 1; i < head->count(); i++)
		{
			head->setSectionResizeMode(i, QHeaderView::ResizeToContents);
		}
	}

	auto selectionModel = ui->serversView->selectionModel();
	connect(selectionModel, &QItemSelectionModel::currentChanged, this, &ServersPage::currentChanged);
	connect(m_inst, &MinecraftInstance::runningStatusChanged, this, &ServersPage::on_RunningState_changed);
	connect(ui->nameLine, &QLineEdit::textEdited, this, &ServersPage::nameEdited);
	connect(ui->addressLine, &QLineEdit::textEdited, this, &ServersPage::addressEdited);
	connect(ui->resourceComboBox, SIGNAL(currentIndexChanged(int)), this, SLOT(resourceIndexChanged(int)));
	connect(m_model, &QAbstractItemModel::rowsRemoved, this, &ServersPage::rowsRemoved);

	m_locked = m_inst->isRunning();
	if(m_locked)
	{
		m_model->lock();
	}

	updateState();
}

ServersPage::~ServersPage()
{
	m_model->saveNow();
}

void ServersPage::on_RunningState_changed(bool running)
{
	if(m_locked == running)
	{
		return;
	}
	m_locked = running;
	if(m_locked)
	{
		m_model->lock();
	}
	else
	{
		m_model->unlock();
	}
	updateState();
}

void ServersPage::currentChanged(const QModelIndex &current, const QModelIndex &previous)
{
	int nextServer = -1;
	if (!current.isValid())
	{
		nextServer = -1;
	}
	else
	{
		nextServer = current.row();
	}
	currentServer = nextServer;
	updateState();
}

// WARNING: this is here because currentChanged is not accurate when removing rows. the current item needs to be fixed up after removal.
void ServersPage::rowsRemoved(const QModelIndex& parent, int first, int last)
{
	if(currentServer < first)
	{
		// current was before the removal
		return;
	}
	else if(currentServer >= first && currentServer <= last)
	{
		// current got removed...
		return;
	}
	else
	{
		// current was past the removal
		int count = last - first + 1;
		currentServer -= count;
	}
}

void ServersPage::nameEdited(const QString& name)
{
	m_model->setName(currentServer, name);
}

void ServersPage::addressEdited(const QString& address)
{
	m_model->setAddress(currentServer, address);
}

void ServersPage::resourceIndexChanged(int index)
{
	auto acceptsTextures = Server::AcceptsTextures(index);
	m_model->setAcceptsTextures(currentServer, acceptsTextures);
}

void ServersPage::updateState()
{
	auto server = m_model->at(currentServer);

	bool serverEditEnabled = server && !m_locked;
	ui->addressLine->setEnabled(serverEditEnabled);
	ui->nameLine->setEnabled(serverEditEnabled);
	ui->resourceComboBox->setEnabled(serverEditEnabled);
	ui->moveDownBtn->setEnabled(serverEditEnabled);
	ui->moveUpBtn->setEnabled(serverEditEnabled);
	ui->removeBtn->setEnabled(serverEditEnabled);

	if(server)
	{
		ui->addressLine->setText(server->m_address);
		ui->nameLine->setText(server->m_name);
		ui->resourceComboBox->setCurrentIndex(int(server->m_acceptsTextures));
	}
	else
	{
		ui->addressLine->setText(QString());
		ui->nameLine->setText(QString());
		ui->resourceComboBox->setCurrentIndex(0);
	}

	ui->addBtn->setDisabled(m_locked);
}

void ServersPage::openedImpl()
{
	m_model->observe();
}

void ServersPage::closedImpl()
{
	m_model->unobserve();
}

void ServersPage::on_addBtn_clicked()
{
	int position = m_model->addEmptyRow(currentServer + 1);
	if(position < 0)
	{
		return;
	}
	// select the new row
	ui->serversView->selectionModel()->setCurrentIndex(
		m_model->index(position),
		QItemSelectionModel::SelectCurrent | QItemSelectionModel::Clear | QItemSelectionModel::Rows
	);
	currentServer = position;
}

void ServersPage::on_removeBtn_clicked()
{
	m_model->removeRow(currentServer);
}

void ServersPage::on_moveUpBtn_clicked()
{
	if(m_model->moveUp(currentServer))
	{
		currentServer --;
	}
}

void ServersPage::on_moveDownBtn_clicked()
{
	if(m_model->moveDown(currentServer))
	{
		currentServer ++;
	}
}

void ServersPage::on_refreshBtn_clicked()
{
	m_model->load();
}

#include "ServersPage.moc"