/*
This file is part of Telegram Desktop,
the official desktop version of Telegram messaging app, see https://telegram.org

Telegram Desktop is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.

It is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.

In addition, as a special exception, the copyright holders give permission
to link the code of portions of this program with the OpenSSL library.

Full license: https://github.com/telegramdesktop/tdesktop/blob/master/LICENSE
Copyright (c) 2014-2017 John Preston, https://desktop.telegram.org
*/
#pragma once

#include "mtproto/sender.h"

namespace AdminLog {

class SectionMemento;
class Item;

class LocalIdManager {
public:
	LocalIdManager() = default;
	LocalIdManager(const LocalIdManager &other) = delete;
	LocalIdManager &operator=(const LocalIdManager &other) = delete;
	LocalIdManager(LocalIdManager &&other) : _counter(std::exchange(other._counter, ServerMaxMsgId)) {
	}
	LocalIdManager &operator=(LocalIdManager &&other) {
		_counter = std::exchange(other._counter, ServerMaxMsgId);
		return *this;
	}
	MsgId next() {
		return ++_counter;
	}

private:
	MsgId _counter = ServerMaxMsgId;

};

class InnerWidget final : public TWidget, private MTP::Sender {
public:
	InnerWidget(QWidget *parent, gsl::not_null<ChannelData*> channel, base::lambda<void(int top)> scrollTo);

	gsl::not_null<ChannelData*> channel() const {
		return _channel;
	}

	// Updates the area that is visible inside the scroll container.
	void setVisibleTopBottom(int visibleTop, int visibleBottom) override;

	void resizeToWidth(int newWidth, int minHeight) {
		_minHeight = minHeight;
		return TWidget::resizeToWidth(newWidth);
	}

	void saveState(gsl::not_null<SectionMemento*> memento) const;
	void restoreState(gsl::not_null<const SectionMemento*> memento);
	void setCancelledCallback(base::lambda<void()> callback) {
		_cancelledCallback = std::move(callback);
	}

	// Empty "flags" means all events. Empty "admins" means all admins.
	void applyFilter(MTPDchannelAdminLogEventsFilter::Flags flags, const std::vector<gsl::not_null<UserData*>> &admins);

	~InnerWidget();

protected:
	void paintEvent(QPaintEvent *e) override;
	void keyPressEvent(QKeyEvent *e) override;
	void mousePressEvent(QMouseEvent *e) override;
	void mouseMoveEvent(QMouseEvent *e) override;
	void mouseReleaseEvent(QMouseEvent *e) override;

	// Resizes content and counts natural widget height for the desired width.
	int resizeGetHeight(int newWidth) override;

private:
	enum class Direction {
		Up,
		Down,
	};
	void checkPreloadMore();
	void updateVisibleTopItem();
	void preloadMore(Direction direction);
	void itemsAdded(Direction direction);
	void updateSize();
	void paintEmpty(Painter &p);

	gsl::not_null<ChannelData*> _channel;
	gsl::not_null<History*> _history;
	base::lambda<void()> _cancelledCallback;
	base::lambda<void(int top)> _scrollTo;
	std::vector<std::unique_ptr<Item>> _items;

	LocalIdManager _idManager;
	int _minHeight = 0;
	int _visibleTop = 0;
	int _visibleBottom = 0;
	Item *_visibleTopItem = nullptr;
	int _visibleTopFromItem = 0;

	// Up - max, Down - min.
	uint64 _maxId = 0;
	uint64 _minId = 0;
	mtpRequestId _preloadUpRequestId = 0;
	mtpRequestId _preloadDownRequestId = 0;
	bool _upLoaded = false;
	bool _downLoaded = true;

	MTPDchannelAdminLogEventsFilter::Flags _filterFlags = 0;
	std::vector<gsl::not_null<UserData*>> _filterAdmins;

};

} // namespace AdminLog