//
// This file is part of Kepka,
// an unofficial desktop version of Telegram messaging app,
// see https://github.com/procxx/kepka
//
// Kepka 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/procxx/kepka/blob/master/LICENSE
// Copyright (c) 2014-2017 John Preston, https://desktop.telegram.org
// Copyright (c) 2017- Kepka Contributors, https://github.com/procxx
//
#pragma once

#include "mtproto/sender.h"

namespace Ui {
class IconButton;
class RoundButton;
class LinkButton;
class SlideAnimation;
class CrossFadeAnimation;
class FlatLabel;
template <typename Widget> class WidgetFadeWrap;
} // namespace Ui

namespace Intro {

class Widget : public TWidget, private MTP::Sender, private base::Subscriber {
	Q_OBJECT

public:
	Widget(QWidget *parent);

	void showAnimated(const QPixmap &bgAnimCache, bool back = false);

	void setInnerFocus();

	~Widget();

protected:
	void paintEvent(QPaintEvent *e) override;
	void resizeEvent(QResizeEvent *e) override;
	void keyPressEvent(QKeyEvent *e) override;

signals:
	void countryChanged();

	// Internal interface.
public:
	struct Data {
		QString country;
		QString phone;
		QByteArray phoneHash;
		bool phoneIsRegistered = false;

		enum class CallStatus {
			Waiting,
			Calling,
			Called,
			Disabled,
		};
		CallStatus callStatus = CallStatus::Disabled;
		int callTimeout = 0;

		QString code;
		int codeLength = 5;
		bool codeByTelegram = false;

		QByteArray pwdSalt;
		bool hasRecovery = false;
		QString pwdHint;

		base::Observable<void> updated;
	};

	enum class Direction {
		Back,
		Forward,
		Replace,
	};
	class Step : public TWidget, public RPCSender, protected base::Subscriber {
	public:
		Step(QWidget *parent, Data *data, bool hasCover = false);

		virtual void setInnerFocus() {
			setFocus();
		}

		void setGoCallback(Fn<void(Step *step, Direction direction)> callback);
		void setShowResetCallback(Fn<void()> callback);

		void prepareShowAnimated(Step *after);
		void showAnimated(Direction direction);
		void showFast();
		bool animating() const;

		bool hasCover() const;
		virtual bool hasBack() const;
		virtual void activate();
		virtual void cancelled();
		virtual void finished();

		virtual void submit() = 0;
		virtual QString nextButtonText() const;

		int contentLeft() const;
		int contentTop() const;

		void setErrorCentered(bool centered);
		void setErrorBelowLink(bool below);
		void showError(Fn<QString()> textFactory);
		void hideError() {
			showError(Fn<QString()>());
		}

		~Step();

	protected:
		void paintEvent(QPaintEvent *e) override;
		void resizeEvent(QResizeEvent *e) override;

		void setTitleText(Fn<QString()> richTitleTextFactory);
		void setDescriptionText(Fn<QString()> richDescriptionTextFactory);
		bool paintAnimated(Painter &p, QRect clip);

		void fillSentCodeData(const MTPauth_SentCodeType &type);

		void showDescription();
		void hideDescription();

		Data *getData() const {
			return _data;
		}
		void finish(const MTPUser &user, QImage photo = QImage());

		void goBack() {
			if (_goCallback) _goCallback(nullptr, Direction::Back);
		}
		void goNext(Step *step) {
			if (_goCallback) _goCallback(step, Direction::Forward);
		}
		void goReplace(Step *step) {
			if (_goCallback) _goCallback(step, Direction::Replace);
		}
		void showResetButton() {
			if (_showResetCallback) _showResetCallback();
		}

	private:
		struct CoverAnimation {
			CoverAnimation() = default;
			CoverAnimation(CoverAnimation &&other) = default;
			CoverAnimation &operator=(CoverAnimation &&other) = default;
			~CoverAnimation();

			std::unique_ptr<Ui::CrossFadeAnimation> title;
			std::unique_ptr<Ui::CrossFadeAnimation> description;

			// From content top till the next button top.
			QPixmap contentSnapshotWas;
			QPixmap contentSnapshotNow;
		};
		void updateLabelsPosition();
		void paintContentSnapshot(Painter &p, const QPixmap &snapshot, double alpha, double howMuchHidden);
		void refreshError();
		void refreshTitle();
		void refreshDescription();
		void refreshLang();

		CoverAnimation prepareCoverAnimation(Step *step);
		QPixmap prepareContentSnapshot();
		QPixmap prepareSlideAnimation();
		void showFinished();

		void prepareCoverMask();
		void paintCover(Painter &p, int top);

		Data *_data = nullptr;
		bool _hasCover = false;
		Fn<void(Step *step, Direction direction)> _goCallback;
		Fn<void()> _showResetCallback;

		object_ptr<Ui::FlatLabel> _title;
		Fn<QString()> _titleTextFactory;
		object_ptr<Ui::WidgetFadeWrap<Ui::FlatLabel>> _description;
		Fn<QString()> _descriptionTextFactory;

		bool _errorCentered = false;
		bool _errorBelowLink = false;
		Fn<QString()> _errorTextFactory;
		object_ptr<Ui::WidgetFadeWrap<Ui::FlatLabel>> _error = {nullptr};

		Animation _a_show;
		CoverAnimation _coverAnimation;
		std::unique_ptr<Ui::SlideAnimation> _slideAnimation;
		QPixmap _coverMask;
	};

private:
	void refreshLang();
	void animationCallback();
	void createLanguageLink();

	void updateControlsGeometry();
	Data *getData() {
		return &_data;
	}

	void fixOrder();
	void showControls();
	void hideControls();
	QRect calculateStepRect() const;

	void showResetButton();
	void resetAccount();

	Step *getStep(int skip = 0) {
		Assert(_stepHistory.size() + skip > 0);
		return _stepHistory.at(_stepHistory.size() - skip - 1);
	}
	void historyMove(Direction direction);
	void moveToStep(Step *step, Direction direction);
	void appendStep(Step *step);

	void getNearestDC();

	Animation _a_show;
	bool _showBack = false;
	QPixmap _cacheUnder, _cacheOver;

	QVector<Step *> _stepHistory;

	Data _data;

	Animation _coverShownAnimation;
	int _nextTopFrom = 0;
	int _controlsTopFrom = 0;

	object_ptr<Ui::WidgetFadeWrap<Ui::IconButton>> _back;
	object_ptr<Ui::WidgetFadeWrap<Ui::RoundButton>> _update = {nullptr};
	object_ptr<Ui::WidgetFadeWrap<Ui::RoundButton>> _settings;

	object_ptr<Ui::RoundButton> _next;
	object_ptr<Ui::WidgetFadeWrap<Ui::LinkButton>> _changeLanguage = {nullptr};
	object_ptr<Ui::WidgetFadeWrap<Ui::RoundButton>> _resetAccount = {nullptr};

	mtpRequestId _resetRequest = 0;
};

} // namespace Intro