/*
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) 2014-2016 John Preston, https://desktop.telegram.org
*/
#pragma once

#include "core/runtime_composer.h"

class HistoryElement {
public:
	HistoryElement() = default;
	HistoryElement(const HistoryElement &other) = delete;
	HistoryElement &operator=(const HistoryElement &other) = delete;

	int maxWidth() const {
		return _maxw;
	}
	int minHeight() const {
		return _minh;
	}
	int height() const {
		return _height;
	}

	virtual ~HistoryElement() = default;

protected:
	mutable int _maxw = 0;
	mutable int _minh = 0;
	mutable int _height = 0;

};

class HistoryMessage;

enum HistoryCursorState {
	HistoryDefaultCursorState,
	HistoryInTextCursorState,
	HistoryInDateCursorState,
	HistoryInForwardedCursorState,
};

struct HistoryTextState {
	HistoryTextState() = default;
	HistoryTextState(const Text::StateResult &state)
		: cursor(state.uponSymbol ? HistoryInTextCursorState : HistoryDefaultCursorState)
		, link(state.link)
		, afterSymbol(state.afterSymbol)
		, symbol(state.symbol) {
	}
	HistoryTextState &operator=(const Text::StateResult &state) {
		cursor = state.uponSymbol ? HistoryInTextCursorState : HistoryDefaultCursorState;
		link = state.link;
		afterSymbol = state.afterSymbol;
		symbol = state.symbol;
		return *this;
	}
	HistoryCursorState cursor = HistoryDefaultCursorState;
	ClickHandlerPtr link;
	bool afterSymbol = false;
	uint16 symbol = 0;
};

struct HistoryStateRequest {
	Text::StateRequest::Flags flags = Text::StateRequest::Flag::LookupLink;
	Text::StateRequest forText() const {
		Text::StateRequest result;
		result.flags = flags;
		return result;
	}
};

enum InfoDisplayType {
	InfoDisplayDefault,
	InfoDisplayOverImage,
	InfoDisplayOverBackground,
};

enum HistoryItemType {
	HistoryItemMsg = 0,
	HistoryItemJoined
};

struct HistoryMessageVia : public RuntimeComponent<HistoryMessageVia> {
	void create(int32 userId);
	void resize(int32 availw) const;

	UserData *_bot = nullptr;
	mutable QString _text;
	mutable int _width = 0;
	mutable int _maxWidth = 0;
	ClickHandlerPtr _lnk;
};

struct HistoryMessageViews : public RuntimeComponent<HistoryMessageViews> {
	QString _viewsText;
	int _views = 0;
	int _viewsWidth = 0;
};

struct HistoryMessageSigned : public RuntimeComponent<HistoryMessageSigned> {
	void create(UserData *from, const QDateTime &date);
	int maxWidth() const;

	Text _signature;
};

struct HistoryMessageEdited : public RuntimeComponent<HistoryMessageEdited> {
	void create(const QDateTime &editDate, const QDateTime &date);
	int maxWidth() const;

	QDateTime _editDate;
	Text _edited;
};

struct HistoryMessageForwarded : public RuntimeComponent<HistoryMessageForwarded> {
	void create(const HistoryMessageVia *via) const;

	PeerData *_authorOriginal = nullptr;
	PeerData *_fromOriginal = nullptr;
	MsgId _originalId = 0;
	mutable Text _text = { 1 };
};

struct HistoryMessageReply : public RuntimeComponent<HistoryMessageReply> {
	HistoryMessageReply &operator=(HistoryMessageReply &&other) {
		replyToMsgId = other.replyToMsgId;
		std::swap(replyToMsg, other.replyToMsg);
		replyToLnk = std_::move(other.replyToLnk);
		replyToName = std_::move(other.replyToName);
		replyToText = std_::move(other.replyToText);
		replyToVersion = other.replyToVersion;
		_maxReplyWidth = other._maxReplyWidth;
		_replyToVia = std_::move(other._replyToVia);
		return *this;
	}
	~HistoryMessageReply() {
		// clearData() should be called by holder
		t_assert(replyToMsg == nullptr);
		t_assert(_replyToVia == nullptr);
	}

	bool updateData(HistoryMessage *holder, bool force = false);
	void clearData(HistoryMessage *holder); // must be called before destructor

	bool isNameUpdated() const;
	void updateName() const;
	void resize(int width) const;
	void itemRemoved(HistoryMessage *holder, HistoryItem *removed);

	enum PaintFlag {
		PaintInBubble = 0x01,
		PaintSelected = 0x02,
	};
	Q_DECLARE_FLAGS(PaintFlags, PaintFlag);
	void paint(Painter &p, const HistoryItem *holder, int x, int y, int w, PaintFlags flags) const;

	MsgId replyToId() const {
		return replyToMsgId;
	}
	int replyToWidth() const {
		return _maxReplyWidth;
	}
	ClickHandlerPtr replyToLink() const {
		return replyToLnk;
	}

	MsgId replyToMsgId = 0;
	HistoryItem *replyToMsg = nullptr;
	ClickHandlerPtr replyToLnk;
	mutable Text replyToName, replyToText;
	mutable int replyToVersion = 0;
	mutable int _maxReplyWidth = 0;
	std_::unique_ptr<HistoryMessageVia> _replyToVia;
	int toWidth = 0;
};
Q_DECLARE_OPERATORS_FOR_FLAGS(HistoryMessageReply::PaintFlags);

class ReplyKeyboard;
struct HistoryMessageReplyMarkup : public RuntimeComponent<HistoryMessageReplyMarkup> {
	HistoryMessageReplyMarkup() = default;
	HistoryMessageReplyMarkup(MTPDreplyKeyboardMarkup::Flags f) : flags(f) {
	}

	void create(const MTPReplyMarkup &markup);

	struct Button {
		enum class Type {
			Default,
			Url,
			Callback,
			RequestPhone,
			RequestLocation,
			SwitchInline,
			SwitchInlineSame,
			Game,
		};
		Type type;
		QString text;
		QByteArray data;
		mutable mtpRequestId requestId;
	};
	using ButtonRow = QVector<Button>;
	using ButtonRows = QVector<ButtonRow>;

	ButtonRows rows;
	MTPDreplyKeyboardMarkup::Flags flags = 0;

	std_::unique_ptr<ReplyKeyboard> inlineKeyboard;

	// If >= 0 it holds the y coord of the inlineKeyboard before the last edition.
	int oldTop = -1;

private:
	void createFromButtonRows(const QVector<MTPKeyboardButtonRow> &v);

};

class ReplyMarkupClickHandler : public LeftButtonClickHandler {
public:
	ReplyMarkupClickHandler(const HistoryItem *item, int row, int col);

	QString tooltip() const override {
		return _fullDisplayed ? QString() : buttonText();
	}

	void setFullDisplayed(bool full) {
		_fullDisplayed = full;
	}

	// Copy to clipboard support.
	void copyToClipboard() const override;
	QString copyToClipboardContextItemText() const override;

	// Finds the corresponding button in the items markup struct.
	// If the button is not found it returns nullptr.
	// Note: it is possible that we will point to the different button
	// than the one was used when constructing the handler, but not a big deal.
	const HistoryMessageReplyMarkup::Button *getButton() const;

	// We hold only FullMsgId, not HistoryItem*, because all click handlers
	// are activated async and the item may be already destroyed.
	void setMessageId(const FullMsgId &msgId) {
		_itemId = msgId;
	}

protected:
	void onClickImpl() const override;

private:
	FullMsgId _itemId;
	int _row, _col;
	bool _fullDisplayed = true;

	// Returns the full text of the corresponding button.
	QString buttonText() const;

};

class ReplyKeyboard {
private:
	struct Button;

public:
	class Style {
	public:
		Style(const style::botKeyboardButton &st) : _st(&st) {
		}

		virtual void startPaint(Painter &p) const = 0;
		virtual style::font textFont() const = 0;

		int buttonSkip() const {
			return _st->margin;
		}
		int buttonPadding() const {
			return _st->padding;
		}
		int buttonHeight() const {
			return _st->height;
		}

		virtual void repaint(const HistoryItem *item) const = 0;
		virtual ~Style() {
		}

	protected:
		virtual void paintButtonBg(Painter &p, const QRect &rect, bool pressed, float64 howMuchOver) const = 0;
		virtual void paintButtonIcon(Painter &p, const QRect &rect, HistoryMessageReplyMarkup::Button::Type type) const = 0;
		virtual void paintButtonLoading(Painter &p, const QRect &rect) const = 0;
		virtual int minButtonWidth(HistoryMessageReplyMarkup::Button::Type type) const = 0;

	private:
		const style::botKeyboardButton *_st;

		void paintButton(Painter &p, const ReplyKeyboard::Button &button) const;
		friend class ReplyKeyboard;

	};
	typedef std_::unique_ptr<Style> StylePtr;

	ReplyKeyboard(const HistoryItem *item, StylePtr &&s);
	ReplyKeyboard(const ReplyKeyboard &other) = delete;
	ReplyKeyboard &operator=(const ReplyKeyboard &other) = delete;

	bool isEnoughSpace(int width, const style::botKeyboardButton &st) const;
	void setStyle(StylePtr &&s);
	void resize(int width, int height);

	// what width and height will best fit this keyboard
	int naturalWidth() const;
	int naturalHeight() const;

	void paint(Painter &p, const QRect &clip) const;
	ClickHandlerPtr getState(int x, int y) const;

	void clickHandlerActiveChanged(const ClickHandlerPtr &p, bool active);
	void clickHandlerPressedChanged(const ClickHandlerPtr &p, bool pressed);

	void clearSelection();
	void updateMessageId();

private:
	const HistoryItem *_item;
	int _width = 0;

	friend class Style;
	using ReplyMarkupClickHandlerPtr = QSharedPointer<ReplyMarkupClickHandler>;
	struct Button {
		Text text = { 1 };
		QRect rect;
		int characters = 0;
		float64 howMuchOver = 0.;
		HistoryMessageReplyMarkup::Button::Type type;
		ReplyMarkupClickHandlerPtr link;
	};
	using ButtonRow = QVector<Button>;
	using ButtonRows = QVector<ButtonRow>;
	ButtonRows _rows;

	using Animations = QMap<int, uint64>;
	Animations _animations;
	Animation _a_selected;
	void step_selected(uint64 ms, bool timer);

	StylePtr _st;
};

// any HistoryItem can have this Interface for
// displaying the day mark above the message
struct HistoryMessageDate : public RuntimeComponent<HistoryMessageDate> {
	void init(const QDateTime &date);

	int height() const;
	void paint(Painter &p, int y, int w) const;

	QString _text;
	int _width = 0;
};

// any HistoryItem can have this Interface for
// displaying the unread messages bar above the message
struct HistoryMessageUnreadBar : public RuntimeComponent<HistoryMessageUnreadBar> {
	void init(int count);

	static int height();
	static int marginTop();

	void paint(Painter &p, int y, int w) const;

	QString _text;
	int _width = 0;

	// if unread bar is freezed the new messages do not
	// increment the counter displayed by this bar
	//
	// it happens when we've opened the conversation and
	// we've seen the bar and new messages are marked as read
	// as soon as they are added to the chat history
	bool _freezed = false;
};

// HistoryMedia has a special owning smart pointer
// which regs/unregs this media to the holding HistoryItem
class HistoryMedia;
class HistoryMediaPtr {
public:
	HistoryMediaPtr() = default;
	HistoryMediaPtr(const HistoryMediaPtr &other) = delete;
	HistoryMediaPtr &operator=(const HistoryMediaPtr &other) = delete;
	HistoryMedia *data() const {
		return _p;
	}
	void reset(HistoryMedia *p = nullptr);
	void clear() {
		reset();
	}
	bool isNull() const {
		return data() == nullptr;
	}

	HistoryMedia *operator->() const {
		return data();
	}
	HistoryMedia &operator*() const {
		t_assert(!isNull());
		return *data();
	}
	explicit operator bool() const {
		return !isNull();
	}
	~HistoryMediaPtr() {
		clear();
	}

private:
	HistoryMedia *_p = nullptr;

};

namespace internal {

TextSelection unshiftSelection(TextSelection selection, const Text &byText);
TextSelection shiftSelection(TextSelection selection, const Text &byText);

} // namespace internal

class HistoryItem : public HistoryElement, public RuntimeComposer, public ClickHandlerHost {
public:
	int resizeGetHeight(int width) {
		if (_flags & MTPDmessage_ClientFlag::f_pending_init_dimensions) {
			_flags &= ~MTPDmessage_ClientFlag::f_pending_init_dimensions;
			initDimensions();
		}
		if (_flags & MTPDmessage_ClientFlag::f_pending_resize) {
			_flags &= ~MTPDmessage_ClientFlag::f_pending_resize;
		}
		return resizeGetHeight_(width);
	}
	virtual void draw(Painter &p, const QRect &r, TextSelection selection, uint64 ms) const = 0;

	virtual void dependencyItemRemoved(HistoryItem *dependency) {
	}
	virtual bool updateDependencyItem() {
		return true;
	}
	virtual MsgId dependencyMsgId() const {
		return 0;
	}
	virtual bool notificationReady() const {
		return true;
	}

	UserData *viaBot() const {
		if (const HistoryMessageVia *via = Get<HistoryMessageVia>()) {
			return via->_bot;
		}
		return nullptr;
	}
	UserData *getMessageBot() const {
		if (auto bot = viaBot()) {
			return bot;
		}
		auto bot = from()->asUser();
		if (!bot) {
			bot = history()->peer->asUser();
		}
		return (bot && bot->botInfo) ? bot : nullptr;
	};

	History *history() const {
		return _history;
	}
	PeerData *from() const {
		return _from;
	}
	HistoryBlock *block() {
		return _block;
	}
	const HistoryBlock *block() const {
		return _block;
	}
	void destroy();
	void detach();
	void detachFast();
	bool detached() const {
		return !_block;
	}
	void attachToBlock(HistoryBlock *block, int index) {
		t_assert(_block == nullptr);
		t_assert(_indexInBlock < 0);
		t_assert(block != nullptr);
		t_assert(index >= 0);

		_block = block;
		_indexInBlock = index;
		if (pendingResize()) {
			_history->setHasPendingResizedItems();
		}
	}
	void setIndexInBlock(int index) {
		t_assert(_block != nullptr);
		t_assert(index >= 0);

		_indexInBlock = index;
	}
	int indexInBlock() const {
		if (_indexInBlock >= 0) {
			t_assert(_block != nullptr);
			t_assert(_block->items.at(_indexInBlock) == this);
		} else if (_block != nullptr) {
			t_assert(_indexInBlock >= 0);
			t_assert(_block->items.at(_indexInBlock) == this);
		}
		return _indexInBlock;
	}
	bool out() const {
		return _flags & MTPDmessage::Flag::f_out;
	}
	bool unread() const;
	bool mentionsMe() const {
		return _flags & MTPDmessage::Flag::f_mentioned;
	}
	bool isMediaUnread() const {
		return (_flags & MTPDmessage::Flag::f_media_unread) && (channelId() == NoChannel);
	}
	void markMediaRead() {
		_flags &= ~MTPDmessage::Flag::f_media_unread;
	}
	bool definesReplyKeyboard() const {
		if (auto markup = Get<HistoryMessageReplyMarkup>()) {
			if (markup->flags & MTPDreplyKeyboardMarkup_ClientFlag::f_inline) {
				return false;
			}
			return true;
		}

		// optimization: don't create markup component for the case
		// MTPDreplyKeyboardHide with flags = 0, assume it has f_zero flag
		return (_flags & MTPDmessage::Flag::f_reply_markup);
	}
	MTPDreplyKeyboardMarkup::Flags replyKeyboardFlags() const {
		t_assert(definesReplyKeyboard());
		if (auto markup = Get<HistoryMessageReplyMarkup>()) {
			return markup->flags;
		}

		// optimization: don't create markup component for the case
		// MTPDreplyKeyboardHide with flags = 0, assume it has f_zero flag
		return qFlags(MTPDreplyKeyboardMarkup_ClientFlag::f_zero);
	}
	bool hasSwitchInlineButton() const {
		return _flags & MTPDmessage_ClientFlag::f_has_switch_inline_button;
	}
	bool hasTextLinks() const {
		return _flags & MTPDmessage_ClientFlag::f_has_text_links;
	}
	bool isGroupMigrate() const {
		return _flags & MTPDmessage_ClientFlag::f_is_group_migrate;
	}
	bool hasViews() const {
		return _flags & MTPDmessage::Flag::f_views;
	}
	bool isPost() const {
		return _flags & MTPDmessage::Flag::f_post;
	}
	bool indexInOverview() const {
		return (id > 0) && (!history()->isChannel() || history()->isMegagroup() || isPost());
	}
	bool isSilent() const {
		return _flags & MTPDmessage::Flag::f_silent;
	}
	bool hasOutLayout() const {
		return out() && !isPost();
	}
	virtual int32 viewsCount() const {
		return hasViews() ? 1 : -1;
	}

	virtual bool needCheck() const {
		return out() || (id < 0 && history()->peer->isSelf());
	}
	virtual bool hasPoint(int x, int y) const {
		return false;
	}

	virtual HistoryTextState getState(int x, int y, HistoryStateRequest request) const = 0;

	virtual TextSelection adjustSelection(TextSelection selection, TextSelectType type) const {
		return selection;
	}

	// ClickHandlerHost interface
	void clickHandlerActiveChanged(const ClickHandlerPtr &p, bool active) override;
	void clickHandlerPressedChanged(const ClickHandlerPtr &p, bool pressed) override;

	virtual HistoryItemType type() const {
		return HistoryItemMsg;
	}
	virtual bool serviceMsg() const {
		return false;
	}
	virtual void applyEdition(const MTPDmessage &message) {
	}
	virtual void applyEdition(const MTPDmessageService &message) {
	}
	virtual void updateMedia(const MTPMessageMedia *media) {
	}
	virtual int32 addToOverview(AddToOverviewMethod method) {
		return 0;
	}
	virtual void eraseFromOverview() {
	}
	virtual bool hasBubble() const {
		return false;
	}
	virtual void previousItemChanged();

	virtual TextWithEntities selectedText(TextSelection selection) const {
		return { qsl("[-]"), EntitiesInText() };
	}

	virtual QString notificationHeader() const {
		return QString();
	}
	virtual QString notificationText() const;

	// Returns text with link-start and link-end commands for service-color highlighting.
	// Example: "[link1-start]You:[link1-end] [link1-start]Photo,[link1-end] caption text"
	virtual QString inDialogsText() const;
	virtual QString inReplyText() const {
		return notificationText();
	}
	virtual TextWithEntities originalText() const {
		return { QString(), EntitiesInText() };
	}

	virtual void drawInfo(Painter &p, int32 right, int32 bottom, int32 width, bool selected, InfoDisplayType type) const {
	}
	virtual void setViewsCount(int32 count) {
	}
	virtual void setId(MsgId newId);
	void drawInDialog(Painter &p, const QRect &r, bool act, const HistoryItem *&cacheFor, Text &cache) const;

	bool emptyText() const {
		return _text.isEmpty();
	}

	bool canDelete() const {
		ChannelData *channel = _history->peer->asChannel();
		if (!channel) return !(_flags & MTPDmessage_ClientFlag::f_is_group_migrate);

		if (id == 1) return false;
		if (channel->amCreator()) return true;
		if (isPost()) {
			if (channel->amEditor() && out()) return true;
			return false;
		}
		return (channel->amEditor() || channel->amModerator() || out());
	}

	bool canPin() const {
		return id > 0 && _history->peer->isMegagroup() && (_history->peer->asChannel()->amEditor() || _history->peer->asChannel()->amCreator()) && toHistoryMessage();
	}

	bool canEdit(const QDateTime &cur) const;

	bool suggestBanReportDeleteAll() const {
		ChannelData *channel = history()->peer->asChannel();
		if (!channel || (!channel->amEditor() && !channel->amCreator())) return false;
		return !isPost() && !out() && from()->isUser() && toHistoryMessage();
	}

	bool hasDirectLink() const {
		return id > 0 && _history->peer->isChannel() && _history->peer->asChannel()->isPublic() && !_history->peer->isMegagroup();
	}
	QString directLink() const {
		return hasDirectLink() ? qsl("https://telegram.me/") + _history->peer->asChannel()->username + '/' + QString::number(id) : QString();
	}

	int32 y;
	MsgId id;
	QDateTime date;

	ChannelId channelId() const {
		return _history->channelId();
	}
	FullMsgId fullId() const {
		return FullMsgId(channelId(), id);
	}

	HistoryMedia *getMedia() const {
		return _media.data();
	}
	virtual void setText(const TextWithEntities &textWithEntities) {
	}
	virtual bool textHasLinks() const {
		return false;
	}

	virtual int infoWidth() const {
		return 0;
	}
	virtual int timeLeft() const {
		return 0;
	}
	virtual int timeWidth() const {
		return 0;
	}
	virtual bool pointInTime(int32 right, int32 bottom, int x, int y, InfoDisplayType type) const {
		return false;
	}

	int32 skipBlockWidth() const {
		return st::msgDateSpace + infoWidth() - st::msgDateDelta.x();
	}
	int32 skipBlockHeight() const {
		return st::msgDateFont->height - st::msgDateDelta.y();
	}
	QString skipBlock() const {
		return textcmdSkipBlock(skipBlockWidth(), skipBlockHeight());
	}

	virtual HistoryMessage *toHistoryMessage() { // dynamic_cast optimize
		return nullptr;
	}
	virtual const HistoryMessage *toHistoryMessage() const { // dynamic_cast optimize
		return nullptr;
	}
	MsgId replyToId() const {
		if (auto reply = Get<HistoryMessageReply>()) {
			return reply->replyToId();
		}
		return 0;
	}

	bool hasFromName() const {
		return (!out() || isPost()) && !history()->peer->isUser();
	}
	PeerData *author() const {
		return isPost() ? history()->peer : _from;
	}

	PeerData *fromOriginal() const {
		if (const HistoryMessageForwarded *fwd = Get<HistoryMessageForwarded>()) {
			return fwd->_fromOriginal;
		}
		return from();
	}
	PeerData *authorOriginal() const {
		if (const HistoryMessageForwarded *fwd = Get<HistoryMessageForwarded>()) {
			return fwd->_authorOriginal;
		}
		return author();
	}

	// count > 0 - creates the unread bar if necessary and
	// sets unread messages count if bar is not freezed yet
	// count <= 0 - destroys the unread bar
	void setUnreadBarCount(int count);
	void destroyUnreadBar();

	// marks the unread bar as freezed so that unread
	// messages count will not change for this bar
	// when the new messages arrive in this chat history
	void setUnreadBarFreezed();

	bool pendingResize() const {
		return _flags & MTPDmessage_ClientFlag::f_pending_resize;
	}
	void setPendingResize() {
		_flags |= MTPDmessage_ClientFlag::f_pending_resize;
		if (!detached()) {
			_history->setHasPendingResizedItems();
		}
	}
	bool pendingInitDimensions() const {
		return _flags & MTPDmessage_ClientFlag::f_pending_init_dimensions;
	}
	void setPendingInitDimensions() {
		_flags |= MTPDmessage_ClientFlag::f_pending_init_dimensions;
		setPendingResize();
	}

	int displayedDateHeight() const {
		if (auto date = Get<HistoryMessageDate>()) {
			return date->height();
		}
		return 0;
	}
	int marginTop() const {
		int result = 0;
		if (isAttachedToPrevious()) {
			result += st::msgMarginTopAttached;
		} else {
			result += st::msgMargin.top();
		}
		result += displayedDateHeight();
		if (auto unreadbar = Get<HistoryMessageUnreadBar>()) {
			result += unreadbar->height();
		}
		return result;
	}
	int marginBottom() const {
		return st::msgMargin.bottom();
	}
	bool isAttachedToPrevious() const {
		return _flags & MTPDmessage_ClientFlag::f_attach_to_previous;
	}
	bool displayDate() const {
		return Has<HistoryMessageDate>();
	}

	bool isInOneDayWithPrevious() const {
		return !isEmpty() && !displayDate();
	}

	bool isEmpty() const {
		return _text.isEmpty() && !_media;
	}

	void clipCallback(Media::Clip::Notification notification);

	~HistoryItem();

protected:
	HistoryItem(History *history, MsgId msgId, MTPDmessage::Flags flags, QDateTime msgDate, int32 from);

	// to completely create history item we need to call
	// a virtual method, it can not be done from constructor
	virtual void finishCreate();

	// called from resizeGetHeight() when MTPDmessage_ClientFlag::f_pending_init_dimensions is set
	virtual void initDimensions() = 0;

	virtual int resizeGetHeight_(int width) = 0;

	void finishEdition(int oldKeyboardTop);
	void finishEditionToEmpty();

	PeerData *_from;
	History *_history;
	HistoryBlock *_block = nullptr;
	int _indexInBlock = -1;
	MTPDmessage::Flags _flags;

	mutable int32 _authorNameVersion;

	HistoryItem *previousItem() const {
		if (_block && _indexInBlock >= 0) {
			if (_indexInBlock > 0) {
				return _block->items.at(_indexInBlock - 1);
			}
			if (auto previous = _block->previousBlock()) {
				t_assert(!previous->items.isEmpty());
				return previous->items.back();
			}
		}
		return nullptr;
	}
	HistoryItem *nextItem() const {
		if (_block && _indexInBlock >= 0) {
			if (_indexInBlock + 1 < _block->items.size()) {
				return _block->items.at(_indexInBlock + 1);
			}
			if (auto next = _block->nextBlock()) {
				t_assert(!next->items.isEmpty());
				return next->items.front();
			}
		}
		return nullptr;
	}

	// this should be used only in previousItemChanged()
	// to add required bits to the Composer mask
	// after that always use Has<HistoryMessageDate>()
	void recountDisplayDate();

	// this should be used only in previousItemChanged() or when
	// HistoryMessageDate or HistoryMessageUnreadBar bit is changed in the Composer mask
	// then the result should be cached in a client side flag MTPDmessage_ClientFlag::f_attach_to_previous
	void recountAttachToPrevious();

	const HistoryMessageReplyMarkup *inlineReplyMarkup() const {
		if (auto markup = Get<HistoryMessageReplyMarkup>()) {
			if (markup->flags & MTPDreplyKeyboardMarkup_ClientFlag::f_inline) {
				return markup;
			}
		}
		return nullptr;
	}
	const ReplyKeyboard *inlineReplyKeyboard() const {
		if (auto markup = inlineReplyMarkup()) {
			return markup->inlineKeyboard.get();
		}
		return nullptr;
	}
	HistoryMessageReplyMarkup *inlineReplyMarkup() {
		return const_cast<HistoryMessageReplyMarkup*>(static_cast<const HistoryItem*>(this)->inlineReplyMarkup());
	}
	ReplyKeyboard *inlineReplyKeyboard() {
		return const_cast<ReplyKeyboard*>(static_cast<const HistoryItem*>(this)->inlineReplyKeyboard());
	}

	TextSelection toMediaSelection(TextSelection selection) const {
		return internal::unshiftSelection(selection, _text);
	}
	TextSelection fromMediaSelection(TextSelection selection) const {
		return internal::shiftSelection(selection, _text);
	}

	Text _text = { int(st::msgMinWidth) };
	int _textWidth = -1;
	int _textHeight = 0;

	HistoryMediaPtr _media;

};

// make all the constructors in HistoryItem children protected
// and wrapped with a static create() call with the same args
// so that history item can not be created directly, without
// calling a virtual finishCreate() method
template <typename T>
class HistoryItemInstantiated {
public:
	template <typename ... Args>
	static T *_create(Args ... args) {
		T *result = new T(args ...);
		result->finishCreate();
		return result;
	}
};

class MessageClickHandler : public LeftButtonClickHandler {
public:
	MessageClickHandler(PeerId peer, MsgId msgid) : _peer(peer), _msgid(msgid) {
	}
	MessageClickHandler(HistoryItem *item) : _peer(item->history()->peer->id), _msgid(item->id) {
	}
	PeerId peer() const {
		return _peer;
	}
	MsgId msgid() const {
		return _msgid;
	}

private:
	PeerId _peer;
	MsgId _msgid;

};

class GoToMessageClickHandler : public MessageClickHandler {
public:
	using MessageClickHandler::MessageClickHandler;

protected:
	void onClickImpl() const override;

};