/*
This file is part of Telegram Desktop,
the official desktop application for the Telegram messaging service.

For license and copyright information please follow this link:
https://github.com/telegramdesktop/tdesktop/blob/master/LEGAL
*/
#include "dialogs/ui/dialogs_message_view.h"

#include "history/history.h"
#include "history/history_item.h"
#include "main/main_session.h"
#include "ui/text/text_options.h"
#include "ui/image/image.h"
#include "lang/lang_keys.h"
#include "styles/style_dialogs.h"

namespace {

template <ushort kTag>
struct TextWithTagOffset {
	TextWithTagOffset(QString text) : text(text) {
	}
	static TextWithTagOffset FromString(const QString &text) {
		return { text };
	}

	QString text;
	int offset = -1;
};

} // namespace

namespace Lang {

template <ushort kTag>
struct ReplaceTag<TextWithTagOffset<kTag>> {
	static TextWithTagOffset<kTag> Call(
		TextWithTagOffset<kTag> &&original,
		ushort tag,
		const TextWithTagOffset<kTag> &replacement);
};

template <ushort kTag>
TextWithTagOffset<kTag> ReplaceTag<TextWithTagOffset<kTag>>::Call(
		TextWithTagOffset<kTag> &&original,
		ushort tag,
		const TextWithTagOffset<kTag> &replacement) {
	const auto replacementPosition = FindTagReplacementPosition(
		original.text,
		tag);
	if (replacementPosition < 0) {
		return std::move(original);
	}
	original.text = ReplaceTag<QString>::Replace(
		std::move(original.text),
		replacement.text,
		replacementPosition);
	if (tag == kTag) {
		original.offset = replacementPosition;
	} else if (original.offset > replacementPosition) {
		constexpr auto kReplaceCommandLength = 4;
		original.offset += replacement.text.size() - kReplaceCommandLength;
	}
	return std::move(original);
}

} // namespace Lang

namespace Dialogs::Ui {
namespace {

} // namespace

struct MessageView::LoadingContext {
	std::any context;
	rpl::lifetime lifetime;
};

MessageView::MessageView()
: _senderCache(st::dialogsTextWidthMin)
, _textCache(st::dialogsTextWidthMin) {
}

MessageView::~MessageView() = default;

void MessageView::itemInvalidated(not_null<const HistoryItem*> item) {
	if (_textCachedFor == item.get()) {
		_textCachedFor = nullptr;
	}
}

bool MessageView::dependsOn(not_null<const HistoryItem*> item) const {
	return (_textCachedFor == item.get());
}

void MessageView::paint(
		Painter &p,
		not_null<const HistoryItem*> item,
		const QRect &geometry,
		bool active,
		bool selected,
		ToPreviewOptions options) const {
	if (geometry.isEmpty()) {
		return;
	}
	if (_textCachedFor != item.get()) {
		options.existing = &_imagesCache;
		auto preview = item->toPreview(options);
		if (!preview.images.empty() && preview.imagesInTextPosition > 0) {
			_senderCache.setText(
				st::dialogsTextStyle,
				preview.text.mid(0, preview.imagesInTextPosition).trimmed(),
				DialogTextOptions());
			preview.text = preview.text.mid(preview.imagesInTextPosition);
		} else {
			_senderCache = { st::dialogsTextWidthMin };
		}
		_textCache.setText(
			st::dialogsTextStyle,
			preview.text.trimmed(),
			DialogTextOptions());
		_textCachedFor = item;
		_imagesCache = std::move(preview.images);
		if (preview.loadingContext.has_value()) {
			if (!_loadingContext) {
				_loadingContext = std::make_unique<LoadingContext>();
				item->history()->session().downloaderTaskFinished(
				) | rpl::start_with_next([=] {
					_textCachedFor = nullptr;
				}, _loadingContext->lifetime);
			}
			_loadingContext->context = std::move(preview.loadingContext);
		} else {
			_loadingContext = nullptr;
		}
	}
	p.setTextPalette(active
		? st::dialogsTextPaletteActive
		: selected
		? st::dialogsTextPaletteOver
		: st::dialogsTextPalette);
	p.setFont(st::dialogsTextFont);
	p.setPen(active
		? st::dialogsTextFgActive
		: selected
		? st::dialogsTextFgOver
		: st::dialogsTextFg);
	const auto guard = gsl::finally([&] {
		p.restoreTextPalette();
	});

	auto rect = geometry;
	if (!_senderCache.isEmpty()) {
		_senderCache.drawElided(
			p,
			rect.left(),
			rect.top(),
			rect.width(),
			rect.height() / st::dialogsTextFont->height);
		const auto skip = st::dialogsMiniPreviewSkip
			+ st::dialogsMiniPreviewRight;
		rect.setLeft(rect.x() + _senderCache.maxWidth() + skip);
	}
	for (const auto &image : _imagesCache) {
		if (rect.width() < st::dialogsMiniPreview) {
			break;
		}
		p.drawImage(
			rect.x(),
			rect.y() + st::dialogsMiniPreviewTop,
			image.data);
		rect.setLeft(rect.x()
			+ st::dialogsMiniPreview
			+ st::dialogsMiniPreviewSkip);
	}
	if (!_imagesCache.empty()) {
		rect.setLeft(rect.x() + st::dialogsMiniPreviewRight);
	}
	if (rect.isEmpty()) {
		return;
	}
	_textCache.drawElided(
		p,
		rect.left(),
		rect.top(),
		rect.width(),
		rect.height() / st::dialogsTextFont->height);
}

HistoryView::ItemPreview PreviewWithSender(
		HistoryView::ItemPreview &&preview,
		const QString &sender) {
	auto textWithOffset = tr::lng_dialogs_text_with_from(
		tr::now,
		lt_from_part,
		sender,
		lt_message,
		std::move(preview.text),
		TextWithTagOffset<lt_from_part>::FromString);
	preview.text = std::move(textWithOffset.text);
	preview.imagesInTextPosition = (textWithOffset.offset < 0)
		? 0
		: textWithOffset.offset + sender.size();
	return std::move(preview);
}

} // namespace Dialogs::Ui