export_api_wrap.cpp

/*
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 "export/export_api_wrap.h"

#include "export/export_settings.h"
#include "export/data/export_data_types.h"
#include "export/output/export_output_result.h"
#include "export/output/export_output_file.h"
#include "mtproto/mtproto_response.h"
#include "base/bytes.h"
#include "base/options.h"
#include "base/random.h"
#include <set>
#include <deque>

namespace Export {
namespace {

constexpr auto kUserpicsSliceLimit = 100;
constexpr auto kFileChunkSize = 128 * 1024;
constexpr auto kFileRequestsCount = 2;
//constexpr auto kFileNextRequestDelay = crl::time(20);
constexpr auto kChatsSliceLimit = 100;
constexpr auto kMessagesSliceLimit = 100;
constexpr auto kTopPeerSliceLimit = 100;
constexpr auto kFileMaxSize = 4000 * int64(1024 * 1024);
constexpr auto kLocationCacheSize = 100'000;
constexpr auto kMaxEmojiPerRequest = 100;
constexpr auto kStoriesSliceLimit = 100;

struct LocationKey {
	uint64 type;
	uint64 id;

	inline bool operator<(const LocationKey &other) const {
		return std::tie(type, id) < std::tie(other.type, other.id);
	}
};

LocationKey ComputeLocationKey(const Data::FileLocation &value) {
	auto result = LocationKey();
	result.type = value.dcId;
	value.data.match([&](const MTPDinputDocumentFileLocation &data) {
		const auto letter = data.vthumb_size().v.isEmpty()
			? char(0)
			: data.vthumb_size().v[0];
		result.type |= (2ULL << 24);
		result.type |= (uint64(uint32(letter)) << 16);
		result.id = data.vid().v;
	}, [&](const MTPDinputPhotoFileLocation &data) {
		const auto letter = data.vthumb_size().v.isEmpty()
			? char(0)
			: data.vthumb_size().v[0];
		result.type |= (6ULL << 24);
		result.type |= (uint64(uint32(letter)) << 16);
		result.id = data.vid().v;
	}, [&](const MTPDinputTakeoutFileLocation &data) {
		result.type |= (5ULL << 24);
	}, [](const auto &data) {
		Unexpected("File location type in Export::ComputeLocationKey.");
	});
	return result;
}

Settings::Type SettingsFromDialogsType(Data::DialogInfo::Type type) {
	using DialogType = Data::DialogInfo::Type;
	switch (type) {
	case DialogType::Self:
	case DialogType::Personal:
		return Settings::Type::PersonalChats;
	case DialogType::Bot:
		return Settings::Type::BotChats;
	case DialogType::PrivateGroup:
	case DialogType::PrivateSupergroup:
		return Settings::Type::PrivateGroups;
	case DialogType::PublicSupergroup:
		return Settings::Type::PublicGroups;
	case DialogType::PrivateChannel:
		return Settings::Type::PrivateChannels;
	case DialogType::PublicChannel:
		return Settings::Type::PublicChannels;
	}
	return Settings::Type(0);
}

} // namespace

class ApiWrap::LoadedFileCache {
public:
	using Location = Data::FileLocation;

	LoadedFileCache(int limit);

	void save(const Location &location, const QString &relativePath);
	std::optional<QString> find(const Location &location) const;

private:
	int _limit = 0;
	std::map<LocationKey, QString> _map;
	std::deque<LocationKey> _list;

};

struct ApiWrap::StartProcess {
	FnMut<void(StartInfo)> done;

	enum class Step {
		UserpicsCount,
		StoriesCount,
		SplitRanges,
		DialogsCount,
		LeftChannelsCount,
	};
	std::deque<Step> steps;
	int splitIndex = 0;
	StartInfo info;
};

struct ApiWrap::ContactsProcess {
	FnMut<void(Data::ContactsList&&)> done;

	Data::ContactsList result;

	int topPeersOffset = 0;
};

struct ApiWrap::UserpicsProcess {
	FnMut<bool(Data::UserpicsInfo&&)> start;
	Fn<bool(DownloadProgress)> fileProgress;
	Fn<bool(Data::UserpicsSlice&&)> handleSlice;
	FnMut<void()> finish;

	int processed = 0;
	std::optional<Data::UserpicsSlice> slice;
	uint64 maxId = 0;
	bool lastSlice = false;
	int fileIndex = 0;
};

struct ApiWrap::StoriesProcess {
	FnMut<bool(Data::StoriesInfo&&)> start;
	Fn<bool(DownloadProgress)> fileProgress;
	Fn<bool(Data::StoriesSlice&&)> handleSlice;
	FnMut<void()> finish;

	int processed = 0;
	std::optional<Data::StoriesSlice> slice;
	int offsetId = 0;
	bool lastSlice = false;
	int fileIndex = 0;
};

struct ApiWrap::OtherDataProcess {
	Data::File file;
	FnMut<void(Data::File&&)> done;
};

struct ApiWrap::FileProcess {
	FileProcess(const QString &path, Output::Stats *stats);

	Output::File file;
	QString relativePath;

	Fn<bool(FileProgress)> progress;
	FnMut<void(const QString &relativePath)> done;

	uint64 randomId = 0;
	Data::FileLocation location;
	Data::FileOrigin origin;
	int64 offset = 0;
	int64 size = 0;

	struct Request {
		int64 offset = 0;
		QByteArray bytes;
	};
	std::deque<Request> requests;
	mtpRequestId requestId = 0;
};

struct ApiWrap::FileProgress {
	int64 ready = 0;
	int64 total = 0;
};

struct ApiWrap::ChatsProcess {
	Fn<bool(int count)> progress;
	FnMut<void(Data::DialogsInfo&&)> done;

	Data::DialogsInfo info;
	int processedCount = 0;
	std::map<PeerId, int> indexByPeer;
};

struct ApiWrap::LeftChannelsProcess : ChatsProcess {
	int fullCount = 0;
	int offset = 0;
	bool finished = false;
};

struct ApiWrap::DialogsProcess : ChatsProcess {
	int splitIndexPlusOne = 0;
	TimeId offsetDate = 0;
	int32 offsetId = 0;
	MTPInputPeer offsetPeer = MTP_inputPeerEmpty();
};

struct ApiWrap::ChatProcess {
	Data::DialogInfo info;

	FnMut<bool(const Data::DialogInfo &)> start;
	Fn<bool(DownloadProgress)> fileProgress;
	Fn<bool(Data::MessagesSlice&&)> handleSlice;
	FnMut<void()> done;

	FnMut<void(MTPmessages_Messages&&)> requestDone;

	int localSplitIndex = 0;
	int32 largestIdPlusOne = 1;

	Data::ParseMediaContext context;
	std::optional<Data::MessagesSlice> slice;
	bool lastSlice = false;
	int fileIndex = 0;
};


template <typename Request>
class ApiWrap::RequestBuilder {
public:
	using Original = MTP::ConcurrentSender::SpecificRequestBuilder<Request>;
	using Response = typename Request::ResponseType;

	RequestBuilder(
		Original &&builder,
		Fn<void(const MTP::Error&)> commonFailHandler);

	[[nodiscard]] RequestBuilder &done(FnMut<void()> &&handler);
	[[nodiscard]] RequestBuilder &done(
		FnMut<void(Response &&)> &&handler);
	[[nodiscard]] RequestBuilder &fail(
		Fn<bool(const MTP::Error&)> &&handler);

	mtpRequestId send();

private:
	Original _builder;
	Fn<void(const MTP::Error&)> _commonFailHandler;

};

template <typename Request>
ApiWrap::RequestBuilder<Request>::RequestBuilder(
	Original &&builder,
	Fn<void(const MTP::Error&)> commonFailHandler)
: _builder(std::move(builder))
, _commonFailHandler(std::move(commonFailHandler)) {
}

template <typename Request>
auto ApiWrap::RequestBuilder<Request>::done(
	FnMut<void()> &&handler
) -> RequestBuilder& {
	if (handler) {
		[[maybe_unused]] auto &silence_warning = _builder.done(std::move(handler));
	}
	return *this;
}

template <typename Request>
auto ApiWrap::RequestBuilder<Request>::done(
	FnMut<void(Response &&)> &&handler
) -> RequestBuilder& {
	if (handler) {
		[[maybe_unused]] auto &silence_warning = _builder.done(std::move(handler));
	}
	return *this;
}

template <typename Request>
auto ApiWrap::RequestBuilder<Request>::fail(
	Fn<bool(const MTP::Error &)> &&handler
) -> RequestBuilder& {
	if (handler) {
		[[maybe_unused]] auto &silence_warning = _builder.fail([
			common = base::take(_commonFailHandler),
			specific = std::move(handler)
		](const MTP::Error &error) {
			if (!specific(error)) {
				common(error);
			}
		});
	}
	return *this;
}

template <typename Request>
mtpRequestId ApiWrap::RequestBuilder<Request>::send() {
	return _commonFailHandler
		? _builder.fail(base::take(_commonFailHandler)).send()
		: _builder.send();
}

ApiWrap::LoadedFileCache::LoadedFileCache(int limit) : _limit(limit) {
	Expects(limit >= 0);
}

void ApiWrap::LoadedFileCache::save(
		const Location &location,
		const QString &relativePath) {
	if (!location) {
		return;
	}
	const auto key = ComputeLocationKey(location);
	_map[key] = relativePath;
	_list.push_back(key);
	if (_list.size() > _limit) {
		const auto key = _list.front();
		_list.pop_front();
		_map.erase(key);
	}
}

std::optional<QString> ApiWrap::LoadedFileCache::find(
		const Location &location) const {
	if (!location) {
		return std::nullopt;
	}
	const auto key = ComputeLocationKey(location);
	if (const auto i = _map.find(key); i != end(_map)) {
		return i->second;
	}
	return std::nullopt;
}

ApiWrap::FileProcess::FileProcess(const QString &path, Output::Stats *stats)
: file(path, stats) {
}

template <typename Request>
auto ApiWrap::mainRequest(Request &&request) {
	Expects(_takeoutId.has_value());

	auto original = std::move(_mtp.request(MTPInvokeWithTakeout<Request>(
		MTP_long(*_takeoutId),
		std::forward<Request>(request)
	)).toDC(MTP::ShiftDcId(0, MTP::kExportDcShift)));

	return RequestBuilder<MTPInvokeWithTakeout<Request>>(
		std::move(original),
		[=](const MTP::Error &result) { error(result); });
}

template <typename Request>
auto ApiWrap::splitRequest(int index, Request &&request) {
	Expects(index < _splits.size());

	//if (index == _splits.size() - 1) {
	//	return mainRequest(std::forward<Request>(request));
	//}
	return mainRequest(MTPInvokeWithMessagesRange<Request>(
		_splits[index],
		std::forward<Request>(request)));
}

auto ApiWrap::fileRequest(const Data::FileLocation &location, int64 offset) {
	Expects(location.dcId != 0
		|| location.data.type() == mtpc_inputTakeoutFileLocation);
	Expects(_takeoutId.has_value());
	Expects(_fileProcess->requestId == 0);

	return std::move(_mtp.request(MTPInvokeWithTakeout<MTPupload_GetFile>(
		MTP_long(*_takeoutId),
		MTPupload_GetFile(
			MTP_flags(0),
			location.data,
			MTP_long(offset),
			MTP_int(kFileChunkSize))
	)).fail([=](const MTP::Error &result) {
		_fileProcess->requestId = 0;
		if (result.type() == u"TAKEOUT_FILE_EMPTY"_q
			&& _otherDataProcess != nullptr) {
			filePartDone(
				0,
				MTP_upload_file(
					MTP_storage_filePartial(),
					MTP_int(0),
					MTP_bytes()));
		} else if (result.type() == u"LOCATION_INVALID"_q
			|| result.type() == u"VERSION_INVALID"_q
			|| result.type() == u"LOCATION_NOT_AVAILABLE"_q) {
			filePartUnavailable();
		} else if (result.code() == 400
			&& result.type().startsWith(u"FILE_REFERENCE_"_q)) {
			filePartRefreshReference(offset);
		} else {
			error(std::move(result));
		}
	}).toDC(MTP::ShiftDcId(location.dcId, MTP::kExportMediaDcShift)));
}

ApiWrap::ApiWrap(QPointer<MTP::Instance> weak, Fn<void(FnMut<void()>)> runner)
: _mtp(weak, std::move(runner))
, _fileCache(std::make_unique<LoadedFileCache>(kLocationCacheSize)) {
}

rpl::producer<MTP::Error> ApiWrap::errors() const {
	return _errors.events();
}

rpl::producer<Output::Result> ApiWrap::ioErrors() const {
	return _ioErrors.events();
}

void ApiWrap::startExport(
		const Settings &settings,
		Output::Stats *stats,
		FnMut<void(StartInfo)> done) {
	Expects(_settings == nullptr);
	Expects(_startProcess == nullptr);

	_settings = std::make_unique<Settings>(settings);
	_stats = stats;
	_startProcess = std::make_unique<StartProcess>();
	_startProcess->done = std::move(done);

	using Step = StartProcess::Step;
	if (_settings->types & Settings::Type::Userpics) {
		_startProcess->steps.push_back(Step::UserpicsCount);
	}
	if (_settings->types & Settings::Type::Stories) {
		_startProcess->steps.push_back(Step::StoriesCount);
	}
	if (_settings->types & Settings::Type::AnyChatsMask) {
		_startProcess->steps.push_back(Step::SplitRanges);
		_startProcess->steps.push_back(Step::DialogsCount);
	}
	if (_settings->types & Settings::Type::GroupsChannelsMask) {
		if (!_settings->onlySinglePeer()) {
			_startProcess->steps.push_back(Step::LeftChannelsCount);
		}
	}
	startMainSession([=] {
		sendNextStartRequest();
	});
}

void ApiWrap::sendNextStartRequest() {
	Expects(_startProcess != nullptr);

	auto &steps = _startProcess->steps;
	if (steps.empty()) {
		finishStartProcess();
		return;
	}
	using Step = StartProcess::Step;
	const auto step = steps.front();
	steps.pop_front();
	switch (step) {
	case Step::UserpicsCount:
		return requestUserpicsCount();
	case Step::StoriesCount:
		return requestStoriesCount();
	case Step::SplitRanges:
		return requestSplitRanges();
	case Step::DialogsCount:
		return requestDialogsCount();
	case Step::LeftChannelsCount:
		return requestLeftChannelsCount();
	}
	Unexpected("Step in ApiWrap::sendNextStartRequest.");
}

void ApiWrap::requestUserpicsCount() {
	Expects(_startProcess != nullptr);

	mainRequest(MTPphotos_GetUserPhotos(
		_user,
		MTP_int(0),  // offset
		MTP_long(0), // max_id
		MTP_int(0)   // limit
	)).done([=](const MTPphotos_Photos &result) {
		Expects(_settings != nullptr);
		Expects(_startProcess != nullptr);

		_startProcess->info.userpicsCount = result.match(
		[](const MTPDphotos_photos &data) {
			return int(data.vphotos().v.size());
		}, [](const MTPDphotos_photosSlice &data) {
			return data.vcount().v;
		});

		sendNextStartRequest();
	}).send();
}

void ApiWrap::requestStoriesCount() {
	Expects(_startProcess != nullptr);

	mainRequest(MTPstories_GetStoriesArchive(
		MTP_inputPeerSelf(),
		MTP_int(0), // offset_id
		MTP_int(0) // limit
	)).done([=](const MTPstories_Stories &result) {
		Expects(_settings != nullptr);
		Expects(_startProcess != nullptr);

		_startProcess->info.storiesCount = result.data().vcount().v;

		sendNextStartRequest();
	}).send();
}

void ApiWrap::requestSplitRanges() {
	Expects(_startProcess != nullptr);

	mainRequest(MTPmessages_GetSplitRanges(
	)).done([=](const MTPVector<MTPMessageRange> &result) {
		_splits = result.v;
		if (_splits.empty()) {
			_splits.push_back(MTP_messageRange(
				MTP_int(1),
				MTP_int(std::numeric_limits<int>::max())));
		}
		_startProcess->splitIndex = useOnlyLastSplit()
			? (_splits.size() - 1)
			: 0;

		sendNextStartRequest();
	}).send();
}

void ApiWrap::requestDialogsCount() {
	Expects(_startProcess != nullptr);

	if (_settings->onlySinglePeer()) {
		_startProcess->info.dialogsCount
			= (_settings->singlePeer.type() == mtpc_inputPeerChannel
				? 1
				: _splits.size());
		sendNextStartRequest();
		return;
	}

	const auto offsetDate = 0;
	const auto offsetId = 0;
	const auto offsetPeer = MTP_inputPeerEmpty();
	const auto limit = 1;
	const auto hash = uint64(0);
	splitRequest(_startProcess->splitIndex, MTPmessages_GetDialogs(
		MTP_flags(0),
		MTPint(), // folder_id
		MTP_int(offsetDate),
		MTP_int(offsetId),
		offsetPeer,
		MTP_int(limit),
		MTP_long(hash)
	)).done([=](const MTPmessages_Dialogs &result) {
		Expects(_settings != nullptr);
		Expects(_startProcess != nullptr);

		const auto count = result.match(
		[](const MTPDmessages_dialogs &data) {
			return int(data.vdialogs().v.size());
		}, [](const MTPDmessages_dialogsSlice &data) {
			return data.vcount().v;
		}, [](const MTPDmessages_dialogsNotModified &data) {
			return -1;
		});
		if (count < 0) {
			error("Unexpected dialogsNotModified received.");
			return;
		}
		_startProcess->info.dialogsCount += count;

		if (++_startProcess->splitIndex >= _splits.size()) {
			sendNextStartRequest();
		} else {
			requestDialogsCount();
		}
	}).send();
}

void ApiWrap::requestLeftChannelsCount() {
	Expects(_startProcess != nullptr);
	Expects(_leftChannelsProcess == nullptr);

	_leftChannelsProcess = std::make_unique<LeftChannelsProcess>();
	requestLeftChannelsSliceGeneric([=] {
		Expects(_startProcess != nullptr);
		Expects(_leftChannelsProcess != nullptr);

		_startProcess->info.dialogsCount
			+= _leftChannelsProcess->fullCount;
		sendNextStartRequest();
	});
}

void ApiWrap::finishStartProcess() {
	Expects(_startProcess != nullptr);

	const auto process = base::take(_startProcess);
	process->done(process->info);
}

bool ApiWrap::useOnlyLastSplit() const {
	return !(_settings->types & Settings::Type::NonChannelChatsMask);
}

void ApiWrap::requestLeftChannelsList(
		Fn<bool(int count)> progress,
		FnMut<void(Data::DialogsInfo&&)> done) {
	Expects(_leftChannelsProcess != nullptr);

	_leftChannelsProcess->progress = std::move(progress);
	_leftChannelsProcess->done = std::move(done);
	requestLeftChannelsSlice();
}

void ApiWrap::requestLeftChannelsSlice() {
	requestLeftChannelsSliceGeneric([=] {
		Expects(_leftChannelsProcess != nullptr);

		if (_leftChannelsProcess->finished) {
			const auto process = base::take(_leftChannelsProcess);
			process->done(std::move(process->info));
		} else {
			requestLeftChannelsSlice();
		}
	});
}

void ApiWrap::requestDialogsList(
		Fn<bool(int count)> progress,
		FnMut<void(Data::DialogsInfo&&)> done) {
	Expects(_dialogsProcess == nullptr);

	_dialogsProcess = std::make_unique<DialogsProcess>();
	_dialogsProcess->splitIndexPlusOne = _splits.size();
	_dialogsProcess->progress = std::move(progress);
	_dialogsProcess->done = std::move(done);

	requestDialogsSlice();
}

void ApiWrap::startMainSession(FnMut<void()> done) {
	using Type = Settings::Type;
	const auto sizeLimit = _settings->media.sizeLimit;
	const auto hasFiles = ((_settings->media.types != 0) && (sizeLimit > 0))
		|| (_settings->types & Type::Userpics)
		|| (_settings->types & Type::Stories);

	using Flag = MTPaccount_InitTakeoutSession::Flag;
	const auto flags = Flag(0)
		| (_settings->types & Type::Contacts ? Flag::f_contacts : Flag(0))
		| (hasFiles ? Flag::f_files : Flag(0))
		| ((hasFiles && sizeLimit < kFileMaxSize)
			? Flag::f_file_max_size
			: Flag(0))
		| (_settings->types & (Type::PersonalChats | Type::BotChats)
			? Flag::f_message_users
			: Flag(0))
		| (_settings->types & Type::PrivateGroups
			? (Flag::f_message_chats | Flag::f_message_megagroups)
			: Flag(0))
		| (_settings->types & Type::PublicGroups
			? Flag::f_message_megagroups
			: Flag(0))
		| (_settings->types & (Type::PrivateChannels | Type::PublicChannels)
			? Flag::f_message_channels
			: Flag(0));

	_mtp.request(MTPusers_GetUsers(
		MTP_vector<MTPInputUser>(1, MTP_inputUserSelf())
	)).done([=, done = std::move(done)](
			const MTPVector<MTPUser> &result) mutable {
		for (const auto &user : result.v) {
			user.match([&](const MTPDuser &data) {
				if (data.is_self()) {
					_selfId.emplace(data.vid());
				}
			}, [&](const MTPDuserEmpty&) {
			});
		}
		if (!_selfId) {
			error("Could not retrieve selfId.");
			return;
		}
		_mtp.request(MTPaccount_InitTakeoutSession(
			MTP_flags(flags),
			MTP_long(sizeLimit)
		)).done([=, done = std::move(done)](
				const MTPaccount_Takeout &result) mutable {
			_takeoutId = result.match([](const MTPDaccount_takeout &data) {
				return data.vid().v;
			});
			done();
		}).fail([=](const MTP::Error &result) {
			error(result);
		}).toDC(MTP::ShiftDcId(0, MTP::kExportDcShift)).send();
	}).fail([=](const MTP::Error &result) {
		error(result);
	}).send();
}

void ApiWrap::requestPersonalInfo(FnMut<void(Data::PersonalInfo&&)> done) {
	mainRequest(MTPusers_GetFullUser(
		_user
	)).done([=, done = std::move(done)](const MTPusers_UserFull &result) mutable {
		result.match([&](const MTPDusers_userFull &data) {
			if (!data.vusers().v.empty()) {
				done(Data::ParsePersonalInfo(data));
			} else {
				error("Bad user type.");
			}
		});
	}).send();
}

void ApiWrap::requestOtherData(
		const QString &suggestedPath,
		FnMut<void(Data::File&&)> done) {
	Expects(_otherDataProcess == nullptr);

	_otherDataProcess = std::make_unique<OtherDataProcess>();
	_otherDataProcess->done = std::move(done);
	_otherDataProcess->file.location.data = MTP_inputTakeoutFileLocation();
	_otherDataProcess->file.suggestedPath = suggestedPath;
	loadFile(
		_otherDataProcess->file,
		Data::FileOrigin(),
		[](FileProgress progress) { return true; },
		[=](const QString &result) { otherDataDone(result); });
}

void ApiWrap::otherDataDone(const QString &relativePath) {
	Expects(_otherDataProcess != nullptr);

	const auto process = base::take(_otherDataProcess);
	process->file.relativePath = relativePath;
	if (relativePath.isEmpty()) {
		process->file.skipReason = Data::File::SkipReason::Unavailable;
	}
	process->done(std::move(process->file));
}

void ApiWrap::requestUserpics(
		FnMut<bool(Data::UserpicsInfo&&)> start,
		Fn<bool(DownloadProgress)> progress,
		Fn<bool(Data::UserpicsSlice&&)> slice,
		FnMut<void()> finish) {
	Expects(_userpicsProcess == nullptr);

	_userpicsProcess = std::make_unique<UserpicsProcess>();
	_userpicsProcess->start = std::move(start);
	_userpicsProcess->fileProgress = std::move(progress);
	_userpicsProcess->handleSlice = std::move(slice);
	_userpicsProcess->finish = std::move(finish);

	mainRequest(MTPphotos_GetUserPhotos(
		_user,
		MTP_int(0), // offset
		MTP_long(_userpicsProcess->maxId),
		MTP_int(kUserpicsSliceLimit)
	)).done([=](const MTPphotos_Photos &result) mutable {
		Expects(_userpicsProcess != nullptr);

		auto startInfo = result.match(
		[](const MTPDphotos_photos &data) {
			return Data::UserpicsInfo{ int(data.vphotos().v.size()) };
		}, [](const MTPDphotos_photosSlice &data) {
			return Data::UserpicsInfo{ data.vcount().v };
		});
		if (!_userpicsProcess->start(std::move(startInfo))) {
			return;
		}

		handleUserpicsSlice(result);
	}).send();
}

void ApiWrap::handleUserpicsSlice(const MTPphotos_Photos &result) {
	Expects(_userpicsProcess != nullptr);

	result.match([&](const auto &data) {
		if constexpr (MTPDphotos_photos::Is<decltype(data)>()) {
			_userpicsProcess->lastSlice = true;
		}
		loadUserpicsFiles(Data::ParseUserpicsSlice(
			data.vphotos(),
			_userpicsProcess->processed));
	});
}

void ApiWrap::loadUserpicsFiles(Data::UserpicsSlice &&slice) {
	Expects(_userpicsProcess != nullptr);
	Expects(!_userpicsProcess->slice.has_value());

	if (slice.list.empty()) {
		_userpicsProcess->lastSlice = true;
	}
	_userpicsProcess->slice = std::move(slice);
	_userpicsProcess->fileIndex = 0;
	loadNextUserpic();
}

void ApiWrap::loadNextUserpic() {
	Expects(_userpicsProcess != nullptr);
	Expects(_userpicsProcess->slice.has_value());

	for (auto &list = _userpicsProcess->slice->list
		; _userpicsProcess->fileIndex < list.size()
		; ++_userpicsProcess->fileIndex) {
		const auto ready = processFileLoad(
			list[_userpicsProcess->fileIndex].image.file,
			Data::FileOrigin(),
			[=](FileProgress value) { return loadUserpicProgress(value); },
			[=](const QString &path) { loadUserpicDone(path); });
		if (!ready) {
			return;
		}
	}
	finishUserpicsSlice();
}

void ApiWrap::finishUserpicsSlice() {
	Expects(_userpicsProcess != nullptr);
	Expects(_userpicsProcess->slice.has_value());

	auto slice = *base::take(_userpicsProcess->slice);
	if (!slice.list.empty()) {
		_userpicsProcess->processed += slice.list.size();
		_userpicsProcess->maxId = slice.list.back().id;
		if (!_userpicsProcess->handleSlice(std::move(slice))) {
			return;
		}
	}
	if (_userpicsProcess->lastSlice) {
		finishUserpics();
		return;
	}

	mainRequest(MTPphotos_GetUserPhotos(
		_user,
		MTP_int(0), // offset
		MTP_long(_userpicsProcess->maxId),
		MTP_int(kUserpicsSliceLimit)
	)).done([=](const MTPphotos_Photos &result) {
		handleUserpicsSlice(result);
	}).send();
}

bool ApiWrap::loadUserpicProgress(FileProgress progress) {
	Expects(_fileProcess != nullptr);
	Expects(_userpicsProcess != nullptr);
	Expects(_userpicsProcess->slice.has_value());
	Expects((_userpicsProcess->fileIndex >= 0)
		&& (_userpicsProcess->fileIndex
			< _userpicsProcess->slice->list.size()));

	return _userpicsProcess->fileProgress(DownloadProgress{
		_fileProcess->randomId,
		_fileProcess->relativePath,
		_userpicsProcess->fileIndex,
		progress.ready,
		progress.total });
}

void ApiWrap::loadUserpicDone(const QString &relativePath) {
	Expects(_userpicsProcess != nullptr);
	Expects(_userpicsProcess->slice.has_value());
	Expects((_userpicsProcess->fileIndex >= 0)
		&& (_userpicsProcess->fileIndex
			< _userpicsProcess->slice->list.size()));

	const auto index = _userpicsProcess->fileIndex;
	auto &file = _userpicsProcess->slice->list[index].image.file;
	file.relativePath = relativePath;
	if (relativePath.isEmpty()) {
		file.skipReason = Data::File::SkipReason::Unavailable;
	}
	loadNextUserpic();
}

void ApiWrap::finishUserpics() {
	Expects(_userpicsProcess != nullptr);

	base::take(_userpicsProcess)->finish();
}

void ApiWrap::requestStories(
		FnMut<bool(Data::StoriesInfo&&)> start,
		Fn<bool(DownloadProgress)> progress,
		Fn<bool(Data::StoriesSlice&&)> slice,
		FnMut<void()> finish) {
	Expects(_storiesProcess == nullptr);

	_storiesProcess = std::make_unique<StoriesProcess>();
	_storiesProcess->start = std::move(start);
	_storiesProcess->fileProgress = std::move(progress);
	_storiesProcess->handleSlice = std::move(slice);
	_storiesProcess->finish = std::move(finish);

	mainRequest(MTPstories_GetStoriesArchive(
		MTP_inputPeerSelf(),
		MTP_int(_storiesProcess->offsetId),
		MTP_int(kStoriesSliceLimit)
	)).done([=](const MTPstories_Stories &result) mutable {
		Expects(_storiesProcess != nullptr);

		auto startInfo = Data::StoriesInfo{ result.data().vcount().v };
		if (!_storiesProcess->start(std::move(startInfo))) {
			return;
		}

		handleStoriesSlice(result);
	}).send();
}

void ApiWrap::handleStoriesSlice(const MTPstories_Stories &result) {
	Expects(_storiesProcess != nullptr);

	loadStoriesFiles(Data::ParseStoriesSlice(
		result.data().vstories(),
		_storiesProcess->processed));
}

void ApiWrap::loadStoriesFiles(Data::StoriesSlice &&slice) {
	Expects(_storiesProcess != nullptr);
	Expects(!_storiesProcess->slice.has_value());

	if (!slice.lastId) {
		_storiesProcess->lastSlice = true;
	}
	_storiesProcess->slice = std::move(slice);
	_storiesProcess->fileIndex = 0;
	loadNextStory();
}

void ApiWrap::loadNextStory() {
	Expects(_storiesProcess != nullptr);
	Expects(_storiesProcess->slice.has_value());

	for (auto &list = _storiesProcess->slice->list
		; _storiesProcess->fileIndex < list.size()
		; ++_storiesProcess->fileIndex) {
		auto &story = list[_storiesProcess->fileIndex];
		const auto origin = Data::FileOrigin{ .storyId = story.id };
		const auto ready = processFileLoad(
			story.file(),
			origin,
			[=](FileProgress value) { return loadStoryProgress(value); },
			[=](const QString &path) { loadStoryDone(path); });
		if (!ready) {
			return;
		}
		const auto thumbProgress = [=](FileProgress value) {
			return loadStoryThumbProgress(value);
		};
		const auto thumbReady = processFileLoad(
			story.thumb().file,
			origin,
			thumbProgress,
			[=](const QString &path) { loadStoryThumbDone(path); },
			nullptr,
			&story);
		if (!thumbReady) {
			return;
		}
	}
	finishStoriesSlice();
}

void ApiWrap::finishStoriesSlice() {
	Expects(_storiesProcess != nullptr);
	Expects(_storiesProcess->slice.has_value());

	auto slice = *base::take(_storiesProcess->slice);
	if (slice.lastId) {
		_storiesProcess->processed += slice.list.size();
		_storiesProcess->offsetId = slice.lastId;
		if (!_storiesProcess->handleSlice(std::move(slice))) {
			return;
		}
	}
	if (_storiesProcess->lastSlice) {
		finishStories();
		return;
	}

	mainRequest(MTPstories_GetStoriesArchive(
		MTP_inputPeerSelf(),
		MTP_int(_storiesProcess->offsetId),
		MTP_int(kStoriesSliceLimit)
	)).done([=](const MTPstories_Stories &result) {