/*
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
*/
#include "history/history_shared_media.h"

#include "auth_session.h"
#include "apiwrap.h"
#include "storage/storage_facade.h"
#include "storage/storage_shared_media.h"
#include "history/history_media_types.h"

namespace {

using Type = SharedMediaViewer::Type;

inline MediaOverviewType SharedMediaTypeToOverview(Type type) {
	switch (type) {
	case Type::Photo: return OverviewPhotos;
	case Type::Video: return OverviewVideos;
	case Type::MusicFile: return OverviewMusicFiles;
	case Type::File: return OverviewFiles;
	case Type::VoiceFile: return OverviewVoiceFiles;
	case Type::Link: return OverviewLinks;
	default: break;
	}
	return OverviewCount;
}

} // namespace

base::optional<Storage::SharedMediaType> SharedMediaOverviewType(
	Storage::SharedMediaType type) {
	if (SharedMediaTypeToOverview(type) != OverviewCount) {
		return type;
	}
	return base::none;
}

void SharedMediaShowOverview(
	Storage::SharedMediaType type,
	not_null<History*> history) {
	if (SharedMediaOverviewType(type)) {
		Ui::showPeerOverview(history, SharedMediaTypeToOverview(type));
	}
}

SharedMediaSlice::SharedMediaSlice(Key key) : SharedMediaSlice(key, base::none) {
}

SharedMediaSlice::SharedMediaSlice(
	Key key,
	base::optional<int> fullCount)
	: _key(key)
	, _fullCount(fullCount) {
}

base::optional<int> SharedMediaSlice::indexOf(MsgId msgId) const {
	auto it = _ids.find(msgId);
	if (it != _ids.end()) {
		return (it - _ids.begin());
	}
	return base::none;
}

MsgId SharedMediaSlice::operator[](int index) const {
	Expects(index >= 0 && index < size());

	return *(_ids.begin() + index);
}

base::optional<int> SharedMediaSlice::distance(const Key &a, const Key &b) const {
	if (a.type != _key.type
		|| b.type != _key.type
		|| a.peerId != _key.peerId
		|| b.peerId != _key.peerId) {
		return base::none;
	}
	if (auto i = indexOf(a.messageId)) {
		if (auto j = indexOf(b.messageId)) {
			return *j - *i;
		}
	}
	return base::none;
}

QString SharedMediaSlice::debug() const {
	auto before = _skippedBefore
		? (*_skippedBefore
			? ('(' + QString::number(*_skippedBefore) + ").. ")
			: QString())
		: QString(".. ");
	auto after = _skippedAfter
		? (*_skippedAfter
			? (" ..(" + QString::number(*_skippedAfter) + ')')
			: QString())
		: QString(" ..");
	auto middle = (size() > 2)
		? QString::number((*this)[0]) + " .. " + QString::number((*this)[size() - 1])
		: (size() > 1)
		? QString::number((*this)[0]) + ' ' + QString::number((*this)[1])
		: ((size() > 0) ? QString::number((*this)[0]) : QString());
	return before + middle + after;
}

SharedMediaViewer::SharedMediaViewer(
	Key key,
	int limitBefore,
	int limitAfter)
	: _key(key)
	, _limitBefore(limitBefore)
	, _limitAfter(limitAfter)
	, _data(_key) {
	Expects(IsServerMsgId(key.messageId) || (key.messageId == 0));
	Expects((key.messageId != 0) || (limitBefore == 0 && limitAfter == 0));
}

void SharedMediaViewer::start() {
	auto applyUpdateCallback = [this](auto &update) {
		this->applyUpdate(update);
	};
	subscribe(Auth().storage().sharedMediaSliceUpdated(), applyUpdateCallback);
	subscribe(Auth().storage().sharedMediaOneRemoved(), applyUpdateCallback);
	subscribe(Auth().storage().sharedMediaAllRemoved(), applyUpdateCallback);

	loadInitial();
}

void SharedMediaViewer::loadInitial() {
	auto weak = base::make_weak_unique(this);
	Auth().storage().query(Storage::SharedMediaQuery(
		_key,
		_limitBefore,
		_limitAfter), [weak](Storage::SharedMediaResult &&result) {
		if (weak) {
			weak->applyStoredResult(std::move(result));
		}
	});
}

void SharedMediaViewer::applyStoredResult(Storage::SharedMediaResult &&result) {
	mergeSliceData(
		result.count,
		result.messageIds,
		result.skippedBefore,
		result.skippedAfter);
}

void SharedMediaViewer::mergeSliceData(
		base::optional<int> count,
		const base::flat_set<MsgId> &messageIds,
		base::optional<int> skippedBefore,
		base::optional<int> skippedAfter) {
	if (messageIds.empty()) {
		if (count && _data._fullCount != count) {
			_data._fullCount = count;
			if (*_data._fullCount <= _data.size()) {
				_data._fullCount = _data.size();
				_data._skippedBefore = _data._skippedAfter = 0;
			}
			updated.notify(_data);
		}
		sliceToLimits();
		return;
	}
	if (count) {
		_data._fullCount = count;
	}
	auto wasMinId = _data._ids.empty() ? -1 : _data._ids.front();
	auto wasMaxId = _data._ids.empty() ? -1 : _data._ids.back();
	_data._ids.merge(messageIds.begin(), messageIds.end());

	auto adjustSkippedBefore = [&](MsgId oldId, int oldSkippedBefore) {
		auto it = _data._ids.find(oldId);
		Assert(it != _data._ids.end());
		_data._skippedBefore = oldSkippedBefore - (it - _data._ids.begin());
		accumulate_max(*_data._skippedBefore, 0);
	};
	if (skippedBefore) {
		adjustSkippedBefore(messageIds.front(), *skippedBefore);
	} else if (wasMinId >= 0 && _data._skippedBefore) {
		adjustSkippedBefore(wasMinId, *_data._skippedBefore);
	} else {
		_data._skippedBefore = base::none;
	}

	auto adjustSkippedAfter = [&](MsgId oldId, int oldSkippedAfter) {
		auto it = _data._ids.find(oldId);
		Assert(it != _data._ids.end());
		_data._skippedAfter = oldSkippedAfter - (_data._ids.end() - it - 1);
		accumulate_max(*_data._skippedAfter, 0);
	};
	if (skippedAfter) {
		adjustSkippedAfter(messageIds.back(), *skippedAfter);
	} else if (wasMaxId >= 0 && _data._skippedAfter) {
		adjustSkippedAfter(wasMaxId, *_data._skippedAfter);
	} else {
		_data._skippedAfter = base::none;
	}

	if (_data._fullCount) {
		if (_data._skippedBefore && !_data._skippedAfter) {
			_data._skippedAfter = *_data._fullCount
				- *_data._skippedBefore
				- int(_data._ids.size());
		} else if (_data._skippedAfter && !_data._skippedBefore) {
			_data._skippedBefore = *_data._fullCount
				- *_data._skippedAfter
				- int(_data._ids.size());
		}
	}

	sliceToLimits();

	updated.notify(_data);
}

void SharedMediaViewer::applyUpdate(const SliceUpdate &update) {
	if (update.peerId != _key.peerId || update.type != _key.type) {
		return;
	}
	auto intersects = [](MsgRange range1, MsgRange range2) {
		return (range1.from <= range2.till) && (range2.from <= range1.till);
	};
	if (!intersects(update.range, {
		_data._ids.empty() ? _key.messageId : _data._ids.front(),
		_data._ids.empty() ? _key.messageId : _data._ids.back() })) {
		return;
	}
	auto skippedBefore = (update.range.from == 0)
		? 0
		: base::optional<int> {};
	auto skippedAfter = (update.range.till == ServerMaxMsgId)
		? 0
		: base::optional<int> {};
	mergeSliceData(
		update.count,
		update.messages ? *update.messages : base::flat_set<MsgId> {},
		skippedBefore,
		skippedAfter);
}

void SharedMediaViewer::applyUpdate(const OneRemoved &update) {
	if (update.peerId != _key.peerId || !update.types.test(_key.type)) {
		return;
	}
	auto changed = false;
	if (_data._fullCount && *_data._fullCount > 0) {
		--*_data._fullCount;
		changed = true;
	}
	if (_data._ids.contains(update.messageId)) {
		_data._ids.remove(update.messageId);
		changed = true;
	} else if (!_data._ids.empty()) {
		if (_data._ids.front() > update.messageId
			&& _data._skippedBefore
			&& *_data._skippedBefore > 0) {
			--*_data._skippedBefore;
			changed = true;
		} else if (_data._ids.back() < update.messageId
			&& _data._skippedAfter
			&& *_data._skippedAfter > 0) {
			--*_data._skippedAfter;
			changed = true;
		}
	}
	if (changed) {
		updated.notify(_data);
	}
}

void SharedMediaViewer::applyUpdate(const AllRemoved &update) {
	if (update.peerId != _key.peerId) {
		return;
	}
	_data = SharedMediaSlice(_key, 0);
	updated.notify(_data);
}

void SharedMediaViewer::sliceToLimits() {
	auto aroundIt = base::lower_bound(_data._ids, _key.messageId);
	auto removeFromBegin = (aroundIt - _data._ids.begin() - _limitBefore);
	auto removeFromEnd = (_data._ids.end() - aroundIt - _limitAfter - 1);
	if (removeFromBegin > 0) {
		_data._ids.erase(_data._ids.begin(), _data._ids.begin() + removeFromBegin);
		if (_data._skippedBefore) {
			*_data._skippedBefore += removeFromBegin;
		}
	} else if (removeFromBegin < 0 && (!_data._skippedBefore || *_data._skippedBefore > 0)) {
		requestMessages(RequestDirection::Before);
	}
	if (removeFromEnd > 0) {
		_data._ids.erase(_data._ids.end() - removeFromEnd, _data._ids.end());
		if (_data._skippedAfter) {
			*_data._skippedAfter += removeFromEnd;
		}
	} else if (removeFromEnd < 0 && (!_data._skippedAfter || *_data._skippedAfter > 0)) {
		requestMessages(RequestDirection::After);
	}
}

void SharedMediaViewer::requestMessages(RequestDirection direction) {
	using SliceType = ApiWrap::SliceType;
	auto requestAroundData = [&]() -> std::pair<MsgId, SliceType> {
		if (_data._ids.empty()) {
			return { _key.messageId, SliceType::Around };
		} else if (direction == RequestDirection::Before) {
			return { _data._ids.front(), SliceType::Before };
		}
		return { _data._ids.back(), SliceType::After };
	}();
	Auth().api().requestSharedMedia(
		App::peer(_key.peerId),
		_key.type,
		requestAroundData.first,
		requestAroundData.second);
}

SharedMediaSliceMerged::SharedMediaSliceMerged(Key key) : SharedMediaSliceMerged(
	key,
	SharedMediaSlice(PartKey(key)),
	MigratedSlice(key)) {
}

SharedMediaSliceMerged::SharedMediaSliceMerged(
	Key key,
	SharedMediaSlice part,
	base::optional<SharedMediaSlice> migrated)
	: _key(key)
	, _part(std::move(part))
	, _migrated(std::move(migrated)) {
}

base::optional<int> SharedMediaSliceMerged::fullCount() const {
	return Add(
		_part.fullCount(),
		_migrated ? _migrated->fullCount() : 0);
}

base::optional<int> SharedMediaSliceMerged::skippedBefore() const {
	return Add(
		isolatedInMigrated() ? 0 : _part.skippedBefore(),
		_migrated
			? (isolatedInPart()
				? _migrated->fullCount()
				: _migrated->skippedBefore())
			: 0
	);
}

base::optional<int> SharedMediaSliceMerged::skippedAfter() const {
	return Add(
		isolatedInMigrated() ? _part.fullCount() : _part.skippedAfter(),
		isolatedInPart() ? 0 : _migrated->skippedAfter()
	);
}

base::optional<int> SharedMediaSliceMerged::indexOf(FullMsgId fullId) const {
	return isFromPart(fullId)
		? (_part.indexOf(fullId.msg) | func::add(migratedSize()))
		: isolatedInPart()
			? base::none
			: isFromMigrated(fullId)
				? _migrated->indexOf(fullId.msg)
				: base::none;
}

int SharedMediaSliceMerged::size() const {
	return (isolatedInPart() ? 0 : migratedSize())
		+ (isolatedInMigrated() ? 0 : _part.size());
}

FullMsgId SharedMediaSliceMerged::operator[](int index) const {
	Expects(index >= 0 && index < size());

	if (auto size = migratedSize()) {
		if (index < size) {
			return ComputeId(*_migrated, index);
		}
		index -= size;
	}
	return ComputeId(_part, index);
}

base::optional<int> SharedMediaSliceMerged::distance(const Key &a, const Key &b) const {
	if (a.type != _key.type
		|| b.type != _key.type
		|| a.peerId != _key.peerId
		|| b.peerId != _key.peerId
		|| a.migratedPeerId != _key.migratedPeerId
		|| b.migratedPeerId != _key.migratedPeerId) {
		return base::none;
	}
	if (auto i = indexOf(ComputeId(a))) {
		if (auto j = indexOf(ComputeId(b))) {
			return *j - *i;
		}
	}
	return base::none;
}

QString SharedMediaSliceMerged::debug() const {
	return (_migrated ? (_migrated->debug() + '|') : QString()) + _part.debug();
}

SharedMediaViewerMerged::SharedMediaViewerMerged(
	Key key,
	int limitBefore,
	int limitAfter)
	: _key(key)
	, _limitBefore(limitBefore)
	, _limitAfter(limitAfter)
	, _part(SharedMediaSliceMerged::PartKey(_key), _limitBefore, _limitAfter)
	, _migrated(MigratedViewer(_key, _limitBefore, _limitAfter))
	, _data(_key) {
	Expects(IsServerMsgId(key.universalId)
		|| (key.universalId == 0)
		|| (IsServerMsgId(-key.universalId) && key.migratedPeerId != 0));
	Expects((key.universalId != 0) || (limitBefore == 0 && limitAfter == 0));
}

std::unique_ptr<SharedMediaViewer> SharedMediaViewerMerged::MigratedViewer(
		const Key &key,
		int limitBefore,
		int limitAfter) {
	return key.migratedPeerId
		? std::make_unique<SharedMediaViewer>(
			SharedMediaSliceMerged::MigratedKey(key),
			limitBefore,
			limitAfter)
		: nullptr;
}

void SharedMediaViewerMerged::start() {
	subscribe(_part.updated, [this](const SharedMediaSlice &update) {
		_data = SharedMediaSliceMerged(_key, update, std::move(_data._migrated));
		updated.notify(_data);
	});
	if (_migrated) {
		subscribe(_migrated->updated, [this](const SharedMediaSlice &update) {
			_data = SharedMediaSliceMerged(_key, std::move(_data._part), update);
			updated.notify(_data);
		});
	}
	_part.start();
	if (_migrated) {
		_migrated->start();
	}
}

SharedMediaSliceWithLast::SharedMediaSliceWithLast(Key key) : SharedMediaSliceWithLast(
	key,
	SharedMediaSliceMerged(ViewerKey(key)),
	EndingSlice(key)) {
}

SharedMediaSliceWithLast::SharedMediaSliceWithLast(
	Key key,
	SharedMediaSliceMerged slice,
	base::optional<SharedMediaSliceMerged> ending)
	: _key(key)
	, _slice(std::move(slice))
	, _ending(std::move(ending))
	, _lastPhotoId(LastPeerPhotoId(key.peerId))
	, _isolatedLastPhoto(_key.type == Type::ChatPhoto
		? IsLastIsolated(_slice, _ending, _lastPhotoId)
		: false) {
}

base::optional<int> SharedMediaSliceWithLast::fullCount() const {
	return Add(
		_slice.fullCount(),
		_isolatedLastPhoto | [](bool isolated) { return isolated ? 1 : 0; });
}

base::optional<int> SharedMediaSliceWithLast::skippedBefore() const {
	return _slice.skippedBefore();
}

base::optional<int> SharedMediaSliceWithLast::skippedAfter() const {
	return isolatedInSlice()
		? Add(
			_slice.skippedAfter(),
			lastPhotoSkip())
		: (lastPhotoSkip() | [](int) { return 0; });
}

base::optional<int> SharedMediaSliceWithLast::indexOf(Value value) const {
	return base::get_if<FullMsgId>(&value)
		? _slice.indexOf(*base::get_if<FullMsgId>(&value))
		: (isolatedInSlice()
			|| (*base::get_if<not_null<PhotoData*>>(&value))->id != _lastPhotoId)
			? base::none
			: Add(_slice.size() - 1, lastPhotoSkip());
}

int SharedMediaSliceWithLast::size() const {
	return _slice.size()
		+ ((!isolatedInSlice() && lastPhotoSkip() == 1) ? 1 : 0);
}

SharedMediaSliceWithLast::Value SharedMediaSliceWithLast::operator[](int index) const {
	Expects(index >= 0 && index < size());

	return (index < _slice.size())
		? Value(_slice[index])
		: Value(App::photo(_lastPhotoId));
}

base::optional<int> SharedMediaSliceWithLast::distance(const Key &a, const Key &b) const {
	if (a.type != _key.type
		|| b.type != _key.type
		|| a.peerId != _key.peerId
		|| b.peerId != _key.peerId
		|| a.migratedPeerId != _key.migratedPeerId
		|| b.migratedPeerId != _key.migratedPeerId) {
		return base::none;
	}
	if (auto i = indexOf(ComputeId(a))) {
		if (auto j = indexOf(ComputeId(b))) {
			return *j - *i;
		}
	}
	return base::none;
}

QString SharedMediaSliceWithLast::debug() const {
	return _slice.debug() + (_isolatedLastPhoto
		? (*_isolatedLastPhoto ? "@" : "")
		: "?");
}

PhotoId SharedMediaSliceWithLast::LastPeerPhotoId(PeerId peerId) {
	if (auto peer = App::peerLoaded(peerId)) {
		return peer->photoId;
	}
	return UnknownPeerPhotoId;
}

base::optional<bool> SharedMediaSliceWithLast::IsLastIsolated(
		const SharedMediaSliceMerged &slice,
		const base::optional<SharedMediaSliceMerged> &ending,
		PhotoId lastPeerPhotoId) {
	if (lastPeerPhotoId == UnknownPeerPhotoId) {
		return base::none;
	} else if (!lastPeerPhotoId) {
		return false;
	}
	return LastFullMsgId(ending ? *ending : slice)
		| [](FullMsgId msgId) {	return App::histItemById(msgId); }
		| [](HistoryItem *item) { return item ? item->getMedia() : nullptr; }
		| [](HistoryMedia *media) {
			return (media && media->type() == MediaTypePhoto)
				? static_cast<HistoryPhoto*>(media)->photo()
				: nullptr;
		}
		| [](PhotoData *photo) { return photo ? photo->id : 0; }
		| [&](PhotoId photoId) { return lastPeerPhotoId != photoId; };
}

base::optional<FullMsgId> SharedMediaSliceWithLast::LastFullMsgId(
		const SharedMediaSliceMerged &slice) {
	if (slice.fullCount() == 0) {
		return FullMsgId();
	} else if (slice.size() == 0 || slice.skippedAfter() != 0) {
		return base::none;
	}
	return slice[slice.size() - 1];
}

SharedMediaViewerWithLast::SharedMediaViewerWithLast(
	Key key,
	int limitBefore,
	int limitAfter)
	: _key(key)
	, _limitBefore(limitBefore)
	, _limitAfter(limitAfter)
	, _viewer(SharedMediaSliceWithLast::ViewerKey(_key), _limitBefore, _limitAfter)
	, _ending(EndingViewer(_key, _limitBefore, _limitAfter))
	, _data(_key) {
}

std::unique_ptr<SharedMediaViewerMerged> SharedMediaViewerWithLast::EndingViewer(
		const Key &key,
		int limitBefore,
		int limitAfter) {
	return base::get_if<SharedMediaSliceWithLast::MessageId>(&key.universalId)
		? std::make_unique<SharedMediaViewerMerged>(
			SharedMediaSliceWithLast::EndingKey(key),
			1,
			1)
		: nullptr;
}

void SharedMediaViewerWithLast::start() {
	subscribe(_viewer.updated, [this](const SharedMediaSliceMerged &update) {
		_data = SharedMediaSliceWithLast(_key, update, std::move(_data._ending));
		updated.notify(_data);
	});
	if (_ending) {
		subscribe(_ending->updated, [this](const SharedMediaSliceMerged &update) {
			_data = SharedMediaSliceWithLast(_key, std::move(_data._slice), update);
			updated.notify(_data);
		});
	}
	_viewer.start();
	if (_ending) {
		_ending->start();
	}
}