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Telegram/SourceFiles/data/data_stories_ids.cpp

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+/*
+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 "data/data_stories_ids.h"
+
+#include "data/data_changes.h"
+#include "data/data_peer.h"
+#include "data/data_session.h"
+#include "data/data_stories.h"
+#include "main/main_session.h"
+#include "ui/ui_utility.h"
+
+namespace Data {
+
+rpl::producer<StoriesIdsSlice> AlbumStoriesIds(
+		not_null<PeerData*> peer,
+		int albumId,
+		StoryId aroundId,
+		int limit) {
+	return [=](auto consumer) {
+		auto lifetime = rpl::lifetime();
+
+		struct State {
+			StoriesIdsSlice slice;
+			base::has_weak_ptr guard;
+			bool scheduled = false;
+		};
+		const auto state = lifetime.make_state<State>();
+
+		const auto push = [=] {
+			state->scheduled = false;
+
+			const auto peerId = peer->id;
+			const auto stories = &peer->owner().stories();
+			if (!stories->albumIdsCountKnown(peerId, albumId)) {
+				return;
+			}
+			const auto &loaded = stories->albumIds(peerId, albumId);
+			const auto sorted = RespectingPinned(loaded);
+			const auto count = stories->albumIdsCount(peerId, albumId);
+			auto i = ranges::find(sorted, aroundId);
+			if (i == end(sorted)) {
+				i = begin(sorted);
+			}
+			const auto hasBefore = int(i - begin(sorted));
+			const auto hasAfter = int(end(sorted) - i);
+			if (hasAfter < limit) {
+				stories->albumIdsLoadMore(peerId, albumId);
+			}
+			const auto takeBefore = std::min(hasBefore, limit);
+			const auto takeAfter = std::min(hasAfter, limit);
+			auto ids = std::vector<StoryId>();
+			ids.reserve(takeBefore + takeAfter);
+			for (auto j = i - takeBefore; j != i + takeAfter; ++j) {
+				ids.push_back(*j);
+			}
+			const auto added = int(ids.size());
+			state->slice = StoriesIdsSlice(
+				std::move(ids),
+				count,
+				(hasBefore - takeBefore),
+				count - (hasBefore - takeBefore) - added);
+			consumer.put_next_copy(state->slice);
+		};
+		const auto schedule = [=] {
+			if (state->scheduled) {
+				return;
+			}
+			state->scheduled = true;
+			Ui::PostponeCall(&state->guard, [=] {
+				if (state->scheduled) {
+					push();
+				}
+			});
+		};
+
+		const auto peerId = peer->id;
+		const auto stories = &peer->owner().stories();
+		stories->albumIdsChanged(
+		) | rpl::filter(
+			rpl::mappers::_1 == Data::StoryAlbumIdsKey{ peerId, albumId }
+		) | rpl::on_next(schedule, lifetime);
+
+		if (!stories->albumIdsCountKnown(peerId, albumId)) {
+			stories->albumIdsLoadMore(peerId, albumId);
+		}
+
+		push();
+
+		return lifetime;
+	};
+}
+
+} // namespace Data