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/*
* Copyright 2023 jacqueline <me@jacqueline.id.au>
*
* SPDX-License-Identifier: GPL-3.0-only
*/
#pragma once
#include <list>
#include <memory>
#include <mutex>
#include <vector>
#include "source.hpp"
#include "track.hpp"
namespace audio {
/*
* Owns and manages a complete view of the playback queue. Includes the
* currently playing track, a truncated list of previously played tracks, and
* all future tracks that have been queued.
*
* In order to not use all of our memory, this class deals strictly with track
* ids. Consumers that need more data than this should fetch it from the
* database.
*
* Instances of this class are broadly safe to use from multiple tasks; each
* method represents an atomic operation. No guarantees are made about
* consistency between calls however. For example, there may be data changes
* between consecutive calls to AddNext() and GetUpcoming();
*/
class TrackQueue {
public:
TrackQueue();
/* Returns the currently playing track. */
auto GetCurrent() const -> std::optional<database::TrackId>;
/* Returns, in order, tracks that have been queued to be played next. */
auto GetUpcoming(std::size_t limit) const -> std::vector<database::TrackId>;
/*
* Enqueues a track, placing it immediately after the current track and
* before anything already queued.
*
* If there is no current track, the given track will begin playback.
*/
auto AddNext(database::TrackId) -> void;
auto AddNext(std::shared_ptr<playlist::ISource>) -> void;
auto IncludeNext(std::shared_ptr<playlist::IResetableSource>) -> void;
/*
* Enqueues a track, placing it the end of all enqueued tracks.
*
* If there is no current track, the given track will begin playback.
*/
auto AddLast(database::TrackId) -> void;
auto AddLast(std::shared_ptr<playlist::ISource>) -> void;
auto IncludeLast(std::shared_ptr<playlist::IResetableSource>) -> void;
/*
* Advances to the next track in the queue, placing the current track at the
* front of the 'played' queue.
*/
auto Next() -> void;
auto Previous() -> void;
/*
* Removes all tracks from all queues, and stops any currently playing track.
*/
auto Clear() -> void;
TrackQueue(const TrackQueue&) = delete;
TrackQueue& operator=(const TrackQueue&) = delete;
private:
mutable std::mutex mutex_;
std::list<std::variant<database::TrackId,
std::shared_ptr<playlist::IResetableSource>>>
played_;
std::list<std::variant<database::TrackId,
std::shared_ptr<playlist::ISource>,
std::shared_ptr<playlist::IResetableSource>>>
enqueued_;
};
} // namespace audio
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