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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 <shared_mutex>
#include <vector>
#include "database.hpp"
#include "tasks.hpp"
#include "track.hpp"
namespace audio {
/*
* Utility that uses a Miller shuffle to yield well-distributed random indexes
* from within a range.
*/
class RandomIterator {
public:
RandomIterator(size_t size);
auto current() const -> size_t;
auto next() -> void;
auto prev() -> void;
// Note resizing has the side-effect of restarting iteration.
auto resize(size_t) -> void;
auto repeat(bool) -> void;
private:
size_t seed_;
size_t pos_;
size_t size_;
bool repeat_;
};
/*
* 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.
*/
class TrackQueue {
public:
TrackQueue(tasks::WorkerPool& bg_worker);
/* Returns the currently playing track. */
auto current() const -> std::optional<database::TrackId>;
/* Returns, in order, tracks that have been queued to be played next. */
auto peekNext(std::size_t limit) const -> std::vector<database::TrackId>;
/*
* Returns the tracks in the queue that have already been played, ordered
* most recently played first.
*/
auto peekPrevious(std::size_t limit) const -> std::vector<database::TrackId>;
auto currentPosition() const -> size_t;
auto totalSize() const -> size_t;
using Item = std::variant<database::TrackId, database::TrackIterator>;
auto insert(Item, size_t index = 0) -> void;
auto append(Item i) -> 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;
auto skipTo(database::TrackId) -> void;
/*
* Removes all tracks from all queues, and stops any currently playing track.
*/
auto clear() -> void;
auto random(bool) -> void;
auto random() const -> bool;
auto repeat(bool) -> void;
auto repeat() const -> bool;
auto serialise() -> std::string;
auto deserialise(const std::string&) -> void;
// Cannot be copied or moved.
TrackQueue(const TrackQueue&) = delete;
TrackQueue& operator=(const TrackQueue&) = delete;
private:
mutable std::shared_mutex mutex_;
tasks::WorkerPool& bg_worker_;
size_t pos_;
std::pmr::vector<database::TrackId> tracks_;
std::optional<RandomIterator> shuffle_;
bool repeat_;
};
} // namespace audio
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