torque-tracker-engine / src / lib.rs

pub mod audio_processing;
pub mod file;
mod live_audio;
pub mod project;
pub mod sample;

use std::{
    fmt::Debug,
    num::{NonZero, NonZeroU16},
    ops::Deref,
    time::Duration,
};

use simple_left_right::{WriteGuard, Writer};

use crate::{
    audio_processing::{Interpolation, playback::PlaybackStatus},
    live_audio::LiveAudio,
    project::{
        note_event::NoteEvent,
        song::{Song, SongOperation, ValidOperation},
    },
    sample::Sample,
};

#[derive(Debug, Clone, Copy)]
pub enum ToWorkerMsg {
    Playback(PlaybackSettings),
    StopPlayback,
    PlayEvent(NoteEvent),
    StopLiveNote,
    SetInterpolation(Interpolation),
}

// don't leak the dependency types
pub struct StatusRecv<StreamData>(rt_write_lock::Reader<(Option<PlaybackStatus>, StreamData)>);

// don't leak the dependency types
pub struct StatusRead<'a, StreamData>(
    rt_write_lock::ReadGuard<'a, (Option<PlaybackStatus>, StreamData)>,
);

impl<S> Deref for StatusRead<'_, S> {
    type Target = (Option<PlaybackStatus>, S);

    fn deref(&self) -> &Self::Target {
        &self.0
    }
}

impl<S> StatusRecv<S> {
    pub fn try_get(&mut self) -> Option<StatusRead<'_, S>> {
        self.0.try_read().map(|r| StatusRead(r))
    }
}

pub struct StreamSend(rtrb::Producer<ToWorkerMsg>);

impl StreamSend {
    #[expect(clippy::result_unit_err)]
    pub fn try_msg_worker(&mut self, msg: ToWorkerMsg) -> Result<(), ()> {
        match self.0.push(msg) {
            Ok(_) => Ok(()),
            Err(_) => Err(()),
        }
    }
}

#[derive(Debug, Default)]
pub(crate) struct Collector {
    samples: Vec<Sample>,
}

impl Collector {
    pub fn add_sample(&mut self, sample: Sample) {
        self.samples.push(sample);
    }

    fn collect(&mut self) {
        self.samples.retain(|s| s.strongcount() != 1);
    }
}

pub struct AudioManager {
    song: Writer<Song, ValidOperation>,
    gc: Collector,
    buffer_time: Duration,
}

impl AudioManager {
    pub fn new(song: Song) -> Self {
        let mut gc = Collector::default();
        for (_, sample) in song.samples.iter().flatten() {
            gc.add_sample(sample.clone());
        }
        let left_right = simple_left_right::Writer::new(song);

        Self {
            song: left_right,
            gc,
            buffer_time: Duration::ZERO,
        }
    }

    /// If this returns None, waiting buffer_time should (weird threading issues aside) always be enough time
    /// and it should return Some after that.
    pub fn try_edit_song(&mut self) -> Option<SongEdit<'_>> {
        self.song.try_lock().map(|song| SongEdit {
            song,
            gc: &mut self.gc,
        })
    }

    pub fn get_song(&self) -> &Song {
        self.song.read()
    }

    pub fn collect_garbage(&mut self) {
        self.gc.collect();
    }

    /// If the config specifies more than two channels only the first two will be filled with audio.
    /// The rest get silence.
    ///
    /// The callback in for example Cpal provides an additional arguement, where a timestamp is give.
    /// That should ba handled by wrapping this function in another callback, where this argument could
    /// then be ignored or send somewhere for processing. This Sending needs to happen wait-free!! There are
    /// a couple of libaries that can do this, i would recommend triple_buffer or rtrb.
    ///
    /// The OutputConfig has to match the config of the AudioStream that will call this. If for example the
    /// buffer size is different Panics may occur.
    ///
    /// In my testing i noticed that when using Cpal with non-standard buffer sizes Cpal would just give
    /// another buffer size. This may also lead to panics.
    ///
    /// ## Panics
    ///
    /// Will panic if there is an active stream.
    pub fn get_callback<
        Sample: dasp::sample::Sample + dasp::sample::FromSample<f32>,
        StreamData: Clone,
    >(
        &mut self,
        config: OutputConfig,
        initial_stream_data: StreamData,
    ) -> (
        impl FnMut(&mut [Sample], StreamData) + use<Sample, StreamData>,
        Duration,
        StatusRecv<StreamData>,
        StreamSend,
    ) {
        const SEND_SIZE: usize = 10;
        let mut from_worker = rt_write_lock::Reader::new((None, initial_stream_data));
        // let from_worker = triple_buffer::triple_buffer(&(None, initial_stream_data));
        let to_worker = rtrb::RingBuffer::new(SEND_SIZE);
        let reader = self.song.build_reader().expect("another stream is active");

        let audio_worker = LiveAudio::<StreamData>::new(
            reader,
            to_worker.1,
            // doesn't panic because i just created the reader
            from_worker.get_writer().unwrap(),
            config,
        );
        let buffer_time =
            Duration::from_millis((config.buffer_size * 1000 / config.sample_rate).into());

        self.buffer_time = buffer_time;

        (
            audio_worker.get_typed_callback(),
            buffer_time,
            StatusRecv(from_worker),
            StreamSend(to_worker.0),
        )
    }

    /// Buffer time of the last created callback.
    pub fn last_buffer_time(&self) -> Duration {
        self.buffer_time
    }
}

/// the changes made to the song will be made available to the playing live audio as soon as
/// this struct is dropped.
///
/// With this you can load the full song without ever playing a half initialised state
/// when doing mulitple operations this object should be kept as it is
#[derive(Debug)]
pub struct SongEdit<'a> {
    song: WriteGuard<'a, Song, ValidOperation>,
    gc: &'a mut Collector,
}

impl SongEdit<'_> {
    pub fn apply_operation(&mut self, op: SongOperation) -> Result<(), SongOperation> {
        let valid_operation = ValidOperation::new(op, self.gc, self.song.read())?;
        self.song.apply_op(valid_operation);
        Ok(())
    }

    pub fn song(&self) -> &Song {
        self.song.read()
    }

    /// Finish the changes and publish them to the live playing song.
    /// Equivalent to std::mem::drop(SongEdit)
    pub fn finish(self) {}
}

#[derive(Debug, Clone, Copy)]
pub struct OutputConfig {
    pub buffer_size: u32,
    pub channel_count: NonZeroU16,
    pub sample_rate: NonZero<u32>,
    pub interpolation: Interpolation,
}

#[derive(Debug, Clone, Copy)]
pub enum PlaybackSettings {
    Pattern { idx: u8, should_loop: bool },
    Order { idx: u16, should_loop: bool },
}