fcb_looper/audio_engine/src/persistence_manager.rs

use crate::*;
use std::path::PathBuf;
use tokio::sync::{broadcast, watch};

#[derive(Debug)]
pub struct PersistenceManagerController {
    sender: kanal::Sender<PersistenceUpdate>,
}

#[derive(Debug)]
pub enum PersistenceUpdate {
    UpdateTrackVolume {
        column: usize,
        row: usize,
        volume: f32,
    },
}

impl PersistenceManagerController {
    pub fn update_track_volume(&self, column: usize, row: usize, volume: f32) -> Result<()> {
        let update = PersistenceUpdate::UpdateTrackVolume {
            column,
            row,
            volume,
        };
        match self.sender.try_send(update) {
            Ok(true) => Ok(()),
            Ok(false) => Err(LooperError::StateSave(std::panic::Location::caller())), // Channel full
            Err(_) => Err(LooperError::StateSave(std::panic::Location::caller())), // Channel closed
        }
    }
}

pub struct PersistenceManager {
    state: watch::Sender<State>,
    notification_rx: broadcast::Receiver<JackNotification>,
    update_rx: kanal::AsyncReceiver<PersistenceUpdate>,
    state_file_path: PathBuf,
}

impl PersistenceManager {
    pub fn new(
        args: &Args,
        notification_rx: broadcast::Receiver<JackNotification>,
    ) -> (Self, PersistenceManagerController) {
        let state_file_path = args.config_file.join("state.json");
        std::fs::create_dir_all(&args.config_file).ok(); // Create directory if it doesn't exist
        let initial_state = Self::load_from_disk(&state_file_path).unwrap_or_default();
        let (state, _) = watch::channel(initial_state);

        let (update_tx, update_rx) = kanal::bounded(64);
        let update_rx = update_rx.to_async();
        let controller = PersistenceManagerController { sender: update_tx };

        let manager = Self {
            state,
            notification_rx,
            update_rx,
            state_file_path,
        };

        (manager, controller)
    }

    pub fn state(&self) -> watch::Receiver<State> {
        self.state.subscribe()
    }

    pub async fn run(&mut self) -> Result<()> {
        loop {
            tokio::select! {
                notification = self.notification_rx.recv() => {
                    match notification {
                        Ok(JackNotification::PortConnect { port_a, port_b, connected }) => {
                            self.handle_port_connection(port_a, port_b, connected)?;
                        }
                        Ok(_) => {}
                        Err(_) => break,
                    }
                }

                // Handle state updates
                update = self.update_rx.recv() => {
                    match update {
                        Ok(update) => {
                            self.handle_state_update(update)?;
                        }
                        Err(_) => break,
                    }
                }
            }
        }

        Ok(())
    }

    fn handle_state_update(&mut self, update: PersistenceUpdate) -> Result<()> {
        match update {
            PersistenceUpdate::UpdateTrackVolume {
                column,
                row,
                volume,
            } => {
                self.state
                    .send_modify(|state| state.track_volumes.set_volume(column, row, volume));
                self.save_to_disk()?;
            }
        }

        Ok(())
    }

    fn handle_port_connection(
        &mut self,
        port_a: String,
        port_b: String,
        connected: bool,
    ) -> Result<()> {
        // Determine which port is ours and which is external
        let (our_port, external_port) = if port_a.starts_with("looper:") {
            (port_a, port_b)
        } else if port_b.starts_with("looper:") {
            (port_b, port_a)
        } else {
            // Neither port is ours, ignore
            return Ok(());
        };

        // Update the connections state
        let our_port_name = our_port.strip_prefix("looper:").unwrap_or(&our_port);
        self.state.send_if_modified(|state| {
            let connections = &mut state.connections;

            let port_list = match our_port_name {
                "midi_in" => &mut connections.midi_in,
                "midi_out" => &mut connections.midi_out,
                "audio_in" => &mut connections.audio_in,
                "audio_out" => &mut connections.audio_out,
                "click_track" => &mut connections.click_track_out,
                _ => {
                    log::warn!("Unknown port: {}", our_port_name);
                    return false;
                }
            };

            if connected {
                // Add connection if not already present
                if !port_list.contains(&external_port) {
                    port_list.push(external_port.clone());
                    log::info!("Added connection: {} -> {}", our_port, external_port);
                    true
                } else {
                    false
                }
            } else {
                // Remove connection
                port_list.retain(|p| p != &external_port);
                log::info!("Removed connection: {} -> {}", our_port, external_port);
                true
            }
        });
        self.save_to_disk()?;

        Ok(())
    }

    fn load_from_disk(path: &PathBuf) -> Result<State> {
        match std::fs::read_to_string(path) {
            Ok(content) => {
                let state: State = serde_json::from_str(&content)
                    .map_err(|_| LooperError::StateLoad(std::panic::Location::caller()))?;
                log::info!("Loaded state from {:?}", path);
                Ok(state)
            }
            Err(_) => {
                log::info!("Could not load state from {:?}. Using defaults.", path);
                Err(LooperError::StateLoad(std::panic::Location::caller()))
            }
        }
    }

    fn save_to_disk(&self) -> Result<()> {
        let json = serde_json::to_string_pretty(&*self.state.borrow())
            .map_err(|_| LooperError::StateSave(std::panic::Location::caller()))?;

        std::fs::write(&self.state_file_path, json)
            .map_err(|_| LooperError::StateSave(std::panic::Location::caller()))?;

        log::debug!("Saved state to {:?}", self.state_file_path);
        Ok(())
    }
}