//! Signal routing — connects module outputs to inputs.
//!
//! A `Patch` is a fixed-size connection graph. Each cable routes
//! the output buffer of one slot into the CV or audio input of another.
//! Const generics keep everything on the stack.

/// A single cable: from slot `src` output to slot `dst` input.
#[derive(Clone, Copy, Debug, PartialEq)]
pub struct Cable {
    pub src: usize,
    pub dst: usize,
}

/// A fixed-capacity patch with up to `MAX_CABLES` connections.
pub struct Patch<const MAX_CABLES: usize> {
    cables: heapless::Vec<Cable, MAX_CABLES>,
}

impl<const MAX_CABLES: usize> Patch<MAX_CABLES> {
    pub fn new() -> Self {
        Self { cables: heapless::Vec::new() }
    }

    /// Add a cable; returns `Err(cable)` if the patch is full.
    pub fn connect(&mut self, src: usize, dst: usize) -> Result<(), Cable> {
        self.cables.push(Cable { src, dst }).map_err(|_| Cable { src, dst })
    }

    pub fn disconnect(&mut self, src: usize, dst: usize) {
        self.cables.retain(|c| !(c.src == src && c.dst == dst));
    }

    pub fn cables(&self) -> &[Cable] {
        &self.cables
    }
}

impl<const MAX_CABLES: usize> Default for Patch<MAX_CABLES> {
    fn default() -> Self { Self::new() }
}