continuum-proxy/src/printer/mod.rs

//! Printer hierarchy — the Rust answer to
//! `GenericPrinter -> BambuV1/BambuV2/PrusaLink/PrusaSerial/Klipper`-style
//! inheritance, since Rust structs can't `extend` each other.
//!
//! Three pieces, each doing one job an OOP base class would normally do:
//!
//! 1. `PrinterBase` — a plain struct holding the shared *fields*. Every
//!    printer struct below *has* one of these (composition) instead of
//!    *extending* one.
//! 2. `GenericPrinter` — a trait holding the shared *behavior*. `connect()`
//!    has no default body, so every printer type is forced to write its
//!    own — that's what "overriding" looks like when there's no inherited
//!    body to override in the first place.
//! 3. `PrinterHandle` — an enum listing the closed set of printer kinds.
//!    Stands in for "any subclass of GenericPrinter".
//!
//! Run `cargo run --example printer_polymorphism` to see it in action.
//!
//! Deliberately left out of this module for now, to keep it focused on one
//! idea at a time: real MQTT/HTTP/FTPS calls (that's `src/adapters/`) and
//! `Send`-bound futures (matters once this is wired into a multi-threaded
//! `tokio::spawn`, not yet).

mod bambu;
mod klipper;
mod prusa;

pub use bambu::{BambuPrinter, BambuTls};
pub use klipper::KlipperPrinter;
pub use prusa::{PrusaLinkPrinter, PrusaSerialPrinter};

/// A tiny error type: just a message. `String` would work too — this exists
/// mainly so `?` has something concrete to convert into everywhere.
#[derive(Debug, thiserror::Error)]
#[error("{0}")]
pub struct PrinterError(pub String);

/// Fields every printer has, regardless of vendor.
#[derive(Debug, Clone)]
pub struct PrinterBase {
    pub id: String,
    pub name: String,
    pub host: String,
}

/// The shared interface — think `interface GenericPrinter` (Java/TS) or an
/// ABC (Python). Every vendor's struct implements this.
pub trait GenericPrinter {
    /// Read-only access to the shared fields.
    fn base(&self) -> &PrinterBase;

    /// REQUIRED, no default body: every vendor speaks a different protocol,
    /// so there's nothing sensible to share here. Each `impl` in
    /// `bambu.rs`/`prusa.rs`/`klipper.rs` provides a totally different
    /// body — that's the override.
    ///
    /// `cargo check` will warn about `async fn` in a public trait here.
    /// That's about a more advanced concern (whether the resulting work can
    /// safely move across OS threads) that only matters once this is wired
    /// into the multi-threaded daemon — safe to ignore for now.
    async fn connect(&mut self) -> Result<(), PrinterError>;

    /// OPTIONAL: a default body every printer gets for free unless it
    /// writes its own. None of ours do below, so all three vendors share
    /// this exact implementation — the trait-method equivalent of
    /// inheriting a base-class method unchanged.
    fn display_name(&self) -> String {
        format!("{} ({})", self.base().name, self.base().id)
    }
}

pub enum PrinterFlavour {
    BambuV1Printer,
    BambuV2Printer,
    PrusaLinkPrinter,
    PrusaSerialPrinter,
    KlipperPrinter,
}

/// The closed set of printer kinds this fleet can talk to.
pub enum PrinterHandle {
    BambuV1(BambuPrinter),
    BambuV2(BambuPrinter),
    PrusaLink(PrusaLinkPrinter),
    PrusaSerial(PrusaSerialPrinter),
    Klipper(KlipperPrinter),
}

// Hand-written delegation: each trait method just matches on the variant
// and forwards to that variant's own implementation. This one block is the
// only "boilerplate tax" for not having inheritance — everything else reads
// like normal code.
impl GenericPrinter for PrinterHandle {
    fn base(&self) -> &PrinterBase {
        match self {
            PrinterHandle::BambuV1(p) => p.base(),
            PrinterHandle::BambuV2(p) => p.base(),
            PrinterHandle::PrusaLink(p) => p.base(),
            PrinterHandle::PrusaSerial(p) => p.base(),
            PrinterHandle::Klipper(p) => p.base(),
        }
    }

    async fn connect(&mut self) -> Result<(), PrinterError> {
        match self {
            PrinterHandle::BambuV1(p) => p.connect().await,
            PrinterHandle::BambuV2(p) => p.connect().await,
            PrinterHandle::PrusaLink(p) => p.connect().await,
            PrinterHandle::PrusaSerial(p) => p.connect().await,
            PrinterHandle::Klipper(p) => p.connect().await,
        }
    }
}