mbus-ffi 0.13.0

use std::sync::OnceLock;

use mbus_core::models::coil::Coils;
use mbus_core::models::discrete_input::DiscreteInputs;
use mbus_core::models::fifo_queue::FifoQueue;
use mbus_core::models::register::{HoldingRegisters, InputRegisters};
use pyo3::prelude::*;
use tokio::runtime::Runtime;

// ── Shared Tokio runtime ─────────────────────────────────────────────────────

static TOKIO_RT: OnceLock<Runtime> = OnceLock::new();

/// Returns a reference to the module-wide Tokio runtime.
///
/// Initialised on first call; the same runtime is shared by all sync clients
/// so we never spin up redundant OS threads.
pub fn get_runtime() -> &'static Runtime {
    TOKIO_RT.get_or_init(|| {
        tokio::runtime::Builder::new_multi_thread()
            .enable_all()
            .build()
            .expect("Failed to create Tokio runtime for modbus_rs")
    })
}

/// Enter the shared Tokio runtime context.
///
/// Some constructors need an active runtime handle to spawn background tasks.
pub fn enter_runtime() -> tokio::runtime::EnterGuard<'static> {
    get_runtime().enter()
}

// ── Response converters ──────────────────────────────────────────────────────

/// Convert a `Coils` value into a Python `list[bool]`.
pub fn coils_to_py(py: Python<'_>, coils: Coils) -> PyResult<Py<PyAny>> {
    let qty = coils.quantity(); // already u16
    let base = coils.from_address();
    let list: Vec<bool> = (0..qty)
        .map(|i| coils.value(base + i).unwrap_or(false))
        .collect();
    Ok(list.into_pyobject(py)?.into_any().unbind())
}

/// Convert a `DiscreteInputs` value into a Python `list[bool]`.
pub fn discrete_inputs_to_py(py: Python<'_>, di: DiscreteInputs) -> PyResult<Py<PyAny>> {
    let qty = di.quantity(); // already u16
    let base = di.from_address();
    let list: Vec<bool> = (0..qty)
        .map(|i| di.value(base + i).unwrap_or(false))
        .collect();
    Ok(list.into_pyobject(py)?.into_any().unbind())
}

macro_rules! impl_registers_to_py {
    ($name:ident, $type:ident) => {
        #[doc = concat!("Convert a `", stringify!($type), "` value into a Python `list[int]`.")]
        pub fn $name<const N: usize>(py: Python<'_>, regs: $type<N>) -> PyResult<Py<PyAny>> {
            let qty = regs.quantity(); // already u16
            let base = regs.from_address();
            let list: Vec<u16> = (0..qty)
                .map(|i| regs.value(base + i).unwrap_or(0))
                .collect();
            Ok(list.into_pyobject(py)?.into_any().unbind())
        }
    };
}

impl_registers_to_py!(holding_registers_to_py, HoldingRegisters);
impl_registers_to_py!(input_registers_to_py, InputRegisters);

/// Convert a `FifoQueue` value into a Python `list[int]`.
pub fn fifo_to_py(py: Python<'_>, queue: FifoQueue) -> PyResult<Py<PyAny>> {
    let list: Vec<u16> = queue.queue().to_vec();
    Ok(list.into_pyobject(py)?.into_any().unbind())
}

/// Convert `AsyncError` to a `PyErr` using our exception hierarchy.
pub use crate::python::errors::async_error_to_py;