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//! `NcResizeCb`

use crate::{c_api, NcIntResult, NcPlane};

/// A callback function called when an [`NcPlane`] is resized.
///
/// See also [`ncresizecb_to_rust`][c_api::ncresizecb_to_rust]
/// & [`ncresizecb_to_c`][c_api::ncresizecb_to_c].
///
pub type NcResizeCb = fn(&mut NcPlane) -> NcIntResult;

/// The unsafe version of [`NcResizeCb`] expected by the notcurses C API.
pub type NcResizeCbUnsafe = unsafe extern "C" fn(*mut NcPlane) -> NcIntResult;

pub(crate) mod reimplemented {
    use super::*;

    /// Converts [`NcResizeCbUnsafe`] to [`NcResizeCb`].
    pub fn ncresizecb_to_rust(resizecb: Option<NcResizeCbUnsafe>) -> Option<NcResizeCb> {
        resizecb.map(|cb| unsafe { core::mem::transmute(cb) })
    }

    /// Converts [`NcResizeCb`] to [`NcResizeCbUnsafe`].
    ///
    // waiting for https://github.com/rust-lang/rust/issues/53605
    // to make this function const, and then NcPlaneOptions constructors.
    pub fn ncresizecb_to_c(resizecb: Option<NcResizeCb>) -> Option<NcResizeCbUnsafe> {
        resizecb.map(|cb| unsafe { core::mem::transmute(cb) })
    }
}

/// Enables the [`NcResizeCb`] associated methods and constants.
pub trait NcResizeCbApi {
    fn to_rust(&self) -> Option<NcResizeCb>;
    fn to_c(&self) -> Option<NcResizeCbUnsafe>;
}

impl NcResizeCbApi for NcResizeCb {
    /// Returns [`NcResizeCbUnsafe`].
    ///
    /// *C style function: [c_api::ncresizecb_to_c()][c_api::ncresizecb_to_c].*
    fn to_c(&self) -> Option<NcResizeCbUnsafe> {
        c_api::ncresizecb_to_c(Some(*self))
    }
    /// no-op.
    fn to_rust(&self) -> Option<NcResizeCb> {
        Some(*self)
    }
}

impl NcResizeCbApi for NcResizeCbUnsafe {
    /// no-op.
    fn to_c(&self) -> Option<NcResizeCbUnsafe> {
        Some(*self)
    }

    /// Returns [`NcResizeCb`].
    ///
    /// *C style function: [c_api::ncresizecb_to_rust()][c_api::ncresizecb_to_rust].*
    fn to_rust(&self) -> Option<NcResizeCb> {
        c_api::ncresizecb_to_rust(Some(*self))
    }
}