use std::mem::MaybeUninit;

use crate::{abi_backing::HeapValueBacking, FfiValue};

pub trait HeapPlacable {
    unsafe extern "C" fn free(value: FfiValue<Self>, taken: bool);
}

impl<T> HeapPlacable for T {
    unsafe extern "C" fn free(value: FfiValue<Self>, taken: bool) {
        if !taken {
            drop(Box::from_raw(value.inner as *mut HeapValueBacking<T>))
        } else {
            let allocation = Box::from_raw(value.inner as *mut T);

            // Since we "took" the value, kindly inform the compiler that it can't
            // treat the value like it exists
            let allocation_uninit: Box<HeapValueBacking<MaybeUninit<T>>> =
                unsafe { core::mem::transmute(allocation) };

            // Since the compiler has no idea whether the value exists or not, it won't try and
            // drop it. Success!
            drop(allocation_uninit);
        }
    }
}