dyn_ext_derive 0.1.1

use proc_macro::TokenStream;
use quote::quote;
use syn::{parse_macro_input, DeriveInput};

#[proc_macro_derive(AsAny)]
pub fn derive_as_any(input: TokenStream) -> TokenStream {
    let input = parse_macro_input!(input as DeriveInput);
    let name = input.ident;

    let expanded = quote! {
        impl dyn_ext::AsAny for #name {
            fn as_any(&self) -> &dyn std::any::Any {
                self
            }
        }
    };

    TokenStream::from(expanded)
}

#[proc_macro_derive(BoxedClone, attributes(boxed_clone))]
pub fn derive_boxed_clone(input: TokenStream) -> TokenStream {
    let input = parse_macro_input!(input as DeriveInput);
    let name = input.ident;

    let mut target: Option<syn::Type> = None;

    for attr in input.attrs.iter() {
        if attr.path().is_ident("boxed_clone") {
            let meta: syn::Meta = attr.parse_args().unwrap();
            if let syn::Meta::NameValue(nv) = meta {
                if nv.path.is_ident("Target") {
                    if let syn::Expr::Lit(syn::ExprLit { lit: syn::Lit::Str(lit_str), .. }) = nv.value {
                        target = Some(lit_str.parse().unwrap());
                    }
                }
            }
        }
    }

    let target = target.unwrap_or_else(|| panic!("Target must be defined, replace `#[derive(BoxedClone)]` by `#[boxed_clone(Target = \"...\")]`"));

    let expanded = quote! {
        impl dyn_ext::BoxedClone<dyn T> for #name {
            type Target = #target;

            fn boxed_clone(&self) -> Box<T> {
                Box::new(self.clone())
            }
        }
    };

    TokenStream::from(expanded)
}