use proc_macro::TokenStream;
use proc_macro_crate::{FoundCrate, crate_name};
use quote::quote;
use syn::{DeriveInput, Ident, parse_macro_input};

#[proc_macro_derive(Secret)]
pub fn derive_secret(input: TokenStream) -> TokenStream {
    let input = parse_macro_input!(input as DeriveInput);
    let struct_ident = &input.ident;

    // The key for the secret will be the stringified name of the struct itself.
    // e.g., `struct OKDClusterSecret` becomes key `"OKDClusterSecret"`.
    let key = struct_ident.to_string(); // TODO: Utiliser path complet de la struct

    // Find the path to the `harmony_secret` crate.
    let secret_crate_path = match crate_name("harmony_secret") {
        Ok(FoundCrate::Itself) => quote!(crate),
        Ok(FoundCrate::Name(name)) => {
            let ident = Ident::new(&name, proc_macro2::Span::call_site());
            quote!(::#ident)
        }
        Err(e) => {
            return syn::Error::new(proc_macro2::Span::call_site(), e.to_string())
                .to_compile_error()
                .into();
        }
    };

    // The generated code now implements `Secret` for the struct itself.
    // The struct must also derive `Serialize` and `Deserialize` for this to be useful.
    let expanded = quote! {
        impl #secret_crate_path::Secret for #struct_ident {
            const KEY: &'static str = #key;
        }
    };

    TokenStream::from(expanded)
}