rust-nex/macros/src/protos.rs

use proc_macro2::{Ident, Span, TokenStream, TokenTree};
use quote::{quote, ToTokens};
use syn::{LitInt, Token, Type};
use syn::token::{Brace, Paren, Semi};

pub struct ProtoMethodData{
    pub id: LitInt,
    pub name: Ident,
    pub parameters: Vec<(Ident, Type)>
}


/// This is a representation of the code generated by `rmc_proto` it serves to split the logic of
/// acquiring data from the actual generation to tidy up the process into first getting then
/// generating.
///
/// Use the [`ToTokens`] trait to generate the actual code.
pub struct RmcProtocolData{
    pub has_returns: bool,
    pub id: LitInt,
    pub name: Ident,
    pub methods: Vec<ProtoMethodData>
}

impl ToTokens for RmcProtocolData{
    fn to_tokens(&self, tokens: &mut TokenStream) {
        let Self{
            has_returns,
            name,
            id,
            methods
        } = self;

        // this gives us the name which the identifier of the corresponding Raw trait
        let raw_name = Ident::new(&format!("Raw{}", name), name.span());


        // boilerplate tokens which all raw traits need
        quote!{
            #[doc(hidden)]
            pub trait #raw_name: #name
        }.to_tokens(tokens);

        // generate the body of the raw protocol trait
        Brace::default().surround(tokens, |tokens|{
            //generate each raw method
            for method in methods{
                let ProtoMethodData {
                    name,
                    parameters,
                    ..
                } = method;

                let raw_name = Ident::new(&format!("raw_{}", name), name.span());
                quote!{
                    async fn #raw_name
                }.to_tokens(tokens);

                Paren::default().surround(tokens, |tokens|{
                    quote!{ &self, data: ::std::vec::Vec<u8> }.to_tokens(tokens);
                });

                quote!{
                    -> ::core::result::Result<Vec<u8>, ErrorCode>
                }.to_tokens(tokens);

                Brace::default().surround(tokens, |tokens|{
                    quote! { let mut cursor = ::std::io::Cursor::new(data); }.to_tokens(tokens);

                    for (param_name, param_type) in parameters{
                        quote!{
                            let Ok(#param_name) =
                                <#param_type as crate::rmc::structures::RmcSerialize>::deserialize(
                                &mut cursor
                            ) else {
                                return Err(ErrorCode::Core_InvalidArgument);
                            };
                        }.to_tokens(tokens)
                    }

                    quote!{
                        let retval = self.#name
                    }.to_tokens(tokens);

                    Paren::default().surround(tokens, |tokens|{
                        for (paren_name, _) in parameters{
                            quote!{#paren_name,}.to_tokens(tokens);
                        }
                    });

                    quote!{
                        .await;
                    }.to_tokens(tokens);

                    if *has_returns{
                        quote!{
                            let retval = retval?;
                            let mut vec = Vec::new();
                            crate::rmc::structures::RmcSerialize::serialize(&retval, &mut vec).ok();
                            Ok(vec)
                        }.to_tokens(tokens);
                    }
                })
            }

            quote!{
                async fn rmc_call_proto(
                    &self,
                    remote_response_connection: &crate::prudp::socket::SendingConnection,
                    method_id: u32,
                    call_id: u32,
                    data: Vec<u8>,
                )
            }.to_tokens(tokens);

            Brace::default().surround(tokens, |tokens|{
                quote! {
                    let ret = match method_id
                }.to_tokens(tokens);

                Brace::default().surround(tokens, |tokens|{
                    for method in methods{
                        let ProtoMethodData{
                            id,
                            name,
                            ..
                        } = method;

                        let raw_name = Ident::new(&format!("raw_{}", name), name.span());

                        quote!{
                            #id => self.#raw_name(data).await,
                        }.to_tokens(tokens);
                    }
                    quote!{
                        _ => Err(crate::rmc::response::ErrorCode::Core_NotImplemented)
                    }.to_tokens(tokens);
                });

                Semi::default().to_tokens(tokens);

                if *has_returns{
                    quote!{
                        crate::rmc::response::send_result(
                            remote_response_connection,
                            ret,
                            #id,
                            method_id,
                            call_id,
                        ).await
                    }.to_tokens(tokens);
                }
            });
        });

        quote!{
            impl<T: #name> RawAuth for T{}
        }.to_tokens(tokens);

        let raw_info_name = Ident::new(&format!("Raw{}Info", name), Span::call_site());


        quote!{
            #[doc(hidden)]
            pub struct #raw_info_name;

            impl #raw_info_name {
                pub const PROTOCOL_ID: u16 = #id;
            }
        }.to_tokens(tokens);
    }
}