From c8c5fdc2d0998c3f691b04876d000b7470dd9d2c Mon Sep 17 00:00:00 2001
From: Alexander Polakov <alex@plhk.dev>
Date: Thu, 27 Jul 2023 20:11:46 +0400
Subject: [PATCH] feat: flatten request

---
 proc-macros/src/render_server.rs | 12 ++++++++++--
 proc-macros/src/rpc_macro.rs     | 12 +++++++++---
 2 files changed, 19 insertions(+), 5 deletions(-)

diff --git a/proc-macros/src/render_server.rs b/proc-macros/src/render_server.rs
index 9f9e0facba..989da82cde 100644
--- a/proc-macros/src/render_server.rs
+++ b/proc-macros/src/render_server.rs
@@ -127,7 +127,7 @@ impl RpcDescription {
 				// provided `Params` object.
 				// `params_seq` is the comma-delimited sequence of parameters we're passing to the rust function
 				// called..
-				let (parsing, params_seq) = self.render_params_decoding(&method.params, None);
+				let (parsing, params_seq) = self.render_params_decoding(&method.params, None, method.flatten);
 
 				let into_response = self.jrps_server_item(quote! { IntoResponse });
 
@@ -170,7 +170,7 @@ impl RpcDescription {
 				// provided `Params` object.
 				// `params_seq` is the comma-delimited sequence of parameters.
 				let pending = proc_macro2::Ident::new("subscription_sink", rust_method_name.span());
-				let (parsing, params_seq) = self.render_params_decoding(&sub.params, Some(pending));
+				let (parsing, params_seq) = self.render_params_decoding(&sub.params, Some(pending), false);
 				let into_sub_response = self.jrps_server_item(quote! { IntoSubscriptionCloseResponse });
 
 				check_name(&rpc_sub_name, rust_method_name.span());
@@ -279,6 +279,7 @@ impl RpcDescription {
 		&self,
 		params: &[(syn::PatIdent, syn::Type)],
 		sub: Option<proc_macro2::Ident>,
+		flatten: bool,
 	) -> (TokenStream2, TokenStream2) {
 		if params.is_empty() {
 			return (TokenStream2::default(), TokenStream2::default());
@@ -380,8 +381,15 @@ impl RpcDescription {
 					tokens: TokenStream2::from_str(&format!("({})", alias_vals.as_str())).unwrap(),
 				};
 
+				let serde_flatten = if flatten {
+					quote! { #[serde(flatten)] }
+				} else {
+					quote! {}
+				};
+
 				quote! {
 					#serde_alias
+					#serde_flatten
 					#name: #ty,
 				}
 			});
diff --git a/proc-macros/src/rpc_macro.rs b/proc-macros/src/rpc_macro.rs
index 738f2d802e..0a26c3192b 100644
--- a/proc-macros/src/rpc_macro.rs
+++ b/proc-macros/src/rpc_macro.rs
@@ -48,17 +48,19 @@ pub struct RpcMethod {
 	pub returns: Option<syn::Type>,
 	pub signature: syn::TraitItemMethod,
 	pub aliases: Vec<String>,
+	pub flatten: bool,
 }
 
 impl RpcMethod {
 	pub fn from_item(attr: Attribute, mut method: syn::TraitItemMethod) -> syn::Result<Self> {
-		let [aliases, blocking, name, param_kind] =
-			AttributeMeta::parse(attr)?.retain(["aliases", "blocking", "name", "param_kind"])?;
+		let [aliases, blocking, name, param_kind, flatten] =
+			AttributeMeta::parse(attr)?.retain(["aliases", "blocking", "name", "param_kind", "flatten"])?;
 
 		let aliases = parse_aliases(aliases)?;
 		let blocking = optional(blocking, Argument::flag)?.is_some();
 		let name = name?.string()?;
 		let param_kind = parse_param_kind(param_kind)?;
+		let flatten = optional(flatten, Argument::flag)?.is_some();
 
 		let sig = method.sig.clone();
 		let docs = extract_doc_comments(&method.attrs);
@@ -67,6 +69,10 @@ impl RpcMethod {
 			None => quote!(),
 		};
 
+		if flatten && !matches!(param_kind, ParamKind::Map) {
+			return Err(syn::Error::new(sig.span(), "Flatten request must have param_kind=map"));
+		}
+
 		if blocking && sig.asyncness.is_some() {
 			return Err(syn::Error::new(sig.span(), "Blocking method must be synchronous"));
 		}
@@ -98,7 +104,7 @@ impl RpcMethod {
 		// We've analyzed attributes and don't need them anymore.
 		method.attrs.clear();
 
-		Ok(Self { aliases, blocking, name, params, param_kind, returns, signature: method, docs, deprecated })
+		Ok(Self { aliases, blocking, name, params, param_kind, returns, signature: method, docs, deprecated, flatten })
 	}
 }