closure like syntax v3

macros/src/lib.rs

@@ -1,89 +1,120 @@
 use proc_macro::TokenStream;
 use quote::quote;
-use syn::{parse_macro_input, Expr, ExprClosure, FnArg, ItemFn, Pat, PatIdent, PatType};
+use syn::{
+    parse_macro_input, Attribute, FnArg, Ident, ItemFn, Pat, PatIdent, PatType, Type,
+};
 
-#[proc_macro_attribute]
-pub fn endpoint(attr: TokenStream, item: TokenStream) -> TokenStream {
-    let input_fn = parse_macro_input!(item as ItemFn);
-    let closure_expr = parse_macro_input!(attr as Expr);
+/// Represents a function argument we care about
+#[derive(Clone)]
+struct Arg {
+    ident: Ident,
+    ty: Type,
+    attrs: Vec<Attribute>,
+}
 
-    let fn_name = input_fn.sig.ident.clone();
-    let vis = input_fn.vis.clone();
-    let generics = input_fn.sig.generics.clone();
-
-    // Collect query and body args
-    let mut query_idents = Vec::new();
-    let mut query_types = Vec::new();
-    let mut body_idents = Vec::new();
-    let mut body_types = Vec::new();
-
-    for input in &input_fn.sig.inputs {
-        if let FnArg::Typed(PatType { pat, ty, attrs, .. }) = input {
+/// Extract arguments marked as `#[path]` or the rest
+fn extract_args<'a, I>(inputs: I, path_only: bool) -> Vec<Arg>
+where
+    I: IntoIterator<Item = &'a FnArg>,
+{
+    let mut args = Vec::new();
+    for fnarg in inputs {
+        if let FnArg::Typed(PatType { pat, ty, attrs, .. }) = fnarg {
             let ident = if let Pat::Ident(PatIdent { ident, .. }) = &**pat {
                 ident.clone()
-            } else { continue; };
-
-            if attrs.iter().any(|a| a.path().is_ident("query")) {
-                query_idents.push(ident);
-                query_types.push(*ty.clone());
             } else {
-                body_idents.push(ident);
-                body_types.push(*ty.clone());
+                panic!("Only simple identifiers are supported in endpoint arguments");
+            };
+
+            if path_only && !attrs.iter().any(|a| a.path().is_ident("path")) {
+                continue;
             }
+
+            args.push(Arg {
+                ident,
+                ty: *ty.clone(),
+                attrs: attrs.clone(),
+            });
         }
     }
+    args
+}
 
-    // Extract path args from closure
-    let mut path_idents = Vec::new();
-    let mut path_types = Vec::new();
+/// Implements #[get("…")] and #[post("…")]
+macro_rules! endpoint_macro {
+    ($method:ident) => {
+        #[proc_macro_attribute]
+        pub fn $method(attr: TokenStream, item: TokenStream) -> TokenStream {
+            let path_lit = parse_macro_input!(attr as syn::LitStr);
+            let input_fn = parse_macro_input!(item as ItemFn);
 
-    if let Expr::Closure(ExprClosure { inputs, .. }) = closure_expr {
-        for input in inputs.iter() {
-            if let Pat::Type(PatType { pat, ty, .. }) = input {
-                if let Pat::Ident(PatIdent { ident, .. }) = &**pat {
-                    path_idents.push(ident.clone());
-                    path_types.push(*ty.clone());
+            let vis = &input_fn.vis;
+            let fn_name = &input_fn.sig.ident;
+            let generics = &input_fn.sig.generics;
+            let inputs = &input_fn.sig.inputs;
+            let output = &input_fn.sig.output;
+
+            let path_args = extract_args(inputs, true);
+            let other_args: Vec<_> = extract_args(inputs, false)
+                .into_iter()
+                .filter(|a| !path_args.iter().any(|p| p.ident == a.ident))
+                .collect();
+
+            // for builder: path args first
+            let path_idents: Vec<_> = path_args.iter().map(|a| &a.ident).collect();
+            let path_types: Vec<_> = path_args.iter().map(|a| &a.ty).collect();
+
+            let body_idents: Vec<_> = other_args.iter().map(|a| &a.ident).collect();
+            let body_types: Vec<_> = other_args.iter().map(|a| &a.ty).collect();
+
+            let method_upper = stringify!($method).to_uppercase();
+
+            let expanded = quote! {
+                #[bon::builder]
+                #vis async fn #fn_name #generics (
+                    #[ builder(finish_fn) ] client: restson::RestClient,
+                    #( #[builder(finish_fn)] #path_idents: #path_types, )*
+                    #( #body_idents: #body_types, )*
+                ) -> Result<#output, restson::Error> {
+                    // build path
+                    let path = format!(#path_lit, #( #path_idents = #path_idents ),*);
+
+                    #[derive(serde::Serialize)]
+                    struct Body {
+                        #( #body_idents: #body_idents, )*
+                    }
+
+                    let body = Body {
+                        #( #body_idents, )*
+                    };
+
+                    // for query arguments, if any
+                    #[derive(serde::Serialize)]
+                    struct Query {
+                        #( #body_idents: #body_idents, )*
+                    }
+
+                    let query = Query {
+                        #( #body_idents, )*
+                    };
+                    // placeholder: convert query to vec of pairs
+                    let query_pairs: Vec<(&str, &str)> = Vec::new();
+
+                    let response = match #method_upper {
+                        "GET" => client.get_with(path, query_pairs).await?,
+                        "POST" => client.post_capture_with(body, query_pairs).await?,
+                        _ => unreachable!(),
+                    };
+
+
+                    todo!(response)
                 }
-            }
-        }
-    }
+            };
 
-    // Generate the final function
-    let expanded = quote! {
-        #[bon::builder]
-        #vis async fn #fn_name #generics (
-            #( #[builder(finish_fn)] #path_idents: #path_types, )*
-            #( #query_idents: #query_types, )*
-            #( #body_idents: #body_types, )*
-        ) -> Result<_, restson::Error> {
-
-            // Query struct
-            #[derive(serde::Serialize)]
-            struct Query {
-                #( #query_idents: #query_types, )*
-            }
-            let query = Query { #( #query_idents ),* };
-            let query_vec = query.to_vec::<(&str, &str)>();
-
-            // Body struct
-            #[derive(serde::Serialize)]
-            struct Body {
-                #( #body_idents: #body_types, )*
-            }
-            let body = Body { #( #body_idents ),* };
-
-            // Response
-            #[derive(serde::de::DeserializeOwned)]
-            struct Response(Vec<serde_json::Value>);
-
-            let response: restson::Response<Response> =
-                client.post_capture_with(body, query_vec).await?;
-
-            | #( #path_idents ),* | {
-                todo!(response -> _)
-            } ( #( #path_idents ),* )
+            expanded.into()
         }
     };
-
-    TokenStream::from(expanded)
 }
+
+endpoint_macro!(get);
+endpoint_macro!(post);