Add config options for Rust binding (#422)

* support custom candid path for export_service

* Add config options for Rust binding

* fix blob

* add codegen for agent

* fix

* fix

rust/candid/src/bindings/motoko.rs

@@ -110,7 +110,8 @@ fn pp_ty(ty: &Type) -> RcDoc {
         Var(ref s) => escape(s, false),
         Principal => str("Principal"),
         Opt(ref t) => str("?").append(pp_ty(t)),
-        Vec(ref t) => enclose("[", pp_ty(t), "]"), // TODO blob
+        Vec(ref t) if matches!(t.as_ref(), Nat8) => str("Blob"),
+        Vec(ref t) => enclose("[", pp_ty(t), "]"),
         Record(ref fs) => {
             if is_tuple(ty) {
                 let tuple = concat(fs.iter().map(|f| pp_ty(&f.ty)), ",");

rust/candid/src/bindings/rust.rs

@@ -4,6 +4,41 @@ use crate::types::{Field, Function, Label, SharedLabel, Type, TypeEnv, TypeInner
 use pretty::RcDoc;
 use std::collections::BTreeSet;
 
+#[derive(Clone)]
+pub enum Target {
+    CanisterCall,
+    Agent,
+    CanisterStub,
+}
+
+#[derive(Clone)]
+pub struct Config {
+    pub candid_crate: String,
+    /// Applies to all types for now
+    pub type_attributes: String,
+    /// Only generates SERVICE struct if canister_id is not provided
+    pub canister_id: Option<crate::Principal>,
+    /// Service name when canister id is provided
+    pub service_name: String,
+    pub target: Target,
+}
+impl Config {
+    pub fn new() -> Self {
+        Config {
+            candid_crate: "candid".to_string(),
+            type_attributes: "".to_string(),
+            canister_id: None,
+            service_name: "service".to_string(),
+            target: Target::CanisterCall,
+        }
+    }
+}
+impl Default for Config {
+    fn default() -> Self {
+        Self::new()
+    }
+}
+
 type RecPoints<'a> = BTreeSet<&'a str>;
 // The definition of tuple is language specific.
 pub(crate) fn is_tuple(fs: &[Field]) -> bool {
@@ -79,8 +114,10 @@ fn pp_ty<'a>(ty: &'a Type, recs: &RecPoints) -> RcDoc<'a> {
                 name
             }
         }
-        Principal => str("candid::Principal"),
+        Principal => str("Principal"),
         Opt(ref t) => str("Option").append(enclose("<", pp_ty(t, recs), ">")),
+        // It's a bit tricky to use `deserialize_with = "serde_bytes"`. It's not working for `type t = blob`
+        Vec(ref t) if matches!(t.as_ref(), Nat8) => str("serde_bytes::ByteBuf"),
         Vec(ref t) => str("Vec").append(enclose("<", pp_ty(t, recs), ">")),
         Record(ref fs) => pp_record_fields(fs, recs),
         Variant(_) => unreachable!(), // not possible after rewriting
@@ -127,8 +164,17 @@ fn pp_variant_fields<'a>(fs: &'a [Field], recs: &RecPoints) -> RcDoc<'a> {
     enclose_space("{", fields, "}")
 }
 
-fn pp_defs<'a>(env: &'a TypeEnv, def_list: &'a [&'a str], recs: &'a RecPoints) -> RcDoc<'a> {
-    let derive = "#[derive(CandidType, Deserialize)]";
+fn pp_defs<'a>(
+    config: &'a Config,
+    env: &'a TypeEnv,
+    def_list: &'a [&'a str],
+    recs: &'a RecPoints,
+) -> RcDoc<'a> {
+    let derive = if config.type_attributes.is_empty() {
+        "#[derive(CandidType, Deserialize)]"
+    } else {
+        &config.type_attributes
+    };
     lines(def_list.iter().map(|id| {
         let ty = env.find_type(id).unwrap();
         let name = ident(id).append(" ");
@@ -223,72 +269,139 @@ fn pp_ty_service(serv: &[(String, Type)]) -> RcDoc {
     enclose_space("{", doc, "}")
 }
 
-fn pp_function<'a>(id: &'a str, func: &'a Function) -> RcDoc<'a> {
+fn pp_function<'a>(config: &Config, id: &'a str, func: &'a Function) -> RcDoc<'a> {
     let name = ident(id);
     let empty = BTreeSet::new();
+    let arg_prefix = str(match config.target {
+        Target::CanisterCall => "&self",
+        Target::Agent => "&self, agent: &ic_agent::Agent",
+        Target::CanisterStub => unimplemented!(),
+    });
     let args = concat(
-        std::iter::once(str("&self")).chain(
+        std::iter::once(arg_prefix).chain(
             func.args
                 .iter()
                 .enumerate()
                 .map(|(i, ty)| RcDoc::as_string(format!("arg{i}: ")).append(pp_ty(ty, &empty))),
         ),
         ",",
     );
-    let rets = enclose(
-        "(",
-        RcDoc::concat(func.rets.iter().map(|ty| pp_ty(ty, &empty).append(","))),
-        ")",
-    );
+    let rets = match config.target {
+        Target::CanisterCall => enclose(
+            "(",
+            RcDoc::concat(func.rets.iter().map(|ty| pp_ty(ty, &empty).append(","))),
+            ")",
+        ),
+        Target::Agent => match func.rets.len() {
+            0 => str("()"),
+            1 => pp_ty(&func.rets[0], &empty),
+            _ => enclose(
+                "(",
+                RcDoc::intersperse(
+                    func.rets.iter().map(|ty| pp_ty(ty, &empty)),
+                    RcDoc::text(", "),
+                ),
+                ")",
+            ),
+        },
+        Target::CanisterStub => unimplemented!(),
+    };
     let sig = kwd("pub async fn")
         .append(name)
         .append(enclose("(", args, ")"))
         .append(kwd(" ->"))
-        .append(enclose("CallResult<", rets, "> "));
-    let args = RcDoc::concat((0..func.args.len()).map(|i| RcDoc::text(format!("arg{i},"))));
+        .append(enclose("Result<", rets, "> "));
     let method = id.escape_debug().to_string();
-    let body = str("ic_cdk::call(self.0, \"")
-        .append(method)
-        .append("\", ")
-        .append(enclose("(", args, ")"))
-        .append(").await");
+    let body = match config.target {
+        Target::CanisterCall => {
+            let args = RcDoc::concat((0..func.args.len()).map(|i| RcDoc::text(format!("arg{i},"))));
+            str("ic_cdk::call(self.0, \"")
+                .append(method)
+                .append("\", ")
+                .append(enclose("(", args, ")"))
+                .append(").await")
+        }
+        Target::Agent => {
+            let is_query = func.is_query();
+            let builder_method = if is_query { "query" } else { "update" };
+            let call = if is_query { "call" } else { "call_and_wait" };
+            let args = RcDoc::intersperse(
+                (0..func.args.len()).map(|i| RcDoc::text(format!("arg{i}"))),
+                RcDoc::text(", "),
+            );
+            let blob = str("candid::Encode!").append(enclose("(", args, ")?;"));
+            let rets = RcDoc::concat(
+                func.rets
+                    .iter()
+                    .map(|ty| str(", ").append(pp_ty(ty, &empty))),
+            );
+            str("let args = ").append(blob).append(RcDoc::hardline())
+                .append(format!("let bytes = agent.{builder_method}(self.0, \"{method}\").with_arg(args).{call}().await?;"))
+                .append(RcDoc::hardline())
+                .append("Ok(candid::Decode!(&bytes").append(rets).append(")?)")
+        }
+        Target::CanisterStub => unimplemented!(),
+    };
     sig.append(enclose_space("{", body, "}"))
 }
 
-fn pp_actor<'a>(env: &'a TypeEnv, actor: &'a Type) -> RcDoc<'a> {
+fn pp_actor<'a>(config: &'a Config, env: &'a TypeEnv, actor: &'a Type) -> RcDoc<'a> {
     // TODO trace to service before we figure out what canister means in Rust
     let serv = env.as_service(actor).unwrap();
     let body = RcDoc::intersperse(
         serv.iter().map(|(id, func)| {
             let func = env.as_func(func).unwrap();
-            pp_function(id, func)
+            pp_function(config, id, func)
         }),
         RcDoc::hardline(),
     );
-    RcDoc::text("pub struct SERVICE(pub candid::Principal);")
+    let res = RcDoc::text("pub struct SERVICE(pub Principal);")
         .append(RcDoc::hardline())
-        .append("impl SERVICE")
+        .append("impl SERVICE ")
         .append(enclose_space("{", body, "}"))
+        .append(RcDoc::hardline());
+    if let Some(cid) = config.canister_id {
+        let slice = cid
+            .as_slice()
+            .iter()
+            .map(|b| b.to_string())
+            .collect::<Vec<_>>()
+            .join(", ");
+        res.append(format!(
+            r#"pub const {}: SERVICE = SERVICE(Principal::from_slice(&[{}])); // {}"#,
+            config.service_name, slice, cid
+        ))
+    } else {
+        res
+    }
 }
 
-pub fn compile(env: &TypeEnv, actor: &Option<Type>) -> String {
-    let header = r#"// This is an experimental feature to generate Rust binding from Candid.
+pub fn compile(config: &Config, env: &TypeEnv, actor: &Option<Type>) -> String {
+    let header = format!(
+        r#"// This is an experimental feature to generate Rust binding from Candid.
 // You may want to manually adjust some of the types.
-use candid::{self, CandidType, Deserialize};
-use ic_cdk::api::call::CallResult;
-"#;
+use {}::{{self, CandidType, Deserialize, Principal}};
+"#,
+        config.candid_crate
+    );
+    let header = header
+        + match &config.target {
+            Target::CanisterCall => "use ic_cdk::api::call::CallResult as Result;\n",
+            Target::Agent => "type Result<T> = std::result::Result<T, ic_agent::AgentError>;",
+            Target::CanisterStub => "",
+        };
     let (env, actor) = nominalize_all(env, actor);
     let def_list: Vec<_> = if let Some(actor) = &actor {
         chase_actor(&env, actor).unwrap()
     } else {
         env.0.iter().map(|pair| pair.0.as_ref()).collect()
     };
     let recs = infer_rec(&env, &def_list).unwrap();
-    let defs = pp_defs(&env, &def_list, &recs);
+    let defs = pp_defs(config, &env, &def_list, &recs);
     let doc = match &actor {
         None => defs,
         Some(actor) => {
-            let actor = pp_actor(&env, actor);
+            let actor = pp_actor(config, &env, actor);
             defs.append(actor)
         }
     };