feat: with wasm executor

Signed-off-by: kjuulh <contact@kjuulh.io>

crates/churn-agent/src/main.rs

@@ -1,6 +1,6 @@
 mod agent;
 
-use std::net::SocketAddr;
+use std::{net::SocketAddr, path::PathBuf};
 
 use agent::AgentService;
 use anyhow::Error;
@@ -14,6 +14,7 @@ use axum::{
 use churn_domain::AgentEnrollReq;
 use clap::{Parser, Subcommand};
 use serde_json::json;
+use wasmtime::{Caller, Engine, Linker, Module, Store};
 
 #[derive(Parser)]
 #[command(author, version, about, long_about = None, subcommand_required = true)]
@@ -40,6 +41,19 @@ enum Commands {
         #[arg(env = "CHURN_TOKEN", long)]
         token: String,
     },
+
+    Execute {
+        #[arg(env = "CHURN_AGENT_EXE", long)]
+        exe: PathBuf,
+
+        #[command(subcommand)]
+        commands: Option<ExecuteCommands>,
+    },
+}
+
+#[derive(Subcommand)]
+enum ExecuteCommands {
+    Source,
 }
 
 #[derive(Clone, Default)]
@@ -60,8 +74,8 @@ async fn main() -> anyhow::Result<()> {
 }
 
 async fn handle_command(cmd: Command) -> anyhow::Result<()> {
-    match cmd.command {
-        Some(Commands::Daemon { host }) => {
+    match cmd.command.unwrap() {
+        Commands::Daemon { host } => {
             tracing::info!("Starting churn server");
 
             let app = Router::new()
@@ -77,12 +91,38 @@ async fn handle_command(cmd: Command) -> anyhow::Result<()> {
 
             Ok(())
         }
-        Some(Commands::Connect {
+        Commands::Connect {
             host: _,
             token: _,
             agent_name: _,
-        }) => todo!(),
-        None => todo!(),
+        } => todo!(),
+        Commands::Execute { exe, commands } => match commands {
+            Some(ExecuteCommands::Source) => Ok(()),
+            None => {
+                let engine = Engine::default();
+                let module = Module::from_file(&engine, exe)?;
+
+                // Create a `Linker` which will be later used to instantiate this module.
+                // Host functionality is defined by name within the `Linker`.
+                let mut linker = Linker::new(&engine);
+                linker.func_wrap("print", "print", |caller: Caller<'_, u32>, param: i32| {
+                    println!("Got {} from WebAssembly", param);
+                    println!("my host state is: {}", caller.data());
+                })?;
+
+                // All wasm objects operate within the context of a "store". Each
+                // `Store` has a type parameter to store host-specific data, which in
+                // this case we're using `4` for.
+                let mut store = Store::new(&engine, 4);
+                let instance = linker.instantiate(&mut store, &module)?;
+                let hello = instance.get_typed_func::<(), ()>(&mut store, "hello")?;
+
+                // And finally we can call the wasm!
+                hello.call(&mut store, ())?;
+
+                Ok(())
+            }
+        },
     }
 }