feat: update with web assembly components

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

crates/churn/src/agent/plugins.rs

@@ -0,0 +1,161 @@
+use anyhow::Context;
+use futures::StreamExt;
+use std::path::PathBuf;
+use std::sync::{Arc, RwLock};
+use tokio::io::AsyncWriteExt;
+use tokio::sync::Mutex;
+use wasmtime::component::*;
+use wasmtime::{Config, Engine, Store};
+use wasmtime_wasi::{WasiCtx, WasiCtxBuilder, WasiView};
+
+wasmtime::component::bindgen!({
+    path: "wit/world.wit",
+    world: "churn",
+    async: true
+});
+
+#[derive(Clone)]
+pub struct PluginStore {
+    inner: Arc<Mutex<InnerPluginStore>>,
+}
+
+impl PluginStore {
+    pub fn new() -> anyhow::Result<Self> {
+        Ok(Self {
+            inner: Arc::new(Mutex::new(InnerPluginStore::new()?)),
+        })
+    }
+
+    pub async fn id(&self, plugin: &str) -> anyhow::Result<String> {
+        let mut inner = self.inner.lock().await;
+        inner.id(plugin).await
+    }
+
+    pub async fn execute(&self, plugin: &str) -> anyhow::Result<()> {
+        let mut inner = self.inner.lock().await;
+        inner.execute(plugin).await
+    }
+}
+
+pub struct InnerPluginStore {
+    store: wasmtime::Store<ServerWasiView>,
+    linker: wasmtime::component::Linker<ServerWasiView>,
+    engine: wasmtime::Engine,
+}
+
+impl InnerPluginStore {
+    pub fn new() -> anyhow::Result<Self> {
+        let mut config = Config::default();
+        config.wasm_component_model(true);
+        config.async_support(true);
+        let engine = Engine::new(&config)?;
+        let mut linker: wasmtime::component::Linker<ServerWasiView> = Linker::new(&engine);
+
+        // Add the command world (aka WASI CLI) to the linker
+        wasmtime_wasi::add_to_linker_async(&mut linker).context("Failed to link command world")?;
+        let wasi_view = ServerWasiView::new();
+        let store = Store::new(&engine, wasi_view);
+
+        Ok(Self {
+            store,
+            linker,
+            engine,
+        })
+    }
+
+    pub async fn id(&mut self, plugin: &str) -> anyhow::Result<String> {
+        let plugin = self.ensure_plugin(plugin).await?;
+
+        plugin
+            .interface0
+            .call_id(&mut self.store)
+            .await
+            .context("Failed to call add function")
+    }
+
+    pub async fn execute(&mut self, plugin: &str) -> anyhow::Result<()> {
+        let plugin = self.ensure_plugin(plugin).await?;
+
+        plugin
+            .interface0
+            .call_execute(&mut self.store)
+            .await
+            .context("Failed to call add function")
+    }
+
+    async fn ensure_plugin(&mut self, plugin: &str) -> anyhow::Result<Churn> {
+        let cache = dirs::cache_dir()
+            .ok_or(anyhow::anyhow!("failed to find cache dir"))?
+            .join("io.kjuulh.churn");
+
+        let (plugin_name, plugin_version) = plugin.split_once("@").unwrap_or((plugin, "latest"));
+
+        let plugin_path = cache
+            .join("plugins")
+            .join(plugin_name)
+            .join(plugin_version)
+            .join(format!("{plugin_name}.wasm"));
+
+        let no_cache: bool = std::env::var("CHURN_NO_CACHE")
+            .unwrap_or("false".into())
+            .parse()?;
+
+        if !plugin_path.exists() || no_cache {
+            tracing::info!(
+                plugin_name = plugin_name,
+                plugin_version = plugin_version,
+                "downloading plugin"
+            );
+            if let Some(parent) = plugin_path.parent() {
+                tokio::fs::create_dir_all(parent).await?;
+            }
+
+            let req = reqwest::get(format!("https://api-minio.front.kjuulh.io/churn-registry/{plugin_name}/{plugin_version}/{plugin_name}.wasm")).await.context("failed to get plugin from registry")?;
+            let mut stream = req.bytes_stream();
+            let mut file = tokio::fs::File::create(&plugin_path).await?;
+            while let Some(chunk) = stream.next().await {
+                let chunk = chunk?;
+                file.write_all(&chunk).await?;
+            }
+            file.flush().await?;
+        }
+
+        let component =
+            Component::from_file(&self.engine, plugin_path).context("Component file not found")?;
+
+        tracing::debug!(
+            plugin_name = plugin_name,
+            plugin_version = plugin_version,
+            "instantiating plugin"
+        );
+        let instance = Churn::instantiate_async(&mut self.store, &component, &self.linker)
+            .await
+            .context("Failed to instantiate the example world")?;
+
+        Ok(instance)
+    }
+}
+
+struct ServerWasiView {
+    table: ResourceTable,
+    ctx: WasiCtx,
+}
+
+impl ServerWasiView {
+    fn new() -> Self {
+        let table = ResourceTable::new();
+        let ctx = WasiCtxBuilder::new().inherit_stdio().build();
+
+        Self { table, ctx }
+    }
+}
+
+impl WasiView for ServerWasiView {
+    fn table(&mut self) -> &mut ResourceTable {
+        &mut self.table
+    }
+
+    fn ctx(&mut self) -> &mut WasiCtx {
+        &mut self.ctx
+    }
+}