wip: Basic LSP lifecycle requests/notifications.

2 files changed, 355 insertions, 44 deletions

diff --git a/helix-lsp/Cargo.toml b/helix-lsp/Cargo.toml
index 6fd59bf4..1942fc24 100644
--- a/helix-lsp/Cargo.toml
+++ b/helix-lsp/Cargo.toml
@@ -9,7 +9,12 @@ edition = "2018"
 [dependencies]
 lsp-types = { version = "0.82", features = ["proposed"] }
 smol = "1.2"
-url = "2.1.1"
+url = "2"
 pathdiff = "0.2.0"
 shellexpand = "2.0.0"
-glob = "0.3.0"
+glob = "0.3"
+anyhow = "1"
+serde_json = "1.0"
+serde = { version = "1.0", features = ["derive"] }
+jsonrpc-core = "15.1"
+futures-util = "0.3"
diff --git a/helix-lsp/src/lib.rs b/helix-lsp/src/lib.rs
index 14d53bea..b371f337 100644
--- a/helix-lsp/src/lib.rs
+++ b/helix-lsp/src/lib.rs
@@ -1,19 +1,44 @@
-use std::{
-    collections::HashMap,
-    process::{ChildStderr, ChildStdin, ChildStdout, Command, Stdio},
-};
+use std::collections::HashMap;
 
+use jsonrpc_core as jsonrpc;
+use lsp_types as lsp;
+
+use serde::{Deserialize, Serialize};
+use serde_json::Value;
+
+use smol::channel::{Receiver, Sender};
 use smol::io::{BufReader, BufWriter};
 use smol::prelude::*;
-use smol::Unblock;
+use smol::process::{Child, ChildStderr, ChildStdin, ChildStdout, Command, Stdio};
+use smol::Executor;
+
+use futures_util::{select, FutureExt};
+
+/// A type representing all possible values sent from the server to the client.
+#[derive(Debug, PartialEq, Clone, Deserialize, Serialize)]
+#[serde(deny_unknown_fields)]
+#[serde(untagged)]
+enum Message {
+    /// A regular JSON-RPC request output (single response).
+    Output(jsonrpc::Output),
+    /// A notification.
+    Notification(jsonrpc::Notification),
+    /// A JSON-RPC request
+    Call(jsonrpc::Call),
+}
+
+pub struct Client {
+    process: Child,
+    stderr: BufReader<ChildStderr>,
+    outgoing: Sender<Payload>,
+
+    pub request_counter: u64,
 
-struct Client {
-    // process: Command,
-    reader: BufReader<Unblock<ChildStdout>>,
+    capabilities: Option<lsp::ServerCapabilities>,
 }
 
 impl Client {
-    fn start(cmd: &str, args: &[String]) -> Self {
+    pub fn start(ex: &Executor, cmd: &str, args: &[String]) -> Self {
         let mut process = Command::new(cmd)
             .args(args)
             .stdin(Stdio::piped())
@@ -21,51 +46,332 @@ impl Client {
             .stderr(Stdio::piped())
             .spawn()
             .expect("Failed to start language server");
-        // TODO: impl drop that kills the process
+        // smol makes sure the process is reaped on drop, but using kill_on_drop(true) maybe?
 
         // TODO: do we need bufreader/writer here? or do we use async wrappers on unblock?
-        let writer = BufWriter::new(Unblock::new(
-            process.stdin.take().expect("Failed to open stdin"),
-        ));
-        let reader = BufReader::new(Unblock::new(
-            process.stdout.take().expect("Failed to open stdout"),
-        ));
-        let stderr = BufReader::new(Unblock::new(
-            process.stderr.take().expect("Failed to open stderr"),
-        ));
+        let writer = BufWriter::new(process.stdin.take().expect("Failed to open stdin"));
+        let reader = BufReader::new(process.stdout.take().expect("Failed to open stdout"));
+        let stderr = BufReader::new(process.stderr.take().expect("Failed to open stderr"));
+
+        let (incoming, outgoing) = Transport::start(ex, reader, writer);
+
+        Client {
+            process,
+            stderr,
+            outgoing,
+
+            request_counter: 0,
+
+            capabilities: None,
+        }
+    }
+
+    fn next_request_id(&mut self) -> jsonrpc::Id {
+        let id = jsonrpc::Id::Num(self.request_counter);
+        self.request_counter += 1;
+        id
+    }
+
+    fn to_params(value: Value) -> anyhow::Result<jsonrpc::Params> {
+        use jsonrpc::Params;
+
+        let params = match value {
+            Value::Null => Params::None,
+            Value::Bool(_) | Value::Number(_) | Value::String(_) => Params::Array(vec![value]),
+            Value::Array(vec) => Params::Array(vec),
+            Value::Object(map) => Params::Map(map),
+        };
+
+        Ok(params)
+    }
+
+    pub async fn request<R: lsp::request::Request>(
+        &mut self,
+        params: R::Params,
+    ) -> anyhow::Result<R::Result>
+    where
+        R::Params: serde::Serialize,
+        R::Result: core::fmt::Debug, // TODO: temporary
+    {
+        let params = serde_json::to_value(params)?;
+
+        let request = jsonrpc::MethodCall {
+            jsonrpc: Some(jsonrpc::Version::V2),
+            id: self.next_request_id(),
+            method: R::METHOD.to_string(),
+            params: Self::to_params(params)?,
+        };
+
+        let (tx, rx) = smol::channel::bounded::<anyhow::Result<Value>>(1);
+
+        self.outgoing
+            .send(Payload::Request {
+                chan: tx,
+                value: request,
+            })
+            .await?;
+
+        let response = rx.recv().await??;
+
+        let response = serde_json::from_value(response)?;
+
+        // TODO: we should pass request to a sender thread via a channel
+        // so it can't be interleaved
+
+        // TODO: responses can be out of order, we need to register a single shot response channel
+
+        Ok(response)
+    }
+
+    pub async fn notify<R: lsp::notification::Notification>(
+        &mut self,
+        params: R::Params,
+    ) -> anyhow::Result<()>
+    where
+        R::Params: serde::Serialize,
+    {
+        let params = serde_json::to_value(params)?;
+
+        let notification = jsonrpc::Notification {
+            jsonrpc: Some(jsonrpc::Version::V2),
+            method: R::METHOD.to_string(),
+            params: Self::to_params(params)?,
+        };
+
+        self.outgoing
+            .send(Payload::Notification(notification))
+            .await?;
+
+        Ok(())
+    }
+
+    // -------------------------------------------------------------------------------------------
+    // General messages
+    // -------------------------------------------------------------------------------------------
+
+    pub async fn initialize(&mut self) -> anyhow::Result<()> {
+        // TODO: delay any requests that are triggered prior to initialize
+
+        #[allow(deprecated)]
+        let params = lsp::InitializeParams {
+            process_id: Some(u64::from(std::process::id())),
+            root_path: None,
+            // root_uri: Some(lsp_types::Url::parse("file://localhost/")?),
+            root_uri: None, // set to project root in the future
+            initialization_options: None,
+            capabilities: lsp::ClientCapabilities::default(),
+            trace: None,
+            workspace_folders: None,
+            client_info: None,
+        };
+
+        let response = self.request::<lsp::request::Initialize>(params).await?;
+        self.capabilities = Some(response.capabilities);
+
+        // next up, notify<initialized>
+        self.notify::<lsp::notification::Initialized>(lsp::InitializedParams {})
+            .await?;
+
+        Ok(())
+    }
+
+    pub async fn shutdown(&mut self) -> anyhow::Result<()> {
+        self.request::<lsp::request::Shutdown>(()).await
+    }
+
+    pub async fn exit(&mut self) -> anyhow::Result<()> {
+        self.notify::<lsp::notification::Exit>(()).await
+    }
+
+    // -------------------------------------------------------------------------------------------
+    // Text document
+    // -------------------------------------------------------------------------------------------
+
+    pub async fn text_document_did_open(&mut self) -> anyhow::Result<()> {
+        self.notify::<lsp::notification::DidOpenTextDocument>(lsp::DidOpenTextDocumentParams {
+            text_document: lsp::TextDocumentItem {
+                uri: lsp::Url::parse(".")?,
+                language_id: "rust".to_string(),
+                version: 0,
+                text: "".to_string(),
+            },
+        })
+        .await
+    }
 
-        Client { reader }
+    pub async fn text_document_did_change(&mut self) -> anyhow::Result<()> {
+        unimplemented!()
     }
 
-    async fn receiver(&mut self) -> Result<(), std::io::Error> {
-        let mut headers: HashMap<String, String> = HashMap::default();
+    // will_save / will_save_wait_until
+
+    pub async fn text_document_did_save(&mut self) -> anyhow::Result<()> {
+        unimplemented!()
+    }
+
+    pub async fn text_document_did_close(&mut self) -> anyhow::Result<()> {
+        unimplemented!()
+    }
+}
+
+enum Payload {
+    Request {
+        chan: Sender<anyhow::Result<Value>>,
+        value: jsonrpc::MethodCall,
+    },
+    Notification(jsonrpc::Notification),
+}
+
+struct Transport {
+    incoming: Sender<Message>,
+    outgoing: Receiver<Payload>,
+
+    pending_requests: HashMap<jsonrpc::Id, Sender<anyhow::Result<Value>>>,
+    headers: HashMap<String, String>,
+
+    writer: BufWriter<ChildStdin>,
+    reader: BufReader<ChildStdout>,
+}
+
+impl Transport {
+    pub fn start(
+        ex: &Executor,
+        reader: BufReader<ChildStdout>,
+        writer: BufWriter<ChildStdin>,
+    ) -> (Receiver<Message>, Sender<Payload>) {
+        let (incoming, rx) = smol::channel::unbounded();
+        let (tx, outgoing) = smol::channel::unbounded();
+
+        let transport = Self {
+            reader,
+            writer,
+            incoming,
+            outgoing,
+            pending_requests: Default::default(),
+            headers: Default::default(),
+        };
+
+        ex.spawn(transport.duplex()).detach();
+
+        (rx, tx)
+    }
+
+    async fn recv(
+        reader: &mut (impl AsyncBufRead + Unpin),
+        headers: &mut HashMap<String, String>,
+    ) -> Result<Message, std::io::Error> {
+        // read headers
         loop {
-            // read headers
-            loop {
-                let mut header = String::new();
-                // detect pipe closed if 0
-                self.reader.read_line(&mut header).await?;
-                let header = header.trim();
-
-                if header.is_empty() {
-                    break;
-                }
+            let mut header = String::new();
+            // detect pipe closed if 0
+            reader.read_line(&mut header).await?;
+            let header = header.trim();
 
-                let parts: Vec<&str> = header.split(": ").collect();
-                if parts.len() != 2 {
-                    // return Err(Error::new(ErrorKind::Other, "Failed to parse header"));
-                    panic!()
-                }
-                headers.insert(parts[0].to_string(), parts[1].to_string());
+            if header.is_empty() {
+                break;
             }
 
-            // find content-length
+            let parts: Vec<&str> = header.split(": ").collect();
+            if parts.len() != 2 {
+                // return Err(Error::new(ErrorKind::Other, "Failed to parse header"));
+                panic!()
+            }
+            headers.insert(parts[0].to_string(), parts[1].to_string());
+        }
+
+        // find content-length
+        let content_length = headers.get("Content-Length").unwrap().parse().unwrap();
+
+        let mut content = vec![0; content_length];
+        reader.read_exact(&mut content).await?;
+        let msg = String::from_utf8(content).unwrap();
+
+        // read data
+
+        // try parsing as output (server response) or call (server request)
+        let output: serde_json::Result<Message> = serde_json::from_str(&msg);
 
-            // read data
-            // decode via serde_json decoding into jsonrpc_core Output
-            break;
+        Ok(output?)
+    }
+
+    pub async fn send_payload(&mut self, payload: Payload) -> anyhow::Result<()> {
+        match payload {
+            Payload::Request { chan, value } => {
+                self.pending_requests.insert(value.id.clone(), chan);
+
+                let json = serde_json::to_string(&value)?;
+                self.send(json).await
+            }
+            Payload::Notification(value) => {
+                let json = serde_json::to_string(&value)?;
+                self.send(json).await
+            }
         }
+    }
+
+    pub async fn send(&mut self, request: String) -> anyhow::Result<()> {
+        println!("-> {}", request);
+
+        // send the headers
+        self.writer
+            .write_all(format!("Content-Length: {}\r\n\r\n", request.len()).as_bytes())
+            .await?;
+
+        // send the body
+        self.writer.write_all(request.as_bytes()).await?;
+
+        self.writer.flush().await?;
 
         Ok(())
     }
+
+    pub async fn recv_response(&mut self, output: jsonrpc::Output) -> anyhow::Result<()> {
+        match output {
+            jsonrpc::Output::Success(jsonrpc::Success { id, result, .. }) => {
+                println!("<- {}", result);
+
+                let tx = self
+                    .pending_requests
+                    .remove(&id)
+                    .expect("pending_request with id not found!");
+                tx.send(Ok(result)).await?;
+            }
+            jsonrpc::Output::Failure(_) => panic!("recv fail"),
+            msg => unimplemented!("{:?}", msg),
+        }
+        Ok(())
+    }
+
+    pub async fn duplex(mut self) {
+        loop {
+            select! {
+                // client -> server
+                msg = self.outgoing.next().fuse() => {
+                    if msg.is_none() {
+                        break;
+                    }
+                    let msg = msg.unwrap();
+
+                    self.send_payload(msg).await.unwrap();
+                }
+                // server <- client
+                msg = Self::recv(&mut self.reader, &mut self.headers).fuse() => {
+                    if msg.is_err() {
+                        break;
+                    }
+                    let msg = msg.unwrap();
+
+                    match msg {
+                        Message::Output(output) => self.recv_response(output).await.unwrap(),
+                        Message::Notification(_) => {
+                            // dispatch
+                        }
+                        Message::Call(_) => {
+                            // dispatch
+                        }
+                    };
+                }
+            }
+        }
+    }
 }