1 files changed, 165 insertions, 0 deletions
diff --git a/src/client/mod.rs b/src/client/mod.rs
new file mode 100644
index 0000000..d2589fa
--- /dev/null
+++ b/src/client/mod.rs
@@ -0,0 +1,165 @@
+//! Client consists of n + 1 threads:
+//! * one is communicating with tdlib api (api thread)
+//! * n threads, sending requests to the api thread through crossbeam channel.
+//!
+//! when Client::send is called:
+//!     - creates
+//!     * api thread receives Request:
+//!         - adds `@extra` field to request
+//!         - sends modified request to tdlib
+//!     * sending thread returns future,
+//!       that has a reference to the (not yet filled) response
+//!
+
+pub(crate) mod client_builder;
+mod responder;
+
+use crate::raw_ptr::TdPtr;
+use crate::update::Handler;
+use crossbeam::channel::{self, Sender};
+use log::debug;
+use serde::{de::DeserializeOwned, ser::Serialize};
+use serde_json::Value as JsonValue;
+use std::{
+    future::Future,
+    marker::PhantomData,
+    pin::Pin,
+    sync::{Arc, Mutex},
+    task::{Context, Poll, Waker},
+    thread,
+};
+
+#[derive(Debug, Clone)]
+pub struct Response {
+    resp: Option<JsonValue>,
+    waker: Option<Waker>,
+}
+
+impl Response {
+    pub fn new_empty() -> Self {
+        Self {
+            resp: None,
+            waker: None,
+        }
+    }
+}
+
+type SafeResponse = Arc<Mutex<Response>>;
+
+pub trait Request: Serialize {
+    /// Tag request with type
+    /// TDLib infers type from @type field of sent json, so `tag` should insert
+    /// this field into the value.
+    fn tag(&self) -> crate::error::Result<JsonValue>;
+
+    /// Convenience method to tag json made from self
+    fn tag_json<S: AsRef<str>>(&self, type_: S) -> crate::error::Result<JsonValue> {
+        let mut self_json = serde_json::to_value(self)?;
+        if self_json.get("@type").is_some() {
+            return Err(crate::error::Error::HasTypeInJson);
+        }
+        self_json["@type"] = type_.as_ref().into();
+        Ok(self_json)
+    }
+}
+
+impl Request for JsonValue {
+    fn tag(&self) -> crate::error::Result<JsonValue> {
+        if !self["@type"].is_string() {
+            return Err(crate::error::Error::HasNoTypeInJson);
+        }
+        Ok(self.clone())
+    }
+}
+
+#[derive(Debug, Clone)]
+pub struct ResponseFuture<R: DeserializeOwned> {
+    response_type_holder: PhantomData<R>,
+    pub response: SafeResponse, // TODO: maybe it is possible to make this lockless
+}
+
+impl<R: DeserializeOwned> Future for ResponseFuture<R> {
+    type Output = Result<R, serde_json::error::Error>;
+
+    fn poll(self: Pin<&mut Self>, ctx: &mut Context) -> Poll<Self::Output> {
+        let mut data = self.response.lock().unwrap();
+        if let Some(resp) = data.resp.clone() {
+            /*                             ^^^^^^^^
+             * TODO: at this point _this thread_ is the only owner of response,
+             * so it is safe to get `resp` without cloning
+             */
+            Poll::Ready(serde_json::from_value(resp.clone()))
+        } else {
+            data.waker = Some(ctx.waker().clone());
+            Poll::Pending
+        }
+    }
+}
+
+#[derive(Debug)]
+pub(crate) enum JoinStreams {
+    NewRequest((JsonValue, SafeResponse)),
+    NewResponse(String),
+}
+
+#[derive(Clone, Debug)]
+pub struct Client {
+    sender: Sender<JoinStreams>,
+}
+
+impl Client {
+    pub(crate) fn new<H: Handler>(updater: H, timeout: f64) -> Self {
+        let (tx, rx) = channel::unbounded();
+
+        let api = Arc::new(TdPtr::new());
+        let rt = tokio::runtime::Handle::try_current().expect("must be in runtime");
+
+        let _responder_handle = {
+            let api = api.clone();
+            let tx = tx.clone();
+            thread::spawn(move || responder::OneshotResponder::new(rx, api, updater, tx, rt).run())
+        };
+        let _tg_handle = {
+            let api = api.clone();
+            let tx = tx.clone();
+            thread::spawn(move || Self::tdlib_receive_loop(tx, api, timeout));
+        };
+        Self { sender: tx }
+    }
+
+    pub fn send<Req: Request, Resp: DeserializeOwned>(
+        &self,
+        req: Req,
+    ) -> crate::error::Result<ResponseFuture<Resp>> {
+        let fut = ResponseFuture {
+            response_type_holder: PhantomData,
+            response: Arc::new(Mutex::new(Response::new_empty())),
+        };
+
+        self.sender.send(JoinStreams::NewRequest((
+            serde_json::to_value(req.tag()?)?,
+            fut.response.clone(),
+        )))?;
+        Ok(fut)
+    }
+
+    /// [`send`] specification to return JsonValue. Intended to be used, when return value is not used.
+    /// Effective return type (now `serde_json::Value`) may be changed in future
+    pub fn send_forget<Req: Request>(
+        &self,
+        req: Req,
+    ) -> crate::error::Result<ResponseFuture<JsonValue>> {
+        self.send(req)
+    }
+
+    /// Receiving side of client
+    fn tdlib_receive_loop(tx: Sender<JoinStreams>, tdlib: Arc<TdPtr>, timeout: f64) {
+        loop {
+            if let Some(msg) = tdlib.receive(timeout) {
+                tx.send(JoinStreams::NewResponse(msg)).unwrap();
+            } else {
+                debug!("receive timed out");
+            }
+        }
+    }
+}