AppFlowy/rust-lib/flowy-sys/src/module/module.rs

use crate::{
    data::container::DataContainer,
    error::SystemError,
    module::ModuleData,
    request::FromRequest,
    response::Responder,
    service::{BoxService, Handler, Service, ServiceFactory, ServiceRequest, ServiceResponse},
};

use crate::{
    error::InternalError,
    request::{payload::Payload, EventRequest},
    response::{EventResponse, EventResponseBuilder},
    rt::SystemCommand,
    service::{factory, BoxServiceFactory, HandlerService},
};
use futures_core::{future::LocalBoxFuture, ready};
use pin_project::pin_project;
use std::{
    collections::HashMap,
    future::Future,
    pin::Pin,
    rc::Rc,
    task::{Context, Poll},
};
use tokio::sync::mpsc::{unbounded_channel, UnboundedReceiver, UnboundedSender};

pub type Event = String;
pub type EventServiceFactory = BoxServiceFactory<(), ServiceRequest, ServiceResponse, SystemError>;

pub struct Module {
    name: String,
    data: DataContainer,
    service_map: Rc<HashMap<Event, EventServiceFactory>>,
    req_tx: UnboundedSender<EventRequest>,
    req_rx: UnboundedReceiver<EventRequest>,
    sys_tx: UnboundedSender<SystemCommand>,
}

impl Module {
    pub fn new(sys_tx: UnboundedSender<SystemCommand>) -> Self {
        let (req_tx, req_rx) = unbounded_channel::<EventRequest>();
        Self {
            name: "".to_owned(),
            data: DataContainer::new(),
            service_map: Rc::new(HashMap::new()),
            req_tx,
            req_rx,
            sys_tx,
        }
    }

    pub fn name(mut self, s: &str) -> Self {
        self.name = s.to_owned();
        self
    }

    pub fn data<D: 'static>(mut self, data: D) -> Self {
        self.data.insert(ModuleData::new(data));
        self
    }

    pub fn event<H, T, R>(mut self, event: Event, handler: H) -> Self
    where
        H: Handler<T, R>,
        T: FromRequest + 'static,
        R: Future + 'static,
        R::Output: Responder + 'static,
    {
        if self.service_map.contains_key(&event) {
            log::error!("Duplicate Event: {}", &event);
        }

        Rc::get_mut(&mut self.service_map)
            .unwrap()
            .insert(event, factory(HandlerService::new(handler)));
        self
    }

    pub fn req_tx(&self) -> UnboundedSender<EventRequest> { self.req_tx.clone() }

    pub fn handle(&self, request: EventRequest) {
        log::debug!("Module: {} receive request: {:?}", self.name, request);
        match self.req_tx.send(request) {
            Ok(_) => {},
            Err(e) => {
                log::error!("Module: {} with error: {:?}", self.name, e);
            },
        }
    }

    pub fn forward_map(&self) -> HashMap<Event, UnboundedSender<EventRequest>> {
        self.service_map
            .keys()
            .map(|key| (key.clone(), self.req_tx()))
            .collect::<HashMap<_, _>>()
    }
}

impl Future for Module {
    type Output = ();
    fn poll(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
        loop {
            match ready!(Pin::new(&mut self.req_rx).poll_recv(cx)) {
                None => return Poll::Ready(()),
                Some(request) => {
                    let mut service = self.new_service(request.get_id().to_string());
                    if let Ok(service) = ready!(Pin::new(&mut service).poll(cx)) {
                        log::trace!("Spawn module service for request {}", request.get_id());
                        tokio::task::spawn_local(async move {
                            let _ = service.call(request).await;
                        });
                    }
                },
            }
        }
    }
}

impl ServiceFactory<EventRequest> for Module {
    type Response = ();
    type Error = SystemError;
    type Service = BoxService<EventRequest, Self::Response, Self::Error>;
    type Config = String;
    type Future = LocalBoxFuture<'static, Result<Self::Service, Self::Error>>;

    fn new_service(&self, cfg: Self::Config) -> Self::Future {
        log::trace!("Create module service for request {}", cfg);
        let sys_tx = self.sys_tx.clone();
        let service_map = self.service_map.clone();
        Box::pin(async move {
            let service = ModuleService { service_map, sys_tx };
            let module_service = Box::new(service) as Self::Service;
            Ok(module_service)
        })
    }
}

pub struct ModuleService {
    service_map: Rc<HashMap<Event, EventServiceFactory>>,
    sys_tx: UnboundedSender<SystemCommand>,
}

impl Service<EventRequest> for ModuleService {
    type Response = ();
    type Error = SystemError;
    type Future = LocalBoxFuture<'static, Result<Self::Response, Self::Error>>;

    fn call(&self, request: EventRequest) -> Self::Future {
        log::trace!("Call module service for request {}", request.get_id());
        match self.service_map.get(request.get_event()) {
            Some(factory) => {
                let fut = ModuleServiceFuture {
                    request,
                    fut: factory.new_service(()),
                };

                let sys_tx = self.sys_tx.clone();
                Box::pin(async move {
                    let resp = fut.await.unwrap_or_else(|e| e.into());
                    sys_tx.send(SystemCommand::EventResponse(resp));
                    Ok(())
                })
            },
            None => Box::pin(async { Err(InternalError::new("".to_string()).into()) }),
        }
    }
}

type BoxModuleService = BoxService<ServiceRequest, ServiceResponse, SystemError>;

#[pin_project]
pub struct ModuleServiceFuture {
    request: EventRequest,
    #[pin]
    fut: LocalBoxFuture<'static, Result<BoxModuleService, SystemError>>,
}

impl Future for ModuleServiceFuture {
    type Output = Result<EventResponse, SystemError>;

    fn poll(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
        loop {
            let service = ready!(self.as_mut().project().fut.poll(cx))?;
            let req = ServiceRequest::new(self.as_mut().request.clone(), Payload::None);
            log::debug!("Call service to handle request {:?}", self.request);
            let (_, resp) = ready!(Pin::new(&mut service.call(req)).poll(cx))?.into_parts();
            return Poll::Ready(Ok(resp));
        }
    }
}

#[cfg(test)]
mod tests {
    use super::*;
    use crate::rt::Runtime;
    use futures_util::{future, pin_mut};
    use tokio::sync::mpsc::unbounded_channel;
    pub async fn hello_service() -> String { "hello".to_string() }
    #[test]
    fn test() {
        let mut runtime = Runtime::new().unwrap();
        runtime.block_on(async {
            let (sys_tx, mut sys_rx) = unbounded_channel::<SystemCommand>();
            let event = "hello".to_string();
            let mut module = Module::new(sys_tx).event(event.clone(), hello_service);
            let req_tx = module.req_tx();
            let mut event = async move {
                let request = EventRequest::new(event.clone());
                req_tx.send(request).unwrap();

                match sys_rx.recv().await {
                    Some(cmd) => {
                        log::info!("{:?}", cmd);
                    },
                    None => panic!(""),
                }
            };

            pin_mut!(module, event);
            future::select(module, event).await;
        });
    }
}