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use crate::{
AsState,
source::Inner,
state::{State, StateEvent},
};
use std::{fmt::Debug, ops::Deref};
use tokio::{
select,
sync::broadcast::{Sender, channel, error::RecvError},
};
/// Reader of state, to receive state change events.
#[derive(Clone, Debug)]
pub struct Reader<S>(Inner<S>)
where
S: 'static + AsState;
impl<S> Deref for Reader<S>
where
S: 'static + AsState,
{
type Target = Inner<S>;
fn deref(&self) -> &Self::Target {
&self.0
}
}
impl<S> Reader<S>
where
S: 'static + AsState,
{
pub(crate) fn from(inner: Inner<S>) -> Self {
Self(inner)
}
pub(crate) fn new(capacity: usize, sender: Sender<StateEvent<S>>) -> Self {
Self(Inner {
capacity,
sender,
pass_checks: Default::default(),
})
}
}
impl<S> Reader<S>
where
S: 'static + AsState + Send,
{
/// Check is the channel has been closed.
pub fn is_closed(&self) -> bool {
self.sender.subscribe().is_closed()
}
/// Convert data type of state reader.
/// # Arguments
/// # Returns
/// Reader of new data type.
pub fn derive<T>(&self) -> Reader<T>
where
T: AsState + From<S> + Send,
{
self.derive_by(T::from)
}
/// Convert data type of state reader, with an closure.
/// # Arguments
/// * `f` - an closure, which takes the old state value as parameter, and return the new state value.
/// # Returns
/// Reader of new data type.
pub fn derive_by<T, F>(&self, f: F) -> Reader<T>
where
T: AsState + Send,
F: Fn(S) -> T + Send + 'static,
{
let (tx, _) = channel(self.capacity);
let tx_c = tx.clone();
let mut rx_o = self.sender.subscribe();
tokio::spawn(async move {
loop {
select! {
res = rx_o.recv() => {
match res {
Ok(s) => {
tracing::trace!("recv -- {:?}", s.state);
let s_new = StateEvent {
state: State {
value: f(s.state.value),
timestamp: s.state.timestamp,
},
is_touch: s.is_touch,
close_handle: s.close_handle,
};
if tx_c.send(s_new).is_err() {
break;
}
},
Err(e) => {
match e {
RecvError::Closed => break,
RecvError::Lagged(n) => {
tracing::warn!("lagged | skipped {n} messages.")
},
}
},
}
}
}
}
});
Reader(Inner {
capacity: self.capacity,
sender: tx,
pass_checks: self.pass_checks.clone(),
})
}
/// Convert data type of state reader, with an async closure.
/// # Arguments
/// * `f` - an async closure, which takes the old state value as parameter, and return the new state value.
/// # Returns
/// Reader of new data type.
pub fn derive_by_async<T, F, Fut>(&self, f: F) -> Reader<T>
where
T: 'static + AsState + Send,
F: Fn(S) -> Fut + Send + Sync + 'static,
Fut: Future<Output = T> + Send,
{
let (tx, _) = channel(self.capacity);
let tx_c = tx.clone();
let mut rx_o = self.sender.subscribe();
tokio::spawn(async move {
loop {
select! {
res = rx_o.recv() => {
match res {
Ok(s) => {
tracing::trace!("recv -- {:?}", s.state);
let s_new = StateEvent {
state: State {
value: f(s.state.value).await,
timestamp: s.state.timestamp,
},
is_touch: s.is_touch,
close_handle: s.close_handle,
};
if tx_c.send(s_new).is_err() {
break;
}
},
Err(e) => {
match e {
RecvError::Closed => break,
RecvError::Lagged(n) => {
tracing::warn!("lagged | skipped {n} messages.")
},
}
},
}
}
}
}
});
Reader(Inner {
capacity: self.capacity,
sender: tx,
pass_checks: self.pass_checks.clone(),
})
}
}