feat: refactor into pub-sub and impl SSE

3 files changed, 261 insertions, 32 deletions

diff --git a/src/service/http.rs b/src/service/http.rs
index fb3ff13..6d21cb7 100644
--- a/src/service/http.rs
+++ b/src/service/http.rs
@@ -1,46 +1,181 @@
-use std::fmt::Display;
+use std::{fmt::Display, time::Duration};
 
+use axum::http::status::StatusCode;
+use futures::Stream;
 use serde::Deserialize;
+use tokio::sync::watch::Sender;
+use tokio_stream::wrappers::WatchStream;
+use url::Url;
 
 use crate::{Error, Status};
 
+use super::ServiceSpawner;
+
 #[derive(Debug, Clone, Deserialize)]
 pub struct Http {
-    pub url: String,
-    #[serde(default = "Http::default_method")]
-    pub method: String,
-    #[serde(default = "Http::default_code")]
-    pub status_code: u16,
+    pub url: Url,
+    #[serde(default)]
+    pub method: Method,
+    #[serde(default, with = "status_code")]
+    pub status_code: StatusCode,
+    #[serde(skip, default)]
+    pub client: Option<reqwest::Client>,
+}
+
+impl Display for Http {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        write!(f, "{} {}", self.method, self.url)
+    }
+}
+
+impl ServiceSpawner for Http {
+    async fn spawn(self, tx: Sender<Status>) -> Result<(), Error> {
+        let client = self.client.unwrap_or_default();
+        let request = client.request(self.method.into(), self.url).build()?;
+
+        let mut interval = tokio::time::interval(Duration::from_secs(5));
+        loop {
+            interval.tick().await;
+            let req = request
+                .try_clone()
+                .expect("Clone with no body should never fail");
+            let resp = client.execute(req).await;
+            let status = match resp.map(|r| r.status().as_u16()) {
+                Ok(code) if code == self.status_code => Status::Pass,
+                Ok(code) => Status::Fail(Some(format!("Status code: {code}"))),
+                Err(err) => {
+                    tracing::error!("HTTP request error: {err}");
+                    Status::Unknown
+                }
+            };
+
+            tx.send_if_modified(|s| s.update(status));
+        }
+    }
 }
 
 impl Http {
-    fn default_method() -> String {
-        "GET".to_string()
+    pub fn into_stream(self, client: reqwest::Client) -> impl Stream<Item = Status> {
+        let request = client
+            .request(self.method.into(), self.url)
+            .build()
+            .expect("Url parsing should not fail");
+
+        let (tx, rx) = tokio::sync::watch::channel(Status::default());
+
+        tokio::spawn(async move {
+            let mut interval = tokio::time::interval(Duration::from_secs(5));
+            loop {
+                interval.tick().await;
+                let req = request
+                    .try_clone()
+                    .expect("Clone with no body should never fail");
+                let resp = client.execute(req).await;
+                let status = match resp.map(|r| r.status().as_u16()) {
+                    Ok(code) if code == self.status_code => Status::Pass,
+                    Ok(code) => Status::Fail(Some(format!("Status code: {code}"))),
+                    Err(err) => {
+                        tracing::error!("HTTP request error: {err}");
+                        Status::Unknown
+                    }
+                };
+
+                tx.send_if_modified(|s| s.update(status));
+            }
+        });
+
+        WatchStream::new(rx)
     }
+}
 
-    fn default_code() -> u16 {
-        200
+#[derive(Debug, Clone, Copy, Default, Deserialize)]
+pub enum Method {
+    #[serde(alias = "get", alias = "GET")]
+    #[default]
+    Get,
+    #[serde(alias = "post", alias = "POST")]
+    Post,
+}
+
+impl From<Method> for reqwest::Method {
+    fn from(value: Method) -> Self {
+        match value {
+            Method::Get => reqwest::Method::GET,
+            Method::Post => reqwest::Method::POST,
+        }
     }
 }
 
-impl Display for Http {
+impl Display for Method {
     fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
-        write!(f, "{} {}", self.method, self.url)
+        match self {
+            Method::Get => write!(f, "GET"),
+            Method::Post => write!(f, "POST"),
+        }
     }
 }
 
-impl Http {
-    pub async fn check(&self, client: reqwest::Client) -> Result<Status, Error> {
-        let status_code = client
-            .request(self.method.parse().map_err(|_| Error::Method)?, &self.url)
-            .send()
-            .await?
-            .status()
-            .as_u16();
-
-        match status_code == self.status_code {
-            true => Ok(Status::Pass),
-            false => Ok(Status::Fail(Some(format!("Status code: {status_code}")))),
+pub mod status_code {
+    use axum::http::StatusCode;
+    use serde::{
+        de::{self, Unexpected, Visitor},
+        Deserializer, Serializer,
+    };
+    use std::fmt;
+
+    /// Implementation detail. Use derive annotations instead.
+    #[inline]
+    pub fn serialize<S: Serializer>(status: &StatusCode, ser: S) -> Result<S::Ok, S::Error> {
+        ser.serialize_u16(status.as_u16())
+    }
+
+    pub(crate) struct StatusVisitor;
+
+    impl StatusVisitor {
+        #[inline(never)]
+        fn make<E: de::Error>(&self, val: u64) -> Result<StatusCode, E> {
+            if (100..1000).contains(&val) {
+                if let Ok(s) = StatusCode::from_u16(val as u16) {
+                    return Ok(s);
+                }
+            }
+            Err(de::Error::invalid_value(Unexpected::Unsigned(val), self))
+        }
+    }
+
+    impl<'de> Visitor<'de> for StatusVisitor {
+        type Value = StatusCode;
+
+        #[inline]
+        fn expecting(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+            formatter.write_str("status code")
+        }
+
+        #[inline]
+        fn visit_some<D: Deserializer<'de>>(
+            self,
+            deserializer: D,
+        ) -> Result<Self::Value, D::Error> {
+            deserializer.deserialize_u16(self)
+        }
+
+        #[inline]
+        fn visit_i64<E: de::Error>(self, val: i64) -> Result<Self::Value, E> {
+            self.make(val as _)
+        }
+
+        #[inline]
+        fn visit_u64<E: de::Error>(self, val: u64) -> Result<Self::Value, E> {
+            self.make(val)
         }
     }
+
+    /// Implementation detail.
+    #[inline]
+    pub fn deserialize<'de, D>(de: D) -> Result<StatusCode, D::Error>
+    where
+        D: Deserializer<'de>,
+    {
+        de.deserialize_u16(StatusVisitor)
+    }
 }
diff --git a/src/service/systemd.rs b/src/service/systemd.rs
index 45f3bf9..e3b4d1b 100644
--- a/src/service/systemd.rs
+++ b/src/service/systemd.rs
@@ -1,9 +1,12 @@
-use std::{fmt::Display, process::Command};
+use std::{fmt::Display, process::Command, time::Duration};
 
 use serde::Deserialize;
+use tokio::sync::watch::Sender;
 
 use crate::{Error, Status};
 
+use super::ServiceSpawner;
+
 #[derive(Debug, Clone, Deserialize)]
 pub struct Systemd {
     pub service: String,
@@ -15,6 +18,32 @@ impl Display for Systemd {
     }
 }
 
+impl ServiceSpawner for Systemd {
+    async fn spawn(self, tx: Sender<Status>) -> Result<(), Error> {
+        let mut command = Command::new("systemctl");
+        command.arg("is-active").arg(&self.service);
+
+        let mut interval = tokio::time::interval(Duration::from_secs(5));
+        loop {
+            interval.tick().await;
+
+            let status = match command.output() {
+                Ok(output) if output.status.success() => Status::Pass,
+                Ok(output) => {
+                    let stdout = String::from_utf8_lossy(&output.stdout).trim().to_string();
+                    Status::Fail(Some(format!("Service state: {}", stdout)))
+                }
+                Err(err) => {
+                    tracing::error!("Failed to spawn process: {err}");
+                    Status::Unknown
+                }
+            };
+
+            tx.send_if_modified(|s| s.update(status));
+        }
+    }
+}
+
 impl Systemd {
     pub async fn check(&self) -> Result<Status, Error> {
         let output = Command::new("systemctl")
diff --git a/src/service/tcp.rs b/src/service/tcp.rs
index 87e696a..5ec5f36 100644
--- a/src/service/tcp.rs
+++ b/src/service/tcp.rs
@@ -1,12 +1,17 @@
-use std::fmt::Display;
+use std::{fmt::Display, net::SocketAddr, time::Duration};
 
+use futures::Stream;
 use serde::Deserialize;
+use tokio::{io::Interest, net::TcpSocket, sync::watch::Sender};
+use tokio_stream::wrappers::WatchStream;
 
 use crate::{Error, Status};
 
+use super::ServiceSpawner;
+
 #[derive(Debug, Clone, Deserialize)]
 pub struct Tcp {
-    pub address: String,
+    pub address: SocketAddr,
 }
 
 impl Display for Tcp {
@@ -15,11 +20,71 @@ impl Display for Tcp {
     }
 }
 
+impl ServiceSpawner for Tcp {
+    #[tracing::instrument(skip(tx))]
+    async fn spawn(self, tx: Sender<Status>) -> Result<(), Error> {
+        let mut interval = tokio::time::interval(Duration::from_secs(5));
+
+        loop {
+            interval.tick().await;
+
+            let sock = TcpSocket::new_v4()?;
+            sock.set_keepalive(true)?;
+
+            match sock.connect(self.address).await {
+                Ok(conn) => {
+                    tracing::info!("Connected");
+                    tx.send_if_modified(|s| s.update(Status::Pass));
+                    conn.ready(Interest::ERROR).await?;
+                    tx.send_replace(Status::Fail(Some("Disconnected".into())));
+                    tracing::info!("Disconnected");
+                }
+                Err(err) => {
+                    tracing::error!("Failed to connect");
+                    tx.send_if_modified(|s| s.update(err.into()));
+                }
+            };
+        }
+    }
+}
+
 impl Tcp {
-    pub async fn check(&self) -> Result<Status, Error> {
-        Ok(std::net::TcpStream::connect(&self.address)
-            .err()
-            .map(Into::into)
-            .unwrap_or_default())
+    pub fn into_stream(self) -> impl Stream<Item = Status> {
+        let (tx, rx) = tokio::sync::watch::channel(Status::default());
+        tokio::spawn(self.spawn(tx));
+        WatchStream::new(rx)
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[tokio::test]
+    #[tracing_test::traced_test]
+    #[ignore]
+    async fn test_tcp_watch() {
+        let (tx, mut rx) = tokio::sync::watch::channel(Status::default());
+
+        let tests = tokio::spawn(async move {
+            assert!(matches!(*rx.borrow_and_update(), Status::Unknown));
+
+            rx.changed().await.unwrap();
+            assert!(matches!(*rx.borrow_and_update(), Status::Pass));
+
+            rx.changed().await.unwrap();
+            assert_eq!(
+                *rx.borrow_and_update(),
+                Status::Fail(Some(String::from("Disconnected")))
+            );
+        });
+
+        let listener = tokio::net::TcpListener::bind("127.0.0.1:0").await.unwrap();
+        let address = listener.local_addr().unwrap();
+        tokio::spawn(async move { Tcp { address }.spawn(tx).await });
+        listener.accept().await.unwrap();
+        drop(listener);
+
+        tests.await.unwrap()
     }
 }