From abd38f0a99c936d1410576437d3012afa6f6c06c Mon Sep 17 00:00:00 2001
From: Aram Peres <aram.peres@wavy.fm>
Date: Sat, 31 Jul 2021 03:44:45 -0400
Subject: [PATCH] rupsc: Implement listing clients

---
 nut-client/src/blocking/mod.rs | 19 +++++++++++++++++++
 nut-client/src/cmd.rs          | 33 +++++++++++++++++++++++++++++++++
 rupsc/src/cmd.rs               | 13 +++++++++++++
 rupsc/src/main.rs              |  2 +-
 4 files changed, 66 insertions(+), 1 deletion(-)

diff --git a/nut-client/src/blocking/mod.rs b/nut-client/src/blocking/mod.rs
index 8b9a203..b5d5d7a 100644
--- a/nut-client/src/blocking/mod.rs
+++ b/nut-client/src/blocking/mod.rs
@@ -28,6 +28,13 @@ impl Connection {
         }
     }
 
+    /// Queries a list of client IP addresses connected to the given device.
+    pub fn list_clients(&mut self, ups_name: &str) -> crate::Result<Vec<String>> {
+        match self {
+            Self::Tcp(conn) => conn.list_clients(ups_name),
+        }
+    }
+
     /// Queries the list of variables for a UPS device.
     pub fn list_vars(&mut self, ups_name: &str) -> crate::Result<Vec<Variable>> {
         match self {
@@ -103,6 +110,18 @@ impl TcpConnection {
         list.into_iter().map(|row| row.expect_ups()).collect()
     }
 
+    fn list_clients(&mut self, ups_name: &str) -> crate::Result<Vec<String>> {
+        let query = &["CLIENT", ups_name];
+        Self::write_cmd(
+            &mut self.tcp_stream,
+            Command::List(query),
+            self.config.debug,
+        )?;
+        let list = Self::read_list(&mut self.tcp_stream, query, self.config.debug)?;
+
+        list.into_iter().map(|row| row.expect_client()).collect()
+    }
+
     fn list_vars(&mut self, ups_name: &str) -> crate::Result<Vec<(String, String)>> {
         let query = &["VAR", ups_name];
         Self::write_cmd(
diff --git a/nut-client/src/cmd.rs b/nut-client/src/cmd.rs
index c1185f4..45b92d1 100644
--- a/nut-client/src/cmd.rs
+++ b/nut-client/src/cmd.rs
@@ -52,9 +52,17 @@ pub enum Response {
     /// Marks the end of a list response.
     EndList(String),
     /// A variable (VAR) response.
+    ///
+    /// Params: (var name, var value)
     Var(String, String),
     /// A UPS (UPS) response.
+    ///
+    /// Params: (device name, device description)
     Ups(String, String),
+    /// A client (CLIENT) response.
+    ///
+    /// Params: (client IP)
+    Client(String),
 }
 
 impl Response {
@@ -157,6 +165,23 @@ impl Response {
                 }?;
                 Ok(Response::Ups(name, description))
             }
+            "CLIENT" => {
+                let _device = if args.is_empty() {
+                    Err(ClientError::from(NutError::Generic(
+                        "Unspecified CLIENT device in response".into(),
+                    )))
+                } else {
+                    Ok(args.remove(0))
+                }?;
+                let ip_address = if args.is_empty() {
+                    Err(ClientError::from(NutError::Generic(
+                        "Unspecified CLIENT IP in response".into(),
+                    )))
+                } else {
+                    Ok(args.remove(0))
+                }?;
+                Ok(Response::Client(ip_address))
+            }
             _ => Err(NutError::UnknownResponseType(cmd_name).into()),
         }
     }
@@ -196,4 +221,12 @@ impl Response {
             Err(NutError::UnexpectedResponse.into())
         }
     }
+
+    pub fn expect_client(&self) -> crate::Result<String> {
+        if let Self::Client(client_ip) = &self {
+            Ok(client_ip.to_owned())
+        } else {
+            Err(NutError::UnexpectedResponse.into())
+        }
+    }
 }
diff --git a/rupsc/src/cmd.rs b/rupsc/src/cmd.rs
index ad911ae..1d44f5b 100644
--- a/rupsc/src/cmd.rs
+++ b/rupsc/src/cmd.rs
@@ -43,6 +43,19 @@ pub fn list_variables(server: UpsdName, debug: bool) -> anyhow::Result<()> {
     Ok(())
 }
 
+pub fn list_clients(server: UpsdName, debug: bool) -> anyhow::Result<()> {
+    let ups_name = server
+        .upsname
+        .with_context(|| "ups name must be specified: <upsname>[@<hostname>[:<port>]]")?;
+    let mut conn = connect(server, debug)?;
+
+    for client_ip in conn.list_clients(ups_name)? {
+        println!("{}", client_ip);
+    }
+
+    Ok(())
+}
+
 fn connect(server: UpsdName, debug: bool) -> anyhow::Result<Connection> {
     let host = server.try_into()?;
     let config = nut_client::ConfigBuilder::new()
diff --git a/rupsc/src/main.rs b/rupsc/src/main.rs
index f221fff..d367f6e 100644
--- a/rupsc/src/main.rs
+++ b/rupsc/src/main.rs
@@ -73,7 +73,7 @@ fn main() -> anyhow::Result<()> {
     }
 
     if args.is_present("clients") {
-        todo!("listing clients")
+        return cmd::list_clients(server, debug);
     }
 
     // Fallback: prints one variable (or all of them)