Implement rupsc, clone of upsc (#5)

Fixes #4

rupsc/src/cmd.rs

@@ -0,0 +1,66 @@
+use crate::parser::UpsdName;
+use anyhow::Context;
+use core::convert::TryInto;
+use nut_client::blocking::Connection;
+
+/// Lists each UPS on the upsd server, one per line.
+pub fn list_devices(server: UpsdName, with_description: bool, debug: bool) -> anyhow::Result<()> {
+    let mut conn = connect(server, debug)?;
+
+    for (name, description) in conn.list_ups()? {
+        if with_description {
+            println!("{}: {}", name, description);
+        } else {
+            println!("{}", name);
+        }
+    }
+
+    Ok(())
+}
+
+pub fn print_variable(server: UpsdName, variable: &str, 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)?;
+
+    let variable = conn.get_var(ups_name, variable)?;
+    println!("{}", variable.value());
+
+    Ok(())
+}
+
+pub fn list_variables(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 var in conn.list_vars(ups_name)? {
+        println!("{}", var);
+    }
+
+    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()
+        .with_host(host)
+        .with_debug(debug)
+        .build();
+    Connection::new(config).with_context(|| format!("Failed to connect to upsd: {}", server))
+}