Implement rupsc, clone of upsc (#5)

Fixes #4

rupsc/src/parser.rs

@@ -0,0 +1,150 @@
+use anyhow::Context;
+use std::convert::{TryFrom, TryInto};
+use std::fmt;
+use std::net::ToSocketAddrs;
+
+pub const DEFAULT_HOSTNAME: &str = "127.0.0.1";
+pub const DEFAULT_PORT: u16 = 3493;
+
+/// Connection information for a upsd server.
+///
+/// The upsname is optional depending on context.
+#[derive(Debug, Clone, Copy, Eq, PartialEq)]
+pub struct UpsdName<'a> {
+    pub upsname: Option<&'a str>,
+    pub hostname: &'a str,
+    pub port: u16,
+}
+
+impl<'a> Default for UpsdName<'a> {
+    fn default() -> Self {
+        UpsdName {
+            upsname: None,
+            hostname: DEFAULT_HOSTNAME,
+            port: DEFAULT_PORT,
+        }
+    }
+}
+
+impl<'a> TryFrom<&'a str> for UpsdName<'a> {
+    type Error = anyhow::Error;
+
+    fn try_from(value: &'a str) -> anyhow::Result<UpsdName<'a>> {
+        let mut upsname: Option<&str> = None;
+        let mut hostname = DEFAULT_HOSTNAME;
+        let mut port = DEFAULT_PORT;
+
+        if value.contains(':') {
+            let mut split = value.splitn(2, ':');
+            let prefix = split.next().unwrap();
+            port = split
+                .next()
+                .unwrap()
+                .parse::<u16>()
+                .with_context(|| "invalid port number")?;
+            if prefix.contains('@') {
+                let mut split = prefix.splitn(2, '@');
+                upsname = Some(split.next().unwrap());
+                hostname = split.next().unwrap();
+            } else {
+                hostname = prefix;
+            }
+        } else if value.contains('@') {
+            let mut split = value.splitn(2, '@');
+            upsname = Some(split.next().unwrap());
+            hostname = split.next().unwrap();
+        } else {
+            upsname = Some(value);
+        }
+
+        Ok(UpsdName {
+            upsname,
+            hostname,
+            port,
+        })
+    }
+}
+
+impl<'a> TryInto<nut_client::Host> for UpsdName<'a> {
+    type Error = anyhow::Error;
+
+    fn try_into(self) -> anyhow::Result<nut_client::Host> {
+        Ok((String::from(self.hostname), self.port)
+            .to_socket_addrs()
+            .with_context(|| "Failed to convert to SocketAddr")?
+            .next()
+            .with_context(|| "Failed to convert to SocketAddr")?
+            .into())
+    }
+}
+
+impl<'a> fmt::Display for UpsdName<'a> {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        if let Some(upsname) = self.upsname {
+            write!(f, "{}@", upsname)?;
+        }
+        write!(f, "{}:{}", self.hostname, self.port)
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use core::convert::TryInto;
+
+    #[test]
+    fn test_upsdname_parser_full() {
+        let name: UpsdName = "ups@notlocal:1234".try_into().unwrap();
+        assert_eq!(
+            name,
+            UpsdName {
+                upsname: Some("ups"),
+                hostname: "notlocal",
+                port: 1234
+            }
+        );
+        assert_eq!(format!("{}", name), "ups@notlocal:1234");
+    }
+
+    #[test]
+    fn test_upsdname_parser_no_name() {
+        let name: UpsdName = "notlocal:5678".try_into().unwrap();
+        assert_eq!(
+            name,
+            UpsdName {
+                upsname: None,
+                hostname: "notlocal",
+                port: 5678
+            }
+        );
+        assert_eq!(format!("{}", name), "notlocal:5678");
+    }
+
+    #[test]
+    fn test_upsdname_parser_no_port_no_hostname() {
+        let name: UpsdName = "ups0".try_into().unwrap();
+        assert_eq!(
+            name,
+            UpsdName {
+                upsname: Some("ups0"),
+                hostname: DEFAULT_HOSTNAME,
+                port: DEFAULT_PORT
+            }
+        );
+        assert_eq!(format!("{}", name), "ups0@127.0.0.1:3493");
+    }
+
+    #[test]
+    fn test_upsdname_parser_no_port() {
+        let name: UpsdName = "ups@notlocal".try_into().unwrap();
+        assert_eq!(
+            name,
+            UpsdName {
+                upsname: Some("ups"),
+                hostname: "notlocal",
+                port: DEFAULT_PORT
+            }
+        );
+        assert_eq!(format!("{}", name), "ups@notlocal:3493");
+    }
+}