Restructure with workspace

nut-client/src/error.rs

@@ -0,0 +1,66 @@
+use core::fmt;
+use std::io;
+
+/// A NUT-native error.
+#[derive(Debug)]
+pub enum NutError {
+    /// Occurs when the username/password combination is rejected.
+    AccessDenied,
+    /// Occurs when the specified UPS device does not exist.
+    UnknownUps,
+    /// Occurs when the response type or content wasn't expected at the current stage.
+    UnexpectedResponse,
+    /// Occurs when the response type is not recognized by the client.
+    UnknownResponseType(String),
+    /// Generic (usually internal) client error.
+    Generic(String),
+}
+
+impl fmt::Display for NutError {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        match self {
+            Self::AccessDenied => write!(f, "Authentication failed"),
+            Self::UnknownUps => write!(f, "Unknown UPS device name"),
+            Self::UnexpectedResponse => write!(f, "Unexpected server response content"),
+            Self::UnknownResponseType(ty) => write!(f, "Unknown response type: {}", ty),
+            Self::Generic(msg) => write!(f, "Internal client error: {}", msg),
+        }
+    }
+}
+
+impl std::error::Error for NutError {}
+
+/// Encapsulation for errors emitted by the client library.
+#[derive(Debug)]
+pub enum ClientError {
+    /// Encapsulates IO errors.
+    Io(io::Error),
+    /// Encapsulates NUT and client-specific errors.
+    Nut(NutError),
+}
+
+impl fmt::Display for ClientError {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        match self {
+            Self::Io(err) => err.fmt(f),
+            Self::Nut(err) => err.fmt(f),
+        }
+    }
+}
+
+impl std::error::Error for ClientError {}
+
+impl From<io::Error> for ClientError {
+    fn from(err: io::Error) -> Self {
+        ClientError::Io(err)
+    }
+}
+
+impl From<NutError> for ClientError {
+    fn from(err: NutError) -> Self {
+        ClientError::Nut(err)
+    }
+}
+
+/// Result type for [`ClientError`]
+pub type Result<T> = std::result::Result<T, ClientError>;