From b97f80997f125d3af8418c09a96bdef21010ce13 Mon Sep 17 00:00:00 2001
From: Chip Senkbeil <chip@senkbeil.org>
Date: Sun, 11 Jun 2023 15:06:24 -0500
Subject: [PATCH] Refactor header into newtype

---
 distant-net/src/common/packet.rs          | 31 ++----------
 distant-net/src/common/packet/header.rs   | 57 +++++++++++++++++++++++
 distant-net/src/common/packet/request.rs  |  1 +
 distant-net/src/common/packet/response.rs |  1 +
 4 files changed, 64 insertions(+), 26 deletions(-)
 create mode 100644 distant-net/src/common/packet/header.rs

diff --git a/distant-net/src/common/packet.rs b/distant-net/src/common/packet.rs
index d76cd7b..c55fe2d 100644
--- a/distant-net/src/common/packet.rs
+++ b/distant-net/src/common/packet.rs
@@ -1,37 +1,16 @@
-/// Represents a generic id type
-pub type Id = String;
-
-/// Represents a packet header for a request or response
-pub type Header = std::collections::HashMap<String, crate::common::Value>;
-
-/// Generates a new [`Header`] of key/value pairs based on literals.
-///
-/// ```
-/// use distant_net::header;
-///
-/// let _header = header!("key" -> "value", "key2" -> 123);
-/// ```
-#[macro_export]
-macro_rules! header {
-    ($($key:literal -> $value:expr),* $(,)?) => {{
-        let mut _header = ::std::collections::HashMap::new();
-
-        $(
-            _header.insert($key.to_string(), $crate::common::Value::from($value));
-        )*
-
-        _header
-    }};
-}
-
+mod header;
 mod request;
 mod response;
 
+pub use header::*;
 pub use request::*;
 pub use response::*;
 
 use std::io::Cursor;
 
+/// Represents a generic id type
+pub type Id = String;
+
 /// Reads the header bytes from msgpack input, including the marker and len bytes.
 ///
 /// * If succeeds, returns (header, remaining).
diff --git a/distant-net/src/common/packet/header.rs b/distant-net/src/common/packet/header.rs
new file mode 100644
index 0000000..a876c0c
--- /dev/null
+++ b/distant-net/src/common/packet/header.rs
@@ -0,0 +1,57 @@
+use crate::common::Value;
+use derive_more::IntoIterator;
+use serde::{Deserialize, Serialize};
+use std::collections::HashMap;
+use std::ops::{Deref, DerefMut};
+
+/// Generates a new [`Header`] of key/value pairs based on literals.
+///
+/// ```
+/// use distant_net::header;
+///
+/// let _header = header!("key" -> "value", "key2" -> 123);
+/// ```
+#[macro_export]
+macro_rules! header {
+    ($($key:literal -> $value:expr),* $(,)?) => {{
+        let mut _header = ::std::collections::HashMap::new();
+
+        $(
+            _header.insert($key.to_string(), $crate::common::Value::from($value));
+        )*
+
+        $crate::common::Header::new(_header)
+    }};
+}
+
+/// Represents a packet header for a request or response
+#[derive(Clone, Debug, Default, PartialEq, Eq, IntoIterator, Serialize, Deserialize)]
+#[serde(transparent)]
+pub struct Header(HashMap<String, Value>);
+
+impl Header {
+    /// Creates a new [`Header`] newtype wrapper.
+    pub fn new(map: HashMap<String, Value>) -> Self {
+        Self(map)
+    }
+
+    /// Exists purely to support serde serialization checks.
+    #[inline]
+    pub(crate) fn is_empty(&self) -> bool {
+        self.0.is_empty()
+    }
+}
+
+impl Deref for Header {
+    type Target = HashMap<String, Value>;
+
+    fn deref(&self) -> &Self::Target {
+        &self.0
+    }
+}
+
+impl DerefMut for Header {
+    fn deref_mut(&mut self) -> &mut Self::Target {
+        &mut self.0
+    }
+}
diff --git a/distant-net/src/common/packet/request.rs b/distant-net/src/common/packet/request.rs
index c70a052..bd74e34 100644
--- a/distant-net/src/common/packet/request.rs
+++ b/distant-net/src/common/packet/request.rs
@@ -7,6 +7,7 @@ use serde::{Deserialize, Serialize};
 
 use super::{read_header_bytes, read_key_eq, read_str_bytes, Header, Id};
 use crate::common::utils;
+use crate::header;
 
 /// Represents a request to send
 #[derive(Clone, Debug, PartialEq, Eq, Serialize, Deserialize)]
diff --git a/distant-net/src/common/packet/response.rs b/distant-net/src/common/packet/response.rs
index 55739a4..6056fe6 100644
--- a/distant-net/src/common/packet/response.rs
+++ b/distant-net/src/common/packet/response.rs
@@ -7,6 +7,7 @@ use serde::{Deserialize, Serialize};
 
 use super::{read_header_bytes, read_key_eq, read_str_bytes, Header, Id};
 use crate::common::utils;
+use crate::header;
 
 /// Represents a response received related to some response
 #[derive(Clone, Debug, PartialEq, Eq, Serialize, Deserialize)]