begin header holder implementation with lazy parser by getters, add request::Mode, add common header_bytes helper

src/client/connection/response/success/default/header.rs

@@ -0,0 +1,43 @@
+pub mod error;
+pub use error::Error;
+
+pub struct Header(Vec<u8>);
+
+impl Header {
+    // Constructors
+
+    pub fn parse(buffer: &[u8]) -> Result<Self, Error> {
+        if !buffer.starts_with(super::CODE) {
+            return Err(Error::Code);
+        }
+        Ok(Self(
+            crate::client::connection::response::header_bytes(buffer)
+                .map_err(|e| Error::Header(e))?
+                .to_vec(),
+        ))
+    }
+
+    // Getters
+
+    /// Parse content type for `Self`
+    pub fn mime(&self) -> Result<String, Error> {
+        glib::Regex::split_simple(
+            r"^\d{2}\s([^\/]+\/[^\s;]+)",
+            std::str::from_utf8(&self.0).map_err(|e| Error::Utf8Error(e))?,
+            glib::RegexCompileFlags::DEFAULT,
+            glib::RegexMatchFlags::DEFAULT,
+        )
+        .get(1)
+        .map(|s| s.trim())
+        .filter(|s| !s.is_empty())
+        .map_or(Err(Error::Mime), |s| Ok(s.to_lowercase()))
+    }
+
+    pub fn len(&self) -> usize {
+        self.0.len()
+    }
+
+    pub fn as_bytes(&self) -> &[u8] {
+        &self.0
+    }
+}