Add content::ContentType header

Author: yoshuawuyts

src/content/content_type.rs

@@ -0,0 +1,122 @@
+use std::{convert::TryInto, str::FromStr};
+
+use crate::headers::{HeaderName, HeaderValue, Headers, CONTENT_TYPE};
+use crate::Mime;
+
+/// Indicate the media type of the resource.
+///
+/// [MDN Documentation](https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Content-Type)
+///
+/// # Specifications
+///
+/// - [RFC 7231, section 3.1.1.5: Content-Type](https://tools.ietf.org/html/rfc7231#section-3.1.1.5)
+/// - [RFC 7233, section 4.1: Content-Type in multipart](https://tools.ietf.org/html/rfc7233#section-4.1)
+///
+/// # Examples
+///
+/// ```
+/// # fn main() -> http_types::Result<()> {
+/// #
+/// use http_types::content::ContentType;
+/// use http_types::{Response, Mime};
+/// use std::str::FromStr;
+///
+/// let ct = ContentType::new(Mime::from_str("text/*")?);
+///
+/// let mut res = Response::new(200);
+/// ct.apply(&mut res);
+///
+/// let ct = ContentType::from_headers(res)?.unwrap();
+/// assert_eq!(ct.value(), format!("{}", Mime::from_str("text/*")?).as_str());
+/// #
+/// # Ok(()) }
+/// ```
+#[derive(Debug)]
+pub struct ContentType {
+    media_type: Mime,
+}
+
+impl ContentType {
+    /// Create a new instance.
+    pub fn new<U>(media_type: U) -> Self
+    where
+        U: TryInto<Mime>,
+        U::Error: std::fmt::Debug,
+    {
+        Self {
+            media_type: media_type
+                .try_into()
+                .expect("could not convert into a valid Mime type"),
+        }
+    }
+
+    /// Create a new instance from headers.
+    ///
+    /// `Content-Type` headers can provide both full and partial URLs. In
+    /// order to always return fully qualified URLs, a base URL must be passed to
+    /// reference the current environment. In HTTP/1.1 and above this value can
+    /// always be determined from the request.
+    pub fn from_headers(headers: impl AsRef<Headers>) -> crate::Result<Option<Self>> {
+        let headers = match headers.as_ref().get(CONTENT_TYPE) {
+            Some(headers) => headers,
+            None => return Ok(None),
+        };
+
+        // If we successfully parsed the header then there's always at least one
+        // entry. We want the last entry.
+        let ctation = headers.iter().last().unwrap();
+
+        let media_type = Mime::from_str(ctation.as_str()).map_err(|mut e| {
+            e.set_status(400);
+            e
+        })?;
+        Ok(Some(Self { media_type }))
+    }
+
+    /// Sets the header.
+    pub fn apply(&self, mut headers: impl AsMut<Headers>) {
+        headers.as_mut().insert(self.name(), self.value());
+    }
+
+    /// Get the `HeaderName`.
+    pub fn name(&self) -> HeaderName {
+        CONTENT_TYPE
+    }
+
+    /// Get the `HeaderValue`.
+    pub fn value(&self) -> HeaderValue {
+        let output = format!("{}", self.media_type);
+        // SAFETY: the internal string is validated to be ASCII.
+        unsafe { HeaderValue::from_bytes_unchecked(output.into()) }
+    }
+}
+
+#[cfg(test)]
+mod test {
+    use super::*;
+    use crate::headers::Headers;
+
+    #[test]
+    fn smoke() -> crate::Result<()> {
+        let ct = ContentType::new(Mime::from_str("text/*")?);
+
+        let mut headers = Headers::new();
+        ct.apply(&mut headers);
+
+        let ct = ContentType::from_headers(headers)?.unwrap();
+        assert_eq!(
+            ct.value(),
+            format!("{}", Mime::from_str("text/*")?).as_str()
+        );
+        Ok(())
+    }
+
+    #[test]
+    fn bad_request_on_parse_error() -> crate::Result<()> {
+        let mut headers = Headers::new();
+        headers.insert(CONTENT_TYPE, "<nori ate the tag. yum.>");
+        let err = ContentType::from_headers(headers).unwrap_err();
+        assert_eq!(err.status(), 400);
+        Ok(())
+    }
+}

src/content/mod.rs

@@ -10,6 +10,7 @@ pub mod content_encoding;
 
 mod content_length;
 mod content_location;
+mod content_type;
 mod encoding;
 mod encoding_proposal;
 
@@ -19,5 +20,6 @@ pub use accept_encoding::AcceptEncoding;
 pub use content_encoding::ContentEncoding;
 pub use content_length::ContentLength;
 pub use content_location::ContentLocation;
+pub use content_type::ContentType;
 pub use encoding::Encoding;
 pub use encoding_proposal::EncodingProposal;