init retry-after

Author: yoshuawuyts

src/other/mod.rs

@@ -3,9 +3,11 @@
 mod date;
 mod expect;
 mod referer;
+mod retry_after;
 mod source_map;
 
 pub use date::Date;
 pub use expect::Expect;
 pub use referer::Referer;
+pub use retry_after::RetryAfter;
 pub use source_map::SourceMap;

src/other/retry_after.rs

@@ -0,0 +1,126 @@
+use std::time::Duration;
+use std::{convert::TryInto, str::FromStr};
+
+use crate::headers::{HeaderName, HeaderValue, Headers, RETRY_AFTER};
+
+/// Indicate an alternate location for the returned data
+///
+/// [MDN Documentation](https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Retry-After)
+///
+/// # Specifications
+///
+/// - [RFC 7231, section 3.1.4.2: Retry-After](https://tools.ietf.org/html/rfc7231#section-3.1.4.2)
+///
+/// # Examples
+///
+/// ```
+/// # fn main() -> http_types::Result<()> {
+/// #
+/// use http_types::other::RetryAfter;
+/// use http_types::{Response, Duration};
+///
+/// let loc = RetryAfter::new(Duration::parse("https://example.com/foo/bar")?);
+///
+/// let mut res = Response::new(200);
+/// loc.apply(&mut res);
+///
+/// let base_url = Duration::parse("https://example.com")?;
+/// let loc = RetryAfter::from_headers(base_url, res)?.unwrap();
+/// assert_eq!(
+///     loc.value(),
+///     Duration::parse("https://example.com/foo/bar")?.as_str()
+/// );
+/// #
+/// # Ok(()) }
+/// ```
+#[derive(Debug)]
+pub struct RetryAfter {
+    dur: Duration,
+}
+
+#[allow(clippy::len_without_is_empty)]
+impl RetryAfter {
+    /// Create a new instance.
+    pub fn new(dur: Duration) -> Self {
+        Self {
+            dur: location
+                .try_into()
+                .expect("could not convert into a valid URL"),
+        }
+    }
+
+    /// Create a new instance from headers.
+    ///
+    /// `Retry-After` 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<U>(base_url: U, headers: impl AsRef<Headers>) -> crate::Result<Option<Self>>
+    where
+        U: TryInto<Duration>,
+        U::Error: std::fmt::Debug,
+    {
+        let headers = match headers.as_ref().get(RETRY_AFTER) {
+            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 location = headers.iter().last().unwrap();
+
+        let location = match Duration::from_str(location.as_str()) {
+            Ok(url) => url,
+            Err(_) => {
+                let base_url = base_url
+                    .try_into()
+                    .expect("Could not convert base_url into a valid URL");
+                let url = base_url.join(location.as_str())?;
+                url
+            }
+        };
+        Ok(Some(Self { dur: location }))
+    }
+
+    /// 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 {
+        RETRY_AFTER
+    }
+
+    /// Get the `HeaderValue`.
+    pub fn value(&self) -> HeaderValue {
+        let output = format!("{}", self.dur);
+        // 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;
+
+    // NOTE(yosh): I couldn't get a 400 test in because I couldn't generate any
+    // invalid URLs. By default they get escaped, so ehhh -- I think it's fine.
+
+    #[test]
+    fn smoke() -> crate::Result<()> {
+        let loc = RetryAfter::new(Duration::parse("https://example.com/foo/bar")?);
+
+        let mut headers = Headers::new();
+        loc.apply(&mut headers);
+
+        let base_url = Duration::parse("https://example.com")?;
+        let loc = RetryAfter::from_headers(base_url, headers)?.unwrap();
+        assert_eq!(
+            loc.value(),
+            Duration::parse("https://example.com/foo/bar")?.as_str()
+        );
+        Ok(())
+    }
+}