From 441a42c75e973bfb8130b170c34320f7417ec93c Mon Sep 17 00:00:00 2001
From: msrd0 <1182023-msrd0@users.noreply.gitlab.com>
Date: Tue, 26 Jan 2021 17:49:11 +0000
Subject: [PATCH] Add a Redirect type that can be returned by endpoints

---
 Cargo.toml             |   1 +
 src/lib.rs             |   2 +-
 src/result/mod.rs      |   3 +
 src/result/redirect.rs | 143 +++++++++++++++++++++++++++++++++++++++++
 4 files changed, 148 insertions(+), 1 deletion(-)
 create mode 100644 src/result/redirect.rs

diff --git a/Cargo.toml b/Cargo.toml
index 9203f31..dff6df4 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -38,6 +38,7 @@ openapiv3 = { version = "0.3.2", optional = true }
 regex = { version = "1.4", optional = true }
 serde = { version = "1.0.110", features = ["derive"] }
 serde_json = "1.0.58"
+thiserror = "1.0"
 uuid = { version = "0.8.1", optional = true }
 
 [dev-dependencies]
diff --git a/src/lib.rs b/src/lib.rs
index 780f053..87cb87c 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -481,7 +481,7 @@ pub use response::Response;
 
 mod result;
 pub use result::{
-	AuthError, AuthError::Forbidden, AuthErrorOrOther, AuthResult, AuthSuccess, IntoResponseError, NoContent, Raw,
+	AuthError, AuthError::Forbidden, AuthErrorOrOther, AuthResult, AuthSuccess, IntoResponseError, NoContent, Raw, Redirect,
 	ResourceResult, Success
 };
 
diff --git a/src/result/mod.rs b/src/result/mod.rs
index 526af33..d5895aa 100644
--- a/src/result/mod.rs
+++ b/src/result/mod.rs
@@ -20,6 +20,9 @@ pub use no_content::NoContent;
 mod raw;
 pub use raw::Raw;
 
+mod redirect;
+pub use redirect::Redirect;
+
 #[allow(clippy::module_inception)]
 mod result;
 pub use result::IntoResponseError;
diff --git a/src/result/redirect.rs b/src/result/redirect.rs
new file mode 100644
index 0000000..5754adc
--- /dev/null
+++ b/src/result/redirect.rs
@@ -0,0 +1,143 @@
+use super::{handle_error, NoContent, ResourceResult};
+#[cfg(feature = "openapi")]
+use crate::OpenapiSchema;
+use crate::{IntoResponseError, Response};
+use futures_util::future::{BoxFuture, FutureExt, TryFutureExt};
+use gotham::hyper::{
+	header::{InvalidHeaderValue, LOCATION},
+	Body, StatusCode
+};
+use std::{
+	error::Error as StdError,
+	fmt::{Debug, Display}
+};
+use thiserror::Error;
+
+/**
+This is the return type of a resource that only returns a redirect. It will result
+in a _303 See Other_ answer, meaning the redirect will always result in a GET request
+on the target.
+
+```
+# #[macro_use] extern crate gotham_restful_derive;
+# mod doc_tests_are_broken {
+# use gotham::state::State;
+# use gotham_restful::*;
+#
+# #[derive(Resource)]
+# #[resource(read_all)]
+# struct MyResource;
+#
+#[read_all]
+fn read_all() -> Redirect {
+	Redirect {
+		to: "http://localhost:8080/cool/new/location".to_owned()
+	}
+}
+# }
+```
+*/
+#[derive(Clone, Debug, Default)]
+pub struct Redirect {
+	pub to: String
+}
+
+impl ResourceResult for Redirect {
+	type Err = InvalidHeaderValue;
+
+	fn into_response(self) -> BoxFuture<'static, Result<Response, Self::Err>> {
+		async move {
+			let mut res = Response::new(StatusCode::SEE_OTHER, Body::empty(), None);
+			res.header(LOCATION, self.to.parse()?);
+			Ok(res)
+		}
+		.boxed()
+	}
+
+	#[cfg(feature = "openapi")]
+	fn default_status() -> StatusCode {
+		StatusCode::SEE_OTHER
+	}
+
+	#[cfg(feature = "openapi")]
+	fn schema() -> OpenapiSchema {
+		<NoContent as ResourceResult>::schema()
+	}
+}
+
+// private type due to parent mod
+#[derive(Debug, Error)]
+pub enum RedirectError<E: StdError + 'static> {
+	#[error("{0}")]
+	InvalidLocation(#[from] InvalidHeaderValue),
+	#[error("{0}")]
+	Other(#[source] E)
+}
+
+#[allow(ambiguous_associated_items)] // an enum variant is not a type. never.
+impl<E> ResourceResult for Result<Redirect, E>
+where
+	E: Display + IntoResponseError,
+	<E as IntoResponseError>::Err: Sync
+{
+	type Err = RedirectError<<E as IntoResponseError>::Err>;
+
+	fn into_response(self) -> BoxFuture<'static, Result<Response, Self::Err>> {
+		match self {
+			Ok(nc) => nc.into_response().map_err(Into::into).boxed(),
+			Err(e) => handle_error(e).map_err(|e| RedirectError::Other(e)).boxed()
+		}
+	}
+
+	#[cfg(feature = "openapi")]
+	fn default_status() -> StatusCode {
+		Redirect::default_status()
+	}
+
+	#[cfg(feature = "openapi")]
+	fn schema() -> OpenapiSchema {
+		<Redirect as ResourceResult>::schema()
+	}
+}
+
+#[cfg(test)]
+mod test {
+	use super::*;
+	use futures_executor::block_on;
+	use gotham::hyper::StatusCode;
+	use thiserror::Error;
+
+	#[derive(Debug, Default, Error)]
+	#[error("An Error")]
+	struct MsgError;
+
+	#[test]
+	fn rediect_has_redirect_response() {
+		let redir = Redirect {
+			to: "http://localhost/foo".to_owned()
+		};
+		let res = block_on(redir.into_response()).expect("didn't expect error response");
+		assert_eq!(res.status, StatusCode::SEE_OTHER);
+		assert_eq!(res.mime, None);
+		assert_eq!(
+			res.headers.get(LOCATION).map(|hdr| hdr.to_str().unwrap()),
+			Some("http://localhost/foo")
+		);
+		assert_eq!(res.full_body().unwrap(), &[] as &[u8]);
+	}
+
+	#[test]
+	fn redirect_result() {
+		let redir: Result<Redirect, MsgError> = Ok(Redirect {
+			to: "http://localhost/foo".to_owned()
+		});
+		let res = block_on(redir.into_response()).expect("didn't expect error response");
+		assert_eq!(res.status, StatusCode::SEE_OTHER);
+		assert_eq!(res.mime, None);
+		assert_eq!(
+			res.headers.get(LOCATION).map(|hdr| hdr.to_str().unwrap()),
+			Some("http://localhost/foo")
+		);
+		assert_eq!(res.full_body().unwrap(), &[] as &[u8]);
+	}
+}