From<fastcgi::Request>: Convert HTTP headers

The HTTP headers from `fastcgi` come with keys in the following format:
"HTTP_USER_AGENT", "HTTP_ACCEPT_LANGUAGE".

Since most headers use an uppercase first letter of a word with hyphen
word separators, make the conversion by:

1. Removing the `HTTP_` prefix
2. Changing `_` to `-`
3. Making the first letter of each word uppercase using the Inflector
   crate

2 files changed, 27 insertions, 2 deletions

diff --git a/Cargo.toml b/Cargo.toml
index 69249f6..fb3da9b 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -6,3 +6,4 @@ edition = "2018"
 [dependencies]
 fastcgi = "1.0.0"
 http = "0.2.1"
+Inflector = "0.11.4"
diff --git a/src/lib.rs b/src/lib.rs
index 88752fb..975308a 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -5,6 +5,7 @@ use std::io::Write;
 
 use http::{Request, Response};
 use http::request;
+use inflector::cases::traincase::to_train_case;
 
 
 pub fn run<F, T>(handler: F)
@@ -49,10 +50,33 @@ impl From<fastcgi::Request> for http::request::Builder {
             request.param("REQUEST_URI").unwrap_or("".to_owned()),
         );
 
-        return http::request::Builder::new()
+        let mut http_request = http::request::Builder::new()
             .method(&*method)
-            .uri(&uri)
+            .uri(&uri);
+
+        let headers = headers_from_params(request.params());
+        for (k, v) in headers {
+            http_request = http_request.header(&k, &v);
+        }
+
+        http_request
 
         // HTTP_* params become headers
     }
 }
+
+fn headers_from_params(params: fastcgi::Params) -> Vec<(String, String)> {
+    return params
+        .filter(|(key, _)| key.starts_with("HTTP_"))
+        .map(|(key, value)| {
+            let mut key = key.get(5..).unwrap_or("").to_owned();
+            key = key.replace("_", "-");
+            key = to_train_case(&key);
+
+            // Change _ to -
+            // Uppercase each word
+
+            (key, value)
+        })
+        .collect()
+}