v4-sign: Extract service mod

v4-sign/src/lib.rs

@@ -1,4 +1,5 @@
 mod request_type;
+mod service;
 mod signing_algorithm;
 
 use std::{
@@ -9,6 +10,8 @@ use std::{
 use request_type::RequestType;
 use signing_algorithm::SigningAlgorithm;
 
+use crate::service::Service;
+
 #[derive(Debug, thiserror::Error)]
 enum Error {
     #[error("FIXME: {0}")]
@@ -41,7 +44,7 @@ fn construct_credential_scope(
 ) -> String {
     let date = request_timestamp.format("%Y%m%d").to_string();
     let location = region; // e.g. "us-central1";
-    let service = "storage";
+    let service = Service::Storage.as_str();
     let request_type = RequestType::Goog4Request.as_str();
     format!("{date}/{location}/{service}/{request_type}")
 }
@@ -344,7 +347,7 @@ UNSIGNED-PAYLOAD
             let credential_scope = {
                 let date = date_time.format("%Y%m%d").to_string();
                 let location = "us-central1";
-                let service = "storage";
+                let service = Service::Storage.as_str();
                 let request_type = RequestType::Goog4Request.as_str();
                 format!("{date}/{location}/{service}/{request_type}")
             };

v4-sign/src/service.rs

@@ -0,0 +1,27 @@
+/// <https://cloud.google.com/storage/docs/authentication/signatures?hl=ja#credential-scope>
+#[derive(Clone, Copy, Debug, Eq, PartialEq)]
+pub(crate) enum Service {
+    Storage,
+    S3,
+}
+
+impl Service {
+    pub(crate) fn as_str(&self) -> &'static str {
+        match self {
+            Self::Storage => "storage",
+            Self::S3 => "s3",
+        }
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test() {
+        use Service::*;
+        assert_eq!(Storage.as_str(), "storage");
+        assert_eq!(S3.as_str(), "s3");
+    }
+}