From 9bc221ee9153a40e43bef5a8e380235e67a4ead9 Mon Sep 17 00:00:00 2001
From: Julien Karst <contact@julienkarst.com>
Date: Tue, 24 Oct 2023 21:08:02 +0200
Subject: [PATCH] feat: add outputFileExtension to specify which output
 extension to use

---
 packages/relay/src/lib.rs           |  6 +++-
 packages/relay/transform/src/lib.rs | 45 ++++++++++++++++++++++++-----
 2 files changed, 42 insertions(+), 9 deletions(-)

diff --git a/packages/relay/src/lib.rs b/packages/relay/src/lib.rs
index c7c296b27..7af81836c 100644
--- a/packages/relay/src/lib.rs
+++ b/packages/relay/src/lib.rs
@@ -6,7 +6,7 @@ use swc_core::{
     ecma::{ast::Program, visit::FoldWith},
     plugin::{plugin_transform, proxies::TransformPluginProgramMetadata},
 };
-use swc_relay::{relay, Config, RelayLanguageConfig};
+use swc_relay::{relay, Config, RelayLanguageConfig, OutputFileExtension};
 
 #[plugin_transform]
 fn relay_plugin_transform(program: Program, metadata: TransformPluginProgramMetadata) -> Program {
@@ -40,6 +40,9 @@ fn relay_plugin_transform(program: Program, metadata: TransformPluginProgramMeta
     let language = plugin_config["language"]
         .as_str()
         .map_or(RelayLanguageConfig::TypeScript, |v| v.try_into().unwrap());
+    let output_file_extension = plugin_config["outputFileExtension"]
+        .as_str()
+        .map_or(OutputFileExtension::Undefined, |v| v.try_into().unwrap());
     let eager_es_modules = plugin_config["eagerEsModules"]
         .as_bool()
         .unwrap_or_default();
@@ -48,6 +51,7 @@ fn relay_plugin_transform(program: Program, metadata: TransformPluginProgramMeta
         artifact_directory,
         language,
         eager_es_modules,
+        output_file_extension
     };
 
     let mut relay = relay(
diff --git a/packages/relay/transform/src/lib.rs b/packages/relay/transform/src/lib.rs
index c697a0cba..200a85e84 100644
--- a/packages/relay/transform/src/lib.rs
+++ b/packages/relay/transform/src/lib.rs
@@ -21,6 +21,14 @@ pub enum RelayLanguageConfig {
     Flow,
 }
 
+#[derive(Copy, Clone, Debug, Deserialize)]
+#[serde(rename_all = "lowercase")]
+pub enum OutputFileExtension {
+    TypeScript,
+    JavaScript,
+    Undefined
+}
+
 impl<'a> TryFrom<&'a str> for RelayLanguageConfig {
     type Error = String;
 
@@ -33,12 +41,31 @@ impl<'a> TryFrom<&'a str> for RelayLanguageConfig {
     }
 }
 
+
+impl<'a> TryFrom<&'a str> for OutputFileExtension {
+    type Error = String;
+
+    fn try_from(value: &'a str) -> Result<Self, Self::Error> {
+        match value {
+            "ts" => Ok(Self::TypeScript),
+            "js" => Ok(Self::JavaScript),
+            _ => Err(format!("Unexpected output file extension value '{}'", value)),
+        }
+    }
+}
+
 impl Default for RelayLanguageConfig {
     fn default() -> Self {
         Self::Flow
     }
 }
 
+impl Default for OutputFileExtension {
+    fn default() -> Self {
+        Self::Undefined
+    }
+}
+
 #[derive(Debug, Clone)]
 struct RelayImport {
     path: JsWord,
@@ -81,6 +108,8 @@ pub struct Config {
     pub language: RelayLanguageConfig,
     #[serde(default)]
     pub eager_es_modules: bool,
+    #[serde(default)]
+    pub output_file_extension: OutputFileExtension,
 }
 
 fn pull_first_operation_name_from_tpl(tpl: &TaggedTpl) -> Option<String> {
@@ -159,14 +188,14 @@ impl<'a> Relay<'a> {
         real_file_name: &Path,
         definition_name: &str,
     ) -> Result<PathBuf, BuildRequirePathError> {
-        let filename = match &self.config.language {
-            RelayLanguageConfig::Flow => format!("{}.graphql.js", definition_name),
-            RelayLanguageConfig::TypeScript => {
-                format!("{}.graphql", definition_name)
-            }
-            RelayLanguageConfig::JavaScript => {
-                format!("{}.graphql.js", definition_name)
-            }
+        let filename = match &self.config.output_file_extension {
+            OutputFileExtension::JavaScript => format!("{}.graphql.js", definition_name),
+            OutputFileExtension::TypeScript => format!("{}.graphql.ts", definition_name),
+            OutputFileExtension::Undefined => match &self.config.language {
+                RelayLanguageConfig::Flow => format!("{}.graphql.js", definition_name),
+                RelayLanguageConfig::TypeScript => format!("{}.graphql.ts", definition_name),
+                RelayLanguageConfig::JavaScript => format!("{}.graphql.js", definition_name),
+            },
         };
 
         if let Some(artifact_directory) = &self.config.artifact_directory {