From 629317b6420e755c0eccffe97ff535fe28644460 Mon Sep 17 00:00:00 2001
From: Colin McDonnell <colinmcd94@gmail.com>
Date: Tue, 4 Apr 2023 20:22:59 -0700
Subject: [PATCH] Add multistage build proposal

---
 docs/rfcs/README.md               |  6 +--
 docs/rfcs/bun-bundler.ts          | 24 +++++-----
 docs/rfcs/bun-multistage-build.ts | 78 +++++++++++++++++++++++++++++++
 3 files changed, 94 insertions(+), 14 deletions(-)
 create mode 100644 docs/rfcs/bun-multistage-build.ts

diff --git a/docs/rfcs/README.md b/docs/rfcs/README.md
index ffa91d8e05..db344af11c 100644
--- a/docs/rfcs/README.md
+++ b/docs/rfcs/README.md
@@ -1,5 +1,5 @@
 # RFCs
 
-| Number | Name              | Issue                        |
-| ------ | ----------------- | ---------------------------- |
-| 1      | `Bun.Bundler` API | (Proposal)[./bun-bundler.ts] |
+| Number | Name              | Issue                             |
+| ------ | ----------------- | --------------------------------- |
+| 1      | `Bun.Bundler` API | (`Bun.Bundler`)[./bun-bundler.ts] |
diff --git a/docs/rfcs/bun-bundler.ts b/docs/rfcs/bun-bundler.ts
index c0c5739f37..22c731e228 100644
--- a/docs/rfcs/bun-bundler.ts
+++ b/docs/rfcs/bun-bundler.ts
@@ -125,15 +125,17 @@ interface BuildOptions extends BundlerOptions {
   entrypoints: string[];
   rootDir?: string; // equiv. outbase
 
-  naming?: {
-    /** Documentation: https://esbuild.github.io/api/#entry-names */
-    entry?: string;
-    /** Documentation: https://esbuild.github.io/api/#chunk-names */
-    chunk?: string;
-    /** Documentation: https://esbuild.github.io/api/#asset-names */
-    asset?: string;
-    extensions?: { [ext: string]: string };
-  };
+  naming?:
+    | string
+    | {
+        /** Documentation: https://esbuild.github.io/api/#entry-names */
+        entry?: string;
+        /** Documentation: https://esbuild.github.io/api/#chunk-names */
+        chunk?: string;
+        /** Documentation: https://esbuild.github.io/api/#asset-names */
+        asset?: string;
+        extensions?: { [ext: string]: string };
+      };
 
   /** Documentation: https://esbuild.github.io/api/#external */
   external?: {
@@ -210,12 +212,12 @@ type BuildResult<T> = {
 };
 
 type LazyBuildResult = {
-  then(cb: (result: LazyBuildResult) => BuildOptions): LazyBuildResult;
+  then(cb: (context: any) => BuildOptions): LazyBuildResult;
   run(): Promise<BuildResult<Blob>>;
   write(dir: string): Promise<BuildResult<FileBlob>>;
 };
 
-declare class Bundler {
+export declare class Bundler {
   constructor(options: BundlerOptions);
   makeBuild: (options: BuildOptions) => LazyBuildResult;
   handle: (
diff --git a/docs/rfcs/bun-multistage-build.ts b/docs/rfcs/bun-multistage-build.ts
new file mode 100644
index 0000000000..f308db7ba9
--- /dev/null
+++ b/docs/rfcs/bun-multistage-build.ts
@@ -0,0 +1,78 @@
+import { Bundler } from "./bun-bundler";
+
+const bundler = new Bundler({
+  // ...
+});
+
+const router = new Bun.FileSystemRouter({
+  dir: "./app",
+  style: "nextjs",
+});
+
+const multistageBuild = bundler
+  .makeBuild({
+    // server build
+    target: "bun",
+    entrypoints: Object.values(router.routes),
+    bundle: true,
+    splitting: true,
+    naming: "rsc/[dir]/[name]-[hash].[ext]", // write to <builddir>/rsc
+    plugins: [
+      {
+        name: "rsc",
+        setup(build: any) {
+          // new hook: onBuild
+          // this is where we'd support various AST transforms in the future
+          build.onBuild(
+            { directive: "client" },
+            (args: {
+              path: string;
+              resolveDir: string;
+              module: {
+                directive?: string;
+                id: string;
+                exports: string[];
+              };
+            }) => {
+              // per-build `context` object
+              // initialized to {}
+              build.context.clientModules = build.context.clientModules || {};
+              build.context.clientModules[args.resolveDir + "/" + args.path] = true;
+
+              // future APIs
+              // client references
+              const exports: any = {};
+              for (const key in args.module.exports) {
+                exports[key] = {
+                  $$typeof: Symbol.for("react.client.element"),
+                  $$id: args.module.id,
+                  $$async: true,
+                };
+              }
+              return {
+                loader: "object",
+                exports,
+              };
+            },
+          );
+        },
+      },
+    ],
+  })
+  .then(context => ({
+    entrypoints: ["./client-entry.tsx", ...Object.keys(context.clientModules)],
+    target: "browser",
+    bundle: true,
+    splitting: true,
+    naming: "client/[dir]/[name]-[hash].[ext]",
+    plugins: [],
+  }))
+  .then(context => ({
+    entrypoints: ["./ssr-entry.tsx", ...Object.keys(context.clientModules)],
+    target: "bun",
+    bundle: true,
+    splitting: true,
+    naming: "ssr/[dir]/[name]-[hash].[ext]",
+    plugins: [],
+  }))
+  .write("/.build");