feat: enabled tsup code splitting and esm directory import, removed manual copy of files

backend/tsup.config.js

@@ -1,14 +1,73 @@
+/* eslint-disable */
+import path from "node:path";
+
+import fs from "fs/promises";
+import { replaceTscAliasPaths } from "tsc-alias";
 import { defineConfig } from "tsup";
 
+// what you need tsup to build instead of tsx or tsc
+// tsx is a drop in replacement for nodejs - rather build on top of nodejs runtime
+// it works exactly like node only catch is it doesn't have a final build step else prod should be started with tsx
+// tsc is great for final build issue is we need to then do a manual copy of all static files like handlebar email etc
+// another issue is commonjs. final output needs to be esm because more and more packages are migrating to esm
+// if the final output is commonjs it will just throw an error
+// the below configuration is best of both worlds
 export default defineConfig({
   shims: true,
+  clean: true,
+  minify: false,
+  keepNames: true,
+  splitting: false,
   format: "esm",
+  // copy the files to output
   loader: {
     ".handlebars": "copy",
-    ".md": "copy"
+    ".md": "copy",
+    ".txt": "copy"
   },
   external: ["../../../frontend/node_modules/next/dist/server/next-server.js"],
   outDir: "dist",
+  tsconfig: "./tsconfig.json",
   entry: ["./src"],
-  sourceMap: "inline"
+  sourceMap: true,
+  skipNodeModulesBundle: true,
+  esbuildPlugins: [
+    {
+      // esm directory import are not allowed
+      // /folder1 should be explicitly imported as /folder1/index.ts
+      // this plugin will append it automatically on build time to all imports
+      name: "commonjs-esm-directory-import",
+      setup(build) {
+        build.onResolve({ filter: /.*/ }, async (args) => {
+          if (args.importer) {
+            if (args.kind === "import-statement") {
+              const isRelativePath = args.path.startsWith(".");
+              const absPath = isRelativePath
+                ? path.join(args.resolveDir, args.path)
+                : path.join(args.path.replace("@app", "./src"));
+
+              const isFile = await fs
+                .stat(`${absPath}.ts`)
+                .then((el) => el.isFile)
+                .catch((err) => err.code === "ENOTDIR");
+
+              return {
+                path: isFile ? `${args.path}.mjs` : `${args.path}/index.mjs`,
+                external: true
+              };
+            }
+          }
+          return undefined;
+        });
+      }
+    }
+  ],
+  async onSuccess() {
+    // this will replace all tsconfig paths
+    await replaceTscAliasPaths({
+      configFile: "tsconfig.json",
+      watch: false,
+      outDir: "dist"
+    });
+  }
 });