tooling: add collapse-barrel.ts for single-namespace barrel migration (#22887)

Author: kitlangton

packages/opencode/script/collapse-barrel.ts

@@ -0,0 +1,161 @@
+#!/usr/bin/env bun
+/**
+ * Collapse a single-namespace barrel directory into a dir/index.ts module.
+ *
+ * Given a directory `src/foo/` that contains:
+ *
+ *   - `index.ts`  (exactly `export * as Foo from "./foo"`)
+ *   - `foo.ts`    (the real implementation)
+ *   - zero or more sibling files
+ *
+ * this script:
+ *
+ *   1. Deletes the old `index.ts` barrel.
+ *   2. `git mv`s `foo.ts` → `index.ts` so the implementation IS the directory entry.
+ *   3. Appends `export * as Foo from "."` to the new `index.ts`.
+ *   4. Rewrites any same-directory sibling `*.ts` files that imported
+ *      `./foo` (with or without the namespace name) to import `"."` instead.
+ *
+ * Consumer files outside the directory keep importing from the directory
+ * (`"@/foo"` / `"../foo"` / etc.) and continue to work, because
+ * `dir/index.ts` now provides the `Foo` named export directly.
+ *
+ * Usage:
+ *
+ *   bun script/collapse-barrel.ts src/bus
+ *   bun script/collapse-barrel.ts src/bus --dry-run
+ *
+ * Notes:
+ *
+ *   - Only works on directories whose barrel is a single
+ *     `export * as Name from "./file"` line. Refuses otherwise.
+ *   - Refuses if the implementation file name already conflicts with
+ *     `index.ts`.
+ *   - Safe to run repeatedly: a second run on an already-collapsed dir
+ *     will exit with a clear message.
+ */
+
+import fs from "node:fs"
+import path from "node:path"
+import { spawnSync } from "node:child_process"
+
+const args = process.argv.slice(2)
+const dryRun = args.includes("--dry-run")
+const targetArg = args.find((a) => !a.startsWith("--"))
+
+if (!targetArg) {
+  console.error("Usage: bun script/collapse-barrel.ts <dir> [--dry-run]")
+  process.exit(1)
+}
+
+const dir = path.resolve(targetArg)
+const indexPath = path.join(dir, "index.ts")
+
+if (!fs.existsSync(dir) || !fs.statSync(dir).isDirectory()) {
+  console.error(`Not a directory: ${dir}`)
+  process.exit(1)
+}
+if (!fs.existsSync(indexPath)) {
+  console.error(`No index.ts in ${dir}`)
+  process.exit(1)
+}
+
+// Validate barrel shape.
+const indexContent = fs.readFileSync(indexPath, "utf-8").trim()
+const match = indexContent.match(/^export\s+\*\s+as\s+(\w+)\s+from\s+["']\.\/([^"']+)["']\s*;?\s*$/)
+if (!match) {
+  console.error(`Not a simple single-namespace barrel:\n${indexContent}`)
+  process.exit(1)
+}
+const namespaceName = match[1]
+const implRel = match[2].replace(/\.ts$/, "")
+const implPath = path.join(dir, `${implRel}.ts`)
+
+if (!fs.existsSync(implPath)) {
+  console.error(`Implementation file not found: ${implPath}`)
+  process.exit(1)
+}
+
+if (implRel === "index") {
+  console.error(`Nothing to do — impl file is already index.ts`)
+  process.exit(0)
+}
+
+console.log(`Collapsing ${path.relative(process.cwd(), dir)}`)
+console.log(`  namespace: ${namespaceName}`)
+console.log(`  impl file: ${implRel}.ts → index.ts`)
+
+// Figure out which sibling files need rewriting.
+const siblings = fs
+  .readdirSync(dir)
+  .filter((f) => f.endsWith(".ts") || f.endsWith(".tsx"))
+  .filter((f) => f !== "index.ts" && f !== `${implRel}.ts`)
+  .map((f) => path.join(dir, f))
+
+type SiblingEdit = { file: string; content: string }
+const siblingEdits: SiblingEdit[] = []
+
+for (const sibling of siblings) {
+  const content = fs.readFileSync(sibling, "utf-8")
+  // Match any import or re-export referring to "./<implRel>" inside this directory.
+  const siblingRegex = new RegExp(`(from\\s*["'])\\.\\/${implRel.replace(/[-\\^$*+?.()|[\]{}]/g, "\\$&")}(["'])`, "g")
+  if (!siblingRegex.test(content)) continue
+  const updated = content.replace(siblingRegex, `$1.$2`)
+  siblingEdits.push({ file: sibling, content: updated })
+}
+
+if (siblingEdits.length > 0) {
+  console.log(`  sibling rewrites: ${siblingEdits.length}`)
+  for (const edit of siblingEdits) {
+    console.log(`    ${path.relative(process.cwd(), edit.file)}`)
+  }
+} else {
+  console.log(`  sibling rewrites: none`)
+}
+
+if (dryRun) {
+  console.log(`\n(dry run) would:`)
+  console.log(`  - delete ${path.relative(process.cwd(), indexPath)}`)
+  console.log(`  - git mv ${path.relative(process.cwd(), implPath)} ${path.relative(process.cwd(), indexPath)}`)
+  console.log(`  - append \`export * as ${namespaceName} from "."\` to the new index.ts`)
+  for (const edit of siblingEdits) {
+    console.log(`  - rewrite sibling: ${path.relative(process.cwd(), edit.file)}`)
+  }
+  process.exit(0)
+}
+
+// Apply: remove the old barrel, git-mv the impl onto it, then rewrite content.
+// We can't git-mv on top of an existing tracked file, so we remove the barrel first.
+function runGit(...cmd: string[]) {
+  const res = spawnSync("git", cmd, { stdio: "inherit" })
+  if (res.status !== 0) {
+    console.error(`git ${cmd.join(" ")} failed`)
+    process.exit(res.status ?? 1)
+  }
+}
+
+// Step 1: remove the barrel
+runGit("rm", "-f", indexPath)
+
+// Step 2: rename the impl file into index.ts
+runGit("mv", implPath, indexPath)
+
+// Step 3: append the self-reexport to the new index.ts
+const newContent = fs.readFileSync(indexPath, "utf-8")
+const trimmed = newContent.endsWith("\n") ? newContent : newContent + "\n"
+fs.writeFileSync(indexPath, `${trimmed}\nexport * as ${namespaceName} from "."\n`)
+console.log(`  appended: export * as ${namespaceName} from "."`)
+
+// Step 4: rewrite siblings
+for (const edit of siblingEdits) {
+  fs.writeFileSync(edit.file, edit.content)
+}
+if (siblingEdits.length > 0) {
+  console.log(`  rewrote ${siblingEdits.length} sibling file(s)`)
+}
+
+console.log(`\nDone. Verify with:`)
+console.log(`  cd packages/opencode`)
+console.log(`  bunx --bun tsgo --noEmit`)
+console.log(`  bun run --conditions=browser ./src/index.ts generate`)
+console.log(`  bun run test`)