From f8b3c8334b43f222a637bb2ee922f2d10815b35d Mon Sep 17 00:00:00 2001
From: Pooya Parsa <pooya@pi0.io>
Date: Tue, 6 Sep 2022 10:11:35 +0200
Subject: [PATCH] feat: `resolveAlias` utility

---
 README.md          |  2 +-
 src/utils.ts       | 13 +++++++++++++
 test/utils.spec.ts | 36 +++++++++++++++++++++++++-----------
 3 files changed, 39 insertions(+), 12 deletions(-)

diff --git a/README.md b/README.md
index beb90be..7a53206 100644
--- a/README.md
+++ b/README.md
@@ -46,7 +46,7 @@ Pathe exports some extra utilities that do not exist in standard Node.js [path m
 In order to use them, you can import from `pathe/utils` subpath:
 
 ```js
-import { filename, normalizeAliases } from 'pathe/utils'
+import { filename, normalizeAliases, resolveAlias } from 'pathe/utils'
 ```
 
 ## License
diff --git a/src/utils.ts b/src/utils.ts
index b4920e1..c02de7c 100644
--- a/src/utils.ts
+++ b/src/utils.ts
@@ -1,3 +1,5 @@
+import { normalize, join } from './path'
+
 const pathSeparators = ['/', '\\', undefined]
 
 export function normalizeAliases (_aliases: Record<string, string>) {
@@ -17,6 +19,17 @@ export function normalizeAliases (_aliases: Record<string, string>) {
   return aliases
 }
 
+export function resolveAlias (path: string, aliases: Record<string, string>) {
+  const _path = normalize(path)
+  aliases = normalizeAliases(aliases)
+  for (const alias in aliases) {
+    if (_path.startsWith(alias)) {
+      return join(aliases[alias], _path.slice(alias.length))
+    }
+  }
+  return _path
+}
+
 const FILENAME_RE = /(^|[\\/])([^\\/]+?)(?=(\.[^.]+)?$)/
 
 export function filename (path: string) {
diff --git a/test/utils.spec.ts b/test/utils.spec.ts
index 93dd605..8446bb8 100644
--- a/test/utils.spec.ts
+++ b/test/utils.spec.ts
@@ -1,25 +1,39 @@
 import { describe, expect, it } from 'vitest'
 
-import { normalizeAliases, filename } from '../src/utils'
+import { normalizeAliases, filename, resolveAlias } from '../src/utils'
 
-describe('normalizeAliases', () => {
-  it('should work', () => {
-    expect(normalizeAliases({
-      '@foo/bar': '@foo/bar/dist/index.mjs',
-      '@foo/bar/utils': '@foo/bar/dist/utils.mjs',
-      '@': '/root',
-      bingpot: '@/bingpot/index.ts',
-      unchanged: '@bingpot/index.ts'
-    })).toMatchInlineSnapshot(`
+describe('alias', () => {
+  const _aliases = {
+    '@foo/bar': '@foo/bar/dist/index.mjs',
+    '@foo/bar/utils': '@foo/bar/dist/utils.mjs',
+    '@': '/root',
+    bingpot: '@/bingpot/index.ts',
+    test: '@bingpot/index.ts'
+  }
+  const aliases = normalizeAliases(_aliases)
+
+  it('normalizeAliases', () => {
+    expect(aliases).toMatchInlineSnapshot(`
       {
         "@": "/root",
         "@foo/bar": "@foo/bar/dist/index.mjs",
         "@foo/bar/utils": "@foo/bar/dist/utils.mjs",
         "bingpot": "/root/bingpot/index.ts",
-        "unchanged": "@bingpot/index.ts",
+        "test": "@bingpot/index.ts",
       }
     `)
   })
+
+  describe('resolveAlias', () => {
+    for (const [from, to] of Object.entries(aliases)) {
+      it(from, () => {
+        expect(resolveAlias(from, aliases)).toBe(to)
+      })
+    }
+    it('unchanged', () => {
+      expect(resolveAlias('foo/bar.js', aliases)).toBe('foo/bar.js')
+    })
+  })
 })
 
 describe('filename', () => {