feat: rename multiple files while copying using glob patterns (#19)

* feat: rename multiple files while copying using glob patterns

Author: ghiscoding

README.md

@@ -34,8 +34,8 @@ npm install native-copyfiles -D
     -E, --error    throw error if nothing is copied                          [boolean]
     -V, --verbose  print more information to console                         [boolean]
     -F, --follow   follow symbolic links                                     [boolean]
-    -v, --version  Show version number                                       [boolean]
-    -h, --help     Show help                                                 [boolean]
+    -v, --version  show version number                                       [boolean]
+    -h, --help     show help                                                 [boolean]
 ```
 
 > [!NOTE]
@@ -122,6 +122,66 @@ copyfiles input/original.txt output/renamed.txt
 
 If the destination path is a directory, the file will be copied into that directory as usual. If the destination path is a filename, the file will be copied and renamed.
 
+---
+
+### Rename Multiple Files During Copy
+
+#### 1. Rename Using Glob Patterns
+
+You can use a wildcard (`*`) in the destination to rename files dynamically. For example, to copy all `.css` files and change their extension to `.scss`:
+
+```bash
+copyfiles "input/**/*.css" "output/*.scss"
+```
+
+This will copy:
+
+- `input/foo.css` → `output/foo.scss`
+- `input/bar/baz.css` → `output/bar/baz.scss`
+
+The `*` in the destination is replaced with the base filename from the source.  
+You can combine this with `--flat` or `--up` to control the output structure.
+
+#### 2. Rename Using a Callback (JavaScript API)
+
+For advanced renaming, you can use the `rename` callback option in the API.  
+This function receives the source and destination path and should return the new destination path.
+
+**Example: Change extension to `.scss` using a callback**
+
+```js
+import { copyfiles } from 'native-copyfiles';
+
+copyfiles(['input/**/*.css', 'output'], {
+  flat: true,
+  rename: (src, dest) => dest.replace(/\.css$/, '.scss')
+}, (err) => {
+  // All files like input/foo.css → output/foo.scss
+});
+```
+
+**Example: Prefix all filenames with `renamed-` but keep the extension**
+
+```js
+copyfiles(['input/**/*.css', 'output'], {
+  up: 1,
+  rename: (src, dest) => dest.replace(/([^/\\]+)\.css$/, 'renamed-$1.css')
+}, (err) => {
+  // input/foo.css → output/renamed-foo.css
+  // input/bar/baz.css → output/bar/renamed-baz.css
+});
+```
+
+The `rename` callback gives you full control over the output filename and path.
+
+> **Tip:**  
+> You can use either the glob pattern approach or the `rename` callback, or even combine them for advanced scenarios!
+
+> [!NOTE]
+> If you use both a destination glob pattern (e.g. `output/*.ext`) and a `rename` callback, the glob pattern is applied first and then the `rename` callback is executed last on the computed destination path. This allows you to combine both features for advanced renaming scenarios.
+
+---
+
 ### JavaScript API
 
 ```js
@@ -136,11 +196,12 @@ and finally the third and last argument is a callback function which is executed
 
 ```js
 {
-	verbose: bool,    // enable debug messages
-	up: number,       // -u value
-	exclude: string,  // exclude pattern
-	all: bool,	  // include dot files
-	follow: bool,	  // Follow symlinked directories when expanding ** patterns
-	error: bool       // raise errors if no files copied
+    verbose: bool,      // enable debug messages
+    up: number,         // -u value
+    exclude: string,    // exclude pattern
+    all: bool,	        // include dot files
+    follow: bool,       // follow symlinked directories when expanding ** patterns
+    error: bool         // raise errors if no files copied
+    rename: (src, dest) => string;  // callback to transform the destination filename(s)
 }
-```
+```

src/__tests__/cli.spec.ts

@@ -1,4 +1,4 @@
-import { existsSync, readdir, rmSync, writeFileSync } from 'node:fs';
+import { existsSync, readdir, readdirSync, rmSync, writeFileSync } from 'node:fs';
 import { afterAll, afterEach, beforeEach, describe, expect, test, vi } from 'vitest';
 
 import { createDir } from '../index';
@@ -62,17 +62,17 @@ describe('copyfiles', () => {
             setTimeout(check, 50);
             return;
           }
-          readdir('output2/input2', (err, files) => {
-            try {
-              expect(err).toBeNull();
+          try {
+            setTimeout(() => {
+              const files = readdirSync('output2/input2');
               expect(files).toEqual(['a.txt', 'b.txt']);
               exitSpy.mockRestore();
               done();
-            } catch (e) {
-              exitSpy.mockRestore();
-              done(e);
-            }
-          });
+            }, 50);
+          } catch (e) {
+            exitSpy.mockRestore();
+            done(e);
+          }
         };
         check();
       })