nodejs - flatten sub-folder's files with a prefix

recursive_flatten_sub_folders.js

/* 

assumed direcotry structure:
	/somedir
		/AF3
			/somefile.txt
			/picture.jpg
		/GD3
			/file.txt
			/picture.png
		/AF2
			/picture.JPG

resault:
	/somedir
		/AF3_somefile.txt
		/AF3_picture.jpg
		/GD3_file.txt
		/GD3_picture.png
		/AF2_piccture.JPG

*/

var fs = require('fs'),
	path = require('path');

var MAIN_DIR_PATH = process.argv[2],
	folders = fs.readdirSync(MAIN_DIR_PATH);

folders.forEach(function(folder){
	var file_stat = fs.statSync(path.join(MAIN_DIR_PATH, folder));

	if (file_stat.isDirectory()){
		var inner_files = 
			fs.readdirSync(path.join(MAIN_DIR_PATH, folder))
			.forEach(function(file){
				fs.renameSync(
					path.join(MAIN_DIR_PATH, folder, file), //oldpath
					path.join(MAIN_DIR_PATH, folder+'_'+file) //newpath&filename with prefix
				);
			});
			
		fs.rmdirSync(path.join(MAIN_DIR_PATH, folder)); //delete the empty dir
	}
});