Rename Lib to NpmHelper and move more methods to it

helpers/GruntHelper.js

@@ -2,7 +2,8 @@ var fs           = require('fs'),
     q            = require('q'),
     exec         = require('child_process').exec,
     EventEmitter = require('events').EventEmitter,
-    util         = require('util');
+    util         = require('util'),
+    utils        = require('./Utils');
 
 module.exports = function (directory) {
   EventEmitter.call(this);
@@ -80,7 +81,7 @@ module.exports.prototype.flushConfig = function (config) {
   if (! config) throw new Error('Grunt config cannot be empty');
 
   var deferred = q.defer(),
-      dirName  = this.directory[this.directory.length - 1] === '/' ? this.directory : this.directory + '/',
+      dirName  = utils.slashDir(this.directory),
       gruntDef = generateGruntfile(config);
 
   // Substitute the generated configuration

helpers/NpmHelper.js

@@ -0,0 +1,88 @@
+var q = require('q'),
+    exec  = require('child_process').exec,
+    fs    = require('fs'),
+    utils = require('./Utils');
+
+// A library/module is already installed if its folder exists
+// within node_modules
+// TODO: Why not just use require.resolve?
+module.exports.isLibInstalled = function (lib) {
+  var installDir = './node_modules/' + lib,
+      deferred = q.defer();
+
+  fs.exists(installDir, function (exists) {
+    deferred.resolve(exists);
+  });
+
+  return deferred.promise;
+};
+
+// Installs the given library as a dev dependency
+// and resolve when done or if the lib was already installed
+module.exports.installLib = function (lib) {
+  var deferred = q.defer(),
+      // Get the grunt package to install
+      installCmd = 'npm install --save-dev ' + lib;
+
+  // Install it
+  exec(installCmd, function(err) {
+    if (err) {
+      console.log(err);
+      deferred.reject(err);
+    } else {
+      deferred.resolve();
+    }
+  });
+
+  return deferred.promise;
+};
+
+module.exports.hasPackageJsonFile = function (directory) {
+  if (! directory) throw new Error('directory not given');
+
+  var deferred = q.defer();
+
+  // TODO: Are we guaranteed for the package.json file to live in supplied directory?
+  directory = utils.slashDir(directory);
+
+  fs.exists(directory + 'package.json', function (exists) {
+    deferred.resolve(exists);
+  });
+
+  return deferred.promise;
+};
+
+// Returns a json object representing an empty package.json file
+module.exports.getDummyPackageJson = function () {
+  return {
+    'author': '',
+    'name': '',
+    'description': '',
+    'version': '',
+    'repository': {
+      'url': ''
+    },
+    'dependencies': {},
+    'devDependencies': {
+      'ya.js': '*'
+    },
+    'main': '',
+    'license': ''
+  };
+};
+
+// Generates and saves an empty package.json file in
+// the passed directory
+module.exports.createEmptyPackageJsonFile = function (directory) {
+  directory = utils.slashDir(directory);
+
+  var emptyPackageFile = JSON.stringify(this.getDummyPackageJson(), null, 2),
+      deferred = q.defer();
+
+  fs.writeFile(directory + 'package.json', emptyPackageFile, function (err) {
+    if (err) deferred.reject();
+    else deferred.resolve();
+  });
+
+  return deferred.promise;
+};

helpers/Utils.js

@@ -0,0 +1,6 @@
+// Collection of little utility helpers
+
+// Helper to return a slash-trailed version of the directory name
+module.exports.slashDir = function (directory) {
+  return directory[directory.length - 1] === '/' ? directory : directory + '/';
+};