improve less build again

cat-gradle-less-plugin/src/main/groovy/cc/catalysts/gradle/less/task/InstallLess.groovy

@@ -2,15 +2,55 @@ package cc.catalysts.gradle.less.task
 
 import cc.catalysts.gradle.less.LessExtension
 import com.moowork.gradle.node.task.NpmTask
+import org.gradle.execution.commandline.TaskConfigurationException
+
 /**
  * @author Thomas Scheinecker, Catalysts GmbH
  */
 class InstallLess extends NpmTask {
+    private static final PACKAGE_JSON = """{
+  "private": true,
+  "dependencies": {
+    "less": "2.5.3",
+    "less-plugin-autoprefix": "1.5.1",
+    "less-plugin-clean-css": "1.5.1"
+  }
+}
+""";
+
+
     public InstallLess() {
         this.group = 'Cat-Boot LESS'
         this.description = 'Prepares the less compiler'
-        File nodeModulesDir = LessExtension.get(project).nodeModulesDir
-        setWorkingDir(nodeModulesDir)
-        setNpmCommand('install', 'less', 'less-plugin-autoprefix',  'less-plugin-clean-css')
+
+
+        project.afterEvaluate({
+            File nodeModulesDir = LessExtension.get(project).nodeModulesDir
+
+            if (!nodeModulesDir.exists() && !nodeModulesDir.mkdirs()) {
+                throw new TaskConfigurationException(path, "Couldn't create ${nodeModulesDir}!", null)
+            }
+
+            File projectPackageJson = new File(nodeModulesDir, 'package.json')
+
+            if (!projectPackageJson.exists()) {
+                // first run
+                outputs.upToDateWhen { false }
+            } else if (!projectPackageJson.delete()) {
+                throw new TaskConfigurationException(path, "Couldn't delete ${projectPackageJson}!", null)
+            }
+
+            projectPackageJson.text = PACKAGE_JSON
+
+            if (!projectPackageJson.exists()) {
+                throw new TaskConfigurationException(path, "Couldn't create ${projectPackageJson}!", null)
+            }
+
+            setWorkingDir(nodeModulesDir)
+            setNpmCommand('install')
+
+            inputs.file(projectPackageJson)
+            outputs.dir(new File(nodeModulesDir, 'node_modules'))
+        })
     }
 }