Write the README

README.md

@@ -6,7 +6,9 @@
 [![Build Status](https://travis-ci.org/elephfront/robo-css-minify.svg?branch=master)](https://travis-ci.org/elephfront/robo-css-minify)
 [![Codecov](https://img.shields.io/codecov/c/github/elephfront/robo-css-minify.svg)](https://github.com/elephfront/robo-css-minify)
 
-This [Robo](https://github.com/consolidation/robo) task ...
+This [Robo](https://github.com/consolidation/robo) task performs a minification of your CSS content.
+
+This task performs the minification using [matthiasmullie/minify](https://github.com/matthiasmullie/minify) library.
 
 ## Requirements
 
@@ -25,6 +27,65 @@ composer require elephfront/robo-css-minify
 
 ## Using the task
 
+You can load the task in your RoboFile using the `LoadCssMinifyTasksTrait` trait:
+
+```php
+use Elephfront\RoboCssMinify\Task\Loader\LoadCssMinifyTasksTrait;
+
+class RoboFile extends Tasks
+{
+
+    use LoadCssMinifyTasksTrait;
+
+    public function minifyCss()
+    {
+        $this
+            ->taskCssMinify([
+                'assets/css/main.css' => 'assets/min/css/main.min.css',
+                'assets/css/home.css' => 'assets/min/css/home.min.css',
+            ])
+            ->run();
+    }
+}
+```
+
+The only argument the `taskCssMinify()` takes is an array (`$destinationsMap`) which maps the source files to the destination files : it will load the **assets/css/main.css**, do its magic and put the final content in **assets/min/main.min.js** and do the same for all of the other files.
+
+## Chained State support
+
+Robo includes a concept called the [Chained State](http://robo.li/collections/#chained-state) that allows tasks that need to work together to be executed in a sequence and pass the state of the execution of a task to the next one.
+For instance, if you are managing assets files, you will have a task that compile SCSS to CSS then another one that minify the results. The first task can pass the state of its work to the next one, without having to call both methods in a separate sequence.
+
+The **robo-css-minify** task is compatible with this feature.
+
+All you need to do is make the previous task return the content the **robo-css-minify** task should operate on using the `data` argument of a `Robo\Result::success()` or `Robo\Result::error()` call. The passed `data` should have the following format:
+
+```php
+$data = [
+    'path/to/source/file' => [
+        'css' => '// Some CSS code',
+        'destination' => 'path/to/destination/file
+    ]
+];
+```
+
+In turn, when the **robo-css-minify** task is done, it will pass the results of its work to the next task following the same format.
+
+## Preventing the results from being written
+
+By default, the **robo-css-minify** task writes the result of its work into the destination file(s) passed in the `$destinationsMap` argument. If the **robo-css-minify** task is not the last one in the sequence, you can disable the file writing using the `disableWriteFile()` method. The files will be processed but the results will not be persisted and only passed to the response :
+
+```php
+$this
+    ->taskCssMinify([
+        'assets/js/main.css' => 'assets/min/css/main.min.css',
+        'assets/js/home.css' => 'assets/min/css/home.min.css',
+    ])
+        ->disableWriteFile()
+    ->someOtherTask()
+    ->run();
+```
+
 ## Contributing
 
 If you find a bug or would like to ask for a feature, please use the [GitHub issue tracker](https://github.com/Elephfront/robo-css-minify/issues).