Allow encoding of an activity with configuration preset durations

fix #11

The activity form allow to receive pre-configured activity durations.

Those duration can be configured through the option
chill_activity.form.time_duration :

```yaml

chill_activity:
   form:
      time_duration:
         - { label: '12 minutes', seconds: 720 }
         # - ...

```

If a pre-existing activity receives a different time, the time is added
to the list of pre-configured duration time.

Form/ActivityType.php

@@ -11,6 +11,13 @@ use Doctrine\Common\Persistence\ObjectManager;
 use Chill\MainBundle\Templating\TranslatableStringHelper;
 use Symfony\Component\Security\Core\Authentication\Token\Storage\TokenStorageInterface;
 use Chill\MainBundle\Entity\User;
+use Symfony\Component\Form\Extension\Core\DataTransformer\DateTimeToTimestampTransformer;
+use Symfony\Component\Form\FormEvent;
+use Symfony\Component\Form\FormEvents;
+use Symfony\Component\Form\Extension\Core\Type\ChoiceType;
+use Symfony\Component\Form\Extension\Core\Type\DateTimeType;
+use Chill\ActivityBundle\Form\Type\TranslatableActivityType;
+use Chill\ActivityBundle\Form\Type\TranslatableActivityReason;
 
 class ActivityType extends AbstractType
 {
@@ -42,9 +49,14 @@ class ActivityType extends AbstractType
      */
     protected $translatableStringHelper;
     
-    public function __construct(TokenStorageInterface $tokenStorage, 
-        AuthorizationHelper $authorizationHelper, ObjectManager $om, 
-        TranslatableStringHelper $translatableStringHelper) 
+    protected $timeChoices;
+    
+    public function __construct(
+            TokenStorageInterface $tokenStorage, 
+            AuthorizationHelper $authorizationHelper, ObjectManager $om, 
+            TranslatableStringHelper $translatableStringHelper,
+            array $timeChoices
+            ) 
     {
         if (!$tokenStorage->getToken()->getUser() instanceof User) {
             throw new \RuntimeException("you should have a valid user");
@@ -53,6 +65,7 @@ class ActivityType extends AbstractType
         $this->authorizationHelper = $authorizationHelper;
         $this->om = $om;
         $this->translatableStringHelper = $translatableStringHelper;
+        $this->timeChoices = $timeChoices;
     }
     
     /**
@@ -61,21 +74,32 @@ class ActivityType extends AbstractType
      */
     public function buildForm(FormBuilderInterface $builder, array $options)
     {
+        // handle times choices
+        $timeChoices = array();
+        
+        foreach ($this->timeChoices as $e) {
+            $timeChoices[$e['label']] = $e['seconds'];
+        };
+        
+        $durationTimeTransformer = new DateTimeToTimestampTransformer('GMT', 'GMT');
+        $durationTimeOptions = array(
+                'choices' => $timeChoices,
+                'choices_as_values' => true,
+                'placeholder' => 'Choose the duration',
+        );
+        
         $builder
             ->add('date', 'date', array(
                'required' => true, 
                'widget' => 'single_text', 
                'format' => 'dd-MM-yyyy')
             )
-            ->add('durationTime', 'time', array(
-                'widget' => 'text',
-                'hours' => array(0, 1, 2, 3, 4, 5, 6, 7, 8)
-            ))
+            ->add('durationTime', ChoiceType::class, $durationTimeOptions)
             ->add('remark', 'textarea', array(
                'required' => false,
                'empty_data' => ''
             ))            
-            ->add('attendee', 'choice', array(
+            ->add('attendee', ChoiceType::class, array(
                'expanded' => true,
                'required' => false,
                'choices' => array(
@@ -85,17 +109,61 @@ class ActivityType extends AbstractType
             ))
             ->add('user')
             ->add('scope')
-            ->add('reasons', 'translatable_activity_reason', array(
+            ->add('reasons', TranslatableActivityReason::class, array(
                 'multiple' => true,
                 'required' => false
             ))
-            ->add('type', 'translatable_activity_type')
-            //->add('person')
+            ->add('type', TranslatableActivityType::class)
         ;
         
         $this->appendScopeChoices($builder, $options['role'], 
               $options['center'], $this->user, $this->authorizationHelper, 
               $this->translatableStringHelper, $this->om);
+        
+        $builder->get('durationTime')
+                ->addModelTransformer($durationTimeTransformer);
+        
+        
+        $builder->get('durationTime')
+                ->addEventListener(
+                        FormEvents::PRE_SET_DATA, 
+                        function(FormEvent $formEvent) use (
+                                $timeChoices, 
+                                $builder,
+                                $durationTimeTransformer,
+                                $durationTimeOptions
+                                ) 
+                        {
+                            // set the timezone to GMT, and fix the difference between current and GMT
+                            // the datetimetransformer will then handle timezone as GMT
+                            $timezoneUTC = new \DateTimeZone('GMT');
+                            /* @var $data \DateTime */
+                            $data = $formEvent->getData() === NULL ? 
+                                    \DateTime::createFromFormat('U', 300) :
+                                    $formEvent->getData();
+                            $seconds = $data->getTimezone()->getOffset($data);
+                            $data->setTimeZone($timezoneUTC);
+                            $data->add(new \DateInterval('PT'.$seconds.'S'));
+
+                            // test if the timestamp is in the choices. 
+                            // If not, recreate the field with the new timestamp
+                            if (!in_array($data->getTimestamp(), $timeChoices)) {
+                                // the data are not in the possible values. add them
+                                $timeChoices[$data->format('H:i')] = $data->getTimestamp();
+                                $form = $builder->create(
+                                        'durationTime', 
+                                        ChoiceType::class, 
+                                        array_merge(
+                                                $durationTimeOptions,
+                                                array(
+                                                    'choices' => $timeChoices,
+                                                    'auto_initialize' => false
+                                                )
+                                                ));
+                                $form->addModelTransformer($durationTimeTransformer);
+                                $formEvent->getForm()->getParent()->add($form->getForm());
+                            }
+                        });
     }
     
     /**