action API planing

<?php
// plugins: PluginInspectionInterface

interface ExecutableInterface extends PluginInspectionInterface {

  // Defined by PluginInspectionInterface
  // Possibility to alter parameter definition upon config. -> getDefinition()
  public function getDefinition();

  /**
   * @param array $arguments
   *   The arguments using typed data wrappers.
   * @param $state
   *
   * @return array
   *   An array of values for the provided variables.
   */
  public function executeByArguments($arguments, $state);
}

/**
 * May return variables, save parameters, ..
 */
interface ActionInterface extends ExecutableInterface {

}

// Restriction to return booleans. Fixed definition to provide a boolean.
// Further restriction: May not change arguments.
interface ConditionInterface extends ActionInterface {

}


/**
 * Handle saving here???
 */
class ActionExecutionManager {

  public function setExecutionState(ExecutionState $state) {
    $this->state = $state;
  }

  public function execute(ActionInterface $action) {
    // Extract arguments by applying action config.
    $arguments = array('arg1' => $value);

    // Execute and then care about saving.
    $action->executeByArguments($arguments, $this->state);

    $this->state->runPostExecutionTasks();
  }
}

// Inject execution manager upon creation.
// Inject configuration form manager upon creation.
abstract class ActionBase {

  public function execute() {
    return $this->executionManager->execute($this, func_get_args());
  }

  public function executeByArguments($arguments, ExecutionState $state) {
    // unwrap arguments.
    $this->execute($arg1, $args2, $state);
  }

  public function evaluate($node, $title) {
    $node->title = $title;
  }
}

// Move to annotations.
function hook_action_info() {
  $defintion = array(
    'label' => t('Update node title'),
    'parameter' => array(
      'node' => array(
        'type' => 'node',
        'label' => t('Content'),
        'save' => TRUE,
      ),
      'text' => array(
        'type' => 'string',
        'label' => t('Text'),
      ),
    ),
    'provides' => array(
      'new var' => array(
        'text' => array(
          'type' => 'string',
          'label' => 'fooo',
        )
      )
    ),
  );
}

function example_usage() {
  $action_manager = new ActionManager();
  $condition_manager = new ConditionManager();

  $action_manager->createInstance('name')
    ->setArgument('node', $node)
    ->setArgument('text', 'new title')
    ->execute();

  $boolean = $condition_manager->createInstance('condition_name')
    ->setArgument('text', 'new title')
    ->execute();

  $action = $action_manager->createInstance('name')
    ->setArgumentBySelector('node', 'user2')
    ->setArgument('text','new title')
    ->execute();

  // Store action configuration.
  $config = $action->getConfiguration();
  // Read/write config to CMI.
  $action_manager->createInstance('name')
    ->applyConfiguration($config)
    ->execute();

  $form = $action_manager->form($action);
  $action_manager->formValidate($action, $form, $form_state);
  $action_manager->formSubmit($action, $form, $form_State);

  list($variable1, $variable2) = $action_manager->createInstance('name')
    ->setArgumentBySelector('node', 'node.referenced_node.entity')
    ->setArgument('text','new title')
    ->addProcessor('text', 'token') // done by the form code?
    ->addProcessor('date', 'offset', '+1 day') // done by the form code?
    ->execute();

}

// Rules: RuleElementPlugin -> "condition", "action", "loop", "or", ...