<?php
/**
* Copyright © Magento, Inc. All rights reserved.
* See COPYING.txt for license details.
*/
namespace Magento\Framework\View\Layout;

use Magento\Framework\App;
use Magento\Framework\Event;
use Magento\Framework\Profiler;
use Magento\Framework\View;

/**
* Class Builder
*/
class Builder implements BuilderInterface
{
/**
* @var \Magento\Framework\Event\ManagerInterface
*/
protected $eventManager;

/**
* @var \Magento\Framework\App\Request\Http
*/
protected $request;

/**
* @var \Magento\Framework\View\LayoutInterface
*/
protected $layout;

/**
* @var bool
*/
protected $isBuilt = false;

/**
* @param View\LayoutInterface $layout
* @param App\Request\Http $request
* @param Event\ManagerInterface $eventManager
*/
public function __construct(
View\LayoutInterface $layout,
App\Request\Http $request,
Event\ManagerInterface $eventManager
) {
$this->layout = $layout;
$this->request = $request;
$this->eventManager = $eventManager;
$this->layout->setBuilder($this);
}

/**
* Build layout structure
*
* @return \Magento\Framework\View\LayoutInterface
*/
public function build()
{
if (!$this->isBuilt) {
$this->isBuilt = true;
$this->loadLayoutUpdates();
$this->generateLayoutXml();
$this->generateLayoutBlocks();
}
return $this->layout;
}

/**
* Load layout updates
*
* @return $this
*/
protected function loadLayoutUpdates()
{
Profiler::start('LAYOUT');
/* dispatch event for adding handles to layout update */
$this->eventManager->dispatch(
'layout_load_before',
['full_action_name' => $this->request->getFullActionName(), 'layout' => $this->layout]
);
Profiler::start('layout_load');

/* load layout updates by specified handles */
$this->layout->getUpdate()->load();

Profiler::stop('layout_load');
Profiler::stop('LAYOUT');
return $this;
}

/**
* Generate layout xml
*
* @return $this
*/
protected function generateLayoutXml()
{
Profiler::start('LAYOUT');
Profiler::start('layout_generate_xml');

/* generate xml from collected text updates */
$this->layout->generateXml();

Profiler::stop('layout_generate_xml');
Profiler::stop('LAYOUT');
return $this;
}

/**
* Generate layout blocks
*
* @return $this
*/
protected function generateLayoutBlocks()
{
$this->beforeGenerateBlock();

Profiler::start('LAYOUT');
/* dispatch event for adding xml layout elements */
$this->eventManager->dispatch(
'layout_generate_blocks_before',
['full_action_name' => $this->request->getFullActionName(), 'layout' => $this->layout]
);
Profiler::start('layout_generate_blocks');

/* generate blocks from xml layout */
$this->layout->generateElements();

Profiler::stop('layout_generate_blocks');
$this->eventManager->dispatch(
'layout_generate_blocks_after',
['full_action_name' => $this->request->getFullActionName(), 'layout' => $this->layout]
);
Profiler::stop('LAYOUT');

$this->afterGenerateBlock();

return $this;
}

/**
* @return $this
*/
protected function beforeGenerateBlock()
{
return $this;
}

/**
* @return $this
*/
protected function afterGenerateBlock()
{
return $this;
}
}