<?php
namespace FluidTYPO3\Vhs\ViewHelpers\Once;

/*
 * This file is part of the FluidTYPO3/Vhs project under GPLv2 or later.
 *
 * For the full copyright and license information, please read the
 * LICENSE.md file that was distributed with this source code.
 */

use TYPO3\CMS\Fluid\Core\ViewHelper\AbstractConditionViewHelper;

/**
 * Base class for "Render Once"-style ViewHelpers: session, cookie,
 * request, template variable set, ViewHelper variable set etc.
 *
 * @author Claus Due <claus@namelesscoder.net>
 * @package Vhs
 * @subpackage ViewHelpers\Once
 */
abstract class AbstractOnceViewHelper extends AbstractConditionViewHelper {

	/**
	 * Standard storage - static variable meaning uniqueness of $identifier
	 * across each Request, i.e. unique to each individual plugin/content.
	 *
	 * @var array
	 */
	protected static $identifiers = array();

	/**
	 * Initialize arguments
	 *
	 * @return void
	 */
	public function initializeArguments() {
		parent::initializeArguments();
		$this->registerArgument('identifier', 'string', 'Identity of this condition - if used in other places, the condition applies to the same identity in the storage (i.e. cookie name or session key)');
		$this->registerArgument('lockToDomain', 'boolean', 'If TRUE, locks this condition to a specific domain, i.e. the storage of $identity is associated with a domain. If same identity is also used without domain lock, it matches any domain locked condition', FALSE, FALSE);
		$this->registerArgument('ttl', 'integer', 'Time-to-live for skip registration, number of seconds. After this expires the registration is unset', FALSE, 86400);
	}

	/**
	 * Standard render method. Implementers should override
	 * the assertShouldSkip() method and/or the getIdentifier()
	 * and storeIdentifier() methods as applies to each
	 * implementers method of storing identifiers.
	 *
	 * @return string
	 */
	public function render() {
		$this->removeIfExpired();
		$evaluation = $this->assertShouldSkip();
		if (FALSE === $evaluation) {
			$content = $this->renderThenChild();
		} else {
			$content = $this->renderElseChild();
		}
		$this->storeIdentifier();
		return $content;
	}

	/**
	 * @return string
	 */
	protected function getIdentifier() {
		if (TRUE === isset($this->arguments['identifier'])) {
			return $this->arguments['identifier'];
		}
		return get_class($this);
	}

	/**
	 * @retrun void
	 */
	protected function storeIdentifier() {
		$identifier = $this->getIdentifier();
		if (FALSE === isset(self::$identifiers[$identifier])) {
			self::$identifiers[$identifier] = time();
		}
	}

	/**
	 * @return void
	 */
	protected function removeIfExpired() {
		$identifier = $this->getIdentifier();
		if (TRUE === isset(self::$identifiers[$identifier]) && self::$identifiers[$identifier] <= time() - $this->arguments['ttl']) {
			unset(self::$identifiers[$identifier]);
		}
	}

	/**
	 * @return boolean
	 */
	protected function assertShouldSkip() {
		$identifier = $this->getIdentifier();
		return (TRUE === isset(self::$identifiers[$identifier]));
	}

	/**
	 * Override: forcibly disables page caching - a TRUE condition
	 * in this ViewHelper means page content would be depending on
	 * the current visitor's session/cookie/auth etc.
	 *
	 * Returns value of "then" attribute.
	 * If then attribute is not set, iterates through child nodes and renders ThenViewHelper.
	 * If then attribute is not set and no ThenViewHelper and no ElseViewHelper is found, all child nodes are rendered
	 *
	 * @return string rendered ThenViewHelper or contents of <f:if> if no ThenViewHelper was found
	 * @api
	 */
	protected function renderThenChild() {
		$GLOBALS['TSFE']->no_cache = 1;
		return parent::renderThenChild();
	}

}