<?php

/**
 * Bitrix Framework
 * @package bitrix
 * @subpackage main
 * @copyright 2001-2023 Bitrix
 */

class CStackCacheEntry
{
	var $entity = "";
	var $id = "";
	var $values = array();
	var $len = 10;
	var $ttl = 3600;
	var $cleanGet = true;
	var $cleanSet = true;

	function __construct($entity, $length = 0, $ttl = 0)
	{
		$this->entity = $entity;

		if($length > 0)
			$this->len = intval($length);

		if($ttl > 0)
			$this->ttl = intval($ttl);
	}

	function SetLength($length)
	{
		if($length > 0)
			$this->len = intval($length);

		while(count($this->values) > $this->len)
		{
			$this->cleanSet = false;
			array_shift($this->values);
		}
	}

	function SetTTL($ttl)
	{
		if($ttl > 0)
			$this->ttl = intval($ttl);
	}

	function Load()
	{
		global $DB;
		$objCache = \Bitrix\Main\Data\Cache::createInstance();
		if($objCache->InitCache($this->ttl, $this->entity, $DB->type."/".$this->entity, "stack_cache"))
		{
			$this->values = $objCache->GetVars();
			$this->cleanGet = true;
			$this->cleanSet = true;
		}
	}

	function DeleteEntry($id)
	{
		if(array_key_exists($id, $this->values))
		{
			unset($this->values[$id]);
			$this->cleanSet = false;
		}
	}

	function Clean()
	{
		global $DB;

		$objCache = \Bitrix\Main\Data\Cache::createInstance();
		$objCache->Clean($this->entity, $DB->type."/".$this->entity, "stack_cache");

		$this->values = array();
		$this->cleanGet = true;
		$this->cleanSet = true;
	}

	function Get($id)
	{
		if(array_key_exists($id, $this->values))
		{
			$result = $this->values[$id];
			//Move accessed value to the top of list only when it is not at the top
			end($this->values);
			if(key($this->values) !== $id)
			{
				$this->cleanGet = false;
				unset($this->values[$id]);
				$this->values = $this->values + array($id => $result);
			}

			return $result;
		}
		else
		{
			return false;
		}
	}

	function Set($id, $value)
	{
		if(array_key_exists($id, $this->values))
		{
			unset($this->values[$id]);
			$this->values = $this->values + array($id => $value);
		}
		else
		{
			$this->values = $this->values + array($id => $value);
			while(count($this->values) > $this->len)
				array_shift($this->values);
		}

		$this->cleanSet = false;
	}

	function Save()
	{
		if (defined("BITRIX_SKIP_STACK_CACHE") && BITRIX_SKIP_STACK_CACHE)
			return;

		global $DB;

		if(
			!$this->cleanSet
			|| (
				!$this->cleanGet
				&& (count($this->values) >= $this->len)
			)
		)
		{
			$objCache = \Bitrix\Main\Data\Cache::createInstance();

			//Force cache rewrite
			$objCache->forceRewriting(true);

			if($objCache->startDataCache($this->ttl, $this->entity, $DB->type."/".$this->entity, $this->values, "stack_cache"))
			{
				$objCache->endDataCache();
			}

			$this->cleanGet = true;
			$this->cleanSet = true;
		}
	}
}