<?php
/**
 * TCache and cache dependency classes.
 *
 * @author Qiang Xue <qiang.xue@gmail.com>
 * @link http://www.pradosoft.com/
 * @copyright Copyright &copy; 2005-2014 PradoSoft
 * @license http://www.pradosoft.com/license/
 * @package Prado\Caching
 */

namespace Prado\Caching;

/**
 * TDirectoryCacheDependency class.
 *
 * TDirectoryCacheDependency performs dependency checking based on the
 * modification time of the files contained in the specified directory.
 * The directory being checked is specified via {@link setDirectory Directory}.
 *
 * By default, all files under the specified directory and subdirectories
 * will be checked. If the last modification time of any of them is changed
 * or if different number of files are contained in a directory, the dependency
 * is reported as changed. By specifying {@link setRecursiveCheck RecursiveCheck}
 * and {@link setRecursiveLevel RecursiveLevel}, one can limit the checking
 * to a certain depth of the subdirectories.
 *
 * @author Qiang Xue <qiang.xue@gmail.com>
 * @package Prado\Caching
 * @since 3.1.0
 */
class TDirectoryCacheDependency extends TCacheDependency
{
	private $_recursiveCheck=true;
	private $_recursiveLevel=-1;
	private $_timestamps;
	private $_directory;

	/**
	 * Constructor.
	 * @param string the directory to be checked
	 */
	public function __construct($directory)
	{
		$this->setDirectory($directory);
	}

	/**
	 * @return string the directory to be checked
	 */
	public function getDirectory()
	{
		return $this->_directory;
	}

	/**
	 * @param string the directory to be checked
	 * @throws TInvalidDataValueException if the directory does not exist
	 */
	public function setDirectory($directory)
	{
		if(($path=realpath($directory))===false || !is_dir($path))
			throw new TInvalidDataValueException('directorycachedependency_directory_invalid',$directory);
		$this->_directory=$path;
		$this->_timestamps=$this->generateTimestamps($path);
	}

	/**
	 * @return boolean whether the subdirectories of the directory will also be checked.
	 * It defaults to true.
	 */
	public function getRecursiveCheck()
	{
		return $this->_recursiveCheck;
	}

	/**
	 * @param boolean whether the subdirectories of the directory will also be checked.
	 */
	public function setRecursiveCheck($value)
	{
		$this->_recursiveCheck=TPropertyValue::ensureBoolean($value);
	}

	/**
	 * @return int the depth of the subdirectories to be checked.
	 * It defaults to -1, meaning unlimited depth.
	 */
	public function getRecursiveLevel()
	{
		return $this->_recursiveLevel;
	}

	/**
	 * Sets a value indicating the depth of the subdirectories to be checked.
	 * This is meaningful only when {@link getRecursiveCheck RecursiveCheck}
	 * is true.
	 * @param int the depth of the subdirectories to be checked.
	 * If the value is less than 0, it means unlimited depth.
	 * If the value is 0, it means checking the files directly under the specified directory.
	 */
	public function setRecursiveLevel($value)
	{
		$this->_recursiveLevel=TPropertyValue::ensureInteger($value);
	}

	/**
	 * Performs the actual dependency checking.
	 * This method returns true if the directory is changed.
	 * @return boolean whether the dependency is changed or not.
	 */
	public function getHasChanged()
	{
		return $this->generateTimestamps($this->_directory)!=$this->_timestamps;
	}

	/**
	 * Checks to see if the file should be checked for dependency.
	 * This method is invoked when dependency of the whole directory is being checked.
	 * By default, it always returns true, meaning the file should be checked.
	 * You may override this method to check only certain files.
	 * @param string the name of the file that may be checked for dependency.
	 * @return boolean whether this file should be checked.
	 */
	protected function validateFile($fileName)
	{
		return true;
	}

	/**
	 * Checks to see if the specified subdirectory should be checked for dependency.
	 * This method is invoked when dependency of the whole directory is being checked.
	 * By default, it always returns true, meaning the subdirectory should be checked.
	 * You may override this method to check only certain subdirectories.
	 * @param string the name of the subdirectory that may be checked for dependency.
	 * @return boolean whether this subdirectory should be checked.
	 */
	protected function validateDirectory($directory)
	{
		return true;
	}

	/**
	 * Determines the last modification time for files under the directory.
	 * This method may go recursively into subdirectories if
	 * {@link setRecursiveCheck RecursiveCheck} is set true.
	 * @param string the directory name
	 * @param int level of the recursion
	 * @return array list of file modification time indexed by the file path
	 */
	protected function generateTimestamps($directory,$level=0)
	{
		if(($dir=opendir($directory))===false)
			throw new TIOException('directorycachedependency_directory_invalid',$directory);
		$timestamps=array();
		while(($file=readdir($dir))!==false)
		{
			$path=$directory.DIRECTORY_SEPARATOR.$file;
			if($file==='.' || $file==='..')
				continue;
			else if(is_dir($path))
			{
				if(($this->_recursiveLevel<0 || $level<$this->_recursiveLevel) && $this->validateDirectory($path))
					$timestamps=array_merge($this->generateTimestamps($path,$level+1));
			}
			else if($this->validateFile($path))
				$timestamps[$path]=filemtime($path);
		}
		closedir($dir);
		return $timestamps;
	}
}