<?php

/* --------------------------------------------------------------
   ClassFinder.inc.php 2016-07-18
   Gambio GmbH
   http://www.gambio.de
   Copyright (c) 2016 Gambio GmbH
   Released under the GNU General Public License (Version 2)
   [http://www.gnu.org/licenses/gpl-2.0.html]
   --------------------------------------------------------------
*/

/**
 * Class Finder
 *
 * @category   System
 * @package    Shared
 * @subpackage ClassFinder
 */
class ClassFinder implements ClassFinderInterface
{
    /**
     * @var array
     */
    protected $availableClassesArray = [];
    
    /**
     * @var array
     */
    protected $allowedDirectories = [];
    
    /**
     * @var array
     */
    protected $disallowedDirectories = [];
    
    /**
     * @var DataCache
     */
    protected $dataCache;
    
    /**
     * @var array
     */
    protected $cachedResults;
    
    
    /**
     * Constructor
     *
     * @param ClassFinderSettingsInterface $settings
     * @param DataCache                    $dataCache
     */
    public function __construct(ClassFinderSettingsInterface $settings, DataCache $dataCache)
    {
        $this->availableClassesArray = $settings->getAvailableClasses();
        $this->allowedDirectories    = $settings->getAllowedDirectories();
        $this->disallowedDirectories = $settings->getDisallowedDirectories();
        $this->cachedResults         = $dataCache->get_persistent_data('ClassFinder');
        $this->dataCache             = $dataCache;
    }
    
    
    /**
     * Destructor
     *
     * Update the cache file with the latest results.
     */
    public function __destruct()
    {
        $this->dataCache->write_persistent_data('ClassFinder', $this->cachedResults);
    }
    
    
    /**
     * Returns an associative array with classes that have the given class in their parent list.
     * Array format: [ClassName] => [ClassFullFilePath]
     *
     * @param string $parentClassName
     *
     * @return array
     */
    public function findByParent($parentClassName)
    {
        if (empty($this->cachedResults[$parentClassName])) {
            $resultArray = [];
            foreach ($this->availableClassesArray as $className => $classFile) {
                if ($this->_hasNeededParent($className, $parentClassName) === true) {
                    $resultArray[$className] = $classFile;
                }
            }
            
            $this->cachedResults[$parentClassName] = $resultArray;
        } else {
            $resultArray = $this->cachedResults[$parentClassName];
        }
        
        return MainFactory::create('KeyValueCollection', $resultArray);
    }
    
    
    /**
     * Returns an associative array with classes that implement the given interface.
     * Array format: [ClassName] => [ClassFullFilePath]
     *
     * @param string $interfaceName
     *
     * @return array
     *
     * @throws RuntimeException
     */
    public function findByInterface($interfaceName)
    {
        throw new RuntimeException('Not implemented yet.');
    }
    
    
    /**
     * Checks if $className a sub-class of $neededParentClassName
     *
     * @param string $className
     * @param string $neededParentClassName
     *
     * @return bool
     */
    protected function _hasNeededParent($className, $neededParentClassName)
    {
        // May I load the class file?
        $classFile = $this->availableClassesArray[$className];
        if ($this->_isLoadableClassFile($classFile) === false) {
            return false;
        }
        
        // Is the expected class inside?
        MainFactory::load_class($className);
        if (class_exists($className, false) === false) {
            return false;
        }
        
        // Does the class have the needed parent?
        $classParentsArray = class_parents($className, false);
        if (is_array($classParentsArray) === false || in_array($neededParentClassName, $classParentsArray) === false) {
            return false;
        }
        
        return true;
    }
    
    
    /**
     * Checks if $classFile is allowed to be included
     *
     * @param string $classFile
     *
     * @return bool
     */
    protected function _isLoadableClassFile($classFile)
    {
        if (substr($classFile, -8, 8) !== '.inc.php') {
            // File needs to end with ".inc.php"
            return false;
        }
        
        foreach ($this->disallowedDirectories as $dirItem) {
            if (strpos($classFile, $dirItem) !== false) {
                // File is located in not allowed directory
                return false;
            }
        }
        
        foreach ($this->allowedDirectories as $dirItem) {
            if (strpos($classFile, $dirItem) !== false) {
                // File is located in allowed directory
                return true;
            }
        }
        
        return false;
    }
    
}