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<?php
/**
* This file is part of RSS-Bridge, a PHP project capable of generating RSS and
* Atom feeds for websites that don't have one.
*
* For the full license information, please view the UNLICENSE file distributed
* with this source code.
*
* @package Core
* @license http://unlicense.org/ UNLICENSE
* @link https://github.com/rss-bridge/rss-bridge
*/
/**
* Factory class responsible for creating bridge objects from a given working
* directory, limited by a whitelist.
*
* This class is capable of:
* - Locating bridge classes in the specified working directory (see {@see Bridge::$workingDir})
* - Filtering bridges based on a whitelist (see {@see Bridge::$whitelist})
* - Creating new bridge instances based on the bridge's name (see {@see Bridge::create()})
*
* The following example illustrates the intended use for this class.
*
* ```PHP
* require_once __DIR__ . '/rssbridge.php';
*
* // Step 1: Set the working directory
* Bridge::setWorkingDir(__DIR__ . '/../bridges/');
*
* // Step 2: Add bridges to the whitelist
* Bridge::setWhitelist(array('GitHubIssue', 'GoogleSearch', 'Facebook', 'Twitter'));
*
* // Step 3: Create a new instance of a bridge (based on the name)
* $bridge = Bridge::create('GitHubIssue');
* ```
*/
class BridgeFactory extends FactoryAbstract {
/**
* Holds a list of whitelisted bridges.
*
* Do not access this property directly!
* Use {@see Bridge::getWhitelist()} instead.
*
* @var array
*/
protected $whitelist = array();
/**
* Creates a new bridge object from the working directory.
*
* @throws \InvalidArgumentException if the requested bridge name is invalid.
* @throws \Exception if the requested bridge doesn't exist in the working
* directory.
* @param string $name Name of the bridge object.
* @return object|bool The bridge object or false if the class is not instantiable.
*/
public function create($name){
if(!$this->isBridgeName($name)) {
throw new \InvalidArgumentException('Bridge name invalid!');
}
$name = $this->sanitizeBridgeName($name) . 'Bridge';
$filePath = $this->getWorkingDir() . $name . '.php';
if(!file_exists($filePath)) {
throw new \Exception('Bridge file ' . $filePath . ' does not exist!');
}
require_once $filePath;
if((new \ReflectionClass($name))->isInstantiable()) {
return new $name();
}
return false;
}
/**
* Returns true if the provided name is a valid bridge name.
*
* A valid bridge name starts with a capital letter ([A-Z]), followed by
* zero or more alphanumeric characters or hyphen ([A-Za-z0-9-]).
*
* @param string $name The bridge name.
* @return bool true if the name is a valid bridge name, false otherwise.
*/
public function isBridgeName($name){
return is_string($name) && preg_match('/^[A-Z][a-zA-Z0-9-]*$/', $name) === 1;
}
/**
* Returns the list of bridge names from the working directory.
*
* The list is cached internally to allow for successive calls.
*
* @return array List of bridge names
*/
public function getBridgeNames(){
static $bridgeNames = array(); // Initialized on first call
if(empty($bridgeNames)) {
$files = scandir($this->getWorkingDir());
if($files !== false) {
foreach($files as $file) {
if(preg_match('/^([^.]+)Bridge\.php$/U', $file, $out)) {
$bridgeNames[] = $out[1];
}
}
}
}
return $bridgeNames;
}
/**
* Checks if a bridge is whitelisted.
*
* @param string $name Name of the bridge.
* @return bool True if the bridge is whitelisted.
*/
public function isWhitelisted($name){
return in_array($this->sanitizeBridgeName($name), $this->getWhitelist());
}
/**
* Returns the whitelist.
*
* On first call this function reads the whitelist from {@see WHITELIST} if
* the file exists, {@see WHITELIST_DEFAULT} otherwise.
* * Each line in the file specifies one bridge on the whitelist.
* * An empty file disables all bridges.
* * If the file only only contains `*`, all bridges are whitelisted.
*
* Use {@see Bridge::setWhitelist()} to specify a default whitelist **before**
* calling this function! The list is cached internally to allow for
* successive calls. If {@see Bridge::setWhitelist()} gets called after this
* function, the whitelist is **not** updated again!
*
* @return array Array of whitelisted bridges
*/
public function getWhitelist() {
static $firstCall = true; // Initialized on first call
if($firstCall) {
if(file_exists(WHITELIST)) {
$contents = trim(file_get_contents(WHITELIST));
} elseif(file_exists(WHITELIST_DEFAULT)) {
$contents = trim(file_get_contents(WHITELIST_DEFAULT));
} else {
$contents = '';
}
if($contents === '*') { // Whitelist all bridges
$this->whitelist = $this->getBridgeNames();
} else {
//$this->$whitelist = array_map('$this->sanitizeBridgeName', explode("\n", $contents));
foreach(explode("\n", $contents) as $bridgeName) {
$this->whitelist[] = $this->sanitizeBridgeName($bridgeName);
}
}
}
return $this->whitelist;
}
/**
* Sets the (default) whitelist.
*
* If this function is called **before** {@see Bridge::getWhitelist()}, the
* provided whitelist will be replaced by a custom whitelist specified in
* {@see WHITELIST} (if it exists).
*
* If this function is called **after** {@see Bridge::getWhitelist()}, the
* provided whitelist is taken as is (not updated by the custom whitelist
* again).
*
* @param array $default The whitelist as array of bridge names.
* @return void
*/
public function setWhitelist($default = array()) {
$this->whitelist = array_map('$this->sanitizeBridgeName', $default);
}
/**
* Returns the sanitized bridge name.
*
* The bridge name can be specified in various ways:
* * The PHP file name (i.e. `GitHubIssueBridge.php`)
* * The PHP file name without file extension (i.e. `GitHubIssueBridge`)
* * The bridge name (i.e. `GitHubIssue`)
*
* Casing is ignored (i.e. `GITHUBISSUE` and `githubissue` are the same).
*
* A bridge file matching the given bridge name must exist in the working
* directory!
*
* @param string $name The bridge name
* @return string|null The sanitized bridge name if the provided name is
* valid, null otherwise.
*/
protected function sanitizeBridgeName($name) {
if(is_string($name)) {
// Trim trailing '.php' if exists
if(preg_match('/(.+)(?:\.php)/', $name, $matches)) {
$name = $matches[1];
}
// Trim trailing 'Bridge' if exists
if(preg_match('/(.+)(?:Bridge)/i', $name, $matches)) {
$name = $matches[1];
}
// Improve performance for correctly written bridge names
if(in_array($name, $this->getBridgeNames())) {
$index = array_search($name, $this->getBridgeNames());
return $this->getBridgeNames()[$index];
}
// The name is valid if a corresponding bridge file is found on disk
if(in_array(strtolower($name), array_map('strtolower', $this->getBridgeNames()))) {
$index = array_search(strtolower($name), array_map('strtolower', $this->getBridgeNames()));
return $this->getBridgeNames()[$index];
}
Debug::log('Invalid bridge name specified: "' . $name . '"!');
}
return null; // Bad parameter
}
}
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