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                <?php  | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                namespace Intraxia\Jaxion\Http;  | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                use Intraxia\Jaxion\Contract\Http\Guard as GuardContract;  | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                use Intraxia\Jaxion\Utility\Str;  | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                use WP_Error;  | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                /**  | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                 * Class Guard  | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                 *  | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                 * Protects routes by validating that  | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                 * the accessing user has required permissions.  | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                 *  | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                 * @package Intraxia\Jaxion  | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                 * @subpackage Http  | 
            
            
                                                                                                            
                                                                
            
                                    
            
            
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                 */  | 
            
            
                                                                        
                            
            
                                    
            
            
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                class Guard implements GuardContract { | 
            
            
                                                                        
                            
            
                                    
            
            
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                	/**  | 
            
            
                                                                        
                            
            
                                    
            
            
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                	 * Default options.  | 
            
            
                                                                        
                            
            
                                    
            
            
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                	 *  | 
            
            
                                                                        
                            
            
                                    
            
            
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                	 * @var array  | 
            
            
                                                                        
                            
            
                                    
            
            
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                	 */  | 
            
            
                                                                        
                            
            
                                    
            
            
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                	protected $defaults = array(  | 
            
            
                                                                        
                            
            
                                    
            
            
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                		'rule'     => 'public',  | 
            
            
                                                                        
                            
            
                                    
            
            
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                		'callback' => null,  | 
            
            
                                                                        
                            
            
                                    
            
            
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                	);  | 
            
            
                                                                        
                            
            
                                    
            
            
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                	/**  | 
            
            
                                                                        
                            
            
                                    
            
            
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                	 * Guard options.  | 
            
            
                                                                        
                            
            
                                    
            
            
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                	 *  | 
            
            
                                                                        
                            
            
                                    
            
            
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                	 * @var array  | 
            
            
                                                                        
                            
            
                                    
            
            
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                	 */  | 
            
            
                                                                        
                            
            
                                    
            
            
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                	protected $options;  | 
            
            
                                                                        
                            
            
                                    
            
            
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                	/**  | 
            
            
                                                                        
                            
            
                                    
            
            
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                	 * Instantiate a new Guard with provided options.  | 
            
            
                                                                        
                            
            
                                    
            
            
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                	 *  | 
            
            
                                                                        
                            
            
                                    
            
            
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                	 * @param array $options  | 
            
            
                                                                        
                            
            
                                    
            
            
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                	 */  | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                	public function __construct( array $options = array() ) { | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                		$this->options = $this->set_defaults( $options );  | 
            
            
                                                                                                            
                                                                
            
                                    
            
            
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                	}  | 
            
            
                                                                        
                            
            
                                    
            
            
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                	/**  | 
            
            
                                                                        
                            
            
                                    
            
            
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                	 * Validates whether the current user is authorized.  | 
            
            
                                                                        
                            
            
                                    
            
            
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                	 *  | 
            
            
                                                                        
                            
            
                                    
            
            
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                	 * @return true|WP_Error  | 
            
            
                                                                        
                            
            
                                    
            
            
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                	 */  | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                	public function authorized() { | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                		// if the rule is public, always authorized  | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                		if ( 'public' === $this->options['rule'] ) { | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                			return true;  | 
            
                            
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                		}  | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                		// enable passing in callback  | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                		if ( 'callback' === $this->options['rule'] && is_callable( $this->options['callback'] ) ) { | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                			return call_user_func( $this->options['callback'] );  | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                		}  | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                		// map rule to method  | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                		if ( method_exists( $this, $method = $this->options['rule'] ) ) { | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                			return $this->{$method}(); | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                		}  | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                		// disable in rule is misconfigused  | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                		// @todo set up internal translations  | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                		return new WP_Error( 'misconfigured_guard', __( 'Misconfigured guard rule', 'jaxion' ), [ 'status' => 500 ] );  | 
            
                            
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                	}  | 
            
            
                                                                        
                            
            
                                    
            
            
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                	/**  | 
            
            
                                                                        
                            
            
                                    
            
            
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                	 * Checks whether the current user can edit other's posts.  | 
            
            
                                                                        
                            
            
                                    
            
            
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                	 *  | 
            
            
                                                                        
                            
            
                                    
            
            
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                	 * @return bool|WP_Error  | 
            
            
                                                                        
                            
            
                                    
            
            
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                	 */  | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                	protected function can_edit_others_posts() { | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                		return current_user_can( 'edit_others_posts' ) ?: $this->make_error();  | 
            
            
                                                                                                            
                                                                
            
                                    
            
            
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                	}  | 
            
            
                                                                        
                            
            
                                    
            
            
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                	/**  | 
            
            
                                                                        
                            
            
                                    
            
            
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                	 * Checks whether the user is currently logged in.  | 
            
            
                                                                        
                            
            
                                    
            
            
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                	 *  | 
            
            
                                                                        
                            
            
                                    
            
            
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                	 * @return bool|WP_Error  | 
            
            
                                                                        
                            
            
                                    
            
            
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                	 */  | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                	protected function user_logged_in() { | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                		return is_user_logged_in() ?: $this->make_error();  | 
            
            
                                                                                                            
                                                                
            
                                    
            
            
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                	}  | 
            
            
                                                                        
                            
            
                                    
            
            
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                	/**  | 
            
            
                                                                        
                            
            
                                    
            
            
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                	 * Checks whether the user can manage the site options.  | 
            
            
                                                                        
                            
            
                                    
            
            
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                	 *  | 
            
            
                                                                        
                            
            
                                    
            
            
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                	 * @return bool|WP_Error  | 
            
            
                                                                        
                            
            
                                    
            
            
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                	 */  | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                	protected function can_manage_options() { | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                		return current_user_can( 'manage_options' ) ?: $this->make_error();  | 
            
            
                                                                                                            
                                                                
            
                                    
            
            
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                	}  | 
            
            
                                                                        
                            
            
                                    
            
            
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                	/**  | 
            
            
                                                                        
                            
            
                                    
            
            
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                	 * Sets the default params for the Guard options.  | 
            
            
                                                                        
                            
            
                                    
            
            
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                	 *  | 
            
            
                                                                        
                            
            
                                    
            
            
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                	 * @param array $options  | 
            
            
                                                                        
                            
            
                                    
            
            
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                	 *  | 
            
            
                                                                        
                            
            
                                    
            
            
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                	 * @return array  | 
            
            
                                                                        
                            
            
                                    
            
            
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                	 */  | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                	protected function set_defaults( $options ) { | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                		// these are the valid options  | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                		return wp_parse_args( $options, $this->defaults );  | 
            
            
                                                                                                            
                                                                
            
                                    
            
            
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                	}  | 
            
            
                                                                        
                            
            
                                    
            
            
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                	/**  | 
            
            
                                                                        
                            
            
                                    
            
            
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                	 * Create an unauthorized error object.  | 
            
            
                                                                        
                            
            
                                    
            
            
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                	 *  | 
            
            
                                                                        
                            
            
                                    
            
            
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                	 * @return WP_Error  | 
            
            
                                                                        
                            
            
                                    
            
            
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                	 */  | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                	protected function make_error() { | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                		return new WP_Error( 'unauthorized', __( 'Unauthorized user', 'jaxion' ), array( 'status' => 401 ) );  | 
            
            
                                                                                                            
                                                                
            
                                    
            
            
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                	}  | 
            
            
                                                        
            
                                    
            
            
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                }  | 
            
            
                                                        
            
                                    
            
            
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If you return a value from a function or method, it should be a sub-type of the type that is given by the parent type f.e. an interface, or abstract method. This is more formally defined by the Lizkov substitution principle, and guarantees that classes that depend on the parent type can use any instance of a child type interchangably. This principle also belongs to the SOLID principles for object oriented design.
Let’s take a look at an example:
Our function
my_functionexpects aPostobject, and outputs the author of the post. The base classPostreturns a simple string and outputting a simple string will work just fine. However, the child classBlogPostwhich is a sub-type ofPostinstead decided to return anobject, and is therefore violating the SOLID principles. If aBlogPostwere passed tomy_function, PHP would not complain, but ultimately fail when executing thestrtouppercall in its body.