Chris@0: <?php
Chris@0: namespace GuzzleHttp;
Chris@0: 
Chris@0: use Psr\Http\Message\RequestInterface;
Chris@0: 
Chris@0: /**
Chris@0:  * Creates a composed Guzzle handler function by stacking middlewares on top of
Chris@0:  * an HTTP handler function.
Chris@0:  */
Chris@0: class HandlerStack
Chris@0: {
Chris@0:     /** @var callable */
Chris@0:     private $handler;
Chris@0: 
Chris@0:     /** @var array */
Chris@0:     private $stack = [];
Chris@0: 
Chris@0:     /** @var callable|null */
Chris@0:     private $cached;
Chris@0: 
Chris@0:     /**
Chris@0:      * Creates a default handler stack that can be used by clients.
Chris@0:      *
Chris@0:      * The returned handler will wrap the provided handler or use the most
Chris@13:      * appropriate default handler for your system. The returned HandlerStack has
Chris@0:      * support for cookies, redirects, HTTP error exceptions, and preparing a body
Chris@0:      * before sending.
Chris@0:      *
Chris@0:      * The returned handler stack can be passed to a client in the "handler"
Chris@0:      * option.
Chris@0:      *
Chris@0:      * @param callable $handler HTTP handler function to use with the stack. If no
Chris@0:      *                          handler is provided, the best handler for your
Chris@0:      *                          system will be utilized.
Chris@0:      *
Chris@0:      * @return HandlerStack
Chris@0:      */
Chris@0:     public static function create(callable $handler = null)
Chris@0:     {
Chris@0:         $stack = new self($handler ?: choose_handler());
Chris@0:         $stack->push(Middleware::httpErrors(), 'http_errors');
Chris@0:         $stack->push(Middleware::redirect(), 'allow_redirects');
Chris@0:         $stack->push(Middleware::cookies(), 'cookies');
Chris@0:         $stack->push(Middleware::prepareBody(), 'prepare_body');
Chris@0: 
Chris@0:         return $stack;
Chris@0:     }
Chris@0: 
Chris@0:     /**
Chris@0:      * @param callable $handler Underlying HTTP handler.
Chris@0:      */
Chris@0:     public function __construct(callable $handler = null)
Chris@0:     {
Chris@0:         $this->handler = $handler;
Chris@0:     }
Chris@0: 
Chris@0:     /**
Chris@0:      * Invokes the handler stack as a composed handler
Chris@0:      *
Chris@0:      * @param RequestInterface $request
Chris@0:      * @param array            $options
Chris@0:      */
Chris@0:     public function __invoke(RequestInterface $request, array $options)
Chris@0:     {
Chris@0:         $handler = $this->resolve();
Chris@0: 
Chris@0:         return $handler($request, $options);
Chris@0:     }
Chris@0: 
Chris@0:     /**
Chris@0:      * Dumps a string representation of the stack.
Chris@0:      *
Chris@0:      * @return string
Chris@0:      */
Chris@0:     public function __toString()
Chris@0:     {
Chris@0:         $depth = 0;
Chris@0:         $stack = [];
Chris@0:         if ($this->handler) {
Chris@0:             $stack[] = "0) Handler: " . $this->debugCallable($this->handler);
Chris@0:         }
Chris@0: 
Chris@0:         $result = '';
Chris@0:         foreach (array_reverse($this->stack) as $tuple) {
Chris@0:             $depth++;
Chris@0:             $str = "{$depth}) Name: '{$tuple[1]}', ";
Chris@0:             $str .= "Function: " . $this->debugCallable($tuple[0]);
Chris@0:             $result = "> {$str}\n{$result}";
Chris@0:             $stack[] = $str;
Chris@0:         }
Chris@0: 
Chris@0:         foreach (array_keys($stack) as $k) {
Chris@0:             $result .= "< {$stack[$k]}\n";
Chris@0:         }
Chris@0: 
Chris@0:         return $result;
Chris@0:     }
Chris@0: 
Chris@0:     /**
Chris@0:      * Set the HTTP handler that actually returns a promise.
Chris@0:      *
Chris@0:      * @param callable $handler Accepts a request and array of options and
Chris@0:      *                          returns a Promise.
Chris@0:      */
Chris@0:     public function setHandler(callable $handler)
Chris@0:     {
Chris@0:         $this->handler = $handler;
Chris@0:         $this->cached = null;
Chris@0:     }
Chris@0: 
Chris@0:     /**
Chris@0:      * Returns true if the builder has a handler.
Chris@0:      *
Chris@0:      * @return bool
Chris@0:      */
Chris@0:     public function hasHandler()
Chris@0:     {
Chris@0:         return (bool) $this->handler;
Chris@0:     }
Chris@0: 
Chris@0:     /**
Chris@0:      * Unshift a middleware to the bottom of the stack.
Chris@0:      *
Chris@0:      * @param callable $middleware Middleware function
Chris@0:      * @param string   $name       Name to register for this middleware.
Chris@0:      */
Chris@0:     public function unshift(callable $middleware, $name = null)
Chris@0:     {
Chris@0:         array_unshift($this->stack, [$middleware, $name]);
Chris@0:         $this->cached = null;
Chris@0:     }
Chris@0: 
Chris@0:     /**
Chris@0:      * Push a middleware to the top of the stack.
Chris@0:      *
Chris@0:      * @param callable $middleware Middleware function
Chris@0:      * @param string   $name       Name to register for this middleware.
Chris@0:      */
Chris@0:     public function push(callable $middleware, $name = '')
Chris@0:     {
Chris@0:         $this->stack[] = [$middleware, $name];
Chris@0:         $this->cached = null;
Chris@0:     }
Chris@0: 
Chris@0:     /**
Chris@0:      * Add a middleware before another middleware by name.
Chris@0:      *
Chris@0:      * @param string   $findName   Middleware to find
Chris@0:      * @param callable $middleware Middleware function
Chris@0:      * @param string   $withName   Name to register for this middleware.
Chris@0:      */
Chris@0:     public function before($findName, callable $middleware, $withName = '')
Chris@0:     {
Chris@0:         $this->splice($findName, $withName, $middleware, true);
Chris@0:     }
Chris@0: 
Chris@0:     /**
Chris@0:      * Add a middleware after another middleware by name.
Chris@0:      *
Chris@0:      * @param string   $findName   Middleware to find
Chris@0:      * @param callable $middleware Middleware function
Chris@0:      * @param string   $withName   Name to register for this middleware.
Chris@0:      */
Chris@0:     public function after($findName, callable $middleware, $withName = '')
Chris@0:     {
Chris@0:         $this->splice($findName, $withName, $middleware, false);
Chris@0:     }
Chris@0: 
Chris@0:     /**
Chris@0:      * Remove a middleware by instance or name from the stack.
Chris@0:      *
Chris@0:      * @param callable|string $remove Middleware to remove by instance or name.
Chris@0:      */
Chris@0:     public function remove($remove)
Chris@0:     {
Chris@0:         $this->cached = null;
Chris@0:         $idx = is_callable($remove) ? 0 : 1;
Chris@0:         $this->stack = array_values(array_filter(
Chris@0:             $this->stack,
Chris@0:             function ($tuple) use ($idx, $remove) {
Chris@0:                 return $tuple[$idx] !== $remove;
Chris@0:             }
Chris@0:         ));
Chris@0:     }
Chris@0: 
Chris@0:     /**
Chris@0:      * Compose the middleware and handler into a single callable function.
Chris@0:      *
Chris@0:      * @return callable
Chris@0:      */
Chris@0:     public function resolve()
Chris@0:     {
Chris@0:         if (!$this->cached) {
Chris@0:             if (!($prev = $this->handler)) {
Chris@0:                 throw new \LogicException('No handler has been specified');
Chris@0:             }
Chris@0: 
Chris@0:             foreach (array_reverse($this->stack) as $fn) {
Chris@0:                 $prev = $fn[0]($prev);
Chris@0:             }
Chris@0: 
Chris@0:             $this->cached = $prev;
Chris@0:         }
Chris@0: 
Chris@0:         return $this->cached;
Chris@0:     }
Chris@0: 
Chris@0:     /**
Chris@0:      * @param $name
Chris@0:      * @return int
Chris@0:      */
Chris@0:     private function findByName($name)
Chris@0:     {
Chris@0:         foreach ($this->stack as $k => $v) {
Chris@0:             if ($v[1] === $name) {
Chris@0:                 return $k;
Chris@0:             }
Chris@0:         }
Chris@0: 
Chris@0:         throw new \InvalidArgumentException("Middleware not found: $name");
Chris@0:     }
Chris@0: 
Chris@0:     /**
Chris@0:      * Splices a function into the middleware list at a specific position.
Chris@0:      *
Chris@0:      * @param          $findName
Chris@0:      * @param          $withName
Chris@0:      * @param callable $middleware
Chris@0:      * @param          $before
Chris@0:      */
Chris@0:     private function splice($findName, $withName, callable $middleware, $before)
Chris@0:     {
Chris@0:         $this->cached = null;
Chris@0:         $idx = $this->findByName($findName);
Chris@0:         $tuple = [$middleware, $withName];
Chris@0: 
Chris@0:         if ($before) {
Chris@0:             if ($idx === 0) {
Chris@0:                 array_unshift($this->stack, $tuple);
Chris@0:             } else {
Chris@0:                 $replacement = [$tuple, $this->stack[$idx]];
Chris@0:                 array_splice($this->stack, $idx, 1, $replacement);
Chris@0:             }
Chris@0:         } elseif ($idx === count($this->stack) - 1) {
Chris@0:             $this->stack[] = $tuple;
Chris@0:         } else {
Chris@0:             $replacement = [$this->stack[$idx], $tuple];
Chris@0:             array_splice($this->stack, $idx, 1, $replacement);
Chris@0:         }
Chris@0:     }
Chris@0: 
Chris@0:     /**
Chris@0:      * Provides a debug string for a given callable.
Chris@0:      *
Chris@0:      * @param array|callable $fn Function to write as a string.
Chris@0:      *
Chris@0:      * @return string
Chris@0:      */
Chris@0:     private function debugCallable($fn)
Chris@0:     {
Chris@0:         if (is_string($fn)) {
Chris@0:             return "callable({$fn})";
Chris@0:         }
Chris@0: 
Chris@0:         if (is_array($fn)) {
Chris@0:             return is_string($fn[0])
Chris@0:                 ? "callable({$fn[0]}::{$fn[1]})"
Chris@0:                 : "callable(['" . get_class($fn[0]) . "', '{$fn[1]}'])";
Chris@0:         }
Chris@0: 
Chris@0:         return 'callable(' . spl_object_hash($fn) . ')';
Chris@0:     }
Chris@0: }