<?php

namespace GuzzleHttp;

use GuzzleHttp\Promise\PromiseInterface;
use Psr\Http\Message\RequestInterface;
use Psr\Http\Message\ResponseInterface;

/**
 * Creates a composed Guzzle handler function by stacking middlewares on top of
 * an HTTP handler function.
 *
 * @final
 */
class HandlerStack
{
    /**
     * @var (callable(RequestInterface, array): PromiseInterface)|null
     */
    private $handler;

    /**
     * @var array{(callable(callable(RequestInterface, array): PromiseInterface): callable), (string|null)}[]
     */
    private $stack = [];

    /**
     * @var (callable(RequestInterface, array): PromiseInterface)|null
     */
    private $cached;

    /**
     * Creates a default handler stack that can be used by clients.
     *
     * The returned handler will wrap the provided handler or use the most
     * appropriate default handler for your system. The returned HandlerStack has
     * support for cookies, redirects, HTTP error exceptions, and preparing a body
     * before sending.
     *
     * The returned handler stack can be passed to a client in the "handler"
     * option.
     *
     * @param (callable(RequestInterface, array): PromiseInterface)|null $handler HTTP handler function to use with the stack. If no
     *                                                                            handler is provided, the best handler for your
     *                                                                            system will be utilized.
     */
    public static function create(callable $handler = null): self
    {
        $stack = new self($handler ?: Utils::chooseHandler());
        $stack->push(Middleware::httpErrors(), 'http_errors');
        $stack->push(Middleware::redirect(), 'allow_redirects');
        $stack->push(Middleware::cookies(), 'cookies');
        $stack->push(Middleware::prepareBody(), 'prepare_body');

        return $stack;
    }

    /**
     * @param (callable(RequestInterface, array): PromiseInterface)|null $handler Underlying HTTP handler.
     */
    public function __construct(callable $handler = null)
    {
        $this->handler = $handler;
    }

    /**
     * Invokes the handler stack as a composed handler
     *
     * @return ResponseInterface|PromiseInterface
     */
    public function __invoke(RequestInterface $request, array $options)
    {
        $handler = $this->resolve();

        return $handler($request, $options);
    }

    /**
     * Dumps a string representation of the stack.
     *
     * @return string
     */
    public function __toString()
    {
        $depth = 0;
        $stack = [];

        if ($this->handler !== null) {
            $stack[] = '0) Handler: '.$this->debugCallable($this->handler);
        }

        $result = '';
        foreach (\array_reverse($this->stack) as $tuple) {
            ++$depth;
            $str = "{$depth}) Name: '{$tuple[1]}', ";
            $str .= 'Function: '.$this->debugCallable($tuple[0]);
            $result = "> {$str}\n{$result}";
            $stack[] = $str;
        }

        foreach (\array_keys($stack) as $k) {
            $result .= "< {$stack[$k]}\n";
        }

        return $result;
    }

    /**
     * Set the HTTP handler that actually returns a promise.
     *
     * @param callable(RequestInterface, array): PromiseInterface $handler Accepts a request and array of options and
     *                                                                     returns a Promise.
     */
    public function setHandler(callable $handler): void
    {
        $this->handler = $handler;
        $this->cached = null;
    }

    /**
     * Returns true if the builder has a handler.
     */
    public function hasHandler(): bool
    {
        return $this->handler !== null;
    }

    /**
     * Unshift a middleware to the bottom of the stack.
     *
     * @param callable(callable): callable $middleware Middleware function
     * @param string                       $name       Name to register for this middleware.
     */
    public function unshift(callable $middleware, string $name = null): void
    {
        \array_unshift($this->stack, [$middleware, $name]);
        $this->cached = null;
    }

    /**
     * Push a middleware to the top of the stack.
     *
     * @param callable(callable): callable $middleware Middleware function
     * @param string                       $name       Name to register for this middleware.
     */
    public function push(callable $middleware, string $name = ''): void
    {
        $this->stack[] = [$middleware, $name];
        $this->cached = null;
    }

    /**
     * Add a middleware before another middleware by name.
     *
     * @param string                       $findName   Middleware to find
     * @param callable(callable): callable $middleware Middleware function
     * @param string                       $withName   Name to register for this middleware.
     */
    public function before(string $findName, callable $middleware, string $withName = ''): void
    {
        $this->splice($findName, $withName, $middleware, true);
    }

    /**
     * Add a middleware after another middleware by name.
     *
     * @param string                       $findName   Middleware to find
     * @param callable(callable): callable $middleware Middleware function
     * @param string                       $withName   Name to register for this middleware.
     */
    public function after(string $findName, callable $middleware, string $withName = ''): void
    {
        $this->splice($findName, $withName, $middleware, false);
    }

    /**
     * Remove a middleware by instance or name from the stack.
     *
     * @param callable|string $remove Middleware to remove by instance or name.
     */
    public function remove($remove): void
    {
        if (!is_string($remove) && !is_callable($remove)) {
            trigger_deprecation('guzzlehttp/guzzle', '7.4', 'Not passing a callable or string to %s::%s() is deprecated and will cause an error in 8.0.', __CLASS__, __FUNCTION__);
        }

        $this->cached = null;
        $idx = \is_callable($remove) ? 0 : 1;
        $this->stack = \array_values(\array_filter(
            $this->stack,
            static function ($tuple) use ($idx, $remove) {
                return $tuple[$idx] !== $remove;
            }
        ));
    }

    /**
     * Compose the middleware and handler into a single callable function.
     *
     * @return callable(RequestInterface, array): PromiseInterface
     */
    public function resolve(): callable
    {
        if ($this->cached === null) {
            if (($prev = $this->handler) === null) {
                throw new \LogicException('No handler has been specified');
            }

            foreach (\array_reverse($this->stack) as $fn) {
                /** @var callable(RequestInterface, array): PromiseInterface $prev */
                $prev = $fn[0]($prev);
            }

            $this->cached = $prev;
        }

        return $this->cached;
    }

    private function findByName(string $name): int
    {
        foreach ($this->stack as $k => $v) {
            if ($v[1] === $name) {
                return $k;
            }
        }

        throw new \InvalidArgumentException("Middleware not found: $name");
    }

    /**
     * Splices a function into the middleware list at a specific position.
     */
    private function splice(string $findName, string $withName, callable $middleware, bool $before): void
    {
        $this->cached = null;
        $idx = $this->findByName($findName);
        $tuple = [$middleware, $withName];

        if ($before) {
            if ($idx === 0) {
                \array_unshift($this->stack, $tuple);
            } else {
                $replacement = [$tuple, $this->stack[$idx]];
                \array_splice($this->stack, $idx, 1, $replacement);
            }
        } elseif ($idx === \count($this->stack) - 1) {
            $this->stack[] = $tuple;
        } else {
            $replacement = [$this->stack[$idx], $tuple];
            \array_splice($this->stack, $idx, 1, $replacement);
        }
    }

    /**
     * Provides a debug string for a given callable.
     *
     * @param callable|string $fn Function to write as a string.
     */
    private function debugCallable($fn): string
    {
        if (\is_string($fn)) {
            return "callable({$fn})";
        }

        if (\is_array($fn)) {
            return \is_string($fn[0])
                ? "callable({$fn[0]}::{$fn[1]})"
                : "callable(['".\get_class($fn[0])."', '{$fn[1]}'])";
        }

        /** @var object $fn */
        return 'callable('.\spl_object_hash($fn).')';
    }
}

• [D] Cookie
• [D] Exception
• [D] Handler
• [F] BodySummarizer.php
  Delete
• [F] BodySummarizerInterface.php
  Delete
• [F] Client.php
  Delete
• [F] ClientInterface.php
  Delete
• [F] ClientTrait.php
  Delete
• [F] functions.php
  Delete
• [F] functions_include.php
  Delete
• [F] HandlerStack.php
  Delete
• [F] MessageFormatter.php
  Delete
• [F] MessageFormatterInterface.php
  Delete
• [F] Middleware.php
  Delete
• [F] Pool.php
  Delete
• [F] PrepareBodyMiddleware.php
  Delete
• [F] RedirectMiddleware.php
  Delete
• [F] RequestOptions.php
  Delete
• [F] RetryMiddleware.php
  Delete
• [F] TransferStats.php
  Delete
• [F] Utils.php
  Delete

About Section

About NFC Pay: Our Story and Mission

NFC Pay was founded with a vision to transform the way people handle transactions. Our journey is defined by a commitment to innovation, security, and convenience. We strive to deliver seamless, user-friendly payment solutions that make everyday transactions effortless and secure. Our mission is to empower you to pay with ease and confidence, anytime, anywhere.

• Simplifying Payments, One Tap at a Time.
• Reinventing Your Wallet for Modern Convenience.
• Smart Payments for a Effortless Lifestyle.
• Experience the Ease of Tap and Pay.
• Innovative Solutions for Your Daily Transactions.

FAQ Section

Frequently Asked Questions About NFC Pay

Here are answers to some common questions about NFC Pay. We aim to provide clear and concise information to help you understand how our platform works and how it can benefit you. If you have any further inquiries, please don’t hesitate to contact our support team.

How do I register for NFC Pay?

Download the app and sign up using your email or phone number, then complete the verification process.

Is my payment information secure?

Yes, we use advanced encryption and security protocols to protect your payment details.

Can I add multiple cards to my NFC Pay wallet?

Absolutely, you can link multiple debit or credit cards to your wallet.

How do I transfer money to another user?

Go to the transfer section, select the recipient, enter the amount, and authorize the transfer.

What should I do if I forget my PIN?

Use the “Forgot PIN” feature in the app to reset it following the provided instructions.

How can I activate my merchant account?

Sign up for a merchant account through the app and follow the setup instructions to start accepting payments.

Can I track my payment status?

Yes, you can view and track your payment status in the account dashboard