<?php

declare(strict_types=1);

namespace GuzzleHttp\Promise;

/**
 * Represents a promise that iterates over many promises and invokes
 * side-effect functions in the process.
 *
 * @final
 */
class EachPromise implements PromisorInterface
{
    private $pending = [];

    private $nextPendingIndex = 0;

    /** @var \Iterator|null */
    private $iterable;

    /** @var callable|int|null */
    private $concurrency;

    /** @var callable|null */
    private $onFulfilled;

    /** @var callable|null */
    private $onRejected;

    /** @var Promise|null */
    private $aggregate;

    /** @var bool|null */
    private $mutex;

    /**
     * Configuration hash can include the following key value pairs:
     *
     * - fulfilled: (callable) Invoked when a promise fulfills. The function
     *   is invoked with three arguments: the fulfillment value, the index
     *   position from the iterable list of the promise, and the aggregate
     *   promise that manages all of the promises. The aggregate promise may
     *   be resolved from within the callback to short-circuit the promise.
     * - rejected: (callable) Invoked when a promise is rejected. The
     *   function is invoked with three arguments: the rejection reason, the
     *   index position from the iterable list of the promise, and the
     *   aggregate promise that manages all of the promises. The aggregate
     *   promise may be resolved from within the callback to short-circuit
     *   the promise.
     * - concurrency: (integer) Pass this configuration option to limit the
     *   allowed number of outstanding concurrently executing promises,
     *   creating a capped pool of promises. There is no limit by default.
     *
     * @param mixed $iterable Promises or values to iterate.
     * @param array $config   Configuration options
     */
    public function __construct($iterable, array $config = [])
    {
        $this->iterable = Create::iterFor($iterable);

        if (isset($config['concurrency'])) {
            $this->concurrency = $config['concurrency'];
        }

        if (isset($config['fulfilled'])) {
            $this->onFulfilled = $config['fulfilled'];
        }

        if (isset($config['rejected'])) {
            $this->onRejected = $config['rejected'];
        }
    }

    /** @psalm-suppress InvalidNullableReturnType */
    public function promise(): PromiseInterface
    {
        if ($this->aggregate) {
            return $this->aggregate;
        }

        try {
            $this->createPromise();
            /** @psalm-assert Promise $this->aggregate */
            $this->iterable->rewind();
            $this->refillPending();
        } catch (\Throwable $e) {
            $this->aggregate->reject($e);
        }

        /**
         * @psalm-suppress NullableReturnStatement
         */
        return $this->aggregate;
    }

    private function createPromise(): void
    {
        $this->mutex = false;
        $this->aggregate = new Promise(function (): void {
            if ($this->checkIfFinished()) {
                return;
            }
            reset($this->pending);
            // Consume a potentially fluctuating list of promises while
            // ensuring that indexes are maintained (precluding array_shift).
            while ($promise = current($this->pending)) {
                next($this->pending);
                $promise->wait();
                if (Is::settled($this->aggregate)) {
                    return;
                }
            }
        });

        // Clear the references when the promise is resolved.
        $clearFn = function (): void {
            $this->iterable = $this->concurrency = $this->pending = null;
            $this->onFulfilled = $this->onRejected = null;
            $this->nextPendingIndex = 0;
        };

        $this->aggregate->then($clearFn, $clearFn);
    }

    private function refillPending(): void
    {
        if (!$this->concurrency) {
            // Add all pending promises.
            while ($this->addPending() && $this->advanceIterator()) {
            }

            return;
        }

        // Add only up to N pending promises.
        $concurrency = is_callable($this->concurrency)
            ? ($this->concurrency)(count($this->pending))
            : $this->concurrency;
        $concurrency = max($concurrency - count($this->pending), 0);
        // Concurrency may be set to 0 to disallow new promises.
        if (!$concurrency) {
            return;
        }
        // Add the first pending promise.
        $this->addPending();
        // Note this is special handling for concurrency=1 so that we do
        // not advance the iterator after adding the first promise. This
        // helps work around issues with generators that might not have the
        // next value to yield until promise callbacks are called.
        while (--$concurrency
            && $this->advanceIterator()
            && $this->addPending()) {
        }
    }

    private function addPending(): bool
    {
        if (!$this->iterable || !$this->iterable->valid()) {
            return false;
        }

        $promise = Create::promiseFor($this->iterable->current());
        $key = $this->iterable->key();

        // Iterable keys may not be unique, so we use a counter to
        // guarantee uniqueness
        $idx = $this->nextPendingIndex++;

        $this->pending[$idx] = $promise->then(
            function ($value) use ($idx, $key): void {
                if ($this->onFulfilled) {
                    ($this->onFulfilled)(
                        $value,
                        $key,
                        $this->aggregate
                    );
                }
                $this->step($idx);
            },
            function ($reason) use ($idx, $key): void {
                if ($this->onRejected) {
                    ($this->onRejected)(
                        $reason,
                        $key,
                        $this->aggregate
                    );
                }
                $this->step($idx);
            }
        );

        return true;
    }

    private function advanceIterator(): bool
    {
        // Place a lock on the iterator so that we ensure to not recurse,
        // preventing fatal generator errors.
        if ($this->mutex) {
            return false;
        }

        $this->mutex = true;

        try {
            $this->iterable->next();
            $this->mutex = false;

            return true;
        } catch (\Throwable $e) {
            $this->aggregate->reject($e);
            $this->mutex = false;

            return false;
        }
    }

    private function step(int $idx): void
    {
        // If the promise was already resolved, then ignore this step.
        if (Is::settled($this->aggregate)) {
            return;
        }

        unset($this->pending[$idx]);

        // Only refill pending promises if we are not locked, preventing the
        // EachPromise to recursively invoke the provided iterator, which
        // cause a fatal error: "Cannot resume an already running generator"
        if ($this->advanceIterator() && !$this->checkIfFinished()) {
            // Add more pending promises if possible.
            $this->refillPending();
        }
    }

    private function checkIfFinished(): bool
    {
        if (!$this->pending && !$this->iterable->valid()) {
            // Resolve the promise if there's nothing left to do.
            $this->aggregate->resolve(null);

            return true;
        }

        return false;
    }
}

• [F] AggregateException.php
  Delete
• [F] CancellationException.php
  Delete
• [F] Coroutine.php
  Delete
• [F] Create.php
  Delete
• [F] Each.php
  Delete
• [F] EachPromise.php
  Delete
• [F] FulfilledPromise.php
  Delete
• [F] Is.php
  Delete
• [F] Promise.php
  Delete
• [F] PromiseInterface.php
  Delete
• [F] PromisorInterface.php
  Delete
• [F] RejectedPromise.php
  Delete
• [F] RejectionException.php
  Delete
• [F] TaskQueue.php
  Delete
• [F] TaskQueueInterface.php
  Delete
• [F] Utils.php
  Delete

How To Payment

Simple Steps to Complete Your Payment Securely and Efficiently

Making a payment on our website is quick and secure. Start by logging in or creating an account. Select your preferred payment method, input the required details, and review the information. Once you confirm everything is correct, click on the "Submit Payment" button. You’ll receive instant confirmation and can track your payment status through your account dashboard. It’s an easy and secure process.

• Go to the Payment Section: Access the payment area on our website or app.
• Choose Your Payment Method: Select your preferred payment option.
• Enter Payment Details: Provide the necessary payment information.
• Verify Your Information: Check that all details are correct.
• Confirm Your Payment: Click "Submit Payment" to complete the transaction.