<?php

namespace GuzzleHttp\Subscriber;

use GuzzleHttp\Event\RequestEvents;
use GuzzleHttp\Event\SubscriberInterface;
use GuzzleHttp\Adapter\Transaction;
use GuzzleHttp\Event\BeforeEvent;
use GuzzleHttp\Event\HeadersEvent;
use GuzzleHttp\Exception\RequestException;
use GuzzleHttp\Message\MessageFactory;
use GuzzleHttp\Message\ResponseInterface;

/**
 * Queues mock responses or exceptions and delivers mock responses or
 * exceptions in a fifo order.
 */
class Mock implements SubscriberInterface, \Countable
{
    /** @var array Array of mock responses / exceptions */
    private $queue = [];

    /** @var bool Whether or not to consume an entity body when mocking */
    private $readBodies;

    /** @var MessageFactory */
    private $factory;

    /**
     * @param array $items      Array of responses or exceptions to queue
     * @param bool  $readBodies Set to false to not consume the entity body of
     *                          a request when a mock is served.
     */
    public function __construct(array $items = [], $readBodies = true)
    {
        $this->factory = new MessageFactory();
        $this->readBodies = $readBodies;
        $this->addMultiple($items);
    }

    public function getEvents()
    {
        // Fire the event last, after signing
        return ['before' => ['onBefore', RequestEvents::SIGN_REQUEST - 10]];
    }

    /**
     * @throws \OutOfBoundsException|\Exception
     */
    public function onBefore(BeforeEvent $event)
    {
        if (!$item = array_shift($this->queue)) {
            throw new \OutOfBoundsException('Mock queue is empty');
        } elseif ($item instanceof RequestException) {
            throw $item;
        }

        // Emulate the receiving of the response headers
        $request = $event->getRequest();
        $transaction = new Transaction($event->getClient(), $request);
        $transaction->setResponse($item);
        $request->getEmitter()->emit(
            'headers',
            new HeadersEvent($transaction)
        );

        // Emulate reading a response body
        if ($this->readBodies && $request->getBody()) {
            while (!$request->getBody()->eof()) {
                $request->getBody()->read(8096);
            }
        }

        $event->intercept($item);
    }

    public function count()
    {
        return count($this->queue);
    }

    /**
     * Add a response to the end of the queue
     *
     * @param string|ResponseInterface $response Response or path to response file
     *
     * @return self
     * @throws \InvalidArgumentException if a string or Response is not passed
     */
    public function addResponse($response)
    {
        if (is_string($response)) {
            $response = file_exists($response)
                ? $this->factory->fromMessage(file_get_contents($response))
                : $this->factory->fromMessage($response);
        } elseif (!($response instanceof ResponseInterface)) {
            throw new \InvalidArgumentException('Response must a message '
                . 'string, response object, or path to a file');
        }

        $this->queue[] = $response;

        return $this;
    }

    /**
     * Add an exception to the end of the queue
     *
     * @param RequestException $e Exception to throw when the request is executed
     *
     * @return self
     */
    public function addException(RequestException $e)
    {
        $this->queue[] = $e;

        return $this;
    }

    /**
     * Add multiple items to the queue
     *
     * @param array $items Items to add
     */
    public function addMultiple(array $items)
    {
        foreach ($items as $item) {
            if ($item instanceof RequestException) {
                $this->addException($item);
            } else {
                $this->addResponse($item);
            }
        }
    }

    /**
     * Clear the queue
     */
    public function clearQueue()
    {
        $this->queue = [];
    }
}