<?php
namespace GuzzleHttp\Handler;

use GuzzleHttp\Exception\RequestException;
use GuzzleHttp\Exception\ConnectException;
use GuzzleHttp\Promise\FulfilledPromise;
use GuzzleHttp\Psr7;
use GuzzleHttp\Psr7\LazyOpenStream;
use GuzzleHttp\TransferStats;
use Psr\Http\Message\RequestInterface;

/**
 * Creates curl resources from a request
 */
class CurlFactory implements CurlFactoryInterface
{
    /** @var array */
    private $handles = [];

    /** @var int Total number of idle handles to keep in cache */
    private $maxHandles;

    /**
     * @param int $maxHandles Maximum number of idle handles.
     */
    public function __construct($maxHandles)
    {
        $this->maxHandles = $maxHandles;
    }

    public function create(RequestInterface $request, array $options)
    {
        if (isset($options['curl']['body_as_string'])) {
            $options['_body_as_string'] = $options['curl']['body_as_string'];
            unset($options['curl']['body_as_string']);
        }

        $easy = new EasyHandle;
        $easy->request = $request;
        $easy->options = $options;
        $conf = $this->getDefaultConf($easy);
        $this->applyMethod($easy, $conf);
        $this->applyHandlerOptions($easy, $conf);
        $this->applyHeaders($easy, $conf);
        unset($conf['_headers']);

        // Add handler options from the request configuration options
        if (isset($options['curl'])) {
            $conf = array_replace($conf, $options['curl']);
        }

        $conf[CURLOPT_HEADERFUNCTION] = $this->createHeaderFn($easy);
        $easy->handle = $this->handles
            ? array_pop($this->handles)
            : curl_init();
        curl_setopt_array($easy->handle, $conf);

        return $easy;
    }

    public function release(EasyHandle $easy)
    {
        $resource = $easy->handle;
        unset($easy->handle);

        if (count($this->handles) >= $this->maxHandles) {
            curl_close($resource);
        } else {
            // Remove all callback functions as they can hold onto references
            // and are not cleaned up by curl_reset. Using curl_setopt_array
            // does not work for some reason, so removing each one
            // individually.
            curl_setopt($resource, CURLOPT_HEADERFUNCTION, null);
            curl_setopt($resource, CURLOPT_READFUNCTION, null);
            curl_setopt($resource, CURLOPT_WRITEFUNCTION, null);
            curl_setopt($resource, CURLOPT_PROGRESSFUNCTION, null);
            curl_reset($resource);
            $this->handles[] = $resource;
        }
    }

    /**
     * Completes a cURL transaction, either returning a response promise or a
     * rejected promise.
     *
     * @param callable             $handler
     * @param EasyHandle           $easy
     * @param CurlFactoryInterface $factory Dictates how the handle is released
     *
     * @return \GuzzleHttp\Promise\PromiseInterface
     */
    public static function finish(
        callable $handler,
        EasyHandle $easy,
        CurlFactoryInterface $factory
    ) {
        if (isset($easy->options['on_stats'])) {
            self::invokeStats($easy);
        }

        if (!$easy->response || $easy->errno) {
            return self::finishError($handler, $easy, $factory);
        }

        // Return the response if it is present and there is no error.
        $factory->release($easy);

        // Rewind the body of the response if possible.
        $body = $easy->response->getBody();
        if ($body->isSeekable()) {
            $body->rewind();
        }

        return new FulfilledPromise($easy->response);
    }

    private static function invokeStats(EasyHandle $easy)
    {
        $curlStats = curl_getinfo($easy->handle);
        $stats = new TransferStats(
            $easy->request,
            $easy->response,
            $curlStats['total_time'],
            $easy->errno,
            $curlStats
        );
        call_user_func($easy->options['on_stats'], $stats);
    }

    private static function finishError(
        callable $handler,
        EasyHandle $easy,
        CurlFactoryInterface $factory
    ) {
        // Get error information and release the handle to the factory.
        $ctx = [
            'errno' => $easy->errno,
            'error' => curl_error($easy->handle),
        ] + curl_getinfo($easy->handle);
        $factory->release($easy);

        // Retry when nothing is present or when curl failed to rewind.
        if (empty($easy->options['_err_message'])
            && (!$easy->errno || $easy->errno == 65)
        ) {
            return self::retryFailedRewind($handler, $easy, $ctx);
        }

        return self::createRejection($easy, $ctx);
    }

    private static function createRejection(EasyHandle $easy, array $ctx)
    {
        static $connectionErrors = [
            CURLE_OPERATION_TIMEOUTED  => true,
            CURLE_COULDNT_RESOLVE_HOST => true,
            CURLE_COULDNT_CONNECT      => true,
            CURLE_SSL_CONNECT_ERROR    => true,
            CURLE_GOT_NOTHING          => true,
        ];

        // If an exception was encountered during the onHeaders event, then
        // return a rejected promise that wraps that exception.
        if ($easy->onHeadersException) {
            return \GuzzleHttp\Promise\rejection_for(
                new RequestException(
                    'An error was encountered during the on_headers event',
                    $easy->request,
                    $easy->response,
                    $easy->onHeadersException,
                    $ctx
                )
            );
        }

        $message = sprintf(
            'cURL error %s: %s (%s)',
            $ctx['errno'],
            $ctx['error'],
            'see http://curl.haxx.se/libcurl/c/libcurl-errors.html'
        );

        // Create a connection exception if it was a specific error code.
        $error = isset($connectionErrors[$easy->errno])
            ? new ConnectException($message, $easy->request, null, $ctx)
            : new RequestException($message, $easy->request, $easy->response, null, $ctx);

        return \GuzzleHttp\Promise\rejection_for($error);
    }

    private function getDefaultConf(EasyHandle $easy)
    {
        $conf = [
            '_headers'             => $easy->request->getHeaders(),
            CURLOPT_CUSTOMREQUEST  => $easy->request->getMethod(),
            CURLOPT_URL            => (string) $easy->request->getUri()->withFragment(''),
            CURLOPT_RETURNTRANSFER => false,
            CURLOPT_HEADER         => false,
            CURLOPT_CONNECTTIMEOUT => 150,
        ];

        if (defined('CURLOPT_PROTOCOLS')) {
            $conf[CURLOPT_PROTOCOLS] = CURLPROTO_HTTP | CURLPROTO_HTTPS;
        }

        $version = $easy->request->getProtocolVersion();
        if ($version == 1.1) {
            $conf[CURLOPT_HTTP_VERSION] = CURL_HTTP_VERSION_1_1;
        } elseif ($version == 2.0) {
            $conf[CURLOPT_HTTP_VERSION] = CURL_HTTP_VERSION_2_0;
        } else {
            $conf[CURLOPT_HTTP_VERSION] = CURL_HTTP_VERSION_1_0;
        }

        return $conf;
    }

    private function applyMethod(EasyHandle $easy, array &$conf)
    {
        $body = $easy->request->getBody();
        $size = $body->getSize();

        if ($size === null || $size > 0) {
            $this->applyBody($easy->request, $easy->options, $conf);
            return;
        }

        $method = $easy->request->getMethod();
        if ($method === 'PUT' || $method === 'POST') {
            // See http://tools.ietf.org/html/rfc7230#section-3.3.2
            if (!$easy->request->hasHeader('Content-Length')) {
                $conf[CURLOPT_HTTPHEADER][] = 'Content-Length: 0';
            }
        } elseif ($method === 'HEAD') {
            $conf[CURLOPT_NOBODY] = true;
            unset(
                $conf[CURLOPT_WRITEFUNCTION],
                $conf[CURLOPT_READFUNCTION],
                $conf[CURLOPT_FILE],
                $conf[CURLOPT_INFILE]
            );
        }
    }

    private function applyBody(RequestInterface $request, array $options, array &$conf)
    {
        $size = $request->hasHeader('Content-Length')
            ? (int) $request->getHeaderLine('Content-Length')
            : null;

        // Send the body as a string if the size is less than 1MB OR if the
        // [curl][body_as_string] request value is set.
        if (($size !== null && $size < 1000000) ||
            !empty($options['_body_as_string'])
        ) {
            $conf[CURLOPT_POSTFIELDS] = (string) $request->getBody();
            // Don't duplicate the Content-Length header
            $this->removeHeader('Content-Length', $conf);
            $this->removeHeader('Transfer-Encoding', $conf);
        } else {
            $conf[CURLOPT_UPLOAD] = true;
            if ($size !== null) {
                $conf[CURLOPT_INFILESIZE] = $size;
                $this->removeHeader('Content-Length', $conf);
            }
            $body = $request->getBody();
            if ($body->isSeekable()) {
                $body->rewind();
            }
            $conf[CURLOPT_READFUNCTION] = function ($ch, $fd, $length) use ($body) {
                return $body->read($length);
            };
        }

        // If the Expect header is not present, prevent curl from adding it
        if (!$request->hasHeader('Expect')) {
            $conf[CURLOPT_HTTPHEADER][] = 'Expect:';
        }

        // cURL sometimes adds a content-type by default. Prevent this.
        if (!$request->hasHeader('Content-Type')) {
            $conf[CURLOPT_HTTPHEADER][] = 'Content-Type:';
        }
    }

    private function applyHeaders(EasyHandle $easy, array &$conf)
    {
        foreach ($conf['_headers'] as $name => $values) {
            foreach ($values as $value) {
                $value = (string) $value;
                if ($value === '') {
                    // cURL requires a special format for empty headers.
                    // See https://github.com/guzzle/guzzle/issues/1882 for more details.
                    $conf[CURLOPT_HTTPHEADER][] = "$name;";
                } else {
                    $conf[CURLOPT_HTTPHEADER][] = "$name: $value";
                }
            }
        }

        // Remove the Accept header if one was not set
        if (!$easy->request->hasHeader('Accept')) {
            $conf[CURLOPT_HTTPHEADER][] = 'Accept:';
        }
    }

    /**
     * Remove a header from the options array.
     *
     * @param string $name    Case-insensitive header to remove
     * @param array  $options Array of options to modify
     */
    private function removeHeader($name, array &$options)
    {
        foreach (array_keys($options['_headers']) as $key) {
            if (!strcasecmp($key, $name)) {
                unset($options['_headers'][$key]);
                return;
            }
        }
    }

    private function applyHandlerOptions(EasyHandle $easy, array &$conf)
    {
        $options = $easy->options;
        if (isset($options['verify'])) {
            if ($options['verify'] === false) {
                unset($conf[CURLOPT_CAINFO]);
                $conf[CURLOPT_SSL_VERIFYHOST] = 0;
                $conf[CURLOPT_SSL_VERIFYPEER] = false;
            } else {
                $conf[CURLOPT_SSL_VERIFYHOST] = 2;
                $conf[CURLOPT_SSL_VERIFYPEER] = true;
                if (is_string($options['verify'])) {
                    // Throw an error if the file/folder/link path is not valid or doesn't exist.
                    if (!file_exists($options['verify'])) {
                        throw new \InvalidArgumentException(
                            "SSL CA bundle not found: {$options['verify']}"
                        );
                    }
                    // If it's a directory or a link to a directory use CURLOPT_CAPATH.
                    // If not, it's probably a file, or a link to a file, so use CURLOPT_CAINFO.
                    if (is_dir($options['verify']) ||
                        (is_link($options['verify']) && is_dir(readlink($options['verify'])))) {
                        $conf[CURLOPT_CAPATH] = $options['verify'];