class WP_Http_Curl {

	/**
	 * Temporary header storage for during requests.
	 *
	 * @since 3.2.0
	 * @var string
	 */
	private $headers = '';

	/**
	 * Temporary body storage for during requests.
	 *
	 * @since 3.6.0
	 * @var string
	 */
	private $body = '';

	/**
	 * The maximum amount of data to receive from the remote server.
	 *
	 * @since 3.6.0
	 * @var int|false
	 */
	private $max_body_length = false;

	/**
	 * The file resource used for streaming to file.
	 *
	 * @since 3.6.0
	 * @var resource|false
	 */
	private $stream_handle = false;

	/**
	 * The total bytes written in the current request.
	 *
	 * @since 4.1.0
	 * @var int
	 */
	private $bytes_written_total = 0;

	/**
	 * Send a HTTP request to a URI using cURL extension.
	 *
	 * @since 2.7.0
	 *
	 * @param string $url The request URL.
	 * @param string|array $args Optional. Override the defaults.
	 * @return array|WP_Error Array containing 'headers', 'body', 'response', 'cookies', 'filename'. A WP_Error instance upon error
	 */
	public function request( $url, $args = array() ) {
		$defaults = array(
			'method'      => 'GET',
			'timeout'     => 5,
			'redirection' => 5,
			'httpversion' => '1.0',
			'blocking'    => true,
			'headers'     => array(),
			'body'        => null,
			'cookies'     => array(),
		);

		$parsed_args = wp_parse_args( $args, $defaults );

		if ( isset( $parsed_args['headers']['User-Agent'] ) ) {
			$parsed_args['user-agent'] = $parsed_args['headers']['User-Agent'];
			unset( $parsed_args['headers']['User-Agent'] );
		} elseif ( isset( $parsed_args['headers']['user-agent'] ) ) {
			$parsed_args['user-agent'] = $parsed_args['headers']['user-agent'];
			unset( $parsed_args['headers']['user-agent'] );
		}

		// Construct Cookie: header if any cookies are set.
		WP_Http::buildCookieHeader( $parsed_args );

		$handle = curl_init();

		// cURL offers really easy proxy support.
		$proxy = new WP_HTTP_Proxy();

		if ( $proxy->is_enabled() && $proxy->send_through_proxy( $url ) ) {

			curl_setopt( $handle, CURLOPT_PROXYTYPE, CURLPROXY_HTTP );
			curl_setopt( $handle, CURLOPT_PROXY, $proxy->host() );
			curl_setopt( $handle, CURLOPT_PROXYPORT, $proxy->port() );

			if ( $proxy->use_authentication() ) {
				curl_setopt( $handle, CURLOPT_PROXYAUTH, CURLAUTH_ANY );
				curl_setopt( $handle, CURLOPT_PROXYUSERPWD, $proxy->authentication() );
			}
		}

		$is_local   = isset( $parsed_args['local'] ) && $parsed_args['local'];
		$ssl_verify = isset( $parsed_args['sslverify'] ) && $parsed_args['sslverify'];
		if ( $is_local ) {
			/** This filter is documented in wp-includes/class-wp-http-streams.php */
			$ssl_verify = apply_filters( 'https_local_ssl_verify', $ssl_verify, $url );
		} elseif ( ! $is_local ) {
			/** This filter is documented in wp-includes/class-http.php */
			$ssl_verify = apply_filters( 'https_ssl_verify', $ssl_verify, $url );
		}

		/*
		 * CURLOPT_TIMEOUT and CURLOPT_CONNECTTIMEOUT expect integers. Have to use ceil since.
		 * a value of 0 will allow an unlimited timeout.
		 */
		$timeout = (int) ceil( $parsed_args['timeout'] );
		curl_setopt( $handle, CURLOPT_CONNECTTIMEOUT, $timeout );
		curl_setopt( $handle, CURLOPT_TIMEOUT, $timeout );

		curl_setopt( $handle, CURLOPT_URL, $url );
		curl_setopt( $handle, CURLOPT_RETURNTRANSFER, true );
		curl_setopt( $handle, CURLOPT_SSL_VERIFYHOST, ( $ssl_verify === true ) ? 2 : false );
		curl_setopt( $handle, CURLOPT_SSL_VERIFYPEER, $ssl_verify );

		if ( $ssl_verify ) {
			curl_setopt( $handle, CURLOPT_CAINFO, $parsed_args['sslcertificates'] );
		}

		curl_setopt( $handle, CURLOPT_USERAGENT, $parsed_args['user-agent'] );

		/*
		 * The option doesn't work with safe mode or when open_basedir is set, and there's
		 * a bug #17490 with redirected POST requests, so handle redirections outside Curl.
		 */
		curl_setopt( $handle, CURLOPT_FOLLOWLOCATION, false );
		curl_setopt( $handle, CURLOPT_PROTOCOLS, CURLPROTO_HTTP | CURLPROTO_HTTPS );

		switch ( $parsed_args['method'] ) {
			case 'HEAD':
				curl_setopt( $handle, CURLOPT_NOBODY, true );
				break;
			case 'POST':
				curl_setopt( $handle, CURLOPT_POST, true );
				curl_setopt( $handle, CURLOPT_POSTFIELDS, $parsed_args['body'] );
				break;
			case 'PUT':
				curl_setopt( $handle, CURLOPT_CUSTOMREQUEST, 'PUT' );
				curl_setopt( $handle, CURLOPT_POSTFIELDS, $parsed_args['body'] );
				break;
			default:
				curl_setopt( $handle, CURLOPT_CUSTOMREQUEST, $parsed_args['method'] );
				if ( ! is_null( $parsed_args['body'] ) ) {
					curl_setopt( $handle, CURLOPT_POSTFIELDS, $parsed_args['body'] );
				}
				break;
		}

		if ( true === $parsed_args['blocking'] ) {
			curl_setopt( $handle, CURLOPT_HEADERFUNCTION, array( $this, 'stream_headers' ) );
			curl_setopt( $handle, CURLOPT_WRITEFUNCTION, array( $this, 'stream_body' ) );
		}

		curl_setopt( $handle, CURLOPT_HEADER, false );

		if ( isset( $parsed_args['limit_response_size'] ) ) {
			$this->max_body_length = intval( $parsed_args['limit_response_size'] );
		} else {
			$this->max_body_length = false;
		}

		// If streaming to a file open a file handle, and setup our curl streaming handler.
		if ( $parsed_args['stream'] ) {
			if ( ! WP_DEBUG ) {
				$this->stream_handle = @fopen( $parsed_args['filename'], 'w+' );
			} else {
				$this->stream_handle = fopen( $parsed_args['filename'], 'w+' );
			}
			if ( ! $this->stream_handle ) {
				return new WP_Error(
					'http_request_failed',
					sprintf(
						/* translators: 1: fopen(), 2: File name. */
						__( 'Could not open handle for %1$s to %2$s.' ),
						'fopen()',
						$parsed_args['filename']
					)
				);
			}
		} else {
			$this->stream_handle = false;
		}

		if ( ! empty( $parsed_args['headers'] ) ) {
			// cURL expects full header strings in each element.
			$headers = array();
			foreach ( $parsed_args['headers'] as $name => $value ) {
				$headers[] = "{$name}: $value";
			}
			curl_setopt( $handle, CURLOPT_HTTPHEADER, $headers );
		}

		if ( $parsed_args['httpversion'] == '1.0' ) {
			curl_setopt( $handle, CURLOPT_HTTP_VERSION, CURL_HTTP_VERSION_1_0 );
		} else {
			curl_setopt( $handle, CURLOPT_HTTP_VERSION, CURL_HTTP_VERSION_1_1 );
		}

		/**
		 * Fires before the cURL request is executed.
		 *
		 * Cookies are not currently handled by the HTTP API. This action allows
		 * plugins to handle cookies themselves.
		 *
		 * @since 2.8.0
		 *
		 * @param resource $handle  The cURL handle returned by curl_init() (passed by reference).
		 * @param array    $parsed_args       The HTTP request arguments.
		 * @param string   $url     The request URL.
		 */
		do_action_ref_array( 'http_api_curl', array( &$handle, $parsed_args, $url ) );

		// We don't need to return the body, so don't. Just execute request and return.
		if ( ! $parsed_args['blocking'] ) {
			curl_exec( $handle );

			$curl_error = curl_error( $handle );
			if ( $curl_error ) {
				curl_close( $handle );
				return new WP_Error( 'http_request_failed', $curl_error );
			}
			if ( in_array( curl_getinfo( $handle, CURLINFO_HTTP_CODE ), array( 301, 302 ) ) ) {
				curl_close( $handle );
				return new WP_Error( 'http_request_failed', __( 'Too many redirects.' ) );
			}

			curl_close( $handle );
			return array(
				'headers'  => array(),
				'body'     => '',
				'response' => array(
					'code'    => false,
					'message' => false,
				),
				'cookies'  => array(),
			);
		}

		curl_exec( $handle );
		$theHeaders          = WP_Http::processHeaders( $this->headers, $url );
		$theBody             = $this->body;
		$bytes_written_total = $this->bytes_written_total;

		$this->headers             = '';
		$this->body                = '';
		$this->bytes_written_total = 0;

		$curl_error = curl_errno( $handle );

		// If an error occurred, or, no response.
		if ( $curl_error || ( 0 == strlen( $theBody ) && empty( $theHeaders['headers'] ) ) ) {
			if ( CURLE_WRITE_ERROR /* 23 */ == $curl_error ) {
				if ( ! $this->max_body_length || $this->max_body_length != $bytes_written_total ) {
					if ( $parsed_args['stream'] ) {
						curl_close( $handle );
						fclose( $this->stream_handle );
						return new WP_Error( 'http_request_failed', __( 'Failed to write request to temporary file.' ) );
					} else {
						curl_close( $handle );
						return new WP_Error( 'http_request_failed', curl_error( $handle ) );
					}
				}
			} else {
				$curl_error = curl_error( $handle );
				if ( $curl_error ) {
					curl_close( $handle );
					return new WP_Error( 'http_request_failed', $curl_error );
				}
			}
			if ( in_array( curl_getinfo( $handle, CURLINFO_HTTP_CODE ), array( 301, 302 ) ) ) {
				curl_close( $handle );
				return new WP_Error( 'http_request_failed', __( 'Too many redirects.' ) );
			}
		}

		curl_close( $handle );

		if ( $parsed_args['stream'] ) {
			fclose( $this->stream_handle );
		}

		$response = array(
			'headers'  => $theHeaders['headers'],
			'body'     => null,
			'response' => $theHeaders['response'],
			'cookies'  => $theHeaders['cookies'],
			'filename' => $parsed_args['filename'],
		);

		// Handle redirects.
		$redirect_response = WP_HTTP::handle_redirects( $url, $parsed_args, $response );
		if ( false !== $redirect_response ) {
			return $redirect_response;
		}

		if ( true === $parsed_args['decompress'] && true === WP_Http_Encoding::should_decode( $theHeaders['headers'] ) ) {
			$theBody = WP_Http_Encoding::decompress( $theBody );
		}

		$response['body'] = $theBody;

		return $response;
	}

	/**
	 * Grabs the headers of the cURL request.
	 *
	 * Each header is sent individually to this callback, so we append to the `$header` property
	 * for temporary storage
	 *
	 * @since 3.2.0
	 *
	 * @param resource $handle  cURL handle.
	 * @param string   $headers cURL request headers.
	 * @return int Length of the request headers.
	 */
	private function stream_headers( $handle, $headers ) {
		$this->headers .= $headers;
		return strlen( $headers );
	}

	/**
	 * Grabs the body of the cURL request.
	 *
	 * The contents of the document are passed in chunks, so we append to the `$body`
	 * property for temporary storage. Returning a length shorter than the length of
	 * `$data` passed in will cause cURL to abort the request with `CURLE_WRITE_ERROR`.
	 *
	 * @since 3.6.0
	 *
	 * @param resource $handle  cURL handle.
	 * @param string   $data    cURL request body.
	 * @return int Total bytes of data written.
	 */
	private function stream_body( $handle, $data ) {
		$data_length = strlen( $data );

		if ( $this->max_body_length && ( $this->bytes_written_total + $data_length ) > $this->max_body_length ) {
			$data_length = ( $this->max_body_length - $this->bytes_written_total );
			$data        = substr( $data, 0, $data_length );
		}

		if ( $this->stream_handle ) {
			$bytes_written = fwrite( $this->stream_handle, $data );
		} else {
			$this->body   .= $data;
			$bytes_written = $data_length;
		}

		$this->bytes_written_total += $bytes_written;

		// Upon event of this function returning less than strlen( $data ) curl will error with CURLE_WRITE_ERROR.
		return $bytes_written;
	}

	/**
	 * Determines whether this class can be used for retrieving a URL.
	 *
	 * @since 2.7.0
	 *
	 * @param array $args Optional. Array of request arguments. Default empty array.
	 * @return bool False means this class can not be used, true means it can.
	 */
	public static function test( $args = array() ) {
		if ( ! function_exists( 'curl_init' ) || ! function_exists( 'curl_exec' ) ) {
			return false;
		}

		$is_ssl = isset( $args['ssl'] ) && $args['ssl'];

		if ( $is_ssl ) {
			$curl_version = curl_version();
			// Check whether this cURL version support SSL requests.
			if ( ! ( CURL_VERSION_SSL & $curl_version['features'] ) ) {
				return false;
			}
		}

		/**
		 * Filters whether cURL can be used as a transport for retrieving a URL.
		 *
		 * @since 2.7.0
		 *
		 * @param bool  $use_class Whether the class can be used. Default true.
		 * @param array $args      An array of request arguments.
		 */
		return apply_filters( 'use_curl_transport', true, $args );
	}
}