<?php
/**
 * HTTP Proxy connection interface
 *
 * @package Requests\Proxy
 * @since   1.6
 */

namespace WpOrg\Requests\Proxy;

use WpOrg\Requests\Exception\ArgumentCount;
use WpOrg\Requests\Exception\InvalidArgument;
use WpOrg\Requests\Hooks;
use WpOrg\Requests\Proxy;

/**
 * HTTP Proxy connection interface
 *
 * Provides a handler for connection via an HTTP proxy
 *
 * @package Requests\Proxy
 * @since   1.6
 */
final class Http implements Proxy {
	/**
	 * Proxy host and port
	 *
	 * Notation: "host:port" (eg 127.0.0.1:8080 or someproxy.com:3128)
	 *
	 * @var string
	 */
	public $proxy;

	/**
	 * Username
	 *
	 * @var string
	 */
	public $user;

	/**
	 * Password
	 *
	 * @var string
	 */
	public $pass;

	/**
	 * Do we need to authenticate? (ie username & password have been provided)
	 *
	 * @var boolean
	 */
	public $use_authentication;

	/**
	 * Constructor
	 *
	 * @since 1.6
	 *
	 * @param array|string|null $args Proxy as a string or an array of proxy, user and password.
	 *                                When passed as an array, must have exactly one (proxy)
	 *                                or three elements (proxy, user, password).
	 *
	 * @throws \WpOrg\Requests\Exception\InvalidArgument When the passed argument is not an array, a string or null.
	 * @throws \WpOrg\Requests\Exception\ArgumentCount On incorrect number of arguments (`proxyhttpbadargs`)
	 */
	public function __construct($args = null) {
		if (is_string($args)) {
			$this->proxy = $args;
		}
		elseif (is_array($args)) {
			if (count($args) === 1) {
				list($this->proxy) = $args;
			}
			elseif (count($args) === 3) {
				list($this->proxy, $this->user, $this->pass) = $args;
				$this->use_authentication                    = true;
			}
			else {
				throw ArgumentCount::create(
					'an array with exactly one element or exactly three elements',
					count($args),
					'proxyhttpbadargs'
				);
			}
		} elseif ($args !== null) {
			throw InvalidArgument::create(1, '$args', 'array|string|null', gettype($args));
		}
	}

	/**
	 * Register the necessary callbacks
	 *
	 * @since 1.6
	 * @see \WpOrg\Requests\Proxy\HTTP::curl_before_send()
	 * @see \WpOrg\Requests\Proxy\HTTP::fsockopen_remote_socket()
	 * @see \WpOrg\Requests\Proxy\HTTP::fsockopen_remote_host_path()
	 * @see \WpOrg\Requests\Proxy\HTTP::fsockopen_header()
	 * @param \WpOrg\Requests\Hooks $hooks Hook system
	 */
	public function register(Hooks $hooks) {
		$hooks->register('curl.before_send', [$this, 'curl_before_send']);

		$hooks->register('fsockopen.remote_socket', [$this, 'fsockopen_remote_socket']);
		$hooks->register('fsockopen.remote_host_path', [$this, 'fsockopen_remote_host_path']);
		if ($this->use_authentication) {
			$hooks->register('fsockopen.after_headers', [$this, 'fsockopen_header']);
		}
	}

	/**
	 * Set cURL parameters before the data is sent
	 *
	 * @since 1.6
	 * @param resource|\CurlHandle $handle cURL handle
	 */
	public function curl_before_send(&$handle) {
		curl_setopt($handle, CURLOPT_PROXYTYPE, CURLPROXY_HTTP);
		curl_setopt($handle, CURLOPT_PROXY, $this->proxy);

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

	/**
	 * Alter remote socket information before opening socket connection
	 *
	 * @since 1.6
	 * @param string $remote_socket Socket connection string
	 */
	public function fsockopen_remote_socket(&$remote_socket) {
		$remote_socket = $this->proxy;
	}

	/**
	 * Alter remote path before getting stream data
	 *
	 * @since 1.6
	 * @param string $path Path to send in HTTP request string ("GET ...")
	 * @param string $url Full URL we're requesting
	 */
	public function fsockopen_remote_host_path(&$path, $url) {
		$path = $url;
	}

	/**
	 * Add extra headers to the request before sending
	 *
	 * @since 1.6
	 * @param string $out HTTP header string
	 */
	public function fsockopen_header(&$out) {
		$out .= sprintf("Proxy-Authorization: Basic %s\r\n", base64_encode($this->get_auth_string()));
	}

	/**
	 * Get the authentication string (user:pass)
	 *
	 * @since 1.6
	 * @return string
	 */
	public function get_auth_string() {
		return $this->user . ':' . $this->pass;
	}
}