<?php

/**
 * HTTP Proxy connection interface
 *
 * @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
 *
 * @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 bool
     */
    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($args) === 1) {
                [$this->proxy] = $args;
            } elseif (count($args) === 3) {
                [$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;
    }
}
