<?php

/**
 * fsockopen HTTP transport
 */

namespace WpOrg\Requests\Transport;

use WpOrg\Requests\Capability;
use WpOrg\Requests\Exception;
use WpOrg\Requests\Exception\InvalidArgument;
use WpOrg\Requests\Port;
use WpOrg\Requests\Requests;
use WpOrg\Requests\Ssl;
use WpOrg\Requests\Transport;
use WpOrg\Requests\Utility\CaseInsensitiveDictionary;
use WpOrg\Requests\Utility\InputValidator;

/**
 * fsockopen HTTP transport
 */
final class Fsockopen implements Transport
{
    /**
     * Second to microsecond conversion
     *
     * @var int
     */
    const SECOND_IN_MICROSECONDS = 1000000;

    /**
     * Raw HTTP data
     *
     * @var string
     */
    public $headers = '';

    /**
     * Stream metadata
     *
     * @var array Associative array of properties, see {@link https://www.php.net/stream_get_meta_data}
     */
    public $info;

    /**
     * What's the maximum number of bytes we should keep?
     *
     * @var int|bool Byte count, or false if no limit.
     */
    private $max_bytes = false;

    private $connect_error = '';

    /**
     * Perform a request
     *
     * @param  string|Stringable  $url  URL to request
     * @param  array  $headers  Associative array of request headers
     * @param  string|array  $data  Data to send either as the POST body, or as parameters in the URL for a GET/HEAD
     * @param  array  $options  Request options, see {@see \WpOrg\Requests\Requests::response()} for documentation
     * @return string Raw HTTP result
     *
     * @throws \WpOrg\Requests\Exception\InvalidArgument When the passed $url argument is not a string or Stringable.
     * @throws \WpOrg\Requests\Exception\InvalidArgument When the passed $headers argument is not an array.
     * @throws \WpOrg\Requests\Exception\InvalidArgument When the passed $data parameter is not an array or string.
     * @throws \WpOrg\Requests\Exception\InvalidArgument When the passed $options argument is not an array.
     * @throws \WpOrg\Requests\Exception On failure to connect to socket (`fsockopenerror`)
     * @throws \WpOrg\Requests\Exception On socket timeout (`timeout`)
     */
    public function request($url, $headers = [], $data = [], $options = [])
    {
        if (InputValidator::is_string_or_stringable($url) === false) {
            throw InvalidArgument::create(1, '$url', 'string|Stringable', gettype($url));
        }

        if (is_array($headers) === false) {
            throw InvalidArgument::create(2, '$headers', 'array', gettype($headers));
        }

        if (! is_array($data) && ! is_string($data)) {
            if ($data === null) {
                $data = '';
            } else {
                throw InvalidArgument::create(3, '$data', 'array|string', gettype($data));
            }
        }

        if (is_array($options) === false) {
            throw InvalidArgument::create(4, '$options', 'array', gettype($options));
        }

        $options['hooks']->dispatch('fsockopen.before_request');

        $url_parts = parse_url($url);
        if (empty($url_parts)) {
            throw new Exception('Invalid URL.', 'invalidurl', $url);
        }

        $host = $url_parts['host'];
        $context = stream_context_create();
        $verifyname = false;
        $case_insensitive_headers = new CaseInsensitiveDictionary($headers);

        // HTTPS support
        if (isset($url_parts['scheme']) && strtolower($url_parts['scheme']) === 'https') {
            $remote_socket = 'ssl://'.$host;
            if (! isset($url_parts['port'])) {
                $url_parts['port'] = Port::HTTPS;
            }

            $context_options = [
                'verify_peer' => true,
                'capture_peer_cert' => true,
            ];
            $verifyname = true;

            // SNI, if enabled (OpenSSL >=0.9.8j)
            // phpcs:ignore PHPCompatibility.Constants.NewConstants.openssl_tlsext_server_nameFound
            if (defined('OPENSSL_TLSEXT_SERVER_NAME') && OPENSSL_TLSEXT_SERVER_NAME) {
                $context_options['SNI_enabled'] = true;
                if (isset($options['verifyname']) && $options['verifyname'] === false) {
                    $context_options['SNI_enabled'] = false;
                }
            }

            if (isset($options['verify'])) {
                if ($options['verify'] === false) {
                    $context_options['verify_peer'] = false;
                    $context_options['verify_peer_name'] = false;
                    $verifyname = false;
                } elseif (is_string($options['verify'])) {
                    $context_options['cafile'] = $options['verify'];
                }
            }

            if (isset($options['verifyname']) && $options['verifyname'] === false) {
                $context_options['verify_peer_name'] = false;
                $verifyname = false;
            }

            stream_context_set_option($context, ['ssl' => $context_options]);
        } else {
            $remote_socket = 'tcp://'.$host;
        }

        $this->max_bytes = $options['max_bytes'];

        if (! isset($url_parts['port'])) {
            $url_parts['port'] = Port::HTTP;
        }

        $remote_socket .= ':'.$url_parts['port'];

        // phpcs:ignore WordPress.PHP.DevelopmentFunctions.error_log_set_error_handler
        set_error_handler([$this, 'connect_error_handler'], E_WARNING | E_NOTICE);

        $options['hooks']->dispatch('fsockopen.remote_socket', [&$remote_socket]);

        $socket = stream_socket_client($remote_socket, $errno, $errstr, ceil($options['connect_timeout']), STREAM_CLIENT_CONNECT, $context);

        restore_error_handler();

        if ($verifyname && ! $this->verify_certificate_from_context($host, $context)) {
            throw new Exception('SSL certificate did not match the requested domain name', 'ssl.no_match');
        }

        if (! $socket) {
            if ($errno === 0) {
                // Connection issue
                throw new Exception(rtrim($this->connect_error), 'fsockopen.connect_error');
            }

            throw new Exception($errstr, 'fsockopenerror', null, $errno);
        }

        $data_format = $options['data_format'];

        if ($data_format === 'query') {
            $path = self::format_get($url_parts, $data);
            $data = '';
        } else {
            $path = self::format_get($url_parts, []);
        }

        $options['hooks']->dispatch('fsockopen.remote_host_path', [&$path, $url]);

        $request_body = '';
        $out = sprintf("%s %s HTTP/%.1F\r\n", $options['type'], $path, $options['protocol_version']);

        if ($options['type'] !== Requests::TRACE) {
            if (is_array($data)) {
                $request_body = http_build_query($data, '', '&');
            } else {
                $request_body = $data;
            }

            // Always include Content-length on POST requests to prevent
            // 411 errors from some servers when the body is empty.
            if (! empty($data) || $options['type'] === Requests::POST) {
                if (! isset($case_insensitive_headers['Content-Length'])) {
                    $headers['Content-Length'] = strlen($request_body);
                }

                if (! isset($case_insensitive_headers['Content-Type'])) {
                    $headers['Content-Type'] = 'application/x-www-form-urlencoded; charset=UTF-8';
                }
            }
        }

        if (! isset($case_insensitive_headers['Host'])) {
            $out .= sprintf('Host: %s', $url_parts['host']);
            $scheme_lower = strtolower($url_parts['scheme']);

            if (($scheme_lower === 'http' && $url_parts['port'] !== Port::HTTP) || ($scheme_lower === 'https' && $url_parts['port'] !== Port::HTTPS)) {
                $out .= ':'.$url_parts['port'];
            }

            $out .= "\r\n";
        }

        if (! isset($case_insensitive_headers['User-Agent'])) {
            $out .= sprintf("User-Agent: %s\r\n", $options['useragent']);
        }

        $accept_encoding = $this->accept_encoding();
        if (! isset($case_insensitive_headers['Accept-Encoding']) && ! empty($accept_encoding)) {
            $out .= sprintf("Accept-Encoding: %s\r\n", $accept_encoding);
        }

        $headers = Requests::flatten($headers);

        if (! empty($headers)) {
            $out .= implode("\r\n", $headers)."\r\n";
        }

        $options['hooks']->dispatch('fsockopen.after_headers', [&$out]);

        if (substr($out, -2) !== "\r\n") {
            $out .= "\r\n";
        }

        if (! isset($case_insensitive_headers['Connection'])) {
            $out .= "Connection: Close\r\n";
        }

        $out .= "\r\n".$request_body;

        $options['hooks']->dispatch('fsockopen.before_send', [&$out]);

        fwrite($socket, $out);
        $options['hooks']->dispatch('fsockopen.after_send', [$out]);

        if (! $options['blocking']) {
            fclose($socket);
            $fake_headers = '';
            $options['hooks']->dispatch('fsockopen.after_request', [&$fake_headers]);

            return '';
        }

        $timeout_sec = (int) floor($options['timeout']);
        if ($timeout_sec === $options['timeout']) {
            $timeout_msec = 0;
        } else {
            $timeout_msec = self::SECOND_IN_MICROSECONDS * $options['timeout'] % self::SECOND_IN_MICROSECONDS;
        }

        stream_set_timeout($socket, $timeout_sec, $timeout_msec);

        $response = '';
        $body = '';
        $headers = '';
        $this->info = stream_get_meta_data($socket);
        $size = 0;
        $doingbody = false;
        $download = false;
        if ($options['filename']) {
            // phpcs:ignore WordPress.PHP.NoSilencedErrors -- Silenced the PHP native warning in favour of throwing an exception.
            $download = @fopen($options['filename'], 'wb');
            if ($download === false) {
                $error = error_get_last();
                throw new Exception($error['message'], 'fopen');
            }
        }

        while (! feof($socket)) {
            $this->info = stream_get_meta_data($socket);
            if ($this->info['timed_out']) {
                throw new Exception('fsocket timed out', 'timeout');
            }

            $block = fread($socket, Requests::BUFFER_SIZE);
            if (! $doingbody) {
                $response .= $block;
                if (strpos($response, "\r\n\r\n")) {
                    [$headers, $block] = explode("\r\n\r\n", $response, 2);
                    $doingbody = true;
                }
            }

            // Are we in body mode now?
            if ($doingbody) {
                $options['hooks']->dispatch('request.progress', [$block, $size, $this->max_bytes]);
                $data_length = strlen($block);
                if ($this->max_bytes) {
                    // Have we already hit a limit?
                    if ($size === $this->max_bytes) {
                        continue;
                    }

                    if (($size + $data_length) > $this->max_bytes) {
                        // Limit the length
                        $limited_length = ($this->max_bytes - $size);
                        $block = substr($block, 0, $limited_length);
                    }
                }

                $size += strlen($block);
                if ($download) {
                    fwrite($download, $block);
                } else {
                    $body .= $block;
                }
            }
        }

        $this->headers = $headers;

        if ($download) {
            fclose($download);
        } else {
            $this->headers .= "\r\n\r\n".$body;
        }

        fclose($socket);

        $options['hooks']->dispatch('fsockopen.after_request', [&$this->headers, &$this->info]);

        return $this->headers;
    }

    /**
     * Send multiple requests simultaneously
     *
     * @param  array  $requests  Request data (array of 'url', 'headers', 'data', 'options') as per {@see \WpOrg\Requests\Transport::request()}
     * @param  array  $options  Global options, see {@see \WpOrg\Requests\Requests::response()} for documentation
     * @return array Array of \WpOrg\Requests\Response objects (may contain \WpOrg\Requests\Exception or string responses as well)
     *
     * @throws \WpOrg\Requests\Exception\InvalidArgument When the passed $requests argument is not an array or iterable object with array access.
     * @throws \WpOrg\Requests\Exception\InvalidArgument When the passed $options argument is not an array.
     */
    public function request_multiple($requests, $options)
    {
        // If you're not requesting, we can't get any responses ¯\_(ツ)_/¯
        if (empty($requests)) {
            return [];
        }

        if (InputValidator::has_array_access($requests) === false || InputValidator::is_iterable($requests) === false) {
            throw InvalidArgument::create(1, '$requests', 'array|ArrayAccess&Traversable', gettype($requests));
        }

        if (is_array($options) === false) {
            throw InvalidArgument::create(2, '$options', 'array', gettype($options));
        }

        $responses = [];
        $class = get_class($this);
        foreach ($requests as $id => $request) {
            try {
                $handler = new $class;
                $responses[$id] = $handler->request($request['url'], $request['headers'], $request['data'], $request['options']);

                $request['options']['hooks']->dispatch('transport.internal.parse_response', [&$responses[$id], $request]);
            } catch (Exception $e) {
                $responses[$id] = $e;
            }

            if (! is_string($responses[$id])) {
                $request['options']['hooks']->dispatch('multiple.request.complete', [&$responses[$id], $id]);
            }
        }

        return $responses;
    }

    /**
     * Retrieve the encodings we can accept
     *
     * @return string Accept-Encoding header value
     */
    private static function accept_encoding()
    {
        $type = [];
        if (function_exists('gzinflate')) {
            $type[] = 'deflate;q=1.0';
        }

        if (function_exists('gzuncompress')) {
            $type[] = 'compress;q=0.5';
        }

        $type[] = 'gzip;q=0.5';

        return implode(', ', $type);
    }

    /**
     * Format a URL given GET data
     *
     * @param  array  $url_parts
     * @param  array|object  $data  Data to build query using, see {@link https://www.php.net/http_build_query}
     * @return string URL with data
     */
    private static function format_get($url_parts, $data)
    {
        if (! empty($data)) {
            if (empty($url_parts['query'])) {
                $url_parts['query'] = '';
            }

            $url_parts['query'] .= '&'.http_build_query($data, '', '&');
            $url_parts['query'] = trim($url_parts['query'], '&');
        }

        if (isset($url_parts['path'])) {
            if (isset($url_parts['query'])) {
                $get = $url_parts['path'].'?'.$url_parts['query'];
            } else {
                $get = $url_parts['path'];
            }
        } else {
            $get = '/';
        }

        return $get;
    }

    /**
     * Error handler for stream_socket_client()
     *
     * @param  int  $errno  Error number (e.g. E_WARNING)
     * @param  string  $errstr  Error message
     */
    public function connect_error_handler($errno, $errstr)
    {
        // Double-check we can handle it
        if (($errno & E_WARNING) === 0 && ($errno & E_NOTICE) === 0) {
            // Return false to indicate the default error handler should engage
            return false;
        }

        $this->connect_error .= $errstr."\n";

        return true;
    }

    /**
     * Verify the certificate against common name and subject alternative names
     *
     * Unfortunately, PHP doesn't check the certificate against the alternative
     * names, leading things like 'https://www.github.com/' to be invalid.
     * Instead
     *
     * @link https://tools.ietf.org/html/rfc2818#section-3.1 RFC2818, Section 3.1
     *
     * @param  string  $host  Host name to verify against
     * @param  resource  $context  Stream context
     * @return bool
     *
     * @throws \WpOrg\Requests\Exception On failure to connect via TLS (`fsockopen.ssl.connect_error`)
     * @throws \WpOrg\Requests\Exception On not obtaining a match for the host (`fsockopen.ssl.no_match`)
     */
    public function verify_certificate_from_context($host, $context)
    {
        $meta = stream_context_get_options($context);

        // If we don't have SSL options, then we couldn't make the connection at
        // all
        if (empty($meta) || empty($meta['ssl']) || empty($meta['ssl']['peer_certificate'])) {
            throw new Exception(rtrim($this->connect_error), 'ssl.connect_error');
        }

        $cert = openssl_x509_parse($meta['ssl']['peer_certificate']);

        return Ssl::verify_certificate($host, $cert);
    }

    /**
     * Self-test whether the transport can be used.
     *
     * The available capabilities to test for can be found in {@see \WpOrg\Requests\Capability}.
     *
     * @codeCoverageIgnore
     *
     * @param  array<string, bool>  $capabilities  Optional. Associative array of capabilities to test against, i.e. `['<capability>' => true]`.
     * @return bool Whether the transport can be used.
     */
    public static function test($capabilities = [])
    {
        if (! function_exists('fsockopen')) {
            return false;
        }

        // If needed, check that streams support SSL
        if (isset($capabilities[Capability::SSL]) && $capabilities[Capability::SSL]) {
            if (! extension_loaded('openssl') || ! function_exists('openssl_x509_parse')) {
                return false;
            }
        }

        return true;
    }
}
