<?php declare(strict_types=1);
/**
 * PrivateBin
 *
 * a zero-knowledge paste bin
 *
 * @link      https://github.com/PrivateBin/PrivateBin
 * @copyright 2012 Sébastien SAUVAGE (sebsauvage.net)
 * @license   https://www.opensource.org/licenses/zlib-license.php The zlib/libpng License
 */

namespace PrivateBin;

use Exception;

/**
 * Request
 *
 * parses request parameters and provides helper functions for routing
 */
class Request
{
    /**
     * MIME type for JSON
     *
     * @const string
     */
    const MIME_JSON = 'application/json';

    /**
     * MIME type for HTML
     *
     * @const string
     */
    const MIME_HTML = 'text/html';

    /**
     * MIME type for XHTML
     *
     * @const string
     */
    const MIME_XHTML = 'application/xhtml+xml';

    /**
     * Input stream to use for PUT parameter parsing
     *
     * @access private
     * @var string
     */
    private static $_inputStream = 'php://input';

    /**
     * Operation to perform
     *
     * @access private
     * @var string
     */
    private $_operation = 'view';

    /**
     * Request parameters
     *
     * @access private
     * @var array
     */
    private $_params = array();

    /**
     * If we are in a JSON API context
     *
     * @access private
     * @var bool
     */
    private $_isJsonApi = false;

    /**
     * Return the paste ID of the current paste.
     *
     * @access private
     * @return string
     */
    private function getPasteId()
    {
        foreach ($_GET as $key => $value) {
            // only return if value is empty and key is 16 hex chars
            $key = (string) $key;
            if (($value === '') && strlen($key) === 16 && ctype_xdigit($key)) {
                return $key;
            }
        }

        return 'invalid id';
    }

    /**
     * Constructor
     *
     * @access public
     */
    public function __construct()
    {
        // decide if we are in JSON API or HTML context
        $this->_isJsonApi = $this->_detectJsonRequest();

        // parse parameters, depending on request type
        switch (array_key_exists('REQUEST_METHOD', $_SERVER) ? $_SERVER['REQUEST_METHOD'] : 'GET') {
            case 'DELETE':
            case 'PUT':
            case 'POST':
                // it might be a creation or a deletion, the latter is detected below
                $this->_operation = 'create';
                try {
                    $this->_params = Json::decode(
                        file_get_contents(self::$_inputStream)
                    );
                } catch (Exception $e) {
                    // ignore error, $this->_params will remain empty
                }
                break;
            default:
                $this->_params = filter_var_array($_GET, array(
                    'deletetoken'      => FILTER_SANITIZE_SPECIAL_CHARS,
                    'jsonld'           => FILTER_SANITIZE_SPECIAL_CHARS,
                    'link'             => FILTER_SANITIZE_URL,
                    'pasteid'          => FILTER_SANITIZE_SPECIAL_CHARS,
                    'shortenviayourls' => FILTER_SANITIZE_SPECIAL_CHARS,
                ), false);
        }
        if (
            !array_key_exists('pasteid', $this->_params) &&
            !array_key_exists('jsonld', $this->_params) &&
            !array_key_exists('link', $this->_params) &&
            array_key_exists('QUERY_STRING', $_SERVER) &&
            !empty($_SERVER['QUERY_STRING'])
        ) {
            $this->_params['pasteid'] = $this->getPasteId();
        }

        // prepare operation, depending on current parameters
        if (array_key_exists('pasteid', $this->_params) && !empty($this->_params['pasteid'])) {
            if (array_key_exists('deletetoken', $this->_params) && !empty($this->_params['deletetoken'])) {
                $this->_operation = 'delete';
            } elseif ($this->_operation != 'create') {
                $this->_operation = 'read';
            }
        } elseif (array_key_exists('jsonld', $this->_params) && !empty($this->_params['jsonld'])) {
            $this->_operation = 'jsonld';
        } elseif (array_key_exists('link', $this->_params) && !empty($this->_params['link'])) {
            if (strpos($this->getRequestUri(), '/shortenviayourls') !== false || array_key_exists('shortenviayourls', $this->_params)) {
                $this->_operation = 'yourlsproxy';
            }
        }
    }

    /**
     * Get current operation
     *
     * @access public
     * @return string
     */
    public function getOperation()
    {
        return $this->_operation;
    }

    /**
     * Get data of paste or comment
     *
     * @access public
     * @return array
     */
    public function getData()
    {
        $data = array(
            'adata' => $this->getParam('adata'),
        );
        $required_keys = array('v', 'ct');
        $meta          = $this->getParam('meta');
        if (empty($meta)) {
            $required_keys[] = 'pasteid';
            $required_keys[] = 'parentid';
        } else {
            $data['meta'] = $meta;
        }
        foreach ($required_keys as $key) {
            $data[$key] = $this->getParam($key, $key == 'v' ? 1 : '');
        }
        // forcing a cast to int or float
        $data['v'] = $data['v'] + 0;
        return $data;
    }

    /**
     * Get a request parameter
     *
     * @access public
     * @param  string $param
     * @param  string $default
     * @return string
     */
    public function getParam($param, $default = '')
    {
        return array_key_exists($param, $this->_params) ?
            $this->_params[$param] : $default;
    }

    /**
     * Get host as requested by the client
     *
     * @access public
     * @return string
     */
    public function getHost()
    {
        $host = array_key_exists('HTTP_HOST', $_SERVER) ? filter_var($_SERVER['HTTP_HOST'], FILTER_SANITIZE_URL) : '';
        return empty($host) ? 'localhost' : $host;
    }

    /**
     * Get request URI
     *
     * @access public
     * @return string
     */
    public function getRequestUri()
    {
        $uri = array_key_exists('REQUEST_URI', $_SERVER) ? filter_var($_SERVER['REQUEST_URI'], FILTER_SANITIZE_URL) : '';
        return empty($uri) ? '/' : $uri;
    }

    /**
     * If we are in a JSON API context
     *
     * @access public
     * @return bool
     */
    public function isJsonApiCall()
    {
        return $this->_isJsonApi;
    }

    /**
     * Override the default input stream source, used for unit testing
     *
     * @param string $input
     */
    public static function setInputStream($input)
    {
        self::$_inputStream = $input;
    }

    /**
     * Detect the clients supported media type and decide if its a JSON API call or not
     *
     * Adapted from: https://stackoverflow.com/questions/3770513/detect-browser-language-in-php#3771447
     *
     * @access private
     * @return bool
     */
    private function _detectJsonRequest()
    {
        $hasAcceptHeader = array_key_exists('HTTP_ACCEPT', $_SERVER);
        $acceptHeader    = $hasAcceptHeader ? $_SERVER['HTTP_ACCEPT'] : '';

        // simple cases
        if (
            (array_key_exists('HTTP_X_REQUESTED_WITH', $_SERVER) &&
                $_SERVER['HTTP_X_REQUESTED_WITH'] == 'JSONHttpRequest') ||
            ($hasAcceptHeader &&
                strpos($acceptHeader, self::MIME_JSON) !== false &&
                strpos($acceptHeader, self::MIME_HTML) === false &&
                strpos($acceptHeader, self::MIME_XHTML) === false)
        ) {
            return true;
        }

        // advanced case: media type negotiation
        if ($hasAcceptHeader) {
            $mediaTypes = array();
            foreach (explode(',', trim($acceptHeader)) as $mediaTypeRange) {
                if (preg_match(
                    '#(\*/\*|[a-z\-]+/[a-z\-+*]+(?:\s*;\s*[^q]\S*)*)(?:\s*;\s*q\s*=\s*(0(?:\.\d{0,3})|1(?:\.0{0,3})))?#',
                    trim($mediaTypeRange), $match
                )) {
                    if (!isset($match[2])) {
                        $match[2] = '1.0';
                    } else {
                        $match[2] = (string) floatval($match[2]);
                        if ($match[2] === '0.0') {
                            continue;
                        }
                    }
                    if (!isset($mediaTypes[$match[2]])) {
                        $mediaTypes[$match[2]] = array();
                    }
                    $mediaTypes[$match[2]][] = strtolower($match[1]);
                }
            }
            krsort($mediaTypes);
            foreach ($mediaTypes as $acceptedQuality => $acceptedValues) {
                foreach ($acceptedValues as $acceptedValue) {
                    if (
                        strpos($acceptedValue, self::MIME_HTML) === 0 ||
                        strpos($acceptedValue, self::MIME_XHTML) === 0
                    ) {
                        return false;
                    } elseif (strpos($acceptedValue, self::MIME_JSON) === 0) {
                        return true;
                    }
                }
            }
        }
        return false;
    }
}