<?php

namespace CorpusParole\Libraries\Sparql;

use EasyRdf\Sparql\Client;

use EasyRdf\Sparql\Result;

use EasyRdf\Exception;

use EasyRdf\Format;

use EasyRdf\RdfNamespace;

/**

 * Wraps a Guzzle psr7 response into a EasyRdf\Http\Response interface

 **/

class ResponseWrapper {

    /**

     * Constructor.

     *

     * @param  Response     Guzzle psr7 response

     */

    public function __construct($response) {

        $this->response = $response;

    }

    /**

     * Check whether the response in successful

     *

     * @return boolean

     */

    public function isSuccessful()

    {

        $status = $this->getStatus();

        return ($status >= 200 && $status < 300);

    }

    /**

     * Check whether the response is an error

     *

     * @return boolean

     */

    public function isError()

    {

        $status = $this->getStatus();

        return ($status >= 400 && $status < 600);

    }

    /**

     * Check whether the response is a redirection

     *

     * @return boolean

     */

    public function isRedirect()

    {

        $status = $this->getStatus();

        return ($status >= 300 && $status < 400);

    }

    /**

     * Get the HTTP response status code

     *

     * @return int

     */

    public function getStatus()

    {

        return $this->response->getStatusCode();

    }

    /**

     * Return a message describing the HTTP response code

     * (Eg. "OK", "Not Found", "Moved Permanently")

     *

     * @return string

     */

    public function getMessage()

    {

        return $this->response->getReasonPhrase();

    }

    /**

     * Get the response body as string

     *

     * @return string

     */

    public function getBody()

    {

        return $this->response->getBody();

    }

    /**

     * Get the raw response body (as transfered "on wire") as string

     *

     * If the body is encoded (with Transfer-Encoding, not content-encoding -

     * IE "chunked" body), gzip compressed, etc. it will not be decoded.

     *

     * @return string

     */

    public function getRawBody()

    {

        return $this->getBody();

    }

    /**

     * Get the HTTP version of the response

     *

     * @return string

     */

    public function getVersion()

    {

        return $this->response->getProtocolVersion();

    }

    /**

     * Get the response headers

     *

     * @return array

     */

    public function getHeaders()

    {

        return $this->response->getHeaders();

    }

    /**

     * Get a specific header as string, or null if it is not set

     *

     * @param string$header

     *

     * @return string|array|null

     */

    public function getHeader($header)

    {

        $header = $this->response->getHeader($header);

        if(is_array($header) && count($header) == 1) {

            return $header[0];

        } else {

            return $header;

        }

    }

    /**

     * Get all headers as string

     *

     * @param boolean $statusLine Whether to return the first status line (ie "HTTP 200 OK")

     * @param string  $br         Line breaks (eg. "\n", "\r\n", "<br />")

     *

     * @return string

     */

    public function getHeadersAsString($statusLine = true, $br = "\n")

    {

        $str = '';

        if ($statusLine) {

            $version = $this->getVersion();

            $status = $this->getStatus();

            $message = $this->getMessage();

            $str = "HTTP/{$version} {$status} {$message}{$br}";

        }

        // Iterate over the headers and stringify them

        foreach ($this->getHeaders() as $name => $value) {

            if (is_string($value)) {

                $str .= "{$name}: {$value}{$br}";

            } elseif (is_array($value)) {

                foreach ($value as $subval) {

                    $str .= "{$name}: {$subval}{$br}";

                }

            }

        }

        return $str;

    }

    /**

     * Get the entire response as string

     *

     * @param string $br Line breaks (eg. "\n", "\r\n", "<br />")

     *

     * @return string

     */

    public function asString($br = "\n")

    {

        return $this->getHeadersAsString(true, $br) . $br . $this->getRawBody();

    }

    /**

     * Implements magic __toString()

     *

     * @return string

     */

    public function __toString()

    {

        return $this->asString();

    }

}

class GuzzleSparqlClient extends Client {

    public function __construct($httpClient, $queryUri, $updateUri = null) {

        parent::__construct($queryUri, $updateUri);

        $this->httpClient = $httpClient;

    }

    private function queryUriHasParams() {

        return strlen(parse_url($this->getQueryUri(), PHP_URL_QUERY)) > 0;

    }

    /**

     * Build http-client object, execute request and return a response

     *

     * @param string $processed_query

     * @param string $type            Should be either "query" or "update"

     *

     * @return Http\Response|\Zend\Http\Response

     * @throws Exception

     */

    protected function executeQuery($processed_query, $type)

    {

        // Tell the server which response formats we can parse

        $sparql_results_types = array(

            'application/sparql-results+json' => 1.0,

            'application/sparql-results+xml' => 0.8

        );

        $request_options = [];

        $uri = null;

        $method = 'GET';

        if ($type == 'update') {

            // accept anything, as "response body of a […] update request is implementation defined"

            // @see http://www.w3.org/TR/sparql11-protocol/#update-success

            $accept = Format::getHttpAcceptHeader($sparql_results_types);

            $request_options['headers'] = [

                'Accept' => $accept,

                'Content-Type' => 'application/sparql-update'

            ];

            $uri = $this->getUpdateUri();

            $method = 'POST';

            $request_options['body'] = $processed_query;

        } elseif ($type == 'query') {

            $re = '(?:(?:\s*BASE\s*<.*?>\s*)|(?:\s*PREFIX\s+.+:\s*<.*?>\s*))*'.

                '(CONSTRUCT|SELECT|ASK|DESCRIBE)[\W]';

            $result = null;

            $matched = mb_eregi($re, $processed_query, $result);

            if (false === $matched or count($result) !== 2) {

                // non-standard query. is this something non-standard?

                $query_verb = null;

            } else {

                $query_verb = strtoupper($result[1]);

            }

            if ($query_verb === 'SELECT' or $query_verb === 'ASK') {

                // only "results"

                $accept = Format::formatAcceptHeader($sparql_results_types);

            } elseif ($query_verb === 'CONSTRUCT' or $query_verb === 'DESCRIBE') {

                // only "graph"

                $accept = Format::getHttpAcceptHeader();

            } else {

                // both

                $accept = Format::getHttpAcceptHeader($sparql_results_types);

            }

            $encodedQuery = 'query=' . urlencode($processed_query);

            // Use GET if the query is less than 2kB

            // 2046 = 2kB minus 1 for '?' and 1 for NULL-terminated string on server

            if (strlen($encodedQuery) + strlen($this->getQueryUri()) <= 2046) {

                $delimiter = $this->queryUriHasParams() ? '&' : '?';

                $request_options['headers'] = [

                    'Accept' => $accept,

                ];

                $method = 'GET';

                $uri = $this->getQueryUri() . $delimiter . $encodedQuery;

            } else {

                $request_options['headers'] = [

                    'Accept' => $accept,

                    'Content-Type' => 'application/x-www-form-urlencoded'

                ];

                // Fall back to POST instead (which is un-cacheable)

                $method = 'POST';

                $uri = $this->getQueryUri();

                $request_options['body'] = $encodedQuery;

            }

        } else {

            throw new Exception('unexpected request-type: '.$type);

        }

        $response = $this->httpClient->request($method, $uri, $request_options);

        return new ResponseWrapper($response);

    }

}