<?php

namespace CorpusParole\Libraries\Sparql;

use EasyRdf\Sparql\Client;

use EasyRdf\Exception;

use EasyRdf\Format;

use EasyRdf\Http;

class TimeoutSparqlClient extends Client {

    public function query($query, $timeout=0)

    {

        return $this->request('query', $query, $timeout);

    }

    protected function request($type, $query, $timeout=0)

    {

        $processed_query = $this->preprocessQuery($query);

        $response = $this->executeQuery($processed_query, $type, $timeout);

        if (!$response->isSuccessful()) {

            throw new Http\Exception("HTTP request for SPARQL query failed", 0, null, $response->getBody());

        }

        if ($response->getStatus() == 204) {

            // No content

            return $response;

        }

        return $this->parseResponseToQuery($response);

    }

    /**

     * 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, $timeout=0)

    {

        $client = Http::getDefaultHttpClient();

        $client->resetParameters();

        // 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

        );

        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);

            $client->setHeaders('Accept', $accept);

            $client->setMethod('POST');

            $client->setUri($this->updateUri);

            $client->setRawData($processed_query);

            $client->setHeaders('Content-Type', 'application/sparql-update');

        } 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);

            }

            $client->setHeaders('Accept', $accept);

            $encodedQuery = 'query=' . urlencode($processed_query).(($timeout>0)?"&timeout=$timeout":"");

            // 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->queryUri) <= 2046) {

                $delimiter = $this->queryUri_has_params ? '&' : '?';

                $client->setMethod('GET');

                $client->setUri($this->queryUri . $delimiter . $encodedQuery);

            } else {

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

                $client->setMethod('POST');

                $client->setUri($this->queryUri);

                $client->setRawData($encodedQuery);

                $client->setHeaders('Content-Type', 'application/x-www-form-urlencoded');

            }

        } else {

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

        }

        return $client->request();

    }

}