<?php

namespace CorpusParole\Libraries\Sparql;

use EasyRdf\Graph;

use CorpusParole\Libraries\CorpusParoleException;

use Config;

use Log;

/**

 *

 */

class SparqlClient {

    private $currentTransactionUrl = null;

    function __construct($httpClient, $sparqlClient) {

        $this->sparqlClient = $sparqlClient;

        $this->httpClient = $httpClient;

    }

    private function getHttpClient() {

        return $this->httpClient;

    }

    public function getCurrentTransactionUrl() {

        return $this->currentTransactionUrl;

    }

    /**

     * Start transaction.

     * @return boolean true if a transaction was started, false otherwise

     * @throws CorpusParoleException if the  transaction could not be stared

     */

    public function startTransaction() {

        if(!is_null($this->currentTransactionUrl)) {

            // We just continue the current transaction

            return false;

        }

        //Log::debug('http_client base uri: ' . $this->getHttpClient()->getConfig('base_uri'));

        $sesameRepository = config('corpusparole.sesame_repository');

        $resp = $this->getHttpClient()->post("$sesameRepository/transactions");

        //$resp = $this->getHttpClient()->post('transactions');

        //TODO check errors

        if($resp->getStatusCode() != 201) {

            throw new CorpusParoleException("Error when starting transaction : "

                . $resp->getStatusCode() . " - "

                . $resp->getReasonPhrase() . " : " . $resp->getBody(), 1);

        }

        $this->currentTransactionUrl = $resp->getHeader('Location')[0];

        return true;

    }

    /**

     * Rollback transaction.

     * @return boolean true if a transaction was started, false otherwise

     * @throws CorpusParoleException if the  transaction could not be rollbacked

     */

    public function rollback() {

        if(is_null($this->currentTransactionUrl)) {

            // We just continue the current transaction

            return false;

        }

        $resp = $this->getHttpClient()->delete($this->currentTransactionUrl);

        if($resp->getStatusCode() != 204) {

            throw new CorpusParoleException("Could not cancel transaction : "

                . $resp->getStatusCode() . " - "

                . $resp->getReasonPhrase() . " : " . $resp->getBody(), 1);

        }

        $this->currentTransactionUrl = null;

        return true;

    }

    /**

     * Commit transaction.

     * @return boolean true if a transaction was started, false otherwise

     * @throws CorpusParoleException if the  transaction could not be commited

     */

    public function commit() {

        if(is_null($this->currentTransactionUrl)) {

            // We just continue the current transaction

            return false;

        }

        $resp = $this->getHttpClient()->put($this->currentTransactionUrl, ['query' => ['action' => 'COMMIT']]);

        if($resp->getStatusCode() != 200) {

            throw new CorpusParoleException("Could not commit transaction : "

                . $resp->getStatusCode() . " - "

                . $resp->getReasonPhrase() . " : " . $resp->getBody(), 1);

        }

        $this->currentTransactionUrl = null;

        return true;

    }

    protected function updateData($operation, Graph $graph)

    {

        $graphUri = $graph->getUri();

        $query = "$operation DATA {";

        if ($graphUri) {

            $query .= "GRAPH <$graphUri> {";

        }

        $query .= $graph->serialise('ntriples');

        if ($graphUri) {

            $query .= "}";

        }

        $query .= '}';

        $resp = $this->getHttpClient()->put(

            $this->currentTransactionUrl, [

                'query' => ['action' => 'UPDATE'],

                'form_params'=> ['update' => $query],

            ]

        );

        if($resp->getStatusCode() != 204) {

            throw new CorpusParoleException("Could not update in transaction with operation $operation: "

                . $resp->getStatusCode() . " - "

                . $resp->getReasonPhrase() . " : " . $resp->getBody(), 1);

        }

    }

    public function add(Graph $graph) {

        $this->updateData('INSERT', $graph);

    }

    public function delete(Graph $graph) {

        $this->updateData('DELETE', $graph);

    }

    /** Make a query to the SPARQL endpoint

     *

     * Just call and return EasyRdf\Sparql\Client::query

     *

     * @param string $query The query string to be executed

     * @return object EasyRdf\Sparql\Result|EasyRdf\Graph Result of the query.

     */

    public function query($query) {

        return $this->sparqlClient->query($query);

    }

}