<?php

namespace CorpusParole\Repositories;

use Config;

use Log;

use CorpusParole\Models\Document;

use CorpusParole\Libraries\CorpusParoleException;

use CorpusParole\Libraries\Sparql\SparqlClient;

use EasyRdf\Graph;

use Illuminate\Pagination\LengthAwarePaginator;

use Illuminate\Pagination\Paginator;

/**

 * Implement the DocumentRepository using EasyRdf

 * TODO: certainly split the transaction management (+add, +delete +transaction ) to an external class -> for this extend the sparql client.

 */

class RdfDocumentRepository implements DocumentRepository {

    private $sparqlClient;

    public function __construct(SparqlClient $sparqlClient) {

        $this->sparqlClient = $sparqlClient;

    }

    public function getSparqlClient() {

        return $this->sparqlClient;

    }

    private function queryDocs($query) {

        $docs = $this->sparqlClient->query($query);

        $data = [];

        foreach ($docs as $doc) {

            $newGraph = new Graph($doc->uri->getUri());

            $newGraph->add($doc->uri, "rdf:type", $newGraph->resource("http://www.openarchives.org/ore/terms/Aggregation"));

            $newGraph->add($doc->uri, "http://www.europeana.eu/schemas/edm/aggregatedCHO", $doc->doc);

            $newGraph->add($doc->doc, "rdf:type", $newGraph->resource("http://www.europeana.eu/schemas/edm/ProvidedCHO"));

            $newGraph->add($doc->doc, "http://purl.org/dc/elements/1.1/title", $doc->title);

            if(isset($doc->issued)) {

                $newGraph->add($doc->doc, "http://purl.org/dc/terms/issued", $doc->issued);

            }

            if(isset($doc->modified)) {

                $newGraph->add($doc->doc, "http://purl.org/dc/terms/modified", $doc->modified);

            }

            array_push($data, new Document($doc->uri->getUri(), $newGraph));

        }

        return $data;

    }

    public function all() {

        return $this->queryDocs(

        "SELECT DISTINCT ?uri ?doc ?title ?issued ?modified".

        "    WHERE {".

        "        GRAPH ?uri { ?doc a <http://www.europeana.eu/schemas/edm/ProvidedCHO>.".

        "        ?doc <http://purl.org/dc/elements/1.1/title> ?title.".

        "        OPTIONAL {?doc <http://purl.org/dc/terms/issued> ?issued.} ".

        "        OPTIONAL {?doc <http://purl.org/dc/terms/modified> ?modified.} }".

        "    } ORDER BY ?uri"

        );

    }

    public function get($id) {

        $docUri = Config::get('corpusparole.corpus_doc_id_base_uri').$id;

        // We want the CBD (Concise Bounded Description, cf. http://www.w3.org/Submission/CBD/)

        // WARNING: This seems to work in sesame for our dataset.

        $doc = $this->sparqlClient->query(

            "CONSTRUCT { ?s ?p ?o } WHERE { GRAPH <$docUri> { ?s ?p ?o } }"

        );

        //TODO: return null if not found

        if($doc->isEmpty()) {

            return null;

        }

        return new Document($docUri, $doc);

    }

    /**

     * save document.

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

     * @throws CorpusParoleException if one of the operation could not be performed

     */

    public function save(Document $doc) {

        $transactionStarted = $this->sparqlClient->startTransaction();

        try {

            foreach($doc->getDeltaList() as $delta) {

                $this->sparqlClient->delete($delta->getDeletedGraph());

                $this->sparqlClient->add($delta->getAddedGraph());

            }

            if($transactionStarted) {

                $transactionStarted = false;

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

            }

            else  {

                return false;

            }

        }

        catch(CorpusParoleException $e) {

            if($transactionStarted) {

                $this->sparqlClient->rollback();

            }

            throw $e;

        }

    }

    public function getCount() {

        $res = $this->sparqlClient->query("SELECT (COUNT (DISTINCT ?g) as ?count) WHERE { GRAPH ?g { ?s a <http://www.europeana.eu/schemas/edm/ProvidedCHO> } }");

        assert(!is_null($res) && $res->count()==1);

        return $res[0]->count->getValue();

    }

    //SELECT ?g WHERE { GRAPH ?g { ?s ?p ?o } }

    /**

     * Paginate all document as a paginator.

     *

     * @param  int  $perPage

     * @param  string  $pageName

     * @return \Illuminate\Contracts\Pagination\LengthAwarePaginator

     */

    public function paginateAll($perPage = 15, $pageName = 'page')

    {

        assert(is_numeric($perPage));

        $page = Paginator::resolveCurrentPage($pageName);

        $total = $this->getCount();

        $offset = max(0,($page - 1) * $perPage);

        $query =

            "SELECT DISTINCT ?uri ?doc ?title ?issued ?modified".

            "    WHERE {".

            "        GRAPH ?uri { ?doc a <http://www.europeana.eu/schemas/edm/ProvidedCHO>.".

            "        ?doc <http://purl.org/dc/elements/1.1/title> ?title.".

            "        OPTIONAL {?doc <http://purl.org/dc/terms/issued> ?issued.} ".

            "        OPTIONAL {?doc <http://purl.org/dc/terms/modified> ?modified.} }".

            "    } ORDER BY ?uri OFFSET $offset LIMIT $perPage";

        $results = $this->queryDocs($query);

        return new LengthAwarePaginator($results, $total, $perPage, $page, [

            'path' => Paginator::resolveCurrentPath(),

            'pageName' => $pageName,

        ]);

    }

}