import * as N3 from "n3";
import * as RDF from "@rdfjs/types";

import { RdfNode, Triple } from "./sparqlModels";

export function parseTurtleText(turtleText: string): Promise<Triple[]> {
  return new Promise<Triple[]>((resolve, reject) => {
    const triples: Triple[] = [];
    new N3.Parser().parse(turtleText, (error, triple, _hash) => {
      if (error) {
        reject(error);
      } else if (triple) {
        triples.push({
          subject: n3toRdfNode(triple.subject),
          predicate: n3toRdfNode(triple.predicate),
          object: n3toRdfNode(triple.object),
        });
      } else {
        resolve(triples);
      }
    });
  });
}

export function n3toRdfNode(entity: RDF.Term): RdfNode {
  if (N3.Util.isLiteral(entity)) {
    const literal = entity as RDF.Literal;
    return {
      type: "literal",
      value: literal.value,
      datatype: literal.datatype.value,
      "xml:lang": literal.language,
    };
  } else {
    return { type: "uri", value: entity.value };
  }
}