/* Minimal SPARQL client */
const axios = require('axios');

function validURL(str) {
  const pattern = new RegExp('^(https?:\\/\\/)?' // protocol
    + '((([a-z\\d]([a-z\\d-]*[a-z\\d])*)\\.)+[a-z]{2,}|' // domain name
    + '((\\d{1,3}\\.){3}\\d{1,3}))' // OR ip (v4) address
    + '(\\:\\d+)?(\\/[-a-z\\d%_.~+]*)*' // port and path
    + '(\\?[;&a-z\\d%_.~+=-]*)?' // query string
    + '(\\#[-a-z\\d_]*)?$', 'i'); // fragment locator
  return !!pattern.test(str);
}

module.exports = class sparqlClient {
  constructor(endpoint) {
    if (!endpoint || !validURL(endpoint)) throw new Error(`Not valid endpoint: ${endpoint}`);

    this.endpoint = endpoint;
  }

  query(q) {
    return axios.get(this.endpoint, {
      params: { query: q },
    }).then((res) => {
      if (res.status === 200) return res.data;
      throw new Error(res.statusText);
    });
  }
};