main.js

const fs = require('fs').promises;
const fetch = require('node-fetch');
const { transform } = require('@moneyforward/stream-util');

const WBK = require('wikibase-sdk');
const wdk = WBK({
  instance: 'https://www.wikidata.org',
  sparqlEndpoint: 'https://query.wikidata.org/sparql'
});

let entities = require('./entities.json');

const getEntities = async (id) => {
  const url = wdk.getEntities({
    ids: [id],
    languages: ['ja'],
    props: ['labels', 'descriptions']
  });
  const res = await fetch(url);
  const json = await res.json();
  const entities = await wdk.parse.wb.entities(json);
  return entities
}

const getLabel = async (id) => {
  let entity;
  if (entities[id]) {
    entity = entities[id]
  } else {
    result = await getEntities(id);
    entity = result[id];
    entities = Object.assign(entities, result);
    await fs.writeFile('./entities.json', JSON.stringify(entities));
  }
  let label;
  if (entity.labels['ja']) {
    label = entity.labels.ja;
  } else {
    label = entity.descriptions.ja;
  }
  return label;
}

const snakToLanguage = async (snak) => {
  const propertyLabel = await getLabel(snak.property);
  snak.propertyLabel = propertyLabel;
  switch (snak.datatype) {
    case 'wikibase-item':
      const qualifierLabel = await getLabel(snak.datavalue.value.id);
      snak.datavalue.value.label = qualifierLabel;
      break;
    case 'time':
      const time = new Date(snak.datavalue.value.time);
      snak.datavalue.value.unixtime = time.getTime();
      break;
    default:
      break;
  }
  return snak;
}

/*
const mapSnaks = async (snaks) => {
  let ret = {};
  for (const snak of snaks) {
    for (const [key, value] of Object.entries(snak.snaks)) {
      for (const item of value) {
        let data = await snakToLanguage(item);
        ret = Object.assign(ret, data);
      }
    }
  }
  return ret;
}
*/

const mapClaims = async (claims) => {
  let ret = {};
  for (const [key, value] of Object.entries(claims)) {
    ret[key] = [];
    for (const claim of value) {
      let data = await snakToLanguage(claim.mainsnak);
      /*
      if (claim.qualifiers) {
        await mapSnaks(claim.qualifiers);
      }
      if (claim.references) {
        await mapSnaks(claim.references);
      }
      */
      ret[key].push({'mainsnack': data});
    }
  }
  return ret;
}

(async () => {
  for await (const line of process.stdin.pipe(new transform.Lines())) {
    let data = JSON.parse(line);
    const claims = await mapClaims(data.claims);
    data.claims = Object.assign(data.claims, claims)
    console.log(JSON.stringify(data, null, 2))
  }
})();