import dotenv from 'dotenv';
import { TranslationServiceClient } from '@google-cloud/translate';

dotenv.config();

const client = new TranslationServiceClient();

const translateText = async (contents=[], targetLanguageCode='zh-CN') => {

  if (typeof contents === 'string') {
    contents = [contents];
  }

  else if (!Array.isArray(contents)) {
    return Promise.reject(new Error('contents must be a string or an array of strings', { cause: 400 }));
  }

  if (contents.length === 0) {
    return Promise.resolve([]);
  };

  const projectId = 'flyzto-cloud';
  const location = 'global';

  const request = {
    parent: `projects/${projectId}/locations/${location}`,
    contents,
    targetLanguageCode,
  };

  return client.translateText(request)
  .then(([response]) => {
    const result = {};
    response.translations.forEach((translation, index) => {
      result[contents[index]] = translation.translatedText;
    });
    return result;
  });
}

export default translateText;