#!/usr/bin/env node

const fs = require('fs');
const moment = require('moment');
const _ = require('lodash');
const path = require('path');
const agent = require('superagent-promise')(require('superagent'), Promise);
const { translate } = require("google-translate-api-browser");
let dicc = {};

//Lang Codes https://ctrlq.org/code/19899-google-translate-languages

if (process.argv.length >= 4) {

  //Args
  const inputFile = process.argv[2];
  const destinationCodes = process.argv[3].split(',');
  const apiKey = process.argv.length > 4 && process.argv[4];

  const apiUrl = _.template('https://www.googleapis.com/language/translate/v2?key=<%= apiKey %>&q=<%= value %>&source=en&target=<%= languageKey %>');

  const transformResponse = (res) => {
    return _.get(JSON.parse(res.text), ['data', 'translations', 0, 'translatedText'], '');
  }

  const getCache = (languageKey) => {
    try {
      dicc[languageKey] = {};
      let fileContent = fs.readFileSync(`./translateCache-${languageKey}.txt`, 'utf-8').split('\n');
      fileContent.map((line)=> {
        let cached = line.split('|');
        if(cached[0]) dicc[languageKey][cached[0]] = cached[1];
      });
    } catch (error) {

    }
  }
  const cachedIndex = (key, value, languageKey) => {
    const line = key + '|' + value + '\n';
    dicc[languageKey][key] = value;
    fs.appendFileSync(`./translateCache-${languageKey}.txt`, line);
    return value;
  }

  function iterLeaves(value, keyChain, accumulator, languageKey) {
    accumulator = accumulator || {};
    keyChain = keyChain || [];
    if (_.isObject(value)) {
      return _.chain(value).reduce((handlers, v, k) => {
        return handlers.concat(iterLeaves(v, keyChain.concat(k), accumulator, languageKey));
      }, []).flattenDeep().value();
    } else {
      if(typeof value !== 'string')
        return value;

      return function () {
        if(!(value in dicc[languageKey])) {
          console.log(_.template('Translating <%= value %> to <%= languageKey %>')({value, languageKey}));

          let prom;
          //Translates individual string to language code
          if(apiKey != '') {
            //using apiKey
            prom = agent('GET', apiUrl({
              value: encodeURI(value),
              languageKey,
              apiKey
            })).then(transformResponse)
          }
          else {
            //using free api key
            prom = translate(value, { to: languageKey })
          }

          return prom.then((res) => cachedIndex(value, res, languageKey))
            .catch((err) => console.log(err))
            .then((text) => {
              //Sets the value in the accumulator
              _.set(accumulator, keyChain, text);

              //This needs to be returned to it's eventually written to json
              return accumulator;
            });
        }
        else {
          console.log(value + ' cached: ' + dicc[languageKey][value]);
          _.set(accumulator, keyChain, dicc[languageKey][value]);
          return accumulator;
        }
      };
    }
  }

  Promise.all(_.reduce(destinationCodes, (sum, languageKey) => {
    const fileName = _.template('./<%= languageKey %>-<%= timeStamp %>.json')({
      languageKey,
      timeStamp: moment().unix()
    });

    //read languageKey Cache.
    getCache(languageKey);

    //Starts with the top level strings
    return sum.concat(_.reduce(iterLeaves(JSON.parse(fs.readFileSync(path.resolve(inputFile), 'utf-8')), undefined, undefined, languageKey), (promiseChain, fn) => {
      return promiseChain.then(fn);
    }, Promise.resolve()).then((payload) => {
      fs.writeFileSync(fileName, JSON.stringify(payload));
    }).then(_.partial(console.log, 'Successfully translated all nodes, file output at ' + fileName)));
  }, [])).then(() => {
    process.exit();
  });

} else {
  console.error('You must provide an input json file and a comma-separated list of destination language codes.');
}