const {format: formatDate} = require('date-fns/fp');

const createGlot = dictionary => {
  const parseStrings = (lang, value, strs, exprs) => {
    const key = strs.map((str, i) => str + (exprs[i] || '')).join('');
    const found = dictionary[lang][key];

    if (found === undefined) {
      return `~~NO GLOT FOUND FOR ${key}!!!~~`;
    }

    if (typeof found === 'function') {
      return found(value);
    }

    return found;
  };

  const glot = options => {
    const {lang, value, mkFn} = options;

    return (head, ...tail) => {
      if (Array.isArray(head)) {
        if (mkFn) {
          return mkFn(parseStrings(lang, value, head, tail));
        }
        return parseStrings(lang, value, head, tail);
      } else {
        return glot({
          ...options,
          ...head,
        });
      }
    };
  };

  return glot;
};

const glot = createGlot({
  en: {
    greetings: "'ello, govna'",
    months: date => `${date.getMonth() + 1} months`,
    date: 'yyyy-MM-dd',
    thing_1: 'number one',
    thing_2: 'number two',
  },
  fra: {
    greetings: "'sup, Monsieur",
  },
})({lang: 'en'});

console.log(glot`greetings`);
console.log(glot`INVALID_KEY`);

console.log(glot({lang: 'fra'})`greetings`);
const foreverFrench = glot({lang: 'fra'});
console.log(foreverFrench`greetings`);

console.log(glot({value: new Date()})`months`);
console.log(glot({mkFn: formatDate})`date`(new Date()));

new Array(2).fill(null).map((_, i) => console.log(glot`thing_${i + 1}`));