// BAD - or what I call draft; comments explain what instead of code being self-explanatory
// Main bit
const formConfig = fieldArray.reduce((fields, field) => {
  if (!Array.isArray(fields)) {
    field = [field];
  }

  // Currently last field in section
  const last = fields.slice(-1)[0],
    lastValue = this.values[last.id];

  if (this.values[field.id]) {
    // answered fields always show
    return [...fields, field];
  } else if (this.values[last.id] && lastValue.next_field_id === field.id) {
    // this is the next field depending on the previous value
    return [...fields, field];
  } else {
    // this field shouldn't be visible yet
    return fields;
  }
});


// GOOD - only comment left just explains why, the rest c

const isSectionFirstInArray = (fields) => {
  return !Array.isArray(fields);
};

const makeArray = (field) => {
  return [field];
};

const getLastValue = (fields) => {
  const lastField = fields.slice(-1)[0];
  return this.values[lastField.id];
};

const shouldAddToFieldsList = (fields, field) => {
  return this.isAnsweredField(fields, field) || this.isNextField(fields, field);
};


// Main bit
const formConfig = fieldArray.reduce((fields, field) => {
  if (isSectionFirstInArray(fields)) {
    fields = makeArray(fields);
  }

  if (shouldAddToFieldsList(fields, field)) {
    return [...fields, field];
  }

  // Shouldn't be visible yet - I left this, as it explains what cannot
  // reasonably be refactored to be said in words
  return fields;
});