const deepmerge = require('deepmerge');

/**
 * Transform translation files between flat JSON and hierarchical JSON
 *
 * @module @doodle/i18n/disty/onesky/transform
 */

/**
 * Unflatten a messages object
 *
 * @param {object} messages a flat messages object
 * @returns {object} a hierarchical messages object
 */
const unflatten = messages => {
  const hierarchicalMessages = Object.entries(messages).map(([key, value]) => {
    const keyComponents = key.split('.');
    const leafKeyComponent = keyComponents.pop();

    return keyComponents.reverse().reduce(
      (hierarchicalMessage, keyComponent) => ({
        [keyComponent]: hierarchicalMessage,
      }),
      { [leafKeyComponent]: value }
    );
  });
  return deepmerge.all(hierarchicalMessages);
};

/**
 * Flatten a messages object
 *
 * @param {object} messages hierarchical object
 * @return {object} a flat messages object
 */
const flatten = messages =>
  Object.entries(messages).reduce((result, [key, value]) => {
    if (typeof value === 'object') {
      Object.entries(flatten(value)).forEach(([flatKey, flatValue]) => {
        result[`${key}.${flatKey}`] = flatValue;
      });
    } else {
      result[key] = value;
    }
    return result;
  }, {});

module.exports = {
  flatten,
  unflatten,
};