module.exports = merge;

/**
 * Augments `target` with properties in `options`. Does not override
 * target's properties if they are defined and matches expected type in 
 * options
 *
 * @returns {Object} merged object
 */
function merge(target, options) {
  var key;
  if (!target) { target = {}; }
  if (options) {
    for (key in options) {
      if (options.hasOwnProperty(key)) {
        var targetHasIt = target.hasOwnProperty(key),
            optionsValueType = typeof options[key],
            shouldReplace = !targetHasIt || (typeof target[key] !== optionsValueType);

        if (shouldReplace) {
          target[key] = options[key];
        } else if (optionsValueType === 'object') {
          // go deep, don't care about loops here, we are simple API!:
          target[key] = merge(target[key], options[key]);
        }
      }
    }
  }

  return target;
}