'use strict';

/**
 * Internal conversion helper
 */
module.exports = function strToSnakeCase(str) {
  if (typeof str !== 'string') {
    throw new Error('String expected for conversion to snake case');
  }
  return str.trim().replace(/(\s*\-*\b\w|[A-Z])/g, function($1) {
    $1 = $1.trim().toLowerCase().replace('-', '');
    return ($1[0] === '_' ? '' : '_') + $1;
  }).slice(1);
};