rofrischmann/react-look

import _ from 'lodash'

/**
 * Splits an expression at a given operator and returns both values converted to compare them with ease
 * @param {string} key - key that gets evaluated, in this case the expression
 * @param {operator} operator - operator which splits property and value
 * @param {Object} Component - outer React Component holding props and state to match
 */
export default (key, operator, Component) => {
  if (key.indexOf(operator) === -1) {
    return false
  }

  const matchValues = _.assign({ }, Component.props, Component.state)
  const [ property, value ] = key.split(operator)
  const [ baseProp ] = property.split('.')

  if (matchValues.hasOwnProperty(baseProp)) {
    let match = _.get(matchValues, property)

    match = match === undefined ? 'undefined' : match

    if (!(!isNaN(parseFloat(match)) && isFinite(match))) {
      match = (match + '').toString()
    }

    return { left: match, right: value }
  }

  return false
}