// @flow
import type { TimingFunction } from '../types/timingFunction'

const functionsMap = {
  back: 'cubic-bezier(0.680, -0.550, 0.265, 1.550)',
  circ: 'cubic-bezier(0.785,  0.135, 0.150, 0.860)',
  cubic: 'cubic-bezier(0.645,  0.045, 0.355, 1.000)',
  expo: 'cubic-bezier(1.000,  0.000, 0.000, 1.000)',
  quad: 'cubic-bezier(0.455,  0.030, 0.515, 0.955)',
  quart: 'cubic-bezier(0.770,  0.000, 0.175, 1.000)',
  quint: 'cubic-bezier(0.860,  0.000, 0.070, 1.000)',
  sine: 'cubic-bezier(0.445,  0.050, 0.550, 0.950)',
}

/**
 * String to represent common easing functions as demonstrated here: (github.com/jaukia/easie).
 *
 * @example
 * // Styles as object usage
 * const styles = {
 *   'transitionTimingFunction': easeInOut('quad')
 * }
 *
 * // styled-components usage
 *  const div = styled.div`
 *   transitionTimingFunction: ${easeInOut('quad')};
 * `
 *
 * // CSS as JS Output
 *
 * 'div': {
 *   'transitionTimingFunction': 'cubic-bezier(0.455,  0.030, 0.515, 0.955)',
 * }
 */
export default function easeInOut(functionName: string): TimingFunction {
  return functionsMap[functionName.toLowerCase().trim()]
}