state) {
    return Object.assign({}, state, {
      playbackRates: getPlaybackRates([], state.animations),
    });
  },

  [UPDATE_SELECTED_ANIMATION](state, { selectedAnimation }) {
    const detailVisibility = !!selectedAnimation;

    return Object.assign({}, state, {
      detailVisibility,
      selectedAnimation,
    });
  },

  [UPDATE_SIDEBAR_SIZE](state, { sidebarSize }) {
    return Object.assign({}, state, {
      sidebarSize,
    });
  },
};

function getPlaybackRates(basePlaybackRate, animations) {
  return [
    ...new Set(
      animations.map(a => a.state.playbackRate).concat(basePlaybackRate)
    ),
  ];
}

module.exports = function (state = INITIAL_STATE, action) {
  const reducer = reducers[action.type];
  return reducer ? reducer(state, action) : state;
};
PK