function normalize(a) {
  if (!(a instanceof Array)) {
    a = [a, a];
  }

  return a;
}

function _default(ecModel) {
  ecModel.eachSeriesByType('lines', function (seriesModel) {
    var data = seriesModel.getData();
    var symbolType = normalize(seriesModel.get('symbol'));
    var symbolSize = normalize(seriesModel.get('symbolSize'));
    var opacityQuery = 'lineStyle.normal.opacity'.split('.');
    data.setVisual('fromSymbol', symbolType && symbolType[0]);
    data.setVisual('toSymbol', symbolType && symbolType[1]);
    data.setVisual('fromSymbolSize', symbolSize && symbolSize[0]);
    data.setVisual('toSymbolSize', symbolSize && symbolSize[1]);
    data.setVisual('opacity', seriesModel.get(opacityQuery));
    data.each(function (idx) {
      var itemModel = data.getItemModel(idx);
      var symbolType = normalize(itemModel.getShallow('symbol', true));
      var symbolSize = normalize(itemModel.getShallow('symbolSize', true));
      var opacity = itemModel.get(opacityQuery);
      symbolType[0] && data.setItemVisual(idx, 'fromSymbol', symbolType[0]);
      symbolType[1] && data.setItemVisual(idx, 'toSymbol', symbolType[1]);
      symbolSize[0] && data.setItemVisual(idx, 'fromSymbolSize', symbolSize[0]);
      symbolSize[1] && data.setItemVisual(idx, 'toSymbolSize', symbolSize[1]);
      data.setItemVisual(idx, 'opacity', opacity);
    });
  });
}

module.exports = _default;