Combine by Blend Mode?

Question

I have a tedious production task I'd love help automating.
I receive layouts with mutliple layers of product shots (with transparency) in Normal blend mode. Most of those layers also have separate shadow layers in Multiply blend mode. (Sometimes these layers have masks, othertimes not.) Depending on how the file was built, product layers might be in proximity of their shadow layers, or they may not, making organization and contraction challenging.
(In case it matters, sometimes all layers (products and shadows) are housed inside a single group, sometimes there are no groups at all.)
Ultimately, I'd like to merge all the Product layers into one Normal mode layer, and all the Shadow layers into one Multiply mode layer (with masks applied), with the two layers linked to each other.
Can layers be identified and merged according to blend modes?

Answer 1

This might work.
But this disregards possible masks on groups and just moves the Multiply artLayers into one group and all others into another.
// move all artlayers set to multiply and all other artlayers into two layersets and then merge those;
// 2011; use it at your own risk;
#target photoshop;
if (app.documents.length > 0) {
var myDocument = app.activeDocument;
var artLayers = collectLayers(myDocument);
var multiplyGroup = myDocument.layerSets.add();
multiplyGroup.name = "multiply";
multiplyGroup.blendMode = BlendMode.MULTIPLY;
var normalGroup = myDocument.layerSets.add();
normalGroup.name = "normal";
for (var m = 0; m < artLayers.length; m++) {
     var thisLayer = artLayers[m];
     if (thisLayer.blendMode == BlendMode.MULTIPLY) {
          thisLayer.move(multiplyGroup, ElementPlacement.PLACEATBEGINNING)
     else {
          thisLayer.move(normalGroup, ElementPlacement.PLACEATBEGINNING)
normalGroup.merge();
multiplyGroup.merge();
////// function collect all layers //////
function collectLayers (theParent) {
     if (!allLayers) {
          var allLayers = new Array}
     else {};
     for (var m = theParent.layers.length - 1; m >= 0;m--) {
          var theLayer = theParent.layers[m];
// apply the function to layersets;
          if (theLayer.typename == "ArtLayer") {
// exclude background layer;
               if (theLayer.isBackgroundLayer == false) {
                    allLayers.push(theLayer)
          else {
               allLayers = allLayers.concat(collectLayers(theLayer))
// this line includes the layer groups;
//               allLayers.push(theLayer);
     return allLayers