Scripting apply a preset - How to tell what type of layer from a ffx file? Need some Scripting help

/**
 * Apply Presets from a folder - into a comp staggered
 * =========================================================
 * - Checks if a composition is active; prompts to create one if not.
 * - Asks the user whether to append to the current composition if active.
 * - Determines the starting time for new layers based on CTI or last layer's outPoint.
 * - Prompts for layer duration and selects a folder containing .ffx presets.
 * - Applies each preset to new layers, using a temporary null layer to ensure proper application.
 * - Sets text for empty text layers to the preset's name.
 * - Adjusts composition duration to fit all layers, with user confirmation.
 * - Restores the CTI to its original position after processing.
 * 
 * ========================================================= */

(function () {
    // Store the initial CTI position
    var initialCTI = app.project.activeItem ? app.project.activeItem.time : 0;

    // Check if there's an active composition
    var comp = app.project.activeItem;

    if (!(comp instanceof CompItem)) {
        // Ask the user if they want to create a new composition
        var createComp = confirm("No active composition found. Do you want to create a new composition?");
        if (createComp) {
            // Create a new composition
            comp = app.project.items.addComp("PresetComp", 1920, 1080, 1.0, 10, 30); // Initial duration of 10s
        } else {
            alert("No composition selected or created. Script will exit.");
            return; // Exit the script
        }
        // Set the CTI to 0 for the new composition
        initialCTI = 0;
    } else {
        // Ask if the user wants to append to the current composition
        var appendComp = confirm("An active composition is selected. Do you want to append to the current composition?");
        if (!appendComp) {
            alert("Operation cancelled. Script will exit.");
            return; // Exit the script
        }
    }

    app.beginUndoGroup("Apply Presets to Layers");

    // Determine the starting time for new layers
    var initialStartTime = comp.time; // Default to the CTI
    if (comp.numLayers > 0) {
        // Find the greatest outPoint
        var maxOutPoint = 0;
        for (var i = 1; i <= comp.numLayers; i++) {
            var layer = comp.layer(i);
            if (layer.outPoint > maxOutPoint) {
                maxOutPoint = layer.outPoint;
            }
        }

        // Ask user whether to use CTI or max outPoint
        var useMaxOutPoint = confirm("Existing layers detected. Do you want to start adding new layers at the end of the last layer (at " + maxOutPoint.toFixed(2) + "s) instead of the CTI at " + initialStartTime.toFixed(2) + "s?");
        var maxOutPointOrCTI = "CTI";
        if (useMaxOutPoint) {
            initialStartTime = maxOutPoint;
            maxOutPointOrCTI = "Max Layer Out Point";
        }
    }

    // Prompt the user for the layer duration, defaulting to 3.5 seconds
    var durationInput = prompt("Enter the duration for each preset layer (in seconds):", "3.5");
    if (durationInput === null || durationInput === "") {
        alert("No duration entered. Script will exit.");
        app.endUndoGroup();
        return; // Exit the script
    }
    var layerDuration = parseFloat(durationInput);
    if (isNaN(layerDuration) || layerDuration <= 0) {
        alert("Invalid duration entered. Script will exit.");
        app.endUndoGroup();
        return; // Exit the script
    }

    var presetFolder = Folder.selectDialog("Select the folder containing your presets");
    if (presetFolder == null) {
        alert("No folder selected. Script will exit.");
        app.endUndoGroup();
        return; // Exit the script
    }

    var presets = presetFolder.getFiles("*.ffx"); // Get all .ffx files in the folder
    var presetCount = presets.length;

    if (presetCount > 0) {
        var totalDuration = initialStartTime + (presetCount * layerDuration);
        var totalPresetDuration = presetCount * layerDuration;

        // Ask user if they want to set the composition duration to fit the layers - Show workings to user
        if (totalDuration != comp.duration) {
            var suffixPrompt = "";
            if (initialStartTime != 0) {
                suffixPrompt = " (= " + totalPresetDuration.toFixed(2) + " s) + " + maxOutPointOrCTI + " time at " + initialStartTime.toFixed(2) + " s";
            }
            var trimComp = confirm("Set the composition duration to " + totalDuration.toFixed(2) + " s\n(" + presetCount + " presets x " + layerDuration + "s" + suffixPrompt + ") \nto fit all layers?");
            if (trimComp) {
                comp.duration = totalDuration;
            }
        }

        var createdLayers = []; // Track created layers

        for (var i = 0; i < presets.length; i++) {
            var presetFile = presets[i];

            // Set the CTI to the start time for the new layer
            comp.time = Math.max(0, initialStartTime + ((i - 1) * layerDuration));

            // Create a null layer temporarily
            var tempNull = comp.layers.addNull();
            tempNull.name = "TempNull_" + i;

            // Deselect all layers
            for (var j = 1; j <= comp.numLayers; j++) {
                comp.layer(j).selected = false;
            }

            // Apply the preset to the null layer
            tempNull.applyPreset(presetFile);

            // Identify the new layer created by the preset
            var newLayer = comp.layers[1]; // The new layer is usually the topmost layer

            // Set the new layer's in and out points
            newLayer.startTime = initialStartTime + (i * layerDuration);
            newLayer.outPoint = newLayer.startTime + layerDuration;

            // Remove the temporary null layer
            tempNull.remove();

            // Rename the new layer to match the preset file name, without URL encoding and extension
            newLayer.name = decodeURIComponent(presetFile.name.replace(/\+/g, " ")).replace(/\.ffx$/, "");

            // Store the created layer for further processing
            createdLayers.push(newLayer);

            // Move the CTI to the start of the new layer's out point for the next iteration
            comp.time = newLayer.outPoint;
        }

        // Post-process text layers to set source text if empty
        for (var k = 0; k < createdLayers.length; k++) {
            var layer = createdLayers[k];
            if (layer instanceof TextLayer) {
                var textProp = layer.property("Source Text");
                if (textProp.numKeys == 0 && textProp.value.text == "") {
                    // Set the text to the preset name if it's empty
                    textProp.setValue(new TextDocument(layer.name));
                }
            }
        }

    } else {
        alert("No presets found in the selected folder.");
    }

    // Restore the initial CTI position
    comp.time = initialCTI;

    app.endUndoGroup();
})();

It is semi tested. Worked for what I needed. And I tried a few situations out of interest and to make the script more useful. e.g. appending to a existing comp, Using the CTI as the start of the insertion point, etc.