Watermarking with filenames

I made some rough edits to a script that I hacked last year for another photographer.

This is a draft starting point, without knowing how the watermark should look. If you can provide a before and after image sample then this can be refined.

/* 
https://community.adobe.com/t5/photoshop-ecosystem-discussions/watermarking-with-filenames/td-p/12632295
Draft version 0.1
Stephen Marsh, 4th January 2022
*/

#target photoshop

function waterMarker() {

    if (documents.length > 0) {

        // Save the original dialog display
        var originalDialogMode = app.displayDialogs;
        app.displayDialogs = DialogModes.ERROR;
        // Save the original ruler units
        var originalRulerUnits = app.preferences.rulerUnits;
        // Set the working units
        app.preferences.rulerUnits = Units.PIXELS;
        // Save the original resolution
        var originalRes = app.activeDocument.resolution;
        // Set the working resolution
        app.activeDocument.resolution = 72;

        try {

            /*
            // Add copyright metadata
            // Escaped copyright symbol = \xA9
            app.activeDocument.info.copyrighted = CopyrightedType.COPYRIGHTEDWORK;
            app.activeDocument.info.copyrightNotice = "Copyright \xA9 by ME!";
            */

            // add a text layer
            var LayerRef = app.activeDocument.artLayers.add();
            LayerRef.kind = LayerKind.TEXT;
            var textRef = LayerRef.textItem;

            var fileNameNoExtension = app.activeDocument.name.replace(/\.[^\.]+$/, '');

            textRef.contents = fileNameNoExtension;

            textRef.position = new Array(0, 0);
            app.preferences.rulerUnits = Units.POINTS;
            textRef.size = 30;
            textRef.useAutoLeading = false;
            textRef.leading = 25;
            textRef.font = 'Times-Italic';
            textRef.justification = Justification.CENTER;
            var textColor = new SolidColor;
            textColor.rgb.red = 255;
            textColor.rgb.green = 255;
            textColor.rgb.blue = 255;
            textRef.color = textColor;

            app.preferences.rulerUnits = Units.PIXELS;

            // Blend mode
            app.activeDocument.activeLayer.blendMode = BlendMode.DIFFERENCE;

            // Opacity
            app.activeDocument.activeLayer.opacity = 100;

            // Conditional resize layer by portrait or landscape orientation
            if (app.activeDocument.height > app.activeDocument.width) {
                scaleP();
            } else {
                scaleL();
            }

            // Rotate text -45 degrees
            app.activeDocument.activeLayer.rotate(-45, AnchorPosition.MIDDLECENTER);

            // Reset the original settings
            app.preferences.rulerUnits = originalRulerUnits;
            app.displayDialogs = originalDialogMode;
            app.activeDocument.resolution = originalRes;

            function scaleP() {
                var iLayer = app.activeDocument.activeLayer;
                app.activeDocument.activeLayer = iLayer;
                var scale = Math.min(app.activeDocument.width / (iLayer.bounds[2] - iLayer.bounds[0]), app.activeDocument.width / (iLayer.bounds[3] - iLayer.bounds[1]));
                // Scale to 90% of canvas
                iLayer.resize(scale * 90, scale * 90);
                // Centre the text layer on canvas
                iLayer.translate(app.activeDocument.width / 2 - (iLayer.bounds[0] + iLayer.bounds[2]) / 2, app.activeDocument.height / 2 - (iLayer.bounds[1] + iLayer.bounds[3]) / 2);
            }

            function scaleL() {
                var iLayer = app.activeDocument.activeLayer;
                app.activeDocument.activeLayer = iLayer;
                var scale = Math.min(app.activeDocument.width / (iLayer.bounds[2] - iLayer.bounds[0]), app.activeDocument.height / (iLayer.bounds[3] - iLayer.bounds[1]));
                // Scale to 90% of canvas
                iLayer.resize(scale * 90, scale * 90);
                // Centre the text layer on canvas
                iLayer.translate(app.activeDocument.width / 2 - (iLayer.bounds[0] + iLayer.bounds[2]) / 2, app.activeDocument.height / 2 - (iLayer.bounds[1] + iLayer.bounds[3]) / 2);
            }

        } catch (e) {
            // Reset the original settings
            app.preferences.rulerUnits = originalRulerUnits;
            app.displayDialogs = originalDialogMode;
            app.activeDocument.resolution = originalRes;

            return;
        }
    }
}

// Create a single history step
app.activeDocument.suspendHistory("Watermarker Script", "waterMarker()");

https://prepression.blogspot.com/2017/11/downloading-and-installing-adobe-scripts.html