#target photoshop
// $.level = 2;
// debugger;

var settings = new File(Folder.userData + "/.ShiftotronSettings");
var stepSize = new UnitValue(5, "px");
var stepsLeft = -10;
var stepsRight = 10;
var midLayerName;

if (app.documents.length == 0) {
	Window.alert("This script requires an open Photoshop document to work on.\nPlease open one and try again.", "File not open", true);
} else {
	main();
}

function setDropDown( dd, strSet ) {
	var index = 0;
	for ( var i = 0; i < dd.items.length; i = i + 1 ) {
		if ( dd.items[ i ].toString() == strSet ) {
			index = i;
			break;
		}
	}
	if ( dd.items.length > 0 ) {
		dd.items[ index ].selected = true;
	}
	return index;
}


function multiAdd(drop, arr) {
	var i;
	for (i = 0; i < arr.length; i = i + 1) {
		var curr = arr[i];
		if ((curr.typename == "ArtLayer") || (curr.typename == "LayerSet")) {
			curr = curr.name;
		}
		if (curr == "-") {
			drop.add("separator", "");
		} else {
			drop.add("item", curr);
		}
	}
}

function readSettings(settings) {
	try {
		if (settings.open("r")) {
			var ss = new UnitValue(settings.readln());
			var sl = settings.readln();
			var sr = settings.readln();
			stepSize = ss;
			stepsLeft = sl;
			stepsRight = sr;
		}
	} catch (e) {
	} finally {
		settings.close();
	}
}

function writeSettings(settings) {
	try {
		if (settings.open("w")) {
			settings.writeln(stepSize);
			settings.writeln(stepsLeft);
			settings.writeln(stepsRight);
			app.activeDocument.activeLayer = app.activeDocument.layers.getByName(midLayerName);
		}
	} catch (e) {
	} finally {
		settings.close();
	}
}

function updateParams(dialog) {
	stepsLeft = dialog.step.count.left.edit.text;
	stepsRight = dialog.step.count.right.edit.text;
	stepSize = new UnitValue(dialog.stepSize.edit.text, dialog.stepSize.unit.selection);
	midLayerName = dialog.centralLayer.value.selection;
}

function buildWindow(doc) {
	var dlgResource =
		"dialog { text:'Shiftotron', orientation: 'column', alignChildren: 'fill', \
			stepSize: Panel { orientation: 'row', alignChildren: 'fill', text: 'Step Size',\
				description: StaticText {text: 'Shift step size' }, \
				edit: EditText {preferredSize: [30, 20]}, \
				unit: DropDownList {}\
			}, \
			step: Panel { orientation: 'row', alignChildren: 'fill', text: 'Starting and ending steps', \
				count: Group { orientation: 'column', alignChildren: 'right', \
					left: Group { orientation: 'row', alignChildren: 'center', \
						description: StaticText {text: 'From' }, \
						edit: EditText {preferredSize: [30, 20]}, \
					}, \
					right: Group { orientation: 'row', alignChildren: 'center', \
						description: StaticText {text: 'To' }, \
						edit: EditText {preferredSize: [30, 20]}, \
					} \
				}, \
				lock: Checkbox {text: 'Mirrored' } \
			}, \
			centralLayer: Group { orientation: 'row', alignChildren: 'fill', \
				description: StaticText {text: 'Central layer' }, \
				value: DropDownList {} \
			}, \
			progress: Progressbar {}, \
			commands: Group { orientation: 'row', alignChildren: 'center', \
				ok: Button {text: 'OK' }, \
				cancel: Button {text: 'Cancel' } \
			} \
		}";
	var dlg = new Window(dlgResource);
	dlg.commands.ok.onClick = function() {
		dlg.progress.maxvalue = stepsRight - stepsLeft + 1;
		if (stepsRight < stepsLeft) {
			var z = stepsRight;
			stepsRight = stepsLeft;
			stepsLeft = z;
		}
		doWork(doc, dlg.progress);
		dlg.close();
	}
	multiAdd(dlg.stepSize.unit, ["px", "in", "cm"]);
	multiAdd(dlg.centralLayer.value, app.activeDocument.layers);	
	dlg.onClose = function() { updateParams(dlg); }
	dlg.stepSize.edit.onChange = function() { updateParams(dlg); }
	dlg.stepSize.unit.onChange = function() { updateParams(dlg); }
	dlg.step.count.left.edit.onChange = function() { updateParams(dlg); }
	dlg.step.count.right.edit.onChange = function() {
		updateParams(dlg);
	}
	dlg.step.count.right.edit.onChanging = function() {
		if (dlg.step.lock.value) {
			dlg.step.count.left.edit.text = - (+dlg.step.count.right.edit.text);
		}
	}
	dlg.centralLayer.value.onChange = function() { updateParams(dlg); }
	dlg.stepSize.edit.text = stepSize.value;
	setDropDown(dlg.stepSize.unit, stepSize.type);
	dlg.step.count.left.edit.text = stepsLeft;
	dlg.step.count.right.edit.text = stepsRight;
	dlg.step.lock.onClick = function() { 
		if (this.value) {
			dlg.step.count.left.enabled = false;
			dlg.step.count.left.edit.text = - (+dlg.step.count.right.edit.text);
			updateParams(dlg);
		} else {
			dlg.step.count.left.enabled = true;
		}
	}
	if (+stepsRight == -stepsLeft) {
		dlg.step.lock.value = true;
		dlg.step.count.left.enabled = false;
	}	
	setDropDown(dlg.centralLayer.value, app.activeDocument.activeLayer.name);
	dlg.center();
	dlg.show();
}

function shift(x, y) {
var id970 = charIDToTypeID( "move" );
    var desc209 = new ActionDescriptor();
    var id971 = charIDToTypeID( "null" );
        var ref184 = new ActionReference();
        var id972 = charIDToTypeID( "Lyr " );
        var id973 = charIDToTypeID( "Ordn" );
        var id974 = charIDToTypeID( "Trgt" );
        ref184.putEnumerated( id972, id973, id974 );
    desc209.putReference( id971, ref184 );
    var id975 = charIDToTypeID( "T   " );
    var desc210 = new ActionDescriptor();
        var id976 = charIDToTypeID( "Hrzn" );
        var id977 = charIDToTypeID( "#Pxl" );
        desc210.putUnitDouble( id976, id977, x.as("px"));
        var id978 = charIDToTypeID( "Vrtc" );
        var id979 = charIDToTypeID( "#Pxl" );
        desc210.putUnitDouble( id978, id979, y.as("px"));
    var id980 = charIDToTypeID( "Ofst" );
    desc209.putObject( id975, id980, desc210 );
	executeAction( id970, desc209, DialogModes.NO );
}


function doWork(doc, prog) {
	try {
		var dir = new Folder(String(doc.fullName).replace(/\.[^\.]*$/, ""));
	} catch (e) {
		alert(e, "Document not saved", true);
		return;
	}
	if (!dir.exists && !dir.create()) {
		alert("Could not create a directory to place output files in:\n" + dir.fsName, "Could not create directory", true);
		return;
	}
	var files = dir.getFiles("!frame_?????.*");
	for (var i = 0; i < files.length; i = i + 1) {
		if (!files[i].remove()) {
			alert("Could not remove old output files. Please close applications that may be using them and try again. File:\n" + dir.fsName, "Could not remove old output files", true);
			return;
		}
	}
	var n;
	for (var i = 0; i < doc.layers.length; i = i + 1) {
		if (doc.layers[i].name.toString() == midLayerName.toString()) {
			n = i;
			break;
		}
	}
	var opts = new JPEGSaveOptions();
	var zero = new UnitValue(0, "px");
	var t = doc.layerComps.getByName("!!!TEMP")
	opts.quality = 10;
	for (var j = +stepsLeft; j < +stepsRight + 1; j = j + 1) {
		for (var i = 0; i < doc.layers.length; i = i + 1) {
			curr = doc.layers[i];
			if (curr.visible) {
				doc.activeLayer = curr;
				shift(j * stepSize * (n - i), zero);
			}
		}
		try {
			var file = new File(dir + "/!frame_" + (j + 50000) + ".jpg");
			doc.saveAs(file, opts, true);
		} catch (e) {
			alert("Could not save file:\n" + file.fsName, "Could not create file", true);
			return;
		}
		t.apply();
		prog.value++;
	}
}

function main() {
	readSettings(settings);
	var doc = app.activeDocument;
	var t = doc.layerComps.add("!!!TEMP", "", true, true, true);
	t = doc.layerComps.getByName("!!!TEMP");
	var window = buildWindow(doc);
	writeSettings(settings);
	t.remove();
}