When Ctrl+Z undoes a movement, remove that movement form the movement history as well (resolves #64)

src/main.js

@@ -5,11 +5,11 @@ import {checkDependencies, getHexSizeSupportTokenGridCenter} from "./compatibili
 import {moveEntities, onMouseMove} from "./foundry_imports.js"
 import {performMigrations} from "./migration.js"
 import {DragRulerRuler} from "./ruler.js";
-import {getMovementHistory, resetMovementHistory} from "./movement_tracking.js";
+import {getMovementHistory, removeLastHistoryEntryIfAt, resetMovementHistory} from "./movement_tracking.js";
 import {registerSettings, settingsKey} from "./settings.js"
 import {recalculate} from "./socket.js";
 import {SpeedProvider} from "./speed_provider.js"
-import {setSnapParameterOnOptions} from "./util.js";
+import {isClose, setSnapParameterOnOptions} from "./util.js";
 
 Hooks.once("init", () => {
 	registerSettings()
@@ -17,6 +17,7 @@ Hooks.once("init", () => {
 	hookDragHandlers(Token);
 	hookDragHandlers(MeasuredTemplate);
 	hookKeyboardManagerFunctions()
+	hookLayerFunctions();
 
 	Ruler = DragRulerRuler;
 
@@ -93,6 +94,22 @@ function hookKeyboardManagerFunctions() {
 	}
 }
 
+function hookLayerFunctions() {
+	const originalTokenLayerUndoHistory = TokenLayer.prototype.undoHistory;
+	TokenLayer.prototype.undoHistory = function () {
+		const historyEntry = this.history[this.history.length - 1];
+		return originalTokenLayerUndoHistory.call(this).then((returnValue) => {
+			if (historyEntry.type === "update") {
+				for (const entry of historyEntry.data) {
+					const token = canvas.tokens.get(entry._id);
+					removeLastHistoryEntryIfAt(token, entry.x, entry.y);
+				}
+			}
+			return returnValue;
+		});
+	}
+}
+
 function handleKeys(event, key, up) {
 	if (event.repeat || this.hasFocus)
 		return false

src/movement_tracking.js

@@ -1,6 +1,6 @@
 import {measureDistances} from "./compatibility.js";
 import {recalculate, updateCombatantDragRulerFlags} from "./socket.js";
-import {getTokenShape, zip} from "./util.js";
+import {getTokenShape, isClose, zip} from "./util.js";
 
 function initTrackingFlag(combatant) {
 	const initialFlag = {passedWaypoints: [], trackedRound: 0};
@@ -81,6 +81,20 @@ export function getMovementHistory(token) {
 	return dragRulerFlags.passedWaypoints ?? [];
 }
 
+export async function removeLastHistoryEntryIfAt(token, x, y) {
+	const history = getMovementHistory(token);
+	if (history.length === 0)
+		return;
+	const entry = history[history.length - 1];
+	if (!isClose(x + token.w / 2, entry.x, 0.1) || !isClose(y + token.h / 2, entry.y, 0.1)) {
+		return;
+	}
+	history.pop();
+	const combat = game.combat;
+	const combatant = combat.getCombatantByToken(token.id);
+	await updateCombatantDragRulerFlags(combat, [{_id: combatant.id, dragRulerFlags: combatant.data.flags.dragRuler}]);
+}
+
 export async function resetMovementHistory(combat, combatantId) {
 	const combatant = combat.combatants.get(combatantId);
 	const dragRulerFlags = combatant.data.flags.dragRuler;

src/util.js

@@ -210,3 +210,7 @@ export function setSnapParameterOnOptions(sourceObject, options) {
 		options.snap = !game.keyboard._downKeys.has("Shift");
 	}
 }
+
+export function isClose(a, b, delta) {
+	return Math.abs(a - b) <= delta;
+}