ComfyUI/web/extensions/core/undoRedo.js

import { app } from "../../scripts/app.js";

const MAX_HISTORY = 50;

let undo = [];
let redo = [];
let activeState = null;
let isOurLoad = false;
function checkState() {
	const currentState = app.graph.serialize();
	if (!graphEqual(activeState, currentState)) {
		undo.push(activeState);
        if(undo.length > MAX_HISTORY) {
            undo.shift();
        }
		activeState = clone(currentState);
		redo.length = 0;
	}
}

const loadGraphData = app.loadGraphData;
app.loadGraphData = async function () {
	const v = await loadGraphData.apply(this, arguments);
	if (isOurLoad) {
		isOurLoad = false;
	} else {
		checkState();
	}
	return v;
};

function clone(obj) {
	try {
		if (typeof structuredClone !== "undefined") {
			return structuredClone(obj);
		}
	} catch (error) {
		// structuredClone is stricter than using JSON.parse/stringify so fallback to that
	}

	return JSON.parse(JSON.stringify(obj));
}

function graphEqual(a, b, root = true) {
	if (a === b) return true;

	if (typeof a == "object" && a && typeof b == "object" && b) {
		const keys = Object.getOwnPropertyNames(a);

		if (keys.length != Object.getOwnPropertyNames(b).length) {
			return false;
		}

		for (const key of keys) {
			let av = a[key];
			let bv = b[key];
			if (root && key === "nodes") {
				// Nodes need to be sorted as the order changes when selecting nodes
				av = [...av].sort((a, b) => a.id - b.id);
				bv = [...bv].sort((a, b) => a.id - b.id);
			}
			if (!graphEqual(av, bv, false)) {
				return false;
			}
		}

		return true;
	}

	return false;
}

const undoRedo = async (e) => {
	if (e.ctrlKey || e.metaKey) {
		if (e.key === "y") {
			const prevState = redo.pop();
			if (prevState) {
				undo.push(activeState);
				isOurLoad = true;
				await app.loadGraphData(prevState);
				activeState = prevState;
			}
			return true;
		} else if (e.key === "z") {
			const prevState = undo.pop();
			if (prevState) {
				redo.push(activeState);
				isOurLoad = true;
				await app.loadGraphData(prevState);
				activeState = prevState;
			}
			return true;
		}
	}
};

const bindInput = (activeEl) => {
	if (activeEl?.tagName !== "CANVAS" && activeEl?.tagName !== "BODY") {
		for (const evt of ["change", "input", "blur"]) {
			if (`on${evt}` in activeEl) {
				const listener = () => {
					checkState();
					activeEl.removeEventListener(evt, listener);
				};
				activeEl.addEventListener(evt, listener);
				return true;
			}
		}
	}
};

window.addEventListener(
	"keydown",
	(e) => {
		requestAnimationFrame(async () => {
			const activeEl = document.activeElement;
			if (activeEl?.tagName === "INPUT" || activeEl?.type === "textarea") {
				// Ignore events on inputs, they have their native history
				return;
			}

			// Check if this is a ctrl+z ctrl+y
			if (await undoRedo(e)) return;

			// If our active element is some type of input then handle changes after they're done
			if (bindInput(activeEl)) return;
			checkState();
		});
	},
	true
);

// Handle clicking DOM elements (e.g. widgets)
window.addEventListener("mouseup", () => {
	checkState();
});

// Handle litegraph clicks
const processMouseUp = LGraphCanvas.prototype.processMouseUp;
LGraphCanvas.prototype.processMouseUp = function (e) {
	const v = processMouseUp.apply(this, arguments);
	checkState();
	return v;
};
const processMouseDown = LGraphCanvas.prototype.processMouseDown;
LGraphCanvas.prototype.processMouseDown = function (e) {
	const v = processMouseDown.apply(this, arguments);
	checkState();
	return v;
};