index.js

/* eslint-disable unicorn/prefer-spread */
import {TARGET, UNSUBSCRIBE, PATH_SEPARATOR} from './lib/constants.js';
import {isBuiltinWithMutableMethods, isBuiltinWithoutMutableMethods} from './lib/is-builtin.js';
import path from './lib/path.js';
import isArray from './lib/is-array.js';
import isSymbol from './lib/is-symbol.js';
import isIterator from './lib/is-iterator.js';
import wrapIterator from './lib/wrap-iterator.js';
import ignoreProperty from './lib/ignore-property.js';
import Cache from './lib/cache.js';
import SmartClone from './lib/smart-clone/smart-clone.js';

const defaultOptions = {
	equals: Object.is,
	isShallow: false,
	pathAsArray: false,
	ignoreSymbols: false,
	ignoreUnderscores: false,
	ignoreDetached: false,
	details: false,
};

const onChange = (object, onChange, options = {}) => {
	options = {
		...defaultOptions,
		...options,
	};

	const proxyTarget = Symbol('ProxyTarget');
	const {equals, isShallow, ignoreDetached, details} = options;
	const cache = new Cache(equals);
	const hasOnValidate = typeof options.onValidate === 'function';
	const smartClone = new SmartClone(hasOnValidate);

	// eslint-disable-next-line max-params
	const validate = (target, property, value, previous, applyData) => !hasOnValidate
		|| smartClone.isCloning
		|| options.onValidate(path.concat(cache.getPath(target), property), value, previous, applyData) === true;

	const handleChangeOnTarget = (target, property, value, previous) => {
		if (
			!ignoreProperty(cache, options, property)
			&& !(ignoreDetached && cache.isDetached(target, object))
		) {
			handleChange(cache.getPath(target), property, value, previous);
		}
	};

	// eslint-disable-next-line max-params
	const handleChange = (changePath, property, value, previous, applyData) => {
		if (smartClone.isCloning && smartClone.isPartOfClone(changePath)) {
			smartClone.update(changePath, property, previous);
		} else {
			onChange(path.concat(changePath, property), value, previous, applyData);
		}
	};

	const getProxyTarget = value => value
		? (value[proxyTarget] ?? value)
		: value;

	const prepareValue = (value, target, property, basePath) => {
		if (
			isBuiltinWithoutMutableMethods(value)
			|| property === 'constructor'
			|| (isShallow && !SmartClone.isHandledMethod(target, property))
			|| ignoreProperty(cache, options, property)
			|| cache.isGetInvariant(target, property)
			|| (ignoreDetached && cache.isDetached(target, object))
		) {
			return value;
		}

		if (basePath === undefined) {
			basePath = cache.getPath(target);
		}

		/*
  		Check for circular references.

  		If the value already has a corresponding path/proxy,
		and if the path corresponds to one of the parents,
		then we are on a circular case, where the child is pointing to their parent.
		In this case we return the proxy object with the shortest path.
  		*/
		const childPath = path.concat(basePath, property);
		const existingPath = cache.getPath(value);

		if (existingPath && isSameObjectTree(childPath, existingPath)) {
			// We are on the same object tree but deeper, so we use the parent path.
			return cache.getProxy(value, existingPath, handler, proxyTarget);
		}

		return cache.getProxy(value, childPath, handler, proxyTarget);
	};

	/*
	Returns true if `childPath` is a subpath of `existingPath`
	(if childPath starts with existingPath). Otherwise, it returns false.

 	It also returns false if the 2 paths are identical.

 	For example:
	- childPath    = group.layers.0.parent.layers.0.value
	- existingPath = group.layers.0.parent
	*/
	const isSameObjectTree = (childPath, existingPath) => {
		if (isSymbol(childPath) || childPath.length <= existingPath.length) {
			return false;
		}

		if (isArray(existingPath) && existingPath.length === 0) {
			return false;
		}

		const childParts = isArray(childPath) ? childPath : childPath.split(PATH_SEPARATOR);
		const existingParts = isArray(existingPath) ? existingPath : existingPath.split(PATH_SEPARATOR);

		if (childParts.length <= existingParts.length) {
			return false;
		}

		return !(existingParts.some((part, index) => part !== childParts[index]));
	};

	const handler = {
		get(target, property, receiver) {
			if (isSymbol(property)) {
				if (property === proxyTarget || property === TARGET) {
					return target;
				}

				if (
					property === UNSUBSCRIBE
					&& !cache.isUnsubscribed
					&& cache.getPath(target).length === 0
				) {
					cache.unsubscribe();
					return target;
				}
			}

			const value = isBuiltinWithMutableMethods(target)
				? Reflect.get(target, property)
				: Reflect.get(target, property, receiver);

			return prepareValue(value, target, property);
		},

		set(target, property, value, receiver) {
			value = getProxyTarget(value);

			const reflectTarget = target[proxyTarget] ?? target;
			const previous = reflectTarget[property];

			if (equals(previous, value) && property in target) {
				return true;
			}

			const isValid = validate(target, property, value, previous);

			if (
				isValid
				&& cache.setProperty(reflectTarget, property, value, receiver, previous)
			) {
				handleChangeOnTarget(target, property, target[property], previous);

				return true;
			}

			return !isValid;
		},

		defineProperty(target, property, descriptor) {
			if (!cache.isSameDescriptor(descriptor, target, property)) {
				const previous = target[property];

				if (
					validate(target, property, descriptor.value, previous)
					&& cache.defineProperty(target, property, descriptor, previous)
				) {
					handleChangeOnTarget(target, property, descriptor.value, previous);
				}
			}

			return true;
		},

		deleteProperty(target, property) {
			if (!Reflect.has(target, property)) {
				return true;
			}

			const previous = Reflect.get(target, property);
			const isValid = validate(target, property, undefined, previous);

			if (
				isValid
				&& cache.deleteProperty(target, property, previous)
			) {
				handleChangeOnTarget(target, property, undefined, previous);

				return true;
			}

			return !isValid;
		},

		apply(target, thisArg, argumentsList) {
			const thisProxyTarget = thisArg[proxyTarget] ?? thisArg;

			if (cache.isUnsubscribed) {
				return Reflect.apply(target, thisProxyTarget, argumentsList);
			}

			if (
				(details === false
					|| (details !== true && !details.includes(target.name)))
				&& SmartClone.isHandledType(thisProxyTarget)
			) {
				let applyPath = path.initial(cache.getPath(target));
				const isHandledMethod = SmartClone.isHandledMethod(thisProxyTarget, target.name);

				smartClone.start(thisProxyTarget, applyPath, argumentsList);

				let result = Reflect.apply(
					target,
					smartClone.preferredThisArg(target, thisArg, thisProxyTarget),
					isHandledMethod
						? argumentsList.map(argument => getProxyTarget(argument))
						: argumentsList,
				);

				const isChanged = smartClone.isChanged(thisProxyTarget, equals);
				const previous = smartClone.stop();

				if (SmartClone.isHandledType(result) && isHandledMethod) {
					if (thisArg instanceof Map && target.name === 'get') {
						applyPath = path.concat(applyPath, argumentsList[0]);
					}

					result = cache.getProxy(result, applyPath, handler);
				}

				if (isChanged) {
					const applyData = {
						name: target.name,
						args: argumentsList,
						result,
					};
					const changePath = smartClone.isCloning
						? path.initial(applyPath)
						: applyPath;
					const property = smartClone.isCloning
						? path.last(applyPath)
						: '';

					if (validate(path.get(object, changePath), property, thisProxyTarget, previous, applyData)) {
						handleChange(changePath, property, thisProxyTarget, previous, applyData);
					} else {
						smartClone.undo(thisProxyTarget);
					}
				}

				if (
					(thisArg instanceof Map || thisArg instanceof Set)
					&& isIterator(result)
				) {
					return wrapIterator(result, target, thisArg, applyPath, prepareValue);
				}

				return result;
			}

			return Reflect.apply(target, thisArg, argumentsList);
		},
	};

	const proxy = cache.getProxy(object, options.pathAsArray ? [] : '', handler);
	onChange = onChange.bind(proxy);

	if (hasOnValidate) {
		options.onValidate = options.onValidate.bind(proxy);
	}

	return proxy;
};

onChange.target = proxy => proxy?.[TARGET] ?? proxy;
onChange.unsubscribe = proxy => proxy?.[UNSUBSCRIBE] ?? proxy;

export default onChange;