import { subscribable } from './subscribable.js';

export const hashableContainer = hash => store => {
	let id = hash && hash(store);
	let lockCount = 0;

	const containerMethods = {
		_lock: () => {
			lockCount += 1;
			return p;
		},
		_unlock: () => {
			if (lockCount && --lockCount === 0) {
				checkUpdate(store);
			}
		},
		...subscribable()
	};

	function checkUpdate(target) {
		if (lockCount) {
			return;
		}
		let newId = hash && hash(target);
		if (!hash || id !== newId) {
			id = newId;
			containerMethods._fire(target);
		}
	}

	const p = new Proxy(store, {
		apply: (target, context, args) => {
			return target;
		},
		get: (target, name) => {
			if (name in containerMethods) {
				return containerMethods[name];
			}
			if (name === '_') {
				return target;
			}
			const thing = target[name];
			if (typeof thing === 'function') {
				return (...args) => {
					const ret = target[name](...args);
					checkUpdate(target);
					return ret;
				};
			}
			return thing;
		},
		set: (target, name, newVal) => {
			if (name in containerMethods) {
				throw new ReferenceError(`Cannot set ${name} in ${target}`);
			}
			target[name] = newVal;
			checkUpdate(target);

			// Returning a falsey value causes TypeError
			// https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Proxy/handler/set#Invariants
			return newVal || true;
		}
	});

	return p;
};

export const container = hashableContainer();