import { prop } from '../src/index.js';
import { dirtyMock, hashSet } from '../src/testUtil.js';

describe('A property', () => {
	it('returns its initialized value', () => {
		const a = prop(true);
		expect(a()).toEqual(true);
	});

	it('returns its set value', () => {
		const a = prop();
		expect(a()).toEqual(undefined);
		expect(a(true)).toEqual(true);
	});

	it('returns notifies dependents of updates', () => {
		let runCount = 0;
		let currentValue = 1;
		const a = prop();
		a.subscribe(val => {
			runCount += 1;
			expect(val).toEqual(currentValue);
		});
		expect(a(1)).toEqual(1);
		expect(runCount).toEqual(1);
		expect(a(1)).toEqual(1);
		expect(runCount).toEqual(1);
		currentValue = 2;
		expect(a(2)).toEqual(2);
		expect(runCount).toEqual(2);
		expect(a(2)).toEqual(2);
		expect(runCount).toEqual(2);
		currentValue = 1;
		expect(a(1)).toEqual(1);
		expect(runCount).toEqual(3);
		expect(a(1)).toEqual(1);
		expect(runCount).toEqual(3);
	});

	it('honors cancelled subscriptions', () => {
		let runCount = 0;
		let currentValue = 1;
		const a = prop();
		const cancelSubscription = a.subscribe(val => {
			runCount += 1;
			expect(val).toEqual(currentValue);
		});
		const cancelSubscription2 = a.subscribe(val => {
			runCount += 1;
			expect(val).toEqual(currentValue);
		});
		expect(a(1)).toEqual(1);
		expect(runCount).toEqual(2);
		expect(a(1)).toEqual(1);
		expect(runCount).toEqual(2);
		expect(cancelSubscription()).toEqual(1);
		currentValue = 3;
		expect(a(3)).toEqual(3);
		expect(runCount).toEqual(3);
		expect(cancelSubscription2()).toEqual(0);
		currentValue = 4;
		expect(a(4)).toEqual(4);
		expect(runCount).toEqual(3);
	});

	it('uses a hash function', () => {
		let runCount = 0;

		const a = prop(new Set([1, 2]), hashSet);
		a.subscribe(() => (runCount += 1));
		expect([...a()]).toEqual([1, 2]);
		expect(runCount).toEqual(0);
		expect([...a(new Set([2, 1]))]).toEqual([1, 2]);
		expect(runCount).toEqual(0);
		expect([...a(new Set([3, 2, 1]))]).toEqual([3, 2, 1]);
		expect(runCount).toEqual(1);
	});

	it('flags all subscribers as dirty before propagating change', () => {
		const a = prop(true);

		const [dirtyA, dirtyB, checker] = dirtyMock(2);

		a.subscribe(dirtyA.setDirty);
		a.subscribe(dirtyB.setDirty);

		a(false);

		expect(checker()).toBe(true);
	});

	it('calls subscriptions in order', () => {
		let order = '';

		const a = prop(0);
		a.subscribe(() => (order += 'a'));
		a.subscribe(() => (order += 'b'));
		a.subscribe(() => (order += 'c'));
		a(1);
		expect(order).toEqual('abc');
	});
});