import { describe, it, expect } from 'vitest';
import { AsyncQueue } from '../../src/utils/async-queue';

describe('AsyncQueue', () => {
    describe('push', () => {
        it('should add item to queue', () => {
            const queue = new AsyncQueue<number>();
            queue.push(1);
            expect(queue.length).toBe(1);
        });
    });

    describe('pop', () => {
        it('should return item immediately if queue is not empty', async () => {
            const queue = new AsyncQueue<number>();
            queue.push(1);
            queue.push(2);

            const result = await queue.pop();
            expect(result).toBe(1);
            expect(queue.length).toBe(1);
        });

        it('should wait for item if queue is empty', async () => {
            const queue = new AsyncQueue<number>();

            const popPromise = queue.pop();

            queue.push(42);

            const result = await popPromise;
            expect(result).toBe(42);
            expect(queue.length).toBe(0);
        });

        it('should return items in FIFO order', async () => {
            const queue = new AsyncQueue<number>();
            queue.push(1);
            queue.push(2);
            queue.push(3);

            expect(await queue.pop()).toBe(1);
            expect(await queue.pop()).toBe(2);
            expect(await queue.pop()).toBe(3);
        });
    });

    describe('pushAll', () => {
        it('should add all items to queue', async () => {
            const queue = new AsyncQueue<number>();
            queue.pushAll([1, 2, 3]);

            expect(queue.length).toBe(3);
            expect(await queue.pop()).toBe(1);
            expect(await queue.pop()).toBe(2);
            expect(await queue.pop()).toBe(3);
        });

        it('should accept any iterable', async () => {
            const queue = new AsyncQueue<number>();
            queue.pushAll(new Set([10, 20, 30]));

            expect(await queue.pop()).toBe(10);
            expect(await queue.pop()).toBe(20);
            expect(await queue.pop()).toBe(30);
        });

        it('should resolve waiting pops', async () => {
            const queue = new AsyncQueue<number>();

            const pop1 = queue.pop();
            const pop2 = queue.pop();

            queue.pushAll([1, 2]);

            expect(await pop1).toBe(1);
            expect(await pop2).toBe(2);
            expect(queue.length).toBe(0);
        });
    });

    describe('length', () => {
        it('should return 0 for empty queue', () => {
            const queue = new AsyncQueue<number>();
            expect(queue.length).toBe(0);
        });

        it('should reflect pending consumers as negative', () => {
            const queue = new AsyncQueue<number>();
            queue.pop(); // no await, so it's pending
            expect(queue.length).toBe(-1);
        });

        it('should update after push and pop', async () => {
            const queue = new AsyncQueue<number>();
            queue.push(1);
            queue.push(2);
            expect(queue.length).toBe(2);

            await queue.pop();
            expect(queue.length).toBe(1);
        });
    });
});