import { describe, it, expect } from 'vitest';
import { EventQueue } from '../src/sim/events.js';

describe('EventQueue', () => {
  it('pops events in time order regardless of insertion order', () => {
    const q = new EventQueue();
    q.push(5, 'c', {});
    q.push(1, 'a', {});
    q.push(3, 'b', {});
    expect(q.pop().type).toBe('a');
    expect(q.pop().type).toBe('b');
    expect(q.pop().type).toBe('c');
    expect(q.pop()).toBeNull();
  });

  it('breaks time ties by insertion order', () => {
    const q = new EventQueue();
    q.push(2, 'first', {});
    q.push(2, 'second', {});
    expect(q.pop().type).toBe('first');
    expect(q.pop().type).toBe('second');
  });

  it('peek does not remove; size tracks contents', () => {
    const q = new EventQueue();
    q.push(1, 'a', { n: 7 });
    expect(q.size).toBe(1);
    expect(q.peek().time).toBe(1);
    expect(q.size).toBe(1);
    expect(q.pop().data.n).toBe(7);
    expect(q.size).toBe(0);
    expect(q.peek()).toBeNull();
  });

  it('survives a large randomized load in order', () => {
    const q = new EventQueue();
    const times = Array.from({ length: 500 }, (_, i) => (i * 7919) % 1000);
    for (const t of times) q.push(t, 'e', {});
    let last = -1;
    while (q.size > 0) {
      const e = q.pop();
      expect(e.time).toBeGreaterThanOrEqual(last);
      last = e.time;
    }
  });
});