import { describe, it } from 'node:test';
import assert from 'node:assert/strict';
import { roundRobin, leastBusy } from 'moroutine';
import type { WorkerHandle } from 'moroutine';

function mockHandle(activeCount: number, index = 0): WorkerHandle {
  return { activeCount, index, exec: {} as any };
}

describe('roundRobin()', () => {
  it('cycles through workers in order', () => {
    const b = roundRobin();
    const state = b.initialState();
    const handles = [mockHandle(0, 0), mockHandle(0, 1), mockHandle(0, 2)];
    const task = { id: 'test', args: [], uid: 0 } as any;
    assert.equal(b.select(handles, task, state), handles[0]);
    assert.equal(b.select(handles, task, state), handles[1]);
    assert.equal(b.select(handles, task, state), handles[2]);
    assert.equal(b.select(handles, task, state), handles[0]);
  });

  it('state is externalized (two instances over the same state agree)', () => {
    const b1 = roundRobin();
    const state = b1.initialState();
    const b2 = roundRobin();
    const handles = [mockHandle(0, 0), mockHandle(0, 1)];
    const task = { id: 'test', args: [], uid: 0 } as any;
    assert.equal(b1.select(handles, task, state), handles[0]);
    assert.equal(b2.select(handles, task, state), handles[1]);
  });
});

describe('leastBusy()', () => {
  it('picks worker with lowest activeCount', () => {
    const b = leastBusy();
    const handles = [mockHandle(3), mockHandle(1), mockHandle(2)];
    const task = { id: 'test', args: [], uid: 0 } as any;
    assert.equal(b.select(handles, task, undefined), handles[1]);
  });

  it('breaks ties by index', () => {
    const b = leastBusy();
    const handles = [mockHandle(1), mockHandle(1), mockHandle(1)];
    const task = { id: 'test', args: [], uid: 0 } as any;
    assert.equal(b.select(handles, task, undefined), handles[0]);
  });
});