import { describe, expect, it } from 'vitest';

import { getWorkgroupCounts } from './get-workgroup-counts';

const makeDevice = (maxComputeWorkgroupsPerDimension: number): GPUDevice =>
  ({
    limits: {
      maxComputeWorkgroupsPerDimension,
    },
  }) as GPUDevice;

describe('getWorkgroupCounts', () => {
  it('returns at least one workgroup for positive invocation counts', () => {
    expect(getWorkgroupCounts(makeDevice(65_535), 1, 64)).toEqual([1, 1, 1]);
    expect(getWorkgroupCounts(makeDevice(65_535), 65, 64)).toEqual([2, 1, 1]);
  });

  it('rejects zero and non-finite dispatch inputs', () => {
    const device = makeDevice(65_535);

    expect(() => getWorkgroupCounts(device, 0, 64)).toThrow(/positive finite/);
    expect(() => getWorkgroupCounts(device, -1, 64)).toThrow(/positive finite/);
    expect(() => getWorkgroupCounts(device, Number.POSITIVE_INFINITY, 64)).toThrow(
      /positive finite/
    );
    expect(() => getWorkgroupCounts(device, 1, 0)).toThrow(/positive finite/);
  });

  it('rejects invocation counts that exceed device workgroup limits', () => {
    expect(() => getWorkgroupCounts(makeDevice(2), 9, 1)).toThrow(
      'Cannot have this many invocations'
    );
  });
});