import test from 'node:test';
import assert from 'node:assert/strict';
import { readFileSync } from 'node:fs';
import { createRequire } from 'node:module';
import vm from 'node:vm';

const enginePath = new URL('../vendor/agent-harness/lib/qvac.js', import.meta.url);
const source = readFileSync(enginePath, 'utf8');
const require = createRequire(enginePath);

function engineHarness(required) {
  const attempts = [];
  const fakeSdk = {
    getSystemResources: async () => ({ gpus: [{ name: 'Test GPU', memory: 16e9 }], drivers: { vulkan: true }, vramBytes: 16e9 }),
    lookupModelSrc: async () => 'test-model.gguf',
    loadModel: async ({ modelConfig }) => {
      attempts.push({ ...modelConfig });
      if (modelConfig.device === 'gpu') throw new Error('GPU allocation failed');
      return 'cpu-model';
    },
  };
  const context = vm.createContext({ require, module: { exports: {} }, process: { env: { JARVIS_GPU_REQUIRED: required ? '1' : '0' } }, console: { error() {} }, fakeSdk });
  vm.runInContext(source + '\nsdk = fakeSdk;', context);
  return { engine: context.module.exports, attempts };
}

for (const [requested, required] of [['gpu', false], ['auto', true]]) {
  test(`GPU-required loading does not waste a CPU reload (${requested}, required=${required})`, async () => {
    const { engine, attempts } = engineHarness(required);
    await assert.rejects(engine.load({ model: 'test-model', device: requested, vision: false }), /GPU allocation failed/);
    assert.equal(attempts.length, 1);
    assert.equal(attempts[0].gpu_layers, 99);
  });
}

test('optional automatic CPU fallback reports its actual backend', async () => {
  const { engine, attempts } = engineHarness(false);
  const loaded = await engine.load({ model: 'test-model', device: 'auto', vision: false });
  assert.deepEqual(attempts.map((config) => config.device), ['gpu', 'cpu']);
  assert.equal(loaded.device, 'cpu');
  assert.equal(loaded.backend, 'cpu');
  assert.equal(loaded.backendId, 0);
});