// Headless benchmark: the same Mandelbrot frame rendered by V and by Dart.
//
//   LD_LIBRARY_PATH=build dart example/lib/fractal_bench.dart
//
// Also checks the two implementations agree pixel-for-pixel, which is what
// makes the timing comparison meaningful.
import 'package:vflutter_ffi/vflutter_ffi.dart' as v;

import 'mandelbrot_dart.dart';

Future<void> main() async {
  const view = v.FractalView(width: 800, height: 600, maxIter: 500);
  final pixels = view.width * view.height;

  // Warm both paths: first call pays for library load / JIT.
  v.render(const v.FractalView(width: 64, height: 64, maxIter: 50));
  renderDart(const v.FractalView(width: 64, height: 64, maxIter: 50));

  final swV = Stopwatch()..start();
  final fromV = v.render(view);
  swV.stop();

  final swP = Stopwatch()..start();
  final fromParallel = await v.renderParallel(view, tiles: 4);
  swP.stop();

  final swD = Stopwatch()..start();
  final fromDart = renderDart(view);
  swD.stop();

  print('${view.width}x${view.height}, maxIter ${view.maxIter} '
      '($pixels px)\n');
  print('V, one isolate      ${swV.elapsedMilliseconds} ms');
  print('V, 4 isolates       ${swP.elapsedMilliseconds} ms');
  print('Dart, one isolate   ${swD.elapsedMilliseconds} ms');
  print('speedup vs Dart     '
      '${(swD.elapsedMicroseconds / swV.elapsedMicroseconds).toStringAsFixed(2)}x '
      'serial, '
      '${(swD.elapsedMicroseconds / swP.elapsedMicroseconds).toStringAsFixed(2)}x '
      'parallel');

  print('\nagreement checks');
  print('  V serial vs V parallel : ${_diff(fromV, fromParallel)} bytes differ');
  print('  V serial vs Dart       : ${_diff(fromV, fromDart)} bytes differ');
}

int _diff(List<int> a, List<int> b) {
  if (a.length != b.length) return -1;
  var n = 0;
  for (var i = 0; i < a.length; i++) {
    if (a[i] != b[i]) n++;
  }
  return n;
}