// Headless entry point: runs one iperf3 test with no widgets.
//
// This exists to keep the core honest. If anything in the run path ever starts
// depending on the UI, this stops compiling or stops working — a claim about
// separation that is checked rather than asserted.
//
// It is also the low-noise way to measure. The UI competes with the test for
// CPU (a gigabit run can put the phone near CPU-bound), so figures taken here
// are cleaner than figures taken with a transcript repainting alongside.
//
//   flutter run -t lib/main_headless.dart \
//     --dart-define=IPERF_SERVER=192.168.2.182 \
//     --dart-define=IPERF_STREAMS=4
//
// Nothing below imports lib/ui, and test/architecture_test.dart enforces that.

import 'package:flutter/widgets.dart' show WidgetsFlutterBinding;
import 'package:flutter/foundation.dart' show debugPrint;

import 'package:iperf3gui/data/services/iperf3_service.dart';
import 'package:iperf3gui/domain/models/iperf3_event.dart';
import 'package:iperf3gui/domain/models/iperf3_session.dart';
import 'package:iperf3gui/domain/models/test_configuration.dart';
import 'package:iperf3gui/domain/services/iperf3_runner.dart';

/// Test parameters, supplied at build time with --dart-define.
const String _server = String.fromEnvironment('IPERF_SERVER',
    defaultValue: 'speedtest.uztelecom.uz');
const int _port = int.fromEnvironment('IPERF_PORT', defaultValue: 5201);
const int _seconds = int.fromEnvironment('IPERF_SECONDS', defaultValue: 10);
const int _streams = int.fromEnvironment('IPERF_STREAMS', defaultValue: 1);

Future<void> main() async {
  // Required for the MethodChannel. Notably NOT runApp() — there is no widget
  // tree, no render surface and no Flutter UI thread work in this process.
  WidgetsFlutterBinding.ensureInitialized();

  const config = TestConfiguration(
    server: _server,
    port: _port,
    duration: Duration(seconds: _seconds),
    parallelStreams: _streams,
  );

  final Iperf3Runner runner = Iperf3Service();
  final session = Iperf3Session();

  final subscription = runner.events.listen((event) {
    session.add(event);
    if (event is Iperf3Interval && !event.omitted) {
      _out('interval ${event.start.toStringAsFixed(2)}-'
          '${event.end.toStringAsFixed(2)}s  '
          '${_mbits(event.bitsPerSecond)} Mbit/s'
          '${event.retransmits != null ? '  retr=${event.retransmits}' : ''}');
    } else if (event is Iperf3Error) {
      _out('error: ${event.message}');
    }
  });

  _out('running iperf3 -c ${config.server} -p ${config.port} '
      '-t ${config.duration.inSeconds} -P ${config.parallelStreams}');

  final result = await runner.run(config);
  await subscription.cancel();
  await runner.dispose();

  _report(result.exitCode, session);
}

void _report(int exitCode, Iperf3Session session) {
  _out('--- result ---');
  _out('exit code:    $exitCode');
  _out('samples:      ${session.sampleCount}');

  final mean = session.meanBitsPerSecond;
  final peak = session.peakBitsPerSecond;
  if (mean != null) _out('mean:         ${_mbits(mean)} Mbit/s');
  if (peak != null) _out('peak:         ${_mbits(peak)} Mbit/s');

  final retr = session.totalRetransmits;
  _out('retransmits:  ${retr ?? 'not measured'}');

  final sent = session.summary?.sent;
  final received = session.summary?.received;
  if (sent != null) {
    _out('sent:         ${_mbits(sent.bitsPerSecond)} Mbit/s '
        'over ${sent.seconds.toStringAsFixed(2)}s');
  }
  if (received != null) {
    _out('received:     ${_mbits(received.bitsPerSecond)} Mbit/s '
        'over ${received.seconds.toStringAsFixed(2)}s');
  }
  final cpu = session.summary?.hostCpuPercent;
  if (cpu != null) _out('local cpu:    ${cpu.toStringAsFixed(1)}%');

  if (session.stopped) _out('ended early:  stopped');
  for (final error in session.errors) {
    _out('error:        $error');
  }
}

String _mbits(double bitsPerSecond) =>
    (bitsPerSecond / 1e6).toStringAsFixed(1);

void _out(String line) => debugPrint('[iperf3-headless] $line');