import 'dart:io';

import 'package:flutter/services.dart';
import 'package:path_provider/path_provider.dart';

/// Provides the path to the iperf3 binary on the device.
///
/// Call [initialize] in [main] (before [runApp]) to extract the
/// bundled asset and populate the cache. After initialization,
/// [path] returns a synchronous [String].
class Iperf3BinaryPathProvider {
  static String? _cachedPath;

  /// Extract the bundled iperf3 binary to the app's cache directory.
  ///
  /// Call this once in [main] before [runApp].
  static Future<void> initialize() async {
    if (_cachedPath != null) return;

    final cacheDir = await getApplicationCacheDirectory();
    final binaryDir = Directory('${cacheDir.path}/iperf3');
    if (!await binaryDir.exists()) {
      await binaryDir.create(recursive: true);
    }

    final abi = await _detectAbi();
    final assetPath = 'assets/iperf3/$abi/iperf3';

    final bytes = await rootBundle.load(assetPath);
    final file = File('${binaryDir.path}/iperf3');
    await file.writeAsBytes(bytes.buffer.asUint8List());

    // chmod +x the binary — /system/bin/sh is always present on Android
    await Process.run(
      '/system/bin/sh',
      ['-c', 'chmod +x "\$1"', '_', file.path],
    );

    _cachedPath = file.path;
  }

  /// The resolved path to the iperf3 binary.
  ///
  /// Must call [initialize] first, or this will return a placeholder.
  static String get path {
    return _cachedPath ?? '/data/local/tmp/iperf3';
  }

  static Future<String> _detectAbi() async {
    final result = await Process.run(
      'getprop',
      ['ro.product.cpu.abi'],
    );
    final abi = result.stdout.toString().trim();
    if (abi.contains('arm64')) return 'arm64-v8a';
    return 'armeabi-v7a';
  }
}