import 'dart:io';
import 'dart:typed_data';

final Uint8List _original = Uint8List.fromList([
  45, 0, 105, 0, 110, 0, 118, 0, 105, 0, 116, 0, 101, 0, 115, 0, 101, 0, 115, 0, 115, 0, 105, 0, 111, 0, 110, 0, 32, 0, 45, 0, 105, 0, 110, 0, 118, 0, 105, 0, 116, 0, 101, 0, 102, 0, 114, 0, 111, 0, 109, 0, 32, 0, 45, 0, 112, 0, 97, 0, 114, 0, 116, 0, 121, 0, 95, 0, 106, 0, 111, 0, 105, 0, 110, 0, 105, 0, 110, 0, 102, 0, 111, 0, 95, 0, 116, 0, 111, 0, 107, 0, 101, 0, 110, 0, 32, 0, 45, 0, 114, 0, 101, 0, 112, 0, 108, 0, 97, 0, 121, 0
]);

final Uint8List _patched = Uint8List.fromList([
  45, 0, 108, 0, 111, 0, 103, 0, 32, 0, 45, 0, 110, 0, 111, 0, 115, 0, 112, 0, 108, 0, 97, 0, 115, 0, 104, 0, 32, 0, 45, 0, 110, 0, 111, 0, 115, 0, 111, 0, 117, 0, 110, 0, 100, 0, 32, 0, 45, 0, 110, 0, 117, 0, 108, 0, 108, 0, 114, 0, 104, 0, 105, 0, 32, 0, 45, 0, 117, 0, 115, 0, 101, 0, 111, 0, 108, 0, 100, 0, 105, 0, 116, 0, 101, 0, 109, 0, 99, 0, 97, 0, 114, 0, 100, 0, 115, 0, 32, 0, 32, 0, 32, 0, 32, 0, 32, 0, 32, 0, 32, 0
]);

Future<bool> patchExe(File file) async {
  if(_original.length != _patched.length){
    throw Exception("Cannot mutate length of binary file");
  }

  var read = await file.readAsBytes();
  var length = await file.length();
  var offset = 0;
  var counter = 0;
  while(offset < length){
    if(read[offset] == _original[counter]){
      counter++;
    }else {
      counter = 0;
    }

    offset++;
    if(counter == _original.length){
      for(var index = 0; index < _patched.length; index++){
        read[offset - counter + index] = _patched[index];
      }

      await file.writeAsBytes(read, mode: FileMode.write);
      return true;
    }
  }

  return false;
}