gen_dart.dart

// ignore_for_file: avoid_print

import "dart:io";

Future<void> checkProtoc() async {
  const command = "protoc";
  const args = ["--help"];
  try {
    await Process.run(command, args);
  } on ProcessException {
    print("\nError: Could not find protoc. Please download it from the URL below and add it to your PATH");
    print("https://github.com/protocolbuffers/protobuf/releases/latest");
    exit(1);  // could not find protoc
  }
}

Future<bool> hasProtocPlugin() async {
  const command = "dart";
  const args = ["pub", "global", "list"];
  final result = await Process.run(command, args);
  return result.stdout.contains("protoc_plugin");
}

Future<void> installDartPlugin() async {
  const command = "dart";
  const args = ["pub", "global", "activate", "protoc_plugin"];
  final result = await Process.run(command, args);
  if (result.exitCode != 0) {
    print("\nError: Could not install protoc_plugin from Pub");
    print("Tried running: $command ${args.join(' ')}");
    exit(2);  // could not install protoc_plugin
  }
}

extension on FileSystemEntity {
  String get filename => path.replaceAll(r"\", "/").split("/").last;
}

Future<void> generateProtobuf(String inputDir, String output) async {
  const command = "protoc";
  final files = await Directory(inputDir).list().toList();
  // For some reason, Linux does not like `./*.proto`, so we must list all files
  final filenames = [
    for (final file in files)
      if (file.path.endsWith(".proto"))
        "$inputDir/${file.filename}",
  ];
  final args = ["--dart_out=$output", "-I", inputDir, ...filenames, "google/protobuf/timestamp.proto"];
  final result = await Process.run(command, args);
  if (result.exitCode != 0) {
    print("\nError: Could not generate Protobuf");
    print(result.stderr);
    exit(3);  // could not generate Protobuf
  }
}

void main(List<String> args) async {
  final isTest = args.contains("--test") || args.contains("-t");

  print("Checking for protoc...");
  await checkProtoc();

  if (!await hasProtocPlugin()) {
    print("Installing Dart plugin...");
    await installDartPlugin();
  }

  print("Generating Protobuf...");
  final inputDir = isTest ? "." : "Protobuf";
  final outputDir = Directory(isTest ? "test_output" : "lib/src/generated");
  await outputDir.create(recursive: true);
  await generateProtobuf(inputDir, outputDir.path);

  if (isTest) await outputDir.delete(recursive: true);

  print("Done!");
}