// Copyright (c) 2024, the Dart project authors. Please see the AUTHORS file
// for details. All rights reserved. Use of this source code is governed by a
// BSD-style license that can be found in the LICENSE file.

import 'dart:async';
import 'dart:convert';
import 'dart:io';

import 'package:path/path.dart';

import 'sdk.dart';

class DDSRunner {
  Uri? ddsUri;

  Future<bool> start({
    required Uri vmServiceUri,
    required String ddsHost,
    required String ddsPort,
    required bool disableServiceAuthCodes,
    required bool enableDevTools,
    required bool debugDds,
    required bool enableServicePortFallback,
  }) async {
    final sdkDir = dirname(sdk.dart);
    final fullSdk = sdkDir.endsWith('bin');
    final execName = sdk.dart;
    final snapshotName =
        fullSdk ? sdk.ddsSnapshot : absolute(sdkDir, 'dds.dart.snapshot');
    if (!Sdk.checkArtifactExists(snapshotName)) {
      return false;
    }

    final process = await Process.start(
      execName,
      [
        if (debugDds) '--enable-vm-service=0',
        snapshotName,
        '--vm-service-uri=$vmServiceUri',
        '--bind-address=$ddsHost',
        '--bind-port=$ddsPort',
        if (disableServiceAuthCodes) '--disable-service-auth-codes',
        if (enableDevTools) '--serve-devtools',
        if (debugDds) '--enable-logging',
        if (enableServicePortFallback) '--enable-service-port-fallback',
      ],
      mode: ProcessStartMode.detachedWithStdio,
    );

    // NOTE: update pkg/dartdev/lib/src/commands/run.dart if this message
    // is changed to ensure consistency.
    const devToolsMessagePrefix =
        'The Dart DevTools debugger and profiler is available at:';
    if (debugDds) {
      late final StreamSubscription stdoutSub;
      stdoutSub = process.stdout
          .transform(utf8.decoder)
          .transform(const LineSplitter())
          .listen((event) {
        if (event.startsWith(devToolsMessagePrefix)) {
          final ddsDebuggingUri = event.split(' ').last;
          print(
            'A DevTools debugger for DDS is available at: $ddsDebuggingUri',
          );
          stdoutSub.cancel();
        }
      });
    }

    // DDS will close stderr once it's finished launching.
    final launchResult = await process.stderr.transform(utf8.decoder).join();

    void printError(String details) => stderr.writeln(
          'Could not start the VM service:\n$details',
        );

    try {
      final result = json.decode(launchResult) as Map<String, dynamic>;
      if (result
          case {
            'state': 'started',
            'ddsUri': final String ddsUriStr,
          }) {
        ddsUri = Uri.parse(ddsUriStr);
        if (result case {'devToolsUri': String devToolsUri}) {
          print('$devToolsMessagePrefix $devToolsUri');
        }
      } else {
        final error = result['error'] ?? result;
        final stacktrace = result['stacktrace'] ?? '';
        String message = 'Could not start the VM service: ';
        if (error.contains('Failed to create server socket')) {
          message += '$ddsHost:$ddsPort is already in use.\n';
        } else {
          message += '$error\n$stacktrace\n';
        }
        printError(message);
        return false;
      }
    } catch (_) {
      // Malformed JSON was likely encountered, so output the entirety of
      // stderr in the error message.
      printError(launchResult);
      return false;
    }
    return true;
  }
}