// Copyright (c) 2021, 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:io';

final _client = HttpClient();

/// Runs `dart pub get --offline --no-precompile --enforce-lockfile` with
/// pre-populated packages directly downloaded from the storage bucket.
///
/// This allows us to not depend on a running `pub.dev` while deploying a new
/// version.
Future<void> main(List<String> args) async {
  final pubCachePath = Platform.environment['PUB_CACHE'];
  if (pubCachePath != null) {
    final pubCacheDir = Directory(pubCachePath).absolute;
    print('PUB_CACHE: ${pubCacheDir.path}');
    if (pubCacheDir.existsSync()) {
      pubCacheDir.deleteSync(recursive: true);
    }
    pubCacheDir.createSync(recursive: true);
  }

  final pvs = _parsePubspecLockSync(File.fromUri(
      File.fromUri(Platform.script).parent.parent.uri.resolve('pubspec.lock')));
  final packages = pvs.keys.toList()..sort();
  for (final package in packages) {
    final version = pvs[package]!;
    for (var retry = 0;; retry++) {
      print('Downloading $package: $version (attempt: ${retry + 1})');
      try {
        await _downloadInto(package, version, pubCachePath);
        break;
      } catch (e) {
        if (retry >= 8) {
          rethrow;
        }
        await Future.delayed(Duration(seconds: 1));
      }
    }
  }
  _client.close();

  print('Running `dart pub get --offline --no-precompile --enforce-lockfile`');
  final pr = Process.runSync(
    'dart',
    ['pub', 'get', '--offline', '--no-precompile', '--enforce-lockfile'],
    environment: {if (pubCachePath != null) 'PUB_CACHE': pubCachePath},
  );
  if (pr.exitCode != 0) {
    throw AssertionError(
        'pub get failed with exit code ${pr.exitCode}\n${pr.stdout}\n${pr.stderr}');
  }
  print(pr.stdout);
  print(pr.stderr);
}

/// Returns the map of `<package>:<version>` pairs from the `pubspec.lock` file.
///
/// Only hosted dependencies are included in the result map.
Map<String, String> _parsePubspecLockSync(File file) {
  final versions = <String, String>{};
  final lines = file.readAsLinesSync();

  String? package;
  String? source;
  for (final line in lines) {
    bool startsWithSpaces(int count) =>
        line.startsWith(' ' * count) && !line.startsWith(' ' * (count + 1));
    if (startsWithSpaces(2) && line.endsWith(':')) {
      package = line.trim().split(':').first;
      source = null;
    } else if (startsWithSpaces(4) && package != null) {
      final parts = line.trim().split(':');
      if (parts.first == 'source' && parts.length > 1) {
        source = parts[1].trim();
        continue;
      }
      if (parts.first == 'version' && parts.length > 1) {
        if (source != 'hosted') continue;
        final quoted = parts[1].trim().split('"');
        if (quoted.length == 3 && quoted.first.isEmpty && quoted.last.isEmpty) {
          final version = quoted[1];
          if (version.isNotEmpty) {
            versions[package] = version;
          }
        }
      }
    }
  }
  return versions;
}

/// Downloads the archive and preloads it into the cache at [pubCachePath].
Future<void> _downloadInto(
    String package, String version, String? pubCachePath) async {
  final rq = await _client.getUrl(Uri.parse(
      'https://storage.googleapis.com/dartlang-pub-public-packages/packages/${Uri.encodeComponent(package)}-${Uri.encodeComponent(version)}.tar.gz'));
  final rs = await rq.close();
  if (rs.statusCode != 200) {
    throw Exception('Unable to access archive of $package-$version.');
  }
  final tempDir = Directory.systemTemp.createTempSync();
  try {
    final archiveFile = File.fromUri(
      tempDir.uri.resolve('$package-$version.tar.gz'),
    );
    await rs.pipe(archiveFile.openWrite());
    final result = await Process.run(
      Platform.resolvedExecutable,
      ['pub', 'cache', 'preload', archiveFile.path],
      environment: {if (pubCachePath != null) 'PUB_CACHE': pubCachePath},
    );

    if (result.exitCode != 0) {
      throw Exception(
        'Unable to preload archive of $package-$version: ${result.stdout} ${result.stderr}',
      );
    }
  } finally {
    tempDir.deleteSync(recursive: true);
  }
}