// Copyright (c) 2018, 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';

import 'package:path/path.dart' as p;
import 'package:pub_semver/pub_semver.dart';

import '../io.dart';
import '../sdk.dart';

class FlutterSdk extends Sdk {
  String get name => "Flutter";
  bool get isAvailable => _isAvailable;
  Version get firstPubVersion => new Version.parse('1.19.0');

  static final bool _isAvailable =
      Platform.environment.containsKey("FLUTTER_ROOT");
  static final String _rootDirectory = Platform.environment["FLUTTER_ROOT"];

  String get installMessage =>
      "Flutter users should run `flutter packages get` instead of `pub get`.";

  Version get version {
    if (!_isAvailable) return null;

    _version ??= new Version.parse(
        readTextFile(p.join(_rootDirectory, "version")).trim());
    return _version;
  }

  Version _version;

  String packagePath(String name) {
    if (!isAvailable) return null;

    // Flutter packages exist in both `$flutter/packages` and
    // `$flutter/bin/cache/pkg`. This checks both locations in order. If [name]
    // exists in neither place, it returns the `$flutter/packages` location
    // which is more human-readable for error messages.
    var packagePath = p.join(_rootDirectory, 'packages', name);
    if (dirExists(packagePath)) return packagePath;

    var cachePath = p.join(_rootDirectory, 'bin', 'cache', 'pkg', name);
    if (dirExists(cachePath)) return cachePath;

    return null;
  }
}