// Copyright (c) 2015, 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.

library test.backend.group;

import 'metadata.dart';
import 'operating_system.dart';
import 'group_entry.dart';
import 'test.dart';
import 'test_platform.dart';

/// A group contains one or more tests and subgroups.
///
/// It includes metadata that applies to all contained tests.
class Group implements GroupEntry {
  final String name;

  final Metadata metadata;

  /// The children of this group.
  final List<GroupEntry> entries;

  /// Returns a new root-level group.
  Group.root(Iterable<GroupEntry> entries, {Metadata metadata})
      : this(null, entries, metadata: metadata);

  /// A test to run before all tests in the group.
  ///
  /// This is `null` if no `setUpAll` callbacks were declared.
  final Test setUpAll;

  /// A test to run after all tests in the group.
  ///
  /// This is `null` if no `tearDown` callbacks were declared.
  final Test tearDownAll;

  Group(this.name, Iterable<GroupEntry> entries, {Metadata metadata,
          Test this.setUpAll, Test this.tearDownAll})
      : entries = new List<GroupEntry>.unmodifiable(entries),
        metadata = metadata == null ? new Metadata() : metadata;

  Group forPlatform(TestPlatform platform, {OperatingSystem os}) {
    if (!metadata.testOn.evaluate(platform, os: os)) return null;
    var newMetadata = metadata.forPlatform(platform, os: os);
    var filtered = _map((entry) => entry.forPlatform(platform, os: os));
    if (filtered.isEmpty && !entries.isEmpty) return null;
    return new Group(name, filtered,
        metadata: newMetadata, setUpAll: setUpAll, tearDownAll: tearDownAll);
  }

  Group filter(bool callback(Test test)) {
    var filtered = _map((entry) => entry.filter(callback));
    if (filtered.isEmpty && !entries.isEmpty) return null;
    return new Group(name, filtered,
        metadata: metadata, setUpAll: setUpAll, tearDownAll: tearDownAll);
  }

  /// Returns the entries of this group mapped using [callback].
  ///
  /// Any `null` values returned by [callback] will be removed.
  List<GroupEntry> _map(GroupEntry callback(GroupEntry entry)) {
    return entries
        .map((entry) => callback(entry))
        .where((entry) => entry != null)
        .toList();
  }
}