// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
// See the LICENSE file in the project root for more information.
 
using System;
using System.Collections.Generic;
using System.Collections.Immutable;
using Microsoft.CodeAnalysis.PooledObjects;
using Microsoft.VisualStudio.Text;
using Microsoft.VisualStudio.Text.Tagging;
 
namespace Microsoft.CodeAnalysis.Diagnostics;
 
internal abstract partial class AbstractPushOrPullDiagnosticsTaggerProvider<TTag>
{
    private sealed partial class PullDiagnosticsTaggerProvider
    {
        /// <summary>
        /// Simple tagger that aggregates the underlying syntax/semantic compiler/analyzer taggers and presents them as
        /// a single event source and source of tags.
        /// </summary>
        private sealed class AggregateTagger : ITagger<TTag>, IDisposable
        {
            private readonly ImmutableArray<ITagger<TTag>> _taggers;
 
            public AggregateTagger(ImmutableArray<ITagger<TTag>> taggers)
                => _taggers = taggers;
 
            public void Dispose()
            {
                foreach (var tagger in _taggers)
                    (tagger as IDisposable)?.Dispose();
            }
 
            public event EventHandler<SnapshotSpanEventArgs> TagsChanged
            {
                add
                {
                    foreach (var tagger in _taggers)
                        tagger.TagsChanged += value;
                }
 
                remove
                {
                    foreach (var tagger in _taggers)
                        tagger.TagsChanged -= value;
                }
            }
 
            public IEnumerable<ITagSpan<TTag>> GetTags(NormalizedSnapshotSpanCollection spans)
            {
                using var _ = ArrayBuilder<ITagSpan<TTag>>.GetInstance(out var result);
 
                foreach (var tagger in _taggers)
                    result.AddRange(tagger.GetTags(spans));
 
                return result.ToImmutable();
            }
        }
    }
}