// 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.Collections.Generic;
using Roslyn.Utilities;

namespace Microsoft.CodeAnalysis.NavigateTo;

/// <summary>
/// Comparer that considers to navigate to results the same if they will navigate to the same document and span.
/// This ensures that we don't see tons of results for the same symbol when a file is linked into many projects.
/// <para/>
/// This also has the impact that a linked file (say from a shared project) will only show up for a single project
/// that it is linked into. This is believed to actually be desirable as showing multiple hits for effectively the
/// same symbol, just for different projects just feels like clutter in the UI without real benefit for the user
/// (since navigating will just take the user to the same location).
/// </summary>
internal sealed class NavigateToSearchResultComparer : IEqualityComparer<INavigateToSearchResult>
{
    public static readonly IEqualityComparer<INavigateToSearchResult> Instance = new NavigateToSearchResultComparer();

    private NavigateToSearchResultComparer()
    {
    }

    public bool Equals(INavigateToSearchResult? x, INavigateToSearchResult? y)
        => x?.NavigableItem.Document.FilePath == y?.NavigableItem.Document.FilePath &&
           x?.NavigableItem.SourceSpan == y?.NavigableItem.SourceSpan;

    public int GetHashCode(INavigateToSearchResult? obj)
        => Hash.Combine(obj?.NavigableItem.Document.FilePath, obj?.NavigableItem.SourceSpan.GetHashCode() ?? 0);
}