// 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.Immutable;
using System.Linq;
using Roslyn.Utilities;

namespace Microsoft.CodeAnalysis;

internal static class IDocumentTrackingServiceExtensions
{
    /// <summary>
    /// Gets the active <see cref="Document"/> the user is currently working in. May be null if
    /// there is no active document or the active document is not in this <paramref name="solution"/>.
    /// </summary>
    public static Document? GetActiveDocument(this IDocumentTrackingService service, Solution solution)
    {
        // Note: GetDocument checks that the DocId is contained in the solution, and returns null if not.
        return solution.GetDocument(service.TryGetActiveDocument());
    }

    /// <summary>
    /// Get a read only collection of all the unique visible documents in the workspace that are
    /// contained within <paramref name="solution"/>.
    /// </summary>
    public static ImmutableArray<Document> GetVisibleDocuments(this IDocumentTrackingService service, Solution solution)
        => [.. service.GetVisibleDocuments()
                  .Select(solution.GetDocument)
                  .WhereNotNull()
                  .Distinct()];
}