// 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.

#nullable enable

using System.Diagnostics.CodeAnalysis;
using Microsoft.VisualStudio.Editor;
using Microsoft.VisualStudio.Shell.Interop;
using Microsoft.VisualStudio.Text;
using Microsoft.VisualStudio.TextManager.Interop;

namespace Microsoft.VisualStudio.LanguageServices.Implementation.ProjectSystem
{
    /// <summary>
    /// Helper extensions for calling into the RDT.
    /// These must all be called from the UI thread.
    /// </summary>
    internal static class RunningDocumentTableExtensions
    {
        public static bool TryGetBufferFromMoniker(this IVsRunningDocumentTable4 runningDocumentTable,
            IVsEditorAdaptersFactoryService editorAdaptersFactoryService,
            string moniker, [NotNullWhen(true)] out ITextBuffer? textBuffer)
        {
            textBuffer = null;
            if (!runningDocumentTable.IsFileOpen(moniker))
            {
                return false;
            }

            var cookie = runningDocumentTable.GetDocumentCookie(moniker);
            if (!runningDocumentTable.IsDocumentInitialized(cookie))
            {
                return false;
            }

            return TryGetBuffer(runningDocumentTable, editorAdaptersFactoryService, cookie, out textBuffer);
        }

        public static bool IsFileOpen(this IVsRunningDocumentTable4 runningDocumentTable, string fileName)
            => runningDocumentTable.IsMonikerValid(fileName);

        public static bool TryGetBuffer(this IVsRunningDocumentTable4 runningDocumentTable, IVsEditorAdaptersFactoryService editorAdaptersFactoryService,
            uint docCookie, [NotNullWhen(true)] out ITextBuffer? textBuffer)
        {
            textBuffer = null;

            // The cast from dynamic to object doesn't change semantics, but avoids loading the dynamic binder
            // which saves us JIT time in this method and an assembly load.
            if ((object)runningDocumentTable.GetDocumentData(docCookie) is IVsTextBuffer bufferAdapter)
            {
                textBuffer = editorAdaptersFactoryService.GetDocumentBuffer(bufferAdapter);
                return textBuffer != null;
            }

            return false;
        }
    }
}