// 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 disable
 
using System.Threading;
using Microsoft.CodeAnalysis.Shared.Extensions;
using Microsoft.CodeAnalysis.Text;
using Microsoft.VisualStudio.LanguageServices.Implementation.F1Help;
using Microsoft.VisualStudio.Shell.Interop;
using Microsoft.VisualStudio.TextManager.Interop;
using Roslyn.Utilities;
 
namespace Microsoft.VisualStudio.LanguageServices.Implementation.LanguageService;
 
internal abstract partial class AbstractLanguageService<TPackage, TLanguageService> : IVsLanguageContextProvider
{
    public int UpdateLanguageContext(uint dwHint, IVsTextLines pBuffer, Microsoft.VisualStudio.TextManager.Interop.TextSpan[] ptsSelection, object pUC)
    {
        var textBuffer = EditorAdaptersFactoryService.GetDataBuffer(pBuffer);
        var context = (IVsUserContext)pUC;
 
        if (textBuffer == null || context == null)
        {
            return VSConstants.E_UNEXPECTED;
        }
 
        var document = textBuffer.CurrentSnapshot.GetOpenDocumentInCurrentContextWithChanges();
        if (document == null)
        {
            return VSConstants.E_FAIL;
        }
 
        var start = textBuffer.CurrentSnapshot.GetLineFromLineNumber(ptsSelection[0].iStartLine).Start + ptsSelection[0].iStartIndex;
        var end = textBuffer.CurrentSnapshot.GetLineFromLineNumber(ptsSelection[0].iEndLine).Start + ptsSelection[0].iEndIndex;
        var span = Microsoft.CodeAnalysis.Text.TextSpan.FromBounds(start, end);
 
        var helpService = document.GetLanguageService<IHelpContextService>();
        if (helpService == null)
        {
            return VSConstants.E_NOTIMPL;
        }
 
        // VS help is not cancellable.
        var cancellationToken = CancellationToken.None;
        var helpTerm = helpService.GetHelpTermAsync(document, span, cancellationToken).WaitAndGetResult(cancellationToken);
 
        if (string.IsNullOrWhiteSpace(helpTerm))
        {
            return VSConstants.S_FALSE;
        }
 
        context.RemoveAttribute("keyword", null);
        context.AddAttribute(VSUSERCONTEXTATTRIBUTEUSAGE.VSUC_Usage_Filter, "devlang", helpService.Language);
        context.AddAttribute(VSUSERCONTEXTATTRIBUTEUSAGE.VSUC_Usage_Filter, "product", helpService.Product);
        context.AddAttribute(VSUSERCONTEXTATTRIBUTEUSAGE.VSUC_Usage_Filter, "product", "VS");
        context.AddAttribute(VSUSERCONTEXTATTRIBUTEUSAGE.VSUC_Usage_LookupF1_CaseSensitive, "keyword", helpTerm);
 
        return VSConstants.S_OK;
    }
}