// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
 
using System.Linq;
using System.Threading;
using System.Threading.Tasks;
using Microsoft.VisualStudio.Text;
using Microsoft.VisualStudio.Text.Outlining;
 
namespace Microsoft.VisualStudio.Extensibility.Testing;
 
internal partial class EditorInProcess
{
    public async Task<ICollapsible[]> GetOutlineRegionsAsync(Text.Editor.IWpfTextView textView, CancellationToken cancellationToken)
    {
        var span = new SnapshotSpan(textView.TextSnapshot, 0, textView.TextSnapshot.Length);
        var manager = await GetOutlineManagerAsync(textView, cancellationToken);
 
        var outlines = manager.GetAllRegions(span);
 
        return outlines
            .OrderBy(s => s.Extent.GetStartPoint(textView.TextSnapshot))
            .ToArray();
    }
 
    public async Task WaitForOutlineRegionsAsync(CancellationToken cancellationToken)
    {
        var textView = await TestServices.Editor.GetActiveTextViewAsync(cancellationToken);
        var manager = await GetOutlineManagerAsync(textView, cancellationToken);
 
        using var semaphore = new SemaphoreSlim(1);
        await semaphore.WaitAsync(cancellationToken);
 
        var span = new SnapshotSpan(textView.TextSnapshot, 0, textView.TextSnapshot.Length);
 
        manager.RegionsChanged += On_RegionsChanged;
 
        // Check that we're not ALREADY changed
        var regions = manager.GetAllRegions(span);
        if (regions.Any())
        {
            semaphore.Release();
            manager.RegionsChanged -= On_RegionsChanged;
        }
 
        try
        {
            await semaphore.WaitAsync(cancellationToken);
        }
        finally
        {
            manager.RegionsChanged -= On_RegionsChanged;
        }
 
        void On_RegionsChanged(object sender, RegionsChangedEventArgs e)
        {
            var regions = manager.GetAllRegions(span);
 
            if (regions.Any())
            {
                semaphore.Release();
                manager.RegionsChanged -= On_RegionsChanged;
            }
        }
    }
 
    private async Task<IOutliningManager> GetOutlineManagerAsync(Text.Editor.IWpfTextView textView, CancellationToken cancellationToken)
    {
        await TestServices.JoinableTaskFactory.SwitchToMainThreadAsync();
        var outliningService = await TestServices.Shell.GetComponentModelServiceAsync<IOutliningManagerService>(cancellationToken);
        return outliningService.GetOutliningManager(textView);
    }
}