// 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;
using System.Diagnostics.CodeAnalysis;
using System.Threading;
using System.Threading.Tasks;
using Microsoft.CodeAnalysis.ErrorReporting;
using Microsoft.CodeAnalysis.Internal.Log;
using Microsoft.CodeAnalysis.Serialization;
using Roslyn.Utilities;
 
namespace Microsoft.CodeAnalysis
{
    internal partial class TextDocumentState
    {
        public bool TryGetStateChecksums([NotNullWhen(returnValue: true)] out DocumentStateChecksums? stateChecksums)
            => _lazyChecksums.TryGetValue(out stateChecksums);
 
        public Task<DocumentStateChecksums> GetStateChecksumsAsync(CancellationToken cancellationToken)
            => _lazyChecksums.GetValueAsync(cancellationToken);
 
        public Task<Checksum> GetChecksumAsync(CancellationToken cancellationToken)
        {
            return SpecializedTasks.TransformWithoutIntermediateCancellationExceptionAsync(
                static (lazyChecksums, cancellationToken) => new ValueTask<DocumentStateChecksums>(lazyChecksums.GetValueAsync(cancellationToken)),
                static (documentStateChecksums, _) => documentStateChecksums.Checksum,
                _lazyChecksums,
                cancellationToken).AsTask();
        }
 
        private async Task<DocumentStateChecksums> ComputeChecksumsAsync(CancellationToken cancellationToken)
        {
            try
            {
                using (Logger.LogBlock(FunctionId.DocumentState_ComputeChecksumsAsync, FilePath, cancellationToken))
                {
                    var serializer = solutionServices.GetRequiredService<ISerializerService>();
 
                    var infoChecksum = serializer.CreateChecksum(Attributes, cancellationToken);
                    var serializableText = await SerializableSourceText.FromTextDocumentStateAsync(this, cancellationToken).ConfigureAwait(false);
                    var textChecksum = serializer.CreateChecksum(serializableText, cancellationToken);
 
                    return new DocumentStateChecksums(infoChecksum, textChecksum);
                }
            }
            catch (Exception e) when (FatalError.ReportAndPropagateUnlessCanceled(e, cancellationToken))
            {
                throw ExceptionUtilities.Unreachable();
            }
        }
    }
}