// 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.Linq;
using Microsoft.CodeAnalysis.ErrorReporting;
using Microsoft.CodeAnalysis.Options;
using Microsoft.Internal.VisualStudio.Shell.Interop;
using Roslyn.Utilities;
 
namespace Microsoft.VisualStudio.LanguageServices.Options
{
    internal sealed class FeatureFlagPersister
    {
        private readonly IVsFeatureFlags? _featureFlags;
 
        public FeatureFlagPersister(IVsFeatureFlags? featureFlags)
        {
            _featureFlags = featureFlags;
        }
 
        public bool TryFetch(OptionKey2 optionKey, string flagName, [NotNullWhen(true)] out object? value)
        {
            if (_featureFlags == null)
            {
                value = null;
                return false;
            }
 
            if (optionKey.Option.DefaultValue is not bool defaultValue)
            {
                throw ExceptionUtilities.UnexpectedValue(optionKey.Option.DefaultValue);
            }
 
            try
            {
                value = _featureFlags.IsFeatureEnabled(flagName, defaultValue);
            }
            catch (Exception e) when (FatalError.ReportAndCatch(e))
            {
                value = defaultValue;
            }
 
            return true;
        }
 
        public void Persist(string flagName, object? value)
        {
            if (value is not bool flag)
            {
                throw ExceptionUtilities.UnexpectedValue(value);
            }
 
            try
            {
                ((IVsFeatureFlags2?)_featureFlags)?.EnableFeatureFlag(flagName, flag);
            }
            catch (Exception e) when (FatalError.ReportAndCatch(e))
            {
            }
        }
    }
}