﻿// 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.Collections.Immutable;
using System.Composition;
using System.Threading;
using System.Threading.Tasks;
using Microsoft.CodeAnalysis.Host.Mef;
using Microsoft.CodeAnalysis.Internal.Log;
using Microsoft.CodeAnalysis.Remote;
using Microsoft.CodeAnalysis.UnusedReferences.ProjectAssets;

namespace Microsoft.CodeAnalysis.UnusedReferences
{
    [ExportWorkspaceService(typeof(IUnusedReferenceAnalysisService)), Shared]
    internal partial class UnusedReferenceAnalysisService : IUnusedReferenceAnalysisService
    {
        [ImportingConstructor]
        [Obsolete(MefConstruction.ImportingConstructorMessage, error: true)]
        public UnusedReferenceAnalysisService()
        {
        }

        public async Task<ImmutableArray<ReferenceInfo>> GetUnusedReferencesAsync(Solution solution, string projectFilePath, string projectAssetsFilePath, ImmutableArray<ReferenceInfo> projectReferences, CancellationToken cancellationToken)
        {
            using var logger = Logger.LogBlock(FunctionId.UnusedReferences_GetUnusedReferences, message: null, cancellationToken, LogLevel.Information);
            var client = await RemoteHostClient.TryGetClientAsync(solution.Services, cancellationToken).ConfigureAwait(false);
            if (client != null)
            {
                var result = await client.TryInvokeAsync<IRemoteUnusedReferenceAnalysisService, ImmutableArray<ReferenceInfo>>(
                    solution,
                    (service, solutionInfo, cancellationToken) => service.GetUnusedReferencesAsync(solutionInfo, projectFilePath, projectAssetsFilePath, projectReferences, cancellationToken),
                    cancellationToken).ConfigureAwait(false);

                if (!result.HasValue)
                {
                    return ImmutableArray<ReferenceInfo>.Empty;
                }

                return result.Value;
            }

            // Read specified references with dependency information from the project assets file.
            var references = await ProjectAssetsFileReader.ReadReferencesAsync(projectReferences, projectAssetsFilePath).ConfigureAwait(false);

            // Determine unused references
            var unusedReferences = await UnusedReferencesRemover.GetUnusedReferencesAsync(solution, projectFilePath, references, cancellationToken).ConfigureAwait(false);

            // Remove dependency information before returning.
            return unusedReferences.SelectAsArray(reference => reference.WithDependencies(null));
        }
    }
}
