// 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.Generic;
using System.Threading;
using System.Threading.Tasks;
using Microsoft.CodeAnalysis;
using Microsoft.CodeAnalysis.ErrorReporting;
using Microsoft.CodeAnalysis.FindSymbols;
using Microsoft.CodeAnalysis.Host;
using Microsoft.CodeAnalysis.Shared.Extensions;
using Microsoft.VisualStudio.LanguageServices.Implementation.Library.ObjectBrowser.Lists;
using Microsoft.VisualStudio.Shell.Interop;
 
namespace Microsoft.VisualStudio.LanguageServices
{
    /// <summary>
    /// A Workspace specific to Visual Studio.
    /// </summary>
    public abstract class VisualStudioWorkspace : Workspace
    {
        private BackgroundCompiler? _backgroundCompiler;
        private readonly BackgroundParser? _backgroundParser;
 
        private readonly bool _backgroundCompilationDisabled;
 
        static VisualStudioWorkspace()
        {
            FaultReporter.InitializeFatalErrorHandlers();
        }
 
        internal VisualStudioWorkspace(HostServices hostServices)
            : base(hostServices, WorkspaceKind.Host)
        {
            _backgroundCompilationDisabled = this.Services.GetRequiredService<IWorkspaceConfigurationService>().Options.DisableBackgroundCompilation;
            if (!_backgroundCompilationDisabled)
            {
                _backgroundCompiler = new BackgroundCompiler(this);
 
                var cacheService = Services.GetService<IWorkspaceCacheService>();
                if (cacheService != null)
                {
                    cacheService.CacheFlushRequested += OnCacheFlushRequested;
                }
 
                _backgroundParser = new BackgroundParser(this);
                _backgroundParser.Start();
            }
 
            return;
 
            void OnCacheFlushRequested(object sender, EventArgs e)
            {
                if (_backgroundCompiler != null)
                {
                    _backgroundCompiler.Dispose();
                    _backgroundCompiler = null; // PartialSemanticsEnabled will now return false
                }
 
                // No longer need cache notifications
                var cacheService = Services.GetService<IWorkspaceCacheService>();
                if (cacheService != null)
                    cacheService.CacheFlushRequested -= OnCacheFlushRequested;
            }
        }
 
        protected internal override bool PartialSemanticsEnabled
        {
            get
            {
                // Still allow for partial semantics in the VS workspace, even with background compilation disabled. The
                // presumption here is that there's *always* something implicitly pulling the compilations forward in VS
                // (e.g. tagging, lightbulb, etc.) at a regular cadence.
                if (_backgroundCompilationDisabled)
                    return true;
 
                return _backgroundCompiler != null;
            }
        }
 
        protected override void OnDocumentTextChanged(Document document)
            => _backgroundParser?.Parse(document);
 
        protected override void OnDocumentClosing(DocumentId documentId)
            => _backgroundParser?.CancelParse(documentId);
 
        internal override bool IgnoreUnchangeableDocumentsWhenApplyingChanges => true;
 
        /// <summary>
        /// Returns the hierarchy for a given project. 
        /// </summary>
        /// <param name="projectId">The <see cref="ProjectId"/> for the project.</param>
        /// <returns>The <see cref="IVsHierarchy"/>, or null if the project doesn't have one.</returns>
        public abstract IVsHierarchy? GetHierarchy(ProjectId projectId);
 
        internal abstract Guid GetProjectGuid(ProjectId projectId);
 
        public virtual string? GetFilePath(DocumentId documentId)
            => CurrentSolution.GetTextDocument(documentId)?.FilePath;
 
        /// <summary>
        /// Given a document id, opens an invisible editor for the document.
        /// </summary>
        /// <returns>A unique instance of IInvisibleEditor that must be disposed by the caller.</returns>
        internal abstract IInvisibleEditor OpenInvisibleEditor(DocumentId documentId);
 
        /// <summary>
        /// Returns the <see cref="EnvDTE.FileCodeModel"/> for a given document.
        /// </summary>
        public abstract EnvDTE.FileCodeModel GetFileCodeModel(DocumentId documentId);
 
        internal abstract object? GetBrowseObject(SymbolListItem symbolListItem);
 
        [Obsolete("Use TryGoToDefinitionAsync instead", error: false)]
        public abstract bool TryGoToDefinition(ISymbol symbol, Project project, CancellationToken cancellationToken);
        public abstract Task<bool> TryGoToDefinitionAsync(ISymbol symbol, Project project, CancellationToken cancellationToken);
 
        public abstract bool TryFindAllReferences(ISymbol symbol, Project project, CancellationToken cancellationToken);
 
        public abstract void DisplayReferencedSymbols(Solution solution, IEnumerable<ReferencedSymbol> referencedSymbols);
 
        /// <summary>
        /// Creates a <see cref="PortableExecutableReference" /> that correctly retrieves the Visual Studio context,
        /// such as documentation comments in the correct language.
        /// </summary>
        /// <param name="filePath">The file path of the assembly or module.</param>
        /// <param name="properties">The properties for the reference.</param>
        public PortableExecutableReference CreatePortableExecutableReference(string filePath, MetadataReferenceProperties properties)
            => this.Services.GetRequiredService<IMetadataService>().GetReference(filePath, properties);
 
        internal abstract string? TryGetRuleSetPathForProject(ProjectId projectId);
    }
}