﻿// 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.

#nullable disable

using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading;
using System.Threading.Tasks;
using Microsoft.CodeAnalysis.CodeActions;
using Microsoft.CodeAnalysis.CodeRefactorings;
using Microsoft.CodeAnalysis.CSharp;
using Microsoft.CodeAnalysis.Diagnostics;
using Microsoft.CodeAnalysis.Editor.Implementation.Preview;
using Microsoft.CodeAnalysis.Editor.UnitTests;
using Microsoft.CodeAnalysis.Editor.UnitTests.Diagnostics;
using Microsoft.CodeAnalysis.Editor.UnitTests.Preview;
using Microsoft.CodeAnalysis.Editor.UnitTests.Workspaces;
using Microsoft.CodeAnalysis.Test.Utilities;
using Microsoft.CodeAnalysis.Text;
using Roslyn.Test.Utilities;
using Xunit;

namespace Microsoft.CodeAnalysis.Editor.CSharp.UnitTests.CodeRefactorings
{
    public partial class PreviewTests : AbstractCSharpCodeActionTest
    {
        private static readonly TestComposition s_composition = EditorTestCompositions.EditorFeaturesWpf
            .AddExcludedPartTypes(typeof(IDiagnosticUpdateSourceRegistrationService))
            .AddParts(
                typeof(MockDiagnosticUpdateSourceRegistrationService),
                typeof(MockPreviewPaneService));

        private const string AddedDocumentName = "AddedDocument";
        private const string AddedDocumentText = "class C1 {}";
        private static string s_removedMetadataReferenceDisplayName = "";
        private const string AddedProjectName = "AddedProject";
        private static readonly ProjectId s_addedProjectId = ProjectId.CreateNewId();
        private const string ChangedDocumentText = "class C {}";

        protected override TestComposition GetComposition() => s_composition;

        protected override CodeRefactoringProvider CreateCodeRefactoringProvider(Workspace workspace, TestParameters parameters)
            => new MyCodeRefactoringProvider();

        private class MyCodeRefactoringProvider : CodeRefactoringProvider
        {
            public sealed override Task ComputeRefactoringsAsync(CodeRefactoringContext context)
            {
                var codeAction = new TestCodeAction(context.Document);
                context.RegisterRefactoring(codeAction, context.Span);
                return Task.CompletedTask;
            }

            private class TestCodeAction : CodeAction
            {
                private readonly Document _oldDocument;

                public TestCodeAction(Document document)
                    => _oldDocument = document;

                public override string Title
                {
                    get
                    {
                        return "Title";
                    }
                }

                protected override Task<Solution> GetChangedSolutionAsync(CancellationToken cancellationToken)
                {
                    var solution = _oldDocument.Project.Solution;

                    // Add a document - This will result in IWpfTextView previews.
                    solution = solution.AddDocument(DocumentId.CreateNewId(_oldDocument.Project.Id, AddedDocumentName), AddedDocumentName, AddedDocumentText);

                    // Remove a reference - This will result in a string preview.
                    var removedReference = _oldDocument.Project.MetadataReferences[_oldDocument.Project.MetadataReferences.Count - 1];
                    s_removedMetadataReferenceDisplayName = removedReference.Display;
                    solution = solution.RemoveMetadataReference(_oldDocument.Project.Id, removedReference);

                    // Add a project - This will result in a string preview.
                    solution = solution.AddProject(ProjectInfo.Create(s_addedProjectId, VersionStamp.Create(), AddedProjectName, AddedProjectName, LanguageNames.CSharp));

                    // Change a document - This will result in IWpfTextView previews.
                    solution = solution.WithDocumentSyntaxRoot(_oldDocument.Id, CSharpSyntaxTree.ParseText(ChangedDocumentText, cancellationToken: cancellationToken).GetRoot(cancellationToken));

                    return Task.FromResult(solution);
                }
            }
        }

        private async Task<(Document document, SolutionPreviewResult previews)> GetMainDocumentAndPreviewsAsync(TestParameters parameters, TestWorkspace workspace)
        {
            var document = GetDocument(workspace);
            var provider = CreateCodeRefactoringProvider(workspace, parameters);
            var span = document.GetSyntaxRootAsync().Result.Span;
            var refactorings = new List<CodeAction>();
            var context = new CodeRefactoringContext(document, span, refactorings.Add, CancellationToken.None);
            provider.ComputeRefactoringsAsync(context).Wait();
            var action = refactorings.Single();
            var editHandler = workspace.ExportProvider.GetExportedValue<ICodeActionEditHandlerService>();
            var previews = await editHandler.GetPreviewsAsync(workspace, action.GetPreviewOperationsAsync(CancellationToken.None).Result, CancellationToken.None);

            return (document, previews);
        }

        [WpfFact(Skip = "https://github.com/dotnet/roslyn/issues/14421")]
        public async Task TestPickTheRightPreview_NoPreference()
        {
            var parameters = new TestParameters();
            using var workspace = CreateWorkspaceFromOptions("class D {}", parameters);

            var (document, previews) = await GetMainDocumentAndPreviewsAsync(parameters, workspace);

            // The changed document comes first.
            var previewObjects = await previews.GetPreviewsAsync();
            var preview = previewObjects[0];
            Assert.NotNull(preview);
            Assert.True(preview is DifferenceViewerPreview);
            var diffView = preview as DifferenceViewerPreview;
            var text = diffView.Viewer.RightView.TextBuffer.AsTextContainer().CurrentText.ToString();
            Assert.Equal(ChangedDocumentText, text);
            diffView.Dispose();

            // Then comes the removed metadata reference.
            preview = previewObjects[1];
            Assert.NotNull(preview);
            Assert.True(preview is string);
            text = preview as string;
            Assert.Contains(s_removedMetadataReferenceDisplayName, text, StringComparison.Ordinal);

            // And finally the added project.
            preview = previewObjects[2];
            Assert.NotNull(preview);
            Assert.True(preview is string);
            text = preview as string;
            Assert.Contains(AddedProjectName, text, StringComparison.Ordinal);
        }
    }
}
