' 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.
 
Imports System.Threading
Imports Microsoft.CodeAnalysis.CodeActions
Imports Microsoft.CodeAnalysis.CodeRefactorings
Imports Microsoft.CodeAnalysis.Editor.Implementation.Preview
Imports Microsoft.CodeAnalysis.Editor.UnitTests.Workspaces
Imports Microsoft.CodeAnalysis.Text
 
Namespace Microsoft.CodeAnalysis.Editor.VisualBasic.UnitTests.CodeRefactorings
    Public Class PreviewTests
        Inherits AbstractVisualBasicCodeActionTest
 
        Private Const s_addedDocumentName As String = "AddedDocument"
        Private Const s_addedDocumentText As String = "Class C1 : End Class"
        Private Shared s_removedMetadataReferenceDisplayName As String = ""
        Private Const s_addedProjectName As String = "AddedProject"
        Private Shared ReadOnly s_addedProjectId As ProjectId = ProjectId.CreateNewId()
        Private Const s_changedDocumentText As String = "Class C : End Class"
 
        Protected Overrides Function CreateCodeRefactoringProvider(workspace As Workspace, parameters As TestParameters) As CodeRefactoringProvider
            Return New MyCodeRefactoringProvider()
        End Function
 
        Private Class MyCodeRefactoringProvider : Inherits CodeRefactoringProvider
            Public NotOverridable Overrides Function ComputeRefactoringsAsync(context As CodeRefactoringContext) As Task
                Dim codeAction = New TestCodeAction(context.Document)
                context.RegisterRefactoring(codeAction, context.Span)
                Return Task.CompletedTask
            End Function
 
            Private Class TestCodeAction : Inherits CodeAction
                Private ReadOnly _oldDocument As Document
 
                Public Sub New(oldDocument As Document)
                    Me._oldDocument = oldDocument
                End Sub
 
                Public Overrides ReadOnly Property Title As String
                    Get
                        Return "Title"
                    End Get
                End Property
 
                Protected Overrides Function GetChangedSolutionAsync(cancellationToken As CancellationToken) As Task(Of Solution)
                    Dim solution = _oldDocument.Project.Solution
 
                    ' Add a document - This will result in IWpfTextView previews.
                    solution = solution.AddDocument(DocumentId.CreateNewId(_oldDocument.Project.Id, s_addedDocumentName), s_addedDocumentName, s_addedDocumentText)
 
                    ' Remove a reference - This will result in a string preview.
                    Dim removedReference = _oldDocument.Project.MetadataReferences.Last()
                    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(), s_addedProjectName, s_addedProjectName, LanguageNames.CSharp))
 
                    ' Change a document - This will result in IWpfTextView previews.
                    solution = solution.WithDocumentSyntaxRoot(_oldDocument.Id, VisualBasicSyntaxTree.ParseText(s_changedDocumentText).GetRoot())
 
                    Return Task.FromResult(solution)
                End Function
            End Class
        End Class
 
        Private Async Function GetMainDocumentAndPreviewsAsync(
                parameters As TestParameters,
                workspace As TestWorkspace) As Task(Of (document As Document, previews As SolutionPreviewResult))
            Dim document = GetDocument(workspace)
            Dim provider = CreateCodeRefactoringProvider(workspace, parameters)
            Dim span = document.GetSyntaxRootAsync().Result.Span
            Dim refactorings = New List(Of CodeAction)()
            Dim context = New CodeRefactoringContext(document, span, Sub(a) refactorings.Add(a), CancellationToken.None)
            provider.ComputeRefactoringsAsync(context).Wait()
            Dim action = refactorings.Single()
            Dim editHandler = workspace.ExportProvider.GetExportedValue(Of ICodeActionEditHandlerService)()
            Dim previews = Await editHandler.GetPreviewsAsync(workspace, action.GetPreviewOperationsAsync(CancellationToken.None).Result, CancellationToken.None)
 
            Return (document, previews)
        End Function
 
        <WpfFact(Skip:="https://github.com/dotnet/roslyn/issues/14421")>
        Public Async Function TestPickTheRightPreview_NoPreference() As Task
            Dim parameters As New TestParameters()
            Using workspace = CreateWorkspaceFromOptions("Class D : End Class", parameters)
                Dim tuple = Await GetMainDocumentAndPreviewsAsync(parameters, workspace)
                Dim document = tuple.document
                Dim previews = tuple.previews
 
                ' The changed document comes first.
                Dim previewObjects = Await previews.GetPreviewsAsync()
                Dim preview = previewObjects(0)
                Assert.NotNull(preview)
                Assert.True(TypeOf preview Is DifferenceViewerPreview)
                Dim diffView = DirectCast(preview, DifferenceViewerPreview)
                Dim text = diffView.Viewer.RightView.TextBuffer.AsTextContainer().CurrentText.ToString()
                Assert.Equal(s_changedDocumentText, text)
                diffView.Dispose()
 
                ' Then comes the removed metadata reference.
                preview = previewObjects(1)
                Assert.NotNull(preview)
                Assert.True(TypeOf preview Is String)
                text = DirectCast(preview, String)
                Assert.Contains(s_removedMetadataReferenceDisplayName, text, StringComparison.Ordinal)
 
                ' And finally the added project.
                preview = previewObjects(2)
                Assert.NotNull(preview)
                Assert.True(TypeOf preview Is String)
                text = DirectCast(preview, String)
                Assert.Contains(s_addedProjectName, text, StringComparison.Ordinal)
            End Using
        End Function
    End Class
End Namespace