' Copyright (c) Microsoft.  All Rights Reserved.  Licensed under the Apache License, Version 2.0.  See License.txt in the project root for license information.

Imports System.Composition
Imports System.Threading
Imports System.Threading.Tasks
Imports dnSpy.Roslyn.Internal.QuickInfo
Imports Microsoft.CodeAnalysis
Imports Microsoft.CodeAnalysis.Shared.Extensions
Imports Microsoft.CodeAnalysis.VisualBasic
Imports Microsoft.CodeAnalysis.VisualBasic.Syntax
Imports Microsoft.CodeAnalysis.VisualBasic.Utilities.IntrinsicOperators

Namespace Global.Microsoft.CodeAnalysis.Editor.VisualBasic.QuickInfo

	<ExportQuickInfoProvider(PredefinedQuickInfoProviderNames.Semantic, LanguageNames.VisualBasic)>
	Friend Class SemanticQuickInfoProvider
		Inherits AbstractSemanticQuickInfoProvider

		<ImportingConstructor>
		Public Sub New()
		End Sub

		Protected Overrides Async Function BuildContentAsync(document As Document,
												  token As SyntaxToken,
												  cancellationToken As CancellationToken) As Task(Of QuickInfoContent)
			Dim vbToken = CType(token, SyntaxToken)
			Dim parent = vbToken.Parent

			Dim predefinedCastExpression = TryCast(parent, PredefinedCastExpressionSyntax)
			If predefinedCastExpression IsNot Nothing AndAlso vbToken = predefinedCastExpression.Keyword Then
				Dim compilation = Await document.Project.GetCompilationAsync(cancellationToken).ConfigureAwait(False)
				Dim documentation = New PredefinedCastExpressionDocumentation(predefinedCastExpression.Keyword.Kind, compilation)
				Return Await BuildContentForIntrinsicOperatorAsync(document, parent, documentation, Glyph.MethodPublic, cancellationToken).ConfigureAwait(False)
			End If

			Select Case vbToken.Kind
				Case SyntaxKind.AddHandlerKeyword
					If TypeOf parent Is AddRemoveHandlerStatementSyntax Then
						Return Await BuildContentForIntrinsicOperatorAsync(document, parent, New AddHandlerStatementDocumentation(), Glyph.Keyword, cancellationToken).ConfigureAwait(False)
					End If

				Case SyntaxKind.DimKeyword
					If TypeOf parent Is FieldDeclarationSyntax Then
						Return Await BuildContentAsync(document, token, DirectCast(parent, FieldDeclarationSyntax).Declarators, cancellationToken).ConfigureAwait(False)
					ElseIf TypeOf parent Is LocalDeclarationStatementSyntax Then
						Return Await BuildContentAsync(document, token, DirectCast(parent, LocalDeclarationStatementSyntax).Declarators, cancellationToken).ConfigureAwait(False)
					End If

				Case SyntaxKind.CTypeKeyword
					If TypeOf parent Is CTypeExpressionSyntax Then
						Return Await BuildContentForIntrinsicOperatorAsync(document, parent, New CTypeCastExpressionDocumentation(), Glyph.MethodPublic, cancellationToken).ConfigureAwait(False)
					End If

				Case SyntaxKind.DirectCastKeyword
					If TypeOf parent Is DirectCastExpressionSyntax Then
						Return Await BuildContentForIntrinsicOperatorAsync(document, parent, New DirectCastExpressionDocumentation(), Glyph.MethodPublic, cancellationToken).ConfigureAwait(False)
					End If

				Case SyntaxKind.GetTypeKeyword
					If TypeOf parent Is GetTypeExpressionSyntax Then
						Return Await BuildContentForIntrinsicOperatorAsync(document, parent, New GetTypeExpressionDocumentation(), Glyph.MethodPublic, cancellationToken).ConfigureAwait(False)
					End If

				Case SyntaxKind.GetXmlNamespaceKeyword
					If TypeOf parent Is GetXmlNamespaceExpressionSyntax Then
						Return Await BuildContentForIntrinsicOperatorAsync(document, parent, New GetXmlNamespaceExpressionDocumentation(), Glyph.MethodPublic, cancellationToken).ConfigureAwait(False)
					End If

				Case SyntaxKind.IfKeyword
					If parent.Kind = SyntaxKind.BinaryConditionalExpression Then
						Return Await BuildContentForIntrinsicOperatorAsync(document, parent, New BinaryConditionalExpressionDocumentation(), Glyph.MethodPublic, cancellationToken).ConfigureAwait(False)
					ElseIf parent.Kind = SyntaxKind.TernaryConditionalExpression Then
						Return Await BuildContentForIntrinsicOperatorAsync(document, parent, New TernaryConditionalExpressionDocumentation(), Glyph.MethodPublic, cancellationToken).ConfigureAwait(False)
					End If

				Case SyntaxKind.RemoveHandlerKeyword
					If TypeOf parent Is AddRemoveHandlerStatementSyntax Then
						Return Await BuildContentForIntrinsicOperatorAsync(document, parent, New RemoveHandlerStatementDocumentation(), Glyph.Keyword, cancellationToken).ConfigureAwait(False)
					End If

				Case SyntaxKind.TryCastKeyword
					If TypeOf parent Is TryCastExpressionSyntax Then
						Return Await BuildContentForIntrinsicOperatorAsync(document, parent, New TryCastExpressionDocumentation(), Glyph.MethodPublic, cancellationToken).ConfigureAwait(False)
					End If

				Case SyntaxKind.IdentifierToken
					If SyntaxFacts.GetContextualKeywordKind(token.ToString()) = SyntaxKind.MidKeyword Then
						If parent.Kind = SyntaxKind.MidExpression Then
							Return Await BuildContentForIntrinsicOperatorAsync(document, parent, New MidAssignmentDocumentation(), Glyph.MethodPublic, cancellationToken).ConfigureAwait(False)
						End If
					End If
			End Select

			Return Await MyBase.BuildContentAsync(document, token, cancellationToken).ConfigureAwait(False)
		End Function

		Private Overloads Async Function BuildContentAsync(document As Document,
												token As SyntaxToken,
												declarators As SeparatedSyntaxList(Of VariableDeclaratorSyntax),
												cancellationToken As CancellationToken) As Task(Of QuickInfoContent)

			If declarators.Count = 0 Then
				Return Nothing
			End If

			Dim semantics = Await document.GetSemanticModelForNodeAsync(token.Parent, cancellationToken).ConfigureAwait(False)

			Dim types = dnSpy.Roslyn.Utilities2.EnumerableExtensions2.WhereNotNull(declarators.SelectMany(Function(d) d.Names).Select(
				Function(n)
					Dim symbol = semantics.GetDeclaredSymbol(n, cancellationToken)
					If symbol Is Nothing Then
						Return Nothing
					End If

					If TypeOf symbol Is ILocalSymbol Then
						Return DirectCast(symbol, ILocalSymbol).Type
					ElseIf TypeOf symbol Is IFieldSymbol Then
						Return DirectCast(symbol, IFieldSymbol).Type
					Else
						Return Nothing
					End If
				End Function)).Distinct().ToList()

			If types.Count = 0 Then
				Return Nothing
			End If

			'If types.Count > 1 Then
			'	Dim contentBuilder = New List(Of TaggedText)
			'	contentBuilder.AddText(VBEditorResources.Multiple_Types)
			'	Return Me.CreateClassifiableDeferredContent(contentBuilder)
			'End If

			Return Await CreateContentAsync(document.Project.Solution.Workspace, token, semantics, types, supportedPlatforms:=Nothing, cancellationToken:=cancellationToken).ConfigureAwait(False)
		End Function

		Private Async Function BuildContentForIntrinsicOperatorAsync(document As Document,
																	 expression As SyntaxNode,
																	 documentation As AbstractIntrinsicOperatorDocumentation,
																	 glyph As Glyph,
																	 cancellationToken As CancellationToken) As Task(Of QuickInfoContent)
			Dim builder = New List(Of SymbolDisplayPart)

			builder.AddRange(documentation.PrefixParts)

			Dim semanticModel = Await document.GetSemanticModelForNodeAsync(expression, cancellationToken).ConfigureAwait(False)

			Dim position = expression.SpanStart

			For i = 0 To documentation.ParameterCount - 1
				If i <> 0 Then
					builder.AddPunctuation(",")
					builder.AddSpace()
				End If

				Dim typeNameToBind = documentation.TryGetTypeNameParameter(expression, i)

				If typeNameToBind IsNot Nothing Then
					' We'll try to bind the type name 
					Dim typeInfo = semanticModel.GetTypeInfo(typeNameToBind, cancellationToken)

					If typeInfo.Type IsNot Nothing Then
						builder.AddRange(typeInfo.Type.ToMinimalDisplayParts(semanticModel, position))
						Continue For
					End If
				End If

				builder.AddRange(documentation.GetParameterDisplayParts(i))
			Next

			builder.AddRange(documentation.GetSuffix(semanticModel, position, expression, cancellationToken))

			Return CreateQuickInfoDisplayDeferredContent(
				glyph,
				builder.ToTaggedText(),
				CreateDocumentationCommentDeferredContent(documentation.DocumentationText),
				Array.Empty(Of TaggedText),
				Array.Empty(Of TaggedText),
				Array.Empty(Of TaggedText),
				Array.Empty(Of TaggedText))
		End Function
	End Class
End Namespace