' 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
Imports Microsoft.CodeAnalysis.IntroduceVariable
Imports Microsoft.CodeAnalysis.Host.Mef
Imports Microsoft.CodeAnalysis.Text
Imports Microsoft.CodeAnalysis.VisualBasic.Syntax
Imports System.Composition
 
Namespace Microsoft.CodeAnalysis.VisualBasic.IntroduceVariable
    <ExportLanguageService(GetType(IIntroduceVariableService), LanguageNames.VisualBasic), [Shared]>
    Partial Friend Class VisualBasicIntroduceVariableService
        Inherits AbstractIntroduceVariableService(Of VisualBasicIntroduceVariableService, ExpressionSyntax, TypeSyntax, TypeBlockSyntax, QueryExpressionSyntax, NameSyntax)
 
        <ImportingConstructor>
        <Obsolete(MefConstruction.ImportingConstructorMessage, True)>
        Public Sub New()
        End Sub
 
        Protected Overrides Function GetContainingExecutableBlocks(expression As ExpressionSyntax) As IEnumerable(Of SyntaxNode)
            Return expression.GetContainingExecutableBlocks()
        End Function
 
        Protected Overrides Function GetInsertionIndices(destination As TypeBlockSyntax, cancellationToken As CancellationToken) As IList(Of Boolean)
            Return destination.GetInsertionIndices(cancellationToken)
        End Function
 
        Protected Overrides Function IsInAttributeArgumentInitializer(expression As ExpressionSyntax) As Boolean
            If expression.GetAncestorOrThis(Of ArgumentSyntax)() Is Nothing Then
                Return False
            End If
 
            If expression.GetAncestorOrThis(Of AttributeSyntax)() Is Nothing Then
                Return False
            End If
 
            If expression.DepthFirstTraversal.Any(Function(n) n.Kind() = SyntaxKind.ArrayCreationExpression) OrElse
               expression.DepthFirstTraversal.Any(Function(n) n.Kind() = SyntaxKind.GetTypeExpression) Then
                Return False
            End If
 
            Dim attributeBlock = expression.GetAncestorOrThis(Of AttributeListSyntax)()
            If attributeBlock.IsParentKind(SyntaxKind.CompilationUnit) Then
                Return False
            End If
 
            Return True
        End Function
 
        Protected Overrides Function IsInConstructorInitializer(expression As ExpressionSyntax) As Boolean
            Dim constructorInitializer = expression.GetAncestorsOrThis(Of StatementSyntax)().
                  Where(Function(n) n.IsConstructorInitializer()).
                  FirstOrDefault()
 
            If constructorInitializer Is Nothing Then
                Return False
            End If
 
            ' have to make sure we're not inside a lambda inside the constructor initializer.
            If expression.GetAncestorOrThis(Of LambdaExpressionSyntax)() IsNot Nothing Then
                Return False
            End If
 
            Return True
        End Function
 
        Protected Overrides Function CanIntroduceVariableFor(expression As ExpressionSyntax) As Boolean
            expression = expression.WalkUpParentheses()
 
            If TypeOf expression.Parent Is CallStatementSyntax Then
                Return False
            End If
 
            If Not expression.GetImplicitMemberAccessExpressions.All(Function(e) e.IsParentKind(SyntaxKind.WithStatement)) Then
                Return False
            End If
 
            If expression.IsParentKind(SyntaxKind.EqualsValue) AndAlso
               expression.Parent.IsParentKind(SyntaxKind.VariableDeclarator) Then
                Return False
            End If
 
            ' For Nothing Literals, AllOccurrences could introduce semantic errors.
            If expression.IsKind(SyntaxKind.NothingLiteralExpression) Then
                Return False
            End If
 
            Return True
        End Function
 
        Protected Overrides Function IsInFieldInitializer(expression As ExpressionSyntax) As Boolean
            If expression.GetAncestorOrThis(Of VariableDeclaratorSyntax)().GetAncestorOrThis(Of FieldDeclarationSyntax)() IsNot Nothing Then
                Return True
            End If
 
            Return False
        End Function
 
        Protected Overrides Function IsInNonFirstQueryClause(expression As ExpressionSyntax) As Boolean
            Dim query = expression.GetAncestor(Of QueryExpressionSyntax)()
            If query Is Nothing Then
                Return False
            End If
 
            ' Can't introduce for the first clause in a query.
            Dim fromClause = expression.GetAncestor(Of FromClauseSyntax)()
            If fromClause IsNot Nothing AndAlso query.Clauses.First() Is fromClause Then
                Return False
            End If
 
            Return True
        End Function
 
        Protected Overrides Function IsInParameterInitializer(expression As ExpressionSyntax) As Boolean
            Return expression.GetAncestorOrThis(Of EqualsValueSyntax)().IsParentKind(SyntaxKind.Parameter)
        End Function
 
        Protected Overrides Function IsInAutoPropertyInitializer(expression As ExpressionSyntax) As Boolean
            Dim propertyStatement = expression.GetAncestorOrThis(Of PropertyStatementSyntax)()
            Dim equalsValueStatement = expression.GetAncestorOrThis(Of EqualsValueSyntax)
 
            If propertyStatement IsNot Nothing Then
                Return expression.GetAncestorsOrThis(Of AsClauseSyntax).Contains(propertyStatement.AsClause) OrElse
                    (equalsValueStatement IsNot Nothing AndAlso equalsValueStatement.Contains(propertyStatement.Initializer))
            End If
 
            Return False
        End Function
 
        Protected Overrides Function IsInExpressionBodiedMember(expression As ExpressionSyntax) As Boolean
            Return False
        End Function
 
        Protected Overrides Function CanReplace(expression As ExpressionSyntax) As Boolean
            If expression.CheckParent(Of RangeArgumentSyntax)(Function(n) n.LowerBound Is expression) Then
                Return False
            End If
 
            Return True
        End Function
 
        Protected Overrides Function IsExpressionInStaticLocalFunction(expression As ExpressionSyntax) As Boolean
            ' Local functions don't apply to VB.
            Return False
        End Function
 
        Protected Overrides Function RewriteCore(Of TNode As SyntaxNode)(node As TNode, replacementNode As SyntaxNode, matches As ISet(Of ExpressionSyntax)) As TNode
            Return DirectCast(Rewriter.Visit(node, replacementNode, matches), TNode)
        End Function
 
        Protected Overrides Function BlockOverlapsHiddenPosition(block As SyntaxNode, cancellationToken As CancellationToken) As Boolean
            Dim statements = block.GetStatements()
 
            If statements.Count = 0 Then
                Return block.OverlapsHiddenPosition(cancellationToken)
            End If
 
            Dim first = statements.First()
            Dim last = statements.Last()
 
            Return block.OverlapsHiddenPosition(TextSpan.FromBounds(first.SpanStart, last.SpanStart), cancellationToken)
        End Function
 
    End Class
End Namespace