' 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.Collections.Immutable
Imports System.Diagnostics
Imports Microsoft.CodeAnalysis.RuntimeMembers
Imports Microsoft.CodeAnalysis.VisualBasic.Symbols
 
Namespace Microsoft.CodeAnalysis.VisualBasic
    Partial Friend NotInheritable Class LocalRewriter
        Public Overrides Function VisitRaiseEventStatement(node As BoundRaiseEventStatement) As BoundNode
            Dim syntax = node.Syntax
 
            Dim saveState As UnstructuredExceptionHandlingContext = LeaveUnstructuredExceptionHandlingContext(node)
 
            ' in the absence of errors invocation must be a call 
            '(could also be BadExpression, but that would have errors)
            Dim raiseCallExpression = DirectCast(node.EventInvocation, BoundCall)
 
            Dim result As BoundStatement
            Dim receiver = raiseCallExpression.ReceiverOpt
 
            If receiver Is Nothing OrElse receiver.IsMeReference Then
                result = New BoundExpressionStatement(
                                syntax,
                                VisitExpressionNode(raiseCallExpression))
 
            Else
                Debug.Assert(receiver.Kind = BoundKind.FieldAccess)
 
#If DEBUG Then
                ' NOTE: The receiver is always as lowered as it's going to get (generally, a MeReference), so there's no need to Visit it.
                Dim fieldAccess As BoundFieldAccess = DirectCast(receiver, BoundFieldAccess)
                Dim fieldAccessReceiver = fieldAccess.ReceiverOpt
                Debug.Assert(fieldAccessReceiver Is Nothing OrElse
                             fieldAccessReceiver.Kind = BoundKind.MeReference)
#End If
 
                If node.EventSymbol.IsWindowsRuntimeEvent Then
                    receiver = GetWindowsRuntimeEventReceiver(syntax, receiver)
                End If
 
                ' Need to null-check the receiver before invoking raise -
                '
                ' eventField.raiseCallExpression  === becomes ===>
                '
                ' Block
                '     Dim temp = eventField
                '     if temp is Nothing GoTo skipEventRaise
                '        Call temp.raiseCallExpression
                '     skipEventRaise:
                ' End Block
                '
                Dim temp As LocalSymbol = New SynthesizedLocal(Me._currentMethodOrLambda, receiver.Type, SynthesizedLocalKind.LoweringTemp)
                Dim tempAccess As BoundLocal = New BoundLocal(syntax, temp, temp.Type).MakeCompilerGenerated
 
                Dim tempInit = New BoundExpressionStatement(syntax,
                                                            New BoundAssignmentOperator(syntax, tempAccess, receiver, True, receiver.Type)).MakeCompilerGenerated
 
                ' replace receiver with temp.
                raiseCallExpression = raiseCallExpression.Update(raiseCallExpression.Method,
                                                        raiseCallExpression.MethodGroupOpt,
                                                        tempAccess,
                                                        raiseCallExpression.Arguments,
                                                        raiseCallExpression.DefaultArguments,
                                                        raiseCallExpression.ConstantValueOpt,
                                                        isLValue:=raiseCallExpression.IsLValue,
                                                        suppressObjectClone:=raiseCallExpression.SuppressObjectClone,
                                                        type:=raiseCallExpression.Type)
 
                Dim invokeStatement = New BoundExpressionStatement(
                                            syntax,
                                            VisitExpressionNode(raiseCallExpression))
 
                Dim condition = New BoundBinaryOperator(syntax,
                                                        BinaryOperatorKind.Is,
                                                        tempAccess.MakeRValue(),
                                                        New BoundLiteral(syntax, ConstantValue.Nothing,
                                                                         Me.Compilation.GetSpecialType(SpecialType.System_Object)),
                                                        False,
                                                        Me.Compilation.GetSpecialType(SpecialType.System_Boolean)).MakeCompilerGenerated
 
                Dim skipEventRaise As New GeneratedLabelSymbol("skipEventRaise")
 
                Dim ifNullSkip = New BoundConditionalGoto(syntax, condition, True, skipEventRaise).MakeCompilerGenerated
 
                result = New BoundBlock(syntax,
                                        Nothing,
                                        ImmutableArray.Create(temp),
                                        ImmutableArray.Create(Of BoundStatement)(
                                            tempInit,
                                            ifNullSkip,
                                            invokeStatement,
                                            New BoundLabelStatement(syntax, skipEventRaise)))
            End If
 
            RestoreUnstructuredExceptionHandlingContext(node, saveState)
 
            If ShouldGenerateUnstructuredExceptionHandlingResumeCode(node) Then
                result = RegisterUnstructuredExceptionHandlingResumeTarget(node.Syntax, result, canThrow:=True)
            End If
 
            If Instrument(node, result) Then
                result = _instrumenterOpt.InstrumentRaiseEventStatement(node, result)
            End If
 
            Return result
        End Function
 
        ' If the event is a WinRT event, then the backing field is actually an EventRegistrationTokenTable,
        ' rather than a delegate.  If this is the case, then we replace the receiver with 
        ' EventRegistrationTokenTable(Of Event).GetOrCreateEventRegistrationTokenTable(eventField).InvocationList.
        Private Function GetWindowsRuntimeEventReceiver(syntax As SyntaxNode, rewrittenReceiver As BoundExpression) As BoundExpression
            Dim fieldType As NamedTypeSymbol = DirectCast(rewrittenReceiver.Type, NamedTypeSymbol)
            Debug.Assert(fieldType.Name = "EventRegistrationTokenTable")
 
            Dim getOrCreateMethod As MethodSymbol = DirectCast(Compilation.GetWellKnownTypeMember(
                    WellKnownMember.System_Runtime_InteropServices_WindowsRuntime_EventRegistrationTokenTable_T__GetOrCreateEventRegistrationTokenTable), MethodSymbol)
 
            Debug.Assert(getOrCreateMethod IsNot Nothing, "Checked during initial binding")
            Debug.Assert(TypeSymbol.Equals(getOrCreateMethod.ReturnType, fieldType.OriginalDefinition, TypeCompareKind.ConsiderEverything), "Shape of well-known member")
 
            getOrCreateMethod = getOrCreateMethod.AsMember(fieldType)
 
            Dim invocationListProperty As PropertySymbol = Nothing
            If TryGetWellknownMember(invocationListProperty, WellKnownMember.System_Runtime_InteropServices_WindowsRuntime_EventRegistrationTokenTable_T__InvocationList, syntax) Then
                Dim invocationListAccessor As MethodSymbol = invocationListProperty.GetMethod
 
                If invocationListAccessor IsNot Nothing Then
                    invocationListAccessor = invocationListAccessor.AsMember(fieldType)
 
                    ' EventRegistrationTokenTable(Of Event).GetOrCreateEventRegistrationTokenTable(_tokenTable)
                    Dim getOrCreateCall = New BoundCall(syntax:=syntax,
                                                        method:=getOrCreateMethod,
                                                        methodGroupOpt:=Nothing,
                                                        receiverOpt:=Nothing,
                                                        arguments:=ImmutableArray.Create(Of BoundExpression)(rewrittenReceiver),
                                                        constantValueOpt:=Nothing,
                                                        isLValue:=False,
                                                        suppressObjectClone:=False,
                                                        type:=getOrCreateMethod.ReturnType).MakeCompilerGenerated()
 
                    ' EventRegistrationTokenTable(Of Event).GetOrCreateEventRegistrationTokenTable(_tokenTable).InvocationList
                    Dim invocationListAccessorCall = New BoundCall(syntax:=syntax,
                                                                   method:=invocationListAccessor,
                                                                   methodGroupOpt:=Nothing,
                                                                   receiverOpt:=getOrCreateCall,
                                                                   arguments:=ImmutableArray(Of BoundExpression).Empty,
                                                                   constantValueOpt:=Nothing,
                                                                   isLValue:=False,
                                                                   suppressObjectClone:=False,
                                                                   type:=invocationListAccessor.ReturnType).MakeCompilerGenerated()
 
                    Return invocationListAccessorCall
                End If
 
                Dim memberDescriptor As MemberDescriptor = WellKnownMembers.GetDescriptor(WellKnownMember.System_Runtime_InteropServices_WindowsRuntime_EventRegistrationTokenTable_T__InvocationList)
                ' isWinMd only matters for set accessors, we can safely say false here
                Dim accessorName As String = Binder.GetAccessorName(invocationListProperty.Name, MethodKind.PropertyGet, isWinMd:=False)
                Dim info = GetDiagnosticForMissingRuntimeHelper(memberDescriptor.DeclaringTypeMetadataName, accessorName, _compilationState.Compilation.Options.EmbedVbCoreRuntime)
                _diagnostics.Add(info, syntax.GetLocation())
            End If
 
            Return New BoundBadExpression(syntax, LookupResultKind.NotReferencable, ImmutableArray(Of Symbol).Empty, ImmutableArray.Create(rewrittenReceiver), ErrorTypeSymbol.UnknownResultType, hasErrors:=True)
        End Function
    End Class
End Namespace