' 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 Microsoft.CodeAnalysis.Collections
Imports Microsoft.CodeAnalysis.Operations
Imports Microsoft.CodeAnalysis.VisualBasic.CodeGeneration
Imports Microsoft.CodeAnalysis.VisualBasic.Syntax

Namespace Microsoft.CodeAnalysis.VisualBasic.ConvertIfToSwitch
    Partial Friend NotInheritable Class VisualBasicConvertIfToSwitchCodeRefactoringProvider
        Private Shared ReadOnly s_operatorMap As Dictionary(Of BinaryOperatorKind, (CaseClauseKind As SyntaxKind, OperatorTokenKind As SyntaxKind)) =
            New Dictionary(Of BinaryOperatorKind, (SyntaxKind, SyntaxKind))() From
            {
                {BinaryOperatorKind.NotEquals, (SyntaxKind.CaseNotEqualsClause, SyntaxKind.LessThanGreaterThanToken)},
                {BinaryOperatorKind.LessThan, (SyntaxKind.CaseLessThanClause, SyntaxKind.LessThanToken)},
                {BinaryOperatorKind.GreaterThan, (SyntaxKind.CaseGreaterThanClause, SyntaxKind.GreaterThanToken)},
                {BinaryOperatorKind.LessThanOrEqual, (SyntaxKind.CaseLessThanOrEqualClause, SyntaxKind.LessThanEqualsToken)},
                {BinaryOperatorKind.GreaterThanOrEqual, (SyntaxKind.CaseGreaterThanOrEqualClause, SyntaxKind.GreaterThanEqualsToken)}
            }

        Public Overrides Function CreateSwitchExpressionStatement(target As ExpressionSyntax, sections As ImmutableArray(Of AnalyzedSwitchSection), feature As Feature) As SyntaxNode
            Throw ExceptionUtilities.Unreachable
        End Function

        Public Overrides Function CreateSwitchStatement(ifStatement As ExecutableStatementSyntax, expression As ExpressionSyntax, sectionList As IEnumerable(Of SyntaxNode)) As SyntaxNode
            Return VisualBasicSyntaxGenerator.Instance.SwitchStatement(expression, sectionList)
        End Function

        Public Overrides Function AsSwitchSectionStatements(operation As IOperation) As IEnumerable(Of SyntaxNode)
            Dim node = operation.Syntax
            Return If(node.IsStatementContainerNode(), node.GetStatements(), SpecializedCollections.SingletonEnumerable(node))
        End Function

        Public Overrides Function AsSwitchLabelSyntax(label As AnalyzedSwitchLabel, feature As Feature) As SyntaxNode
            Debug.Assert(label.Guards.IsDefaultOrEmpty)
            Return AsCaseClauseSyntax(label.Pattern).WithAppendedTrailingTrivia(SyntaxFactory.ElasticMarker)
        End Function

        Private Shared Function AsCaseClauseSyntax(pattern As AnalyzedPattern) As CaseClauseSyntax
            Return pattern.TypeSwitch(
                Function(p As AnalyzedPattern.Constant) SyntaxFactory.SimpleCaseClause(p.ExpressionSyntax),
                Function(p As AnalyzedPattern.Range) SyntaxFactory.RangeCaseClause(p.LowerBound, p.HigherBound),
                Function(p As AnalyzedPattern.Relational)
                    Dim relationalOperator = s_operatorMap(p.OperatorKind)
                    Return SyntaxFactory.RelationalCaseClause(
                        relationalOperator.CaseClauseKind,
                        SyntaxFactory.Token(SyntaxKind.IsKeyword),
                        SyntaxFactory.Token(relationalOperator.OperatorTokenKind),
                        p.Value)
                End Function,
                Function(p) As CaseClauseSyntax
                    Throw ExceptionUtilities.UnexpectedValue(p)
                End Function)
        End Function
    End Class
End Namespace