' 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.PooledObjects
Imports Microsoft.CodeAnalysis.Structure
Imports Microsoft.CodeAnalysis.Text
Imports Microsoft.CodeAnalysis.VisualBasic.Syntax

Namespace Microsoft.CodeAnalysis.VisualBasic.Structure
    Friend Class RegionDirectiveStructureProvider
        Inherits AbstractSyntaxNodeStructureProvider(Of RegionDirectiveTriviaSyntax)

        Private Shared Function GetBannerText(regionDirective As RegionDirectiveTriviaSyntax) As String
            Dim text = regionDirective.Name.ToString().Trim(""""c)

            If text.Length = 0 Then
                Return regionDirective.HashToken.ToString() & regionDirective.RegionKeyword.ToString()
            End If

            Return text
        End Function

        Protected Overrides Sub CollectBlockSpans(previousToken As SyntaxToken,
                                                  regionDirective As RegionDirectiveTriviaSyntax,
                                                  spans As ArrayBuilder(Of BlockSpan),
                                                  options As BlockStructureOptions,
                                                  CancellationToken As CancellationToken)
            Dim matchingDirective = regionDirective.GetMatchingStartOrEndDirective(CancellationToken)
            If matchingDirective IsNot Nothing Then
                ' Always auto-collapse regions for Metadata As Source. These generated files only have one region at the
                ' top of the file, which has content like the following:
                '
                '   #Region "Assembly System.Runtime, Version=4.2.2.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a"
                '   ' C:\Program Files\dotnet\packs\Microsoft.NETCore.App.Ref\3.1.0\ref\netcoreapp3.1\System.Runtime.dll
                '   #End Region
                '
                ' For other files, auto-collapse regions based on the user option.
                Dim autoCollapse = options.IsMetadataAsSource OrElse options.CollapseRegionsWhenCollapsingToDefinitions

                Dim span = TextSpan.FromBounds(regionDirective.SpanStart, matchingDirective.Span.End)
                spans.AddIfNotNull(CreateBlockSpan(
                    span, span,
                    GetBannerText(regionDirective),
                    autoCollapse:=autoCollapse,
                    isDefaultCollapsed:=options.CollapseRegionsWhenFirstOpened,
                    type:=BlockTypes.PreprocessorRegion,
                    isCollapsible:=True))
            End If
        End Sub
    End Class
End Namespace