// 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.
 
using System.Linq;
using System.Threading;
using Microsoft.CodeAnalysis.CSharp.Syntax;
using Microsoft.CodeAnalysis.Shared.Collections;
using Microsoft.CodeAnalysis.Structure;
 
namespace Microsoft.CodeAnalysis.CSharp.Structure
{
    internal class NamespaceDeclarationStructureProvider : AbstractSyntaxNodeStructureProvider<NamespaceDeclarationSyntax>
    {
        protected override void CollectBlockSpans(
            SyntaxToken previousToken,
            NamespaceDeclarationSyntax namespaceDeclaration,
            ref TemporaryArray<BlockSpan> spans,
            BlockStructureOptions options,
            CancellationToken cancellationToken)
        {
            // add leading comments
            CSharpStructureHelpers.CollectCommentBlockSpans(namespaceDeclaration, ref spans, options);
 
            if (!namespaceDeclaration.OpenBraceToken.IsMissing &&
                !namespaceDeclaration.CloseBraceToken.IsMissing)
            {
                spans.AddIfNotNull(CSharpStructureHelpers.CreateBlockSpan(
                    namespaceDeclaration,
                    namespaceDeclaration.Name.GetLastToken(includeZeroWidth: true),
                    compressEmptyLines: false,
                    autoCollapse: false,
                    type: BlockTypes.Namespace,
                    isCollapsible: true));
            }
 
            // extern aliases and usings are outlined in a single region
            var externsAndUsings = Enumerable.Union<SyntaxNode>(namespaceDeclaration.Externs, namespaceDeclaration.Usings)
                                       .OrderBy(node => node.SpanStart)
                                       .ToList();
 
            // add any leading comments before the extern aliases and usings
            if (externsAndUsings.Count > 0)
            {
                CSharpStructureHelpers.CollectCommentBlockSpans(externsAndUsings.First(), ref spans, options);
            }
 
            spans.AddIfNotNull(CSharpStructureHelpers.CreateBlockSpan(
                externsAndUsings, compressEmptyLines: false, autoCollapse: true,
                type: BlockTypes.Imports, isCollapsible: true, isDefaultCollapsed: options.CollapseImportsWhenFirstOpened));
 
            // finally, add any leading comments before the end of the namespace block
            if (!namespaceDeclaration.CloseBraceToken.IsMissing)
            {
                CSharpStructureHelpers.CollectCommentBlockSpans(
                    namespaceDeclaration.CloseBraceToken.LeadingTrivia, ref spans);
            }
        }
    }
}