// 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 Microsoft.CodeAnalysis.Test.Utilities;
using Microsoft.CodeAnalysis.Text;
using Roslyn.Test.Utilities;
using Xunit;
using Microsoft.CodeAnalysis.Shared.Extensions;
using CS = Microsoft.CodeAnalysis.CSharp;
using VB = Microsoft.CodeAnalysis.VisualBasic;
using System.Threading.Tasks;
using System.Threading;
 
namespace Microsoft.CodeAnalysis.UnitTests;
 
[UseExportProvider]
[Trait(Traits.Feature, Traits.Features.Workspace)]
public sealed class SyntaxReferenceTests : TestBase
{
    private static Workspace CreateWorkspace()
        => new AdhocWorkspace(FeaturesTestCompositions.Features.GetHostServices());
 
    private static Solution AddSingleFileCSharpProject(Solution solution, string source)
    {
        var pid = ProjectId.CreateNewId();
        var did = DocumentId.CreateNewId(pid);
 
        return solution
            .AddProject(pid, "Test", "Test.dll", LanguageNames.CSharp)
            .AddDocument(did, "Test.cs", SourceText.From(source));
    }
 
    private static Solution AddSingleFileVisualBasicProject(Solution solution, string source)
    {
        var pid = ProjectId.CreateNewId();
        var did = DocumentId.CreateNewId(pid);
 
        return solution
            .AddProject(pid, "Test", "Test.dll", LanguageNames.VisualBasic)
            .AddDocument(did, "Test.vb", SourceText.From(source));
    }
 
    [Fact]
    public async Task TestCSharpReferenceToZeroWidthNode()
    {
        using var workspace = CreateWorkspace();
        var solution = AddSingleFileCSharpProject(workspace.CurrentSolution, @"
public class C<> 
{
}
");
 
        var tree = await solution.Projects.First().Documents.First().GetRequiredSyntaxTreeAsync(CancellationToken.None);
 
        // this is an expected TypeParameterSyntax with a missing identifier token (it is zero-length w/ an error attached to it)
        var node = tree.GetRoot().DescendantNodes().OfType<CS.Syntax.TypeParameterSyntax>().Single();
        Assert.Equal(0, node.FullSpan.Length);
 
        var syntaxRef = tree.GetReference(node);
 
        var refNode = syntaxRef.GetSyntax();
 
        Assert.Equal(node, refNode);
    }
 
    [Fact]
    public async Task TestVisualBasicReferenceToZeroWidthNode()
    {
        using var workspace = CreateWorkspace();
        var solution = AddSingleFileVisualBasicProject(workspace.CurrentSolution, @"
Public Class C(Of )
End Class
");
 
        var tree = await solution.Projects.First().Documents.First().GetRequiredSyntaxTreeAsync(CancellationToken.None);
 
        // this is an expected TypeParameterSyntax with a missing identifier token (it is zero-length w/ an error attached to it)
        var node = tree.GetRoot().DescendantNodes().OfType<VB.Syntax.TypeParameterSyntax>().Single();
        Assert.Equal(0, node.FullSpan.Length);
 
        var syntaxRef = tree.GetReference(node);
 
        var refNode = syntaxRef.GetSyntax();
 
        Assert.Equal(node, refNode);
    }
 
    [Fact]
    public async Task TestCSharpReferenceToNodeInStructuredTrivia()
    {
        using var workspace = CreateWorkspace();
        var solution = AddSingleFileCSharpProject(workspace.CurrentSolution, @"
#if true || true
public class C 
{
}
#endif
");
        var tree = await solution.Projects.First().Documents.First().GetRequiredSyntaxTreeAsync(CancellationToken.None);
 
        // find binary node that is part of #if directive
        var node = tree.GetRoot().DescendantNodes(descendIntoTrivia: true).OfType<CS.Syntax.BinaryExpressionSyntax>().First();
 
        var syntaxRef = tree.GetReference(node);
 
        var refNode = syntaxRef.GetSyntax();
 
        Assert.Equal(node, refNode);
    }
 
    [Fact]
    public async Task TestVisualBasicReferenceToNodeInStructuredTrivia()
    {
        using var workspace = CreateWorkspace();
        var solution = AddSingleFileVisualBasicProject(workspace.CurrentSolution, @"
#If True Or True Then
Public Class C
End Class
#End If
");
 
        var tree = await solution.Projects.First().Documents.First().GetRequiredSyntaxTreeAsync(CancellationToken.None);
 
        // find binary node that is part of #if directive
        var node = tree.GetRoot().DescendantNodes(descendIntoTrivia: true).OfType<VB.Syntax.BinaryExpressionSyntax>().First();
 
        var syntaxRef = tree.GetReference(node);
 
        var refNode = syntaxRef.GetSyntax();
 
        Assert.Equal(node, refNode);
    }
 
    [Fact]
    public async Task TestCSharpReferenceToZeroWidthNodeInStructuredTrivia()
    {
        using var workspace = CreateWorkspace();
        var solution = AddSingleFileCSharpProject(workspace.CurrentSolution, @"
#if true ||
public class C 
{
}
#endif
");
 
        var tree = await solution.Projects.First().Documents.First().GetRequiredSyntaxTreeAsync(CancellationToken.None);
 
        // find binary node that is part of #if directive
        var binary = tree.GetRoot().DescendantNodes(descendIntoTrivia: true).OfType<CS.Syntax.BinaryExpressionSyntax>().First();
 
        // right side should be missing identifier name syntax
        var node = binary.Right;
        Assert.Equal(0, node.FullSpan.Length);
 
        var syntaxRef = tree.GetReference(node);
 
        var refNode = syntaxRef.GetSyntax();
 
        Assert.Equal(node, refNode);
    }
 
    [Fact]
    public async System.Threading.Tasks.Task TestVisualBasicReferenceToZeroWidthNodeInStructuredTriviaAsync()
    {
        using var workspace = CreateWorkspace();
        var solution = AddSingleFileVisualBasicProject(workspace.CurrentSolution, @"
#If (True Or ) Then
Public Class C
End Class
#End If
");
 
        var tree = await solution.Projects.First().Documents.First().GetRequiredSyntaxTreeAsync(CancellationToken.None);
 
        // find binary node that is part of #if directive
        var binary = tree.GetRoot().DescendantNodes(descendIntoTrivia: true).OfType<VB.Syntax.BinaryExpressionSyntax>().First();
 
        // right side should be missing identifier name syntax
        var node = binary.Right;
        Assert.True(node.IsMissing);
        Assert.Equal(0, node.Span.Length);
 
        var syntaxRef = tree.GetReference(node);
 
        var refNode = syntaxRef.GetSyntax();
 
        Assert.Equal(node, refNode);
    }
}