// 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.Threading.Tasks;
using Microsoft.CodeAnalysis.CSharp.CodeFixes.RemoveUnnecessaryNullableDirective;
using Microsoft.CodeAnalysis.Editor.UnitTests.CodeActions;
using Microsoft.CodeAnalysis.RemoveUnnecessaryNullableDirective;
using Microsoft.CodeAnalysis.Shared.Extensions;
using Microsoft.CodeAnalysis.Test.Utilities;
using Roslyn.Utilities;
using Xunit;
 
namespace Microsoft.CodeAnalysis.CSharp.Analyzers.UnitTests.RemoveUnnecessaryNullableDirective;
 
using VerifyCS = CSharpCodeFixVerifier<
    CSharpRemoveUnnecessaryNullableDirectiveDiagnosticAnalyzer,
    CSharpRemoveUnnecessaryNullableDirectiveCodeFixProvider>;
 
[Trait(Traits.Feature, Traits.Features.CodeActionsRemoveUnnecessaryNullableDirective)]
public class CSharpRemoveUnnecessaryNullableDirectiveTests
{
    [Theory]
    [InlineData(NullableContextOptions.Annotations, NullableContextOptions.Annotations)]
    [InlineData(NullableContextOptions.Annotations, NullableContextOptions.Enable)]
    [InlineData(NullableContextOptions.Warnings, NullableContextOptions.Warnings)]
    [InlineData(NullableContextOptions.Warnings, NullableContextOptions.Enable)]
    [InlineData(NullableContextOptions.Enable, NullableContextOptions.Annotations)]
    [InlineData(NullableContextOptions.Enable, NullableContextOptions.Warnings)]
    [InlineData(NullableContextOptions.Enable, NullableContextOptions.Enable)]
    public async Task TestUnnecessaryDisableDiffersFromCompilation(NullableContextOptions compilationContext, NullableContextOptions codeContext)
    {
        await VerifyCodeFixAsync(
            compilationContext,
            $$"""
            [|#nullable {{GetDisableDirectiveContext(codeContext)}}|]
            class Program
            {
            }
            """,
            $$"""
            class Program
            {
            }
            """);
    }
 
    [Fact]
    public async Task TestUnnecessaryDisableEnumDeclaration()
    {
        await VerifyCodeFixAsync(
            NullableContextOptions.Enable,
            """
            [|#nullable disable|]
            enum EnumName
            {
                First,
                Second,
            }
            """,
            """
            enum EnumName
            {
                First,
                Second,
            }
            """);
    }
 
    [Fact]
    public async Task TestUnnecessaryDisableEnumDeclarationWithFileHeader()
    {
        await VerifyCodeFixAsync(
            NullableContextOptions.Enable,
            """
            // File Header
 
            [|#nullable disable|]
 
            enum EnumName
            {
                First,
                Second,
            }
            """,
            """
            // File Header
 
            enum EnumName
            {
                First,
                Second,
            }
            """);
    }
 
    [Fact]
    public async Task TestUnnecessaryDirectiveWithNamespaceAndDerivedType()
    {
        await VerifyCodeFixAsync(
            NullableContextOptions.Enable,
            """
            [|#nullable disable|]
 
            using System;
 
            namespace X.Y
            {
                class ProgramException : Exception
                {
                }
            }
            """,
            """
 
            using System;
 
            namespace X.Y
            {
                class ProgramException : Exception
                {
                }
            }
            """);
    }
 
    [Fact]
    public async Task TestUnnecessaryDirectiveWithNamespaceAndDerivedFromQualifiedBaseType()
    {
        await VerifyCodeFixAsync(
            NullableContextOptions.Enable,
            """
            [|#nullable disable|]
 
            namespace X.Y
            {
                class ProgramException : System.Exception
                {
                }
            }
            """,
            """
 
            namespace X.Y
            {
                class ProgramException : System.Exception
                {
                }
            }
            """);
    }
 
    [Fact]
    public async Task TestUnnecessaryDirectiveWithQualifiedUsingDirectives()
    {
        await VerifyCodeFixAsync(
            NullableContextOptions.Enable,
            """
            [|#nullable disable|]
 
            using System;
            using System.Runtime.InteropServices;
            using CustomException = System.Exception;
            using static System.String;
            """,
            """
 
            using System;
            using System.Runtime.InteropServices;
            using CustomException = System.Exception;
            using static System.String;
            """);
    }
 
    [Theory]
    [InlineData("disable")]
    [InlineData("restore")]
    public async Task TestUnnecessaryDisableAtEndOfFile(string keyword)
    {
        await VerifyCodeFixAsync(
            NullableContextOptions.Disable,
            $$"""
            #nullable enable
            struct StructName
            {
                string Field;
            }
            [|#nullable {{keyword}}|]

            """,
            $$"""
            #nullable enable
            struct StructName
            {
                string Field;
            }
            
            """);
    }
 
    [Fact]
    public async Task TestUnnecessaryDisableIgnoredWhenFollowedByConditionalDirective()
    {
        var code =
            """
            #nullable enable
            struct StructName
            {
                string Field;
            }
            #nullable disable
            #if false
            #endif
            """;
 
        await VerifyCodeFixAsync(NullableContextOptions.Disable, code, code);
    }
 
    private static string GetDisableDirectiveContext(NullableContextOptions options)
    {
        return options switch
        {
            NullableContextOptions.Warnings => "disable warnings",
            NullableContextOptions.Annotations => "disable annotations",
            NullableContextOptions.Enable => "disable",
            _ => throw ExceptionUtilities.UnexpectedValue(options),
        };
    }
 
    private static async Task VerifyCodeFixAsync(NullableContextOptions compilationNullableContextOptions, string source, string fixedSource)
    {
        await new VerifyCS.Test
        {
            TestCode = source,
            FixedCode = fixedSource,
            SolutionTransforms =
            {
                (solution, projectId) =>
                {
                    var compilationOptions = (CSharpCompilationOptions?)solution.GetRequiredProject(projectId).CompilationOptions;
                    Contract.ThrowIfNull(compilationOptions);
 
                    return solution.WithProjectCompilationOptions(projectId, compilationOptions.WithNullableContextOptions(compilationNullableContextOptions));
                },
            },
        }.RunAsync();
    }
}