// 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;
using System.Collections.Immutable;
using System.Threading.Tasks;
using Microsoft.CodeAnalysis.CodeFixes;
using Microsoft.CodeAnalysis.CSharp;
using Microsoft.CodeAnalysis.CSharp.MakeRefStruct;
using Microsoft.CodeAnalysis.Diagnostics;
using Microsoft.CodeAnalysis.Editor.CSharp.UnitTests.Diagnostics;
using Microsoft.CodeAnalysis.Test.Utilities;
using Roslyn.Test.Utilities;
using Xunit;
using Xunit.Abstractions;
 
namespace Microsoft.CodeAnalysis.Editor.CSharp.UnitTests.MakeRefStruct
{
    [Trait(Traits.Feature, Traits.Features.CodeActionsMakeRefStruct)]
    public class MakeRefStructTests : AbstractCSharpDiagnosticProviderBasedUserDiagnosticTest
    {
        private static readonly CSharpParseOptions s_parseOptions =
            CSharpParseOptions.Default.WithLanguageVersion(LanguageVersion.CSharp7_3);
 
        public MakeRefStructTests(ITestOutputHelper logger)
          : base(logger)
        {
        }
 
        private const string SpanDeclarationSourceText = """
            using System;
            namespace System
            {
                public readonly ref struct Span<T> 
                {
                    unsafe public Span(void* pointer, int length) { }
                }
            }
 
 
            """;
 
        internal override (DiagnosticAnalyzer?, CodeFixProvider) CreateDiagnosticProviderAndFixer(Workspace workspace)
            => (null, new MakeRefStructCodeFixProvider());
 
        [Fact]
        public async Task FieldInNotRefStruct()
        {
            var text = CreateTestSource("""
                struct S
                {
                    Span<int>[||] m;
                }
                """);
            var expected = CreateTestSource("""
                ref struct S
                {
                    Span<int> m;
                }
                """);
            await TestInRegularAndScriptAsync(text, expected, parseOptions: s_parseOptions);
        }
 
        [Fact]
        public async Task FieldInRecordStruct()
        {
            var text = CreateTestSource("""
                record struct S
                {
                    Span<int>[||] m;
                }
                """);
            await TestMissingInRegularAndScriptAsync(text, new TestParameters(CSharpParseOptions.Default.WithLanguageVersion(LanguageVersion.Preview)));
        }
 
        [Fact]
        public async Task FieldInNestedClassInsideNotRefStruct()
        {
            var text = CreateTestSource("""
                struct S
                {
                    class C
                    {
                        Span<int>[||] m;
                    }
                }
                """);
            await TestMissingInRegularAndScriptAsync(text, new TestParameters(s_parseOptions));
        }
 
        [Fact]
        public async Task FieldStaticInRefStruct()
        {
            // Note: does not compile
            var text = CreateTestSource("""
                ref struct S
                {
                    static Span<int>[||] m;
                }
                """);
            await TestMissingInRegularAndScriptAsync(text, new TestParameters(s_parseOptions));
        }
 
        [Fact]
        public async Task FieldStaticInNotRefStruct()
        {
            var text = CreateTestSource("""
                struct S
                {
                    static Span<int>[||] m;
                }
                """);
            // Note: still does not compile after fix
            var expected = CreateTestSource("""
                ref struct S
                {
                    static Span<int> m;
                }
                """);
            await TestInRegularAndScriptAsync(text, expected, parseOptions: s_parseOptions);
        }
 
        [Fact]
        public async Task PropInNotRefStruct()
        {
            var text = CreateTestSource("""
                struct S
                {
                    Span<int>[||] M { get; }
                }
                """);
            var expected = CreateTestSource("""
                ref struct S
                {
                    Span<int> M { get; }
                }
                """);
            await TestInRegularAndScriptAsync(text, expected, parseOptions: s_parseOptions);
        }
 
        [Fact]
        public async Task PropInNestedClassInsideNotRefStruct()
        {
            // Note: does not compile
            var text = CreateTestSource("""
                struct S
                {
                    class C
                    {
                        Span<int>[||] M { get; }
                    }
                }
                """);
            await TestMissingInRegularAndScriptAsync(text, new TestParameters(s_parseOptions));
        }
 
        [Fact]
        public async Task PropStaticInRefStruct()
        {
            // Note: does not compile
            var text = CreateTestSource("""
                ref struct S
                {
                    static Span<int>[||] M { get; }
                }
                """);
            await TestMissingInRegularAndScriptAsync(text, new TestParameters(s_parseOptions));
        }
 
        [Fact]
        public async Task PropStaticInNotRefStruct()
        {
            var text = CreateTestSource("""
                struct S
                {
                    static Span<int>[||] M { get; }
                }
                """);
            // Note: still does not compile after fix
            var expected = CreateTestSource("""
                ref struct S
                {
                    static Span<int> M { get; }
                }
                """);
            await TestInRegularAndScriptAsync(text, expected, parseOptions: s_parseOptions);
        }
 
        [Fact]
        public async Task PartialByRefStruct()
        {
            var text = CreateTestSource("""
                ref partial struct S
                {
                }
 
                struct S
                {
                    Span<int>[||] M { get; }
                }
                """);
            await TestMissingInRegularAndScriptAsync(text, new TestParameters(s_parseOptions));
        }
 
        [Fact]
        public async Task PartialStruct()
        {
            var text = CreateTestSource("""
                partial struct S
                {
                }
 
                partial struct S
                {
                    Span<int>[||] M { get; }
                }
                """);
            var expected = CreateTestSource("""
                partial struct S
                {
                }
 
                ref partial struct S
                {
                    Span<int>[||] M { get; }
                }
                """);
            await TestInRegularAndScriptAsync(text, expected, parseOptions: s_parseOptions);
        }
 
        [Fact]
        public async Task ReadonlyPartialStruct()
        {
            var text = CreateTestSource("""
                partial struct S
                {
                }
 
                readonly partial struct S
                {
                    Span<int>[||] M { get; }
                }
                """);
            var expected = CreateTestSource("""
                partial struct S
                {
                }
 
                readonly ref partial struct S
                {
                    Span<int>[||] M { get; }
                }
                """);
            await TestInRegularAndScriptAsync(text, expected, parseOptions: s_parseOptions);
        }
 
        private static string CreateTestSource(string testSource) => SpanDeclarationSourceText + testSource;
    }
}