using System.Collections.Immutable;
using FluentAssertions;
using Microsoft.CodeAnalysis;
using Microsoft.CodeAnalysis.CSharp;
using Microsoft.CodeAnalysis.CSharp.Testing;
using Microsoft.CodeAnalysis.Diagnostics;
using Microsoft.CodeAnalysis.Testing;
using Xunit;

namespace StellaOps.TestKit.Analyzers.Tests;

/// <summary>
/// Unit tests for <see cref="IntentAnalyzer"/>.
/// </summary>
[Trait("Category", "Unit")]
public sealed class IntentAnalyzerTests
{
    [Fact]
    public async Task TrivialTest_NoWarning()
    {
        var code = """
            using Xunit;

            public class MyTests
            {
                [Fact]
                public void TrivialTest()
                {
                    Assert.True(true);
                }
            }
            """;

        await VerifyNoWarningsAsync(code);
    }

    [Fact]
    public async Task NonTrivialTest_WithIntent_NoWarning()
    {
        var code = """
            using Xunit;

            public class MyTests
            {
                [Fact]
                [Intent("Safety", "Test security")]
                public void NonTrivialTest()
                {
                    var a = 1;
                    var b = 2;
                    var c = 3;
                    var d = 4;
                    var e = 5;
                    var f = 6;
                    Assert.Equal(21, a + b + c + d + e + f);
                }
            }

            [System.AttributeUsage(System.AttributeTargets.Method)]
            public class IntentAttribute : System.Attribute
            {
                public IntentAttribute(string intent, string rationale = "") { }
            }
            """;

        await VerifyNoWarningsAsync(code);
    }

    [Fact]
    public async Task NonTrivialTest_WithTraitIntent_NoWarning()
    {
        var code = """
            using Xunit;

            public class MyTests
            {
                [Fact]
                [Trait("Intent", "Safety")]
                public void NonTrivialTest()
                {
                    var a = 1;
                    var b = 2;
                    var c = 3;
                    var d = 4;
                    var e = 5;
                    var f = 6;
                    Assert.Equal(21, a + b + c + d + e + f);
                }
            }
            """;

        await VerifyNoWarningsAsync(code);
    }

    [Fact]
    public async Task NonTrivialTest_WithIntentExempt_NoWarning()
    {
        var code = """
            using Xunit;

            public class MyTests
            {
                [Fact]
                [Trait("IntentExempt", "true")]
                public void NonTrivialTest()
                {
                    var a = 1;
                    var b = 2;
                    var c = 3;
                    var d = 4;
                    var e = 5;
                    var f = 6;
                    Assert.Equal(21, a + b + c + d + e + f);
                }
            }
            """;

        await VerifyNoWarningsAsync(code);
    }

    [Fact]
    public async Task NonTrivialTest_WithoutIntent_Warning()
    {
        var code = """
            using Xunit;

            public class MyTests
            {
                [Fact]
                public void {|#0:NonTrivialTest|}()
                {
                    var a = 1;
                    var b = 2;
                    var c = 3;
                    var d = 4;
                    var e = 5;
                    var f = 6;
                    Assert.Equal(21, a + b + c + d + e + f);
                }
            }
            """;

        var expected = new DiagnosticResult(IntentAnalyzer.MissingIntentDiagnosticId, DiagnosticSeverity.Warning)
            .WithLocation(0)
            .WithArguments("NonTrivialTest");

        await VerifyWarningAsync(code, expected);
    }

    [Fact]
    public async Task MultipleAssertions_WithoutIntent_Warning()
    {
        var code = """
            using Xunit;

            public class MyTests
            {
                [Fact]
                public void {|#0:MultiAssertTest|}()
                {
                    var result = 42;
                    Assert.NotNull(result);
                    Assert.Equal(42, result);
                }
            }
            """;

        var expected = new DiagnosticResult(IntentAnalyzer.MissingIntentDiagnosticId, DiagnosticSeverity.Warning)
            .WithLocation(0)
            .WithArguments("MultiAssertTest");

        await VerifyWarningAsync(code, expected);
    }

    [Fact]
    public async Task IntentWithoutRationale_Info()
    {
        var code = """
            using Xunit;

            public class MyTests
            {
                [Fact]
                [Intent("Safety")]
                public void TestWithIntent()
                {
                    var a = 1;
                    var b = 2;
                    var c = 3;
                    var d = 4;
                    var e = 5;
                    var f = 6;
                    Assert.Equal(21, a + b + c + d + e + f);
                }
            }

            [System.AttributeUsage(System.AttributeTargets.Method)]
            public class IntentAttribute : System.Attribute
            {
                public IntentAttribute(string intent, string rationale = "") { }
            }
            """;

        var expected = new DiagnosticResult(IntentAnalyzer.MissingRationaleDiagnosticId, DiagnosticSeverity.Info)
            .WithSpan(6, 6, 6, 22)
            .WithArguments("TestWithIntent");

        await VerifyWarningAsync(code, expected);
    }

    [Fact]
    public async Task IntentWithRationale_NoInfo()
    {
        var code = """
            using Xunit;

            public class MyTests
            {
                [Fact]
                [Intent("Safety", "Security requirement per OWASP")]
                public void TestWithIntent()
                {
                    var a = 1;
                    var b = 2;
                    var c = 3;
                    var d = 4;
                    var e = 5;
                    var f = 6;
                    Assert.Equal(21, a + b + c + d + e + f);
                }
            }

            [System.AttributeUsage(System.AttributeTargets.Method)]
            public class IntentAttribute : System.Attribute
            {
                public IntentAttribute(string intent, string rationale = "") { }
            }
            """;

        await VerifyNoWarningsAsync(code);
    }

    [Fact]
    public async Task NonTestMethod_NoWarning()
    {
        var code = """
            public class MyClass
            {
                public void NonTestMethod()
                {
                    var a = 1;
                    var b = 2;
                    var c = 3;
                    var d = 4;
                    var e = 5;
                    var f = 6;
                    System.Console.WriteLine(a + b + c + d + e + f);
                }
            }
            """;

        await VerifyNoWarningsAsync(code);
    }

    private static async Task VerifyNoWarningsAsync(string code)
    {
        var test = new CSharpAnalyzerTest<IntentAnalyzer, DefaultVerifier>
        {
            TestCode = code,
            ReferenceAssemblies = ReferenceAssemblies.Net.Net80
        };

        test.TestState.AdditionalReferences.Add(
            MetadataReference.CreateFromFile(typeof(Xunit.FactAttribute).Assembly.Location));
        test.TestState.AdditionalReferences.Add(
            MetadataReference.CreateFromFile(typeof(Xunit.Assert).Assembly.Location));

        await test.RunAsync();
    }

    private static async Task VerifyWarningAsync(string code, DiagnosticResult expected)
    {
        var test = new CSharpAnalyzerTest<IntentAnalyzer, DefaultVerifier>
        {
            TestCode = code,
            ReferenceAssemblies = ReferenceAssemblies.Net.Net80,
            ExpectedDiagnostics = { expected }
        };

        test.TestState.AdditionalReferences.Add(
            MetadataReference.CreateFromFile(typeof(Xunit.FactAttribute).Assembly.Location));
        test.TestState.AdditionalReferences.Add(
            MetadataReference.CreateFromFile(typeof(Xunit.Assert).Assembly.Location));

        await test.RunAsync();
    }
}