// -----------------------------------------------------------------------------
// PolicyDecisionAttestationServiceTests.cs
// Sprint: SPRINT_3801_0001_0001_policy_decision_attestation
// Description: Unit tests for PolicyDecisionAttestationService.
// -----------------------------------------------------------------------------

using Microsoft.Extensions.Logging.Abstractions;
using Microsoft.Extensions.Options;
using Moq;
using StellaOps.Policy.Engine.Attestation;
using StellaOps.Policy.Engine.Vex;
using Xunit;

namespace StellaOps.Policy.Engine.Tests.Attestation;

public class PolicyDecisionAttestationServiceTests
{
    private readonly Mock<IOptionsMonitor<PolicyDecisionAttestationOptions>> _optionsMock;
    private readonly Mock<IVexSignerClient> _signerClientMock;
    private readonly Mock<IVexRekorClient> _rekorClientMock;
    private readonly PolicyDecisionAttestationService _service;

    public PolicyDecisionAttestationServiceTests()
    {
        _optionsMock = new Mock<IOptionsMonitor<PolicyDecisionAttestationOptions>>();
        _optionsMock.Setup(x => x.CurrentValue).Returns(new PolicyDecisionAttestationOptions
        {
            Enabled = true,
            UseSignerService = true,
            DefaultTtlHours = 24
        });

        _signerClientMock = new Mock<IVexSignerClient>();
        _rekorClientMock = new Mock<IVexRekorClient>();

        _service = new PolicyDecisionAttestationService(
            _signerClientMock.Object,
            _rekorClientMock.Object,
            _optionsMock.Object,
            TimeProvider.System,
            NullLogger<PolicyDecisionAttestationService>.Instance);
    }

    [Fact]
    public async Task CreateAttestationAsync_WhenDisabled_ReturnsFailure()
    {
        // Arrange
        _optionsMock.Setup(x => x.CurrentValue).Returns(new PolicyDecisionAttestationOptions
        {
            Enabled = false
        });

        var request = CreateTestRequest();

        // Act
        var result = await _service.CreateAttestationAsync(request);

        // Assert
        Assert.False(result.Success);
        Assert.Contains("disabled", result.Error, StringComparison.OrdinalIgnoreCase);
    }

    [Fact]
    public async Task CreateAttestationAsync_WithSignerClient_CallsSigner()
    {
        // Arrange
        _signerClientMock.Setup(x => x.SignAsync(
                It.IsAny<VexSignerRequest>(),
                It.IsAny<CancellationToken>()))
            .ReturnsAsync(new VexSignerResult
            {
                Success = true,
                Signature = "AQID",
                KeyId = "key-1"
            });

        var request = CreateTestRequest();

        // Act
        var result = await _service.CreateAttestationAsync(request);

        // Assert
        Assert.True(result.Success);
        Assert.NotNull(result.AttestationDigest);
        Assert.Matches("^sha256:[a-f0-9]{64}$", result.AttestationDigest);
        Assert.Equal("key-1", result.KeyId);

        _signerClientMock.Verify(x => x.SignAsync(
            It.Is<VexSignerRequest>(r => r.PayloadType == "stella.ops/policy-decision@v1"),
            It.IsAny<CancellationToken>()),
            Times.Once);
    }

    [Fact]
    public async Task CreateAttestationAsync_WhenSigningFails_ReturnsFailure()
    {
        // Arrange
        _signerClientMock.Setup(x => x.SignAsync(
                It.IsAny<VexSignerRequest>(),
                It.IsAny<CancellationToken>()))
            .ReturnsAsync(new VexSignerResult
            {
                Success = false,
                Error = "Key not found"
            });

        var request = CreateTestRequest();

        // Act
        var result = await _service.CreateAttestationAsync(request);

        // Assert
        Assert.False(result.Success);
        Assert.Contains("Key not found", result.Error);
    }

    [Fact]
    public async Task CreateAttestationAsync_WithRekorSubmission_SubmitsToRekor()
    {
        // Arrange
        _signerClientMock.Setup(x => x.SignAsync(
                It.IsAny<VexSignerRequest>(),
                It.IsAny<CancellationToken>()))
            .ReturnsAsync(new VexSignerResult
            {
                Success = true,
                Signature = "AQID",
                KeyId = "key-1"
            });

        _rekorClientMock.Setup(x => x.SubmitAsync(
                It.IsAny<VexRekorSubmitRequest>(),
                It.IsAny<CancellationToken>()))
            .ReturnsAsync(new VexRekorSubmitResult
            {
                Success = true,
                Metadata = new VexRekorMetadata
                {
                    Uuid = "rekor-uuid-123",
                    Index = 12345,
                    LogUrl = "https://rekor.local/api/v1/log/entries/rekor-uuid-123",
                    IntegratedAt = new DateTimeOffset(2025, 1, 1, 0, 0, 0, TimeSpan.Zero)
                }
            });

        var request = CreateTestRequest() with { SubmitToRekor = true };

        // Act
        var result = await _service.CreateAttestationAsync(request);

        // Assert
        Assert.True(result.Success);
        Assert.NotNull(result.RekorResult);
        Assert.True(result.RekorResult.Success);
        Assert.Equal(12345, result.RekorResult.LogIndex);
        Assert.Equal("rekor-uuid-123", result.RekorResult.Uuid);

        var envelopeDigestHex = result.AttestationDigest!.Substring("sha256:".Length);

        _rekorClientMock.Verify(x => x.SubmitAsync(
            It.Is<VexRekorSubmitRequest>(r =>
                r.ArtifactKind == "policy-decision" &&
                r.Envelope.PayloadType == PredicateTypes.StellaOpsPolicyDecision &&
                r.EnvelopeDigest == envelopeDigestHex &&
                r.SubjectUris!.Contains("example.com/image:v1@sha256:abc123")),
            It.IsAny<CancellationToken>()),
            Times.Once);
    }

    [Fact]
    public async Task CreateAttestationAsync_WithoutSignerClient_CreatesUnsignedAttestation()
    {
        // Arrange
        var serviceWithoutSigner = new PolicyDecisionAttestationService(
            signerClient: null,
            rekorClient: null,
            _optionsMock.Object,
            TimeProvider.System,
            NullLogger<PolicyDecisionAttestationService>.Instance);

        var request = CreateTestRequest();

        // Act
        var result = await serviceWithoutSigner.CreateAttestationAsync(request);

        // Assert
        Assert.True(result.Success);
        Assert.StartsWith("sha256:", result.AttestationDigest);
        Assert.Null(result.KeyId);
    }

    [Fact]
    public async Task CreateAttestationAsync_IncludesAllSubjects()
    {
        // Arrange
        _signerClientMock.Setup(x => x.SignAsync(
                It.IsAny<VexSignerRequest>(),
                It.IsAny<CancellationToken>()))
            .ReturnsAsync(new VexSignerResult
            {
                Success = true,
                Signature = "AQID"
            });

        var request = CreateTestRequest() with
        {
            Subjects = new[]
            {
                new AttestationSubject
                {
                    Name = "example.com/image:v1",
                    Digest = new Dictionary<string, string> { ["sha256"] = "abc123" }
                },
                new AttestationSubject
                {
                    Name = "example.com/image:v2",
                    Digest = new Dictionary<string, string> { ["sha256"] = "def456" }
                }
            }
        };

        // Act
        var result = await _service.CreateAttestationAsync(request);

        // Assert
        Assert.True(result.Success);
    }

    [Fact]
    public async Task CreateAttestationAsync_SetsExpirationFromOptions()
    {
        // Arrange
        _optionsMock.Setup(x => x.CurrentValue).Returns(new PolicyDecisionAttestationOptions
        {
            Enabled = true,
            UseSignerService = false,
            DefaultTtlHours = 48
        });

        var serviceWithOptions = new PolicyDecisionAttestationService(
            signerClient: null,
            rekorClient: null,
            _optionsMock.Object,
            TimeProvider.System,
            NullLogger<PolicyDecisionAttestationService>.Instance);

        var request = CreateTestRequest();

        // Act
        var result = await serviceWithOptions.CreateAttestationAsync(request);

        // Assert
        Assert.True(result.Success);
    }

    [Fact]
    public async Task SubmitToRekorAsync_WhenNoClient_ReturnsFailure()
    {
        // Arrange
        var serviceWithoutRekor = new PolicyDecisionAttestationService(
            _signerClientMock.Object,
            rekorClient: null,
            _optionsMock.Object,
            TimeProvider.System,
            NullLogger<PolicyDecisionAttestationService>.Instance);

        // Act
        var result = await serviceWithoutRekor.SubmitToRekorAsync("sha256:test");

        // Assert
        Assert.False(result.Success);
        Assert.Contains("not available", result.Error);
    }

    [Fact]
    public async Task VerifyAsync_ReturnsNotImplemented()
    {
        // Act
        var result = await _service.VerifyAsync("sha256:test");

        // Assert
        Assert.False(result.Valid);
        Assert.Contains("not yet implemented", result.Issues![0], StringComparison.OrdinalIgnoreCase);
    }

    private static PolicyDecisionAttestationRequest CreateTestRequest()
    {
        return new PolicyDecisionAttestationRequest
        {
            Predicate = new PolicyDecisionPredicate
            {
                Policy = new PolicyReference
                {
                    Id = "test-policy",
                    Version = "1.0.0",
                    Name = "Test Policy"
                },
                Inputs = new PolicyDecisionInputs
                {
                    Subjects = new[]
                    {
                        new SubjectReference
                        {
                            Name = "example.com/image:v1",
                            Digest = "sha256:abc123"
                        }
                    }
                },
                Result = new PolicyDecisionResult
                {
                    Decision = PolicyDecision.Allow,
                    Summary = "All gates passed"
                }
            },
            Subjects = new[]
            {
                new AttestationSubject
                {
                    Name = "example.com/image:v1",
                    Digest = new Dictionary<string, string> { ["sha256"] = "abc123" }
                }
            },
            TenantId = "tenant-1"
        };
    }
}