// -----------------------------------------------------------------------------
// ProofChainIntegrationTests.cs
// Sprint: SPRINT_3500_0004_0003_integration_tests_corpus
// Task: T1 - Proof Chain Integration Tests
// Description: End-to-end tests for complete proof chain workflow:
//              scan → manifest → score → proof bundle → verify
// -----------------------------------------------------------------------------

using System.Net;
using System.Net.Http.Json;
using System.Security.Cryptography;
using System.Text;
using System.Text.Json;
using FluentAssertions;
using Microsoft.AspNetCore.Mvc.Testing;
using Microsoft.Extensions.DependencyInjection;
using Xunit;

namespace StellaOps.Integration.ProofChain;

/// <summary>
/// End-to-end integration tests for the proof chain workflow.
/// Tests the complete flow: scan submission → manifest creation → score computation
/// → proof bundle generation → verification.
/// </summary>
[Collection("ProofChainIntegration")]
public class ProofChainIntegrationTests : IAsyncLifetime
{
    private readonly ProofChainTestFixture _fixture;
    private HttpClient _client = null!;

    public ProofChainIntegrationTests(ProofChainTestFixture fixture)
    {
        _fixture = fixture;
    }

    public async Task InitializeAsync()
    {
        _client = await _fixture.CreateClientAsync();
    }

    public Task DisposeAsync()
    {
        _client.Dispose();
        return Task.CompletedTask;
    }

    #region T1-AC1: Test scan submission creates manifest

    [Fact]
    public async Task ScanSubmission_CreatesManifest_WithCorrectHashes()
    {
        // Arrange
        var sbomContent = CreateMinimalSbom();
        var scanRequest = new
        {
            sbom = sbomContent,
            policyId = "default",
            metadata = new { source = "integration-test" }
        };

        // Act
        var response = await _client.PostAsJsonAsync("/api/v1/scans", scanRequest);

        // Assert
        response.StatusCode.Should().Be(HttpStatusCode.Created);

        var scanResult = await response.Content.ReadFromJsonAsync<ScanResponse>();
        scanResult.Should().NotBeNull();
        scanResult!.ScanId.Should().NotBeEmpty();

        // Verify manifest was created
        var manifestResponse = await _client.GetAsync($"/api/v1/scans/{scanResult.ScanId}/manifest");
        manifestResponse.StatusCode.Should().Be(HttpStatusCode.OK);

        var manifest = await manifestResponse.Content.ReadFromJsonAsync<ManifestResponse>();
        manifest.Should().NotBeNull();
        manifest!.SbomHash.Should().StartWith("sha256:");
        manifest.ManifestHash.Should().StartWith("sha256:");
    }

    #endregion

    #region T1-AC2: Test score computation produces deterministic results

    [Fact]
    public async Task ScoreComputation_IsDeterministic_WithSameInputs()
    {
        // Arrange
        var sbomContent = CreateSbomWithVulnerability("CVE-2024-12345");
        var scanRequest = new
        {
            sbom = sbomContent,
            policyId = "default"
        };

        // Act - Run scan twice with identical inputs
        var response1 = await _client.PostAsJsonAsync("/api/v1/scans", scanRequest);
        var scan1 = await response1.Content.ReadFromJsonAsync<ScanResponse>();

        var response2 = await _client.PostAsJsonAsync("/api/v1/scans", scanRequest);
        var scan2 = await response2.Content.ReadFromJsonAsync<ScanResponse>();

        // Assert - Both scans should produce identical manifest hashes
        var manifest1 = await GetManifestAsync(scan1!.ScanId);
        var manifest2 = await GetManifestAsync(scan2!.ScanId);

        manifest1.SbomHash.Should().Be(manifest2.SbomHash);
        manifest1.RulesHash.Should().Be(manifest2.RulesHash);
        manifest1.PolicyHash.Should().Be(manifest2.PolicyHash);
    }

    #endregion

    #region T1-AC3: Test proof bundle generation and signing

    [Fact]
    public async Task ProofBundle_IsGenerated_WithValidDsseEnvelope()
    {
        // Arrange
        var sbomContent = CreateMinimalSbom();
        var scanRequest = new { sbom = sbomContent, policyId = "default" };

        // Act
        var response = await _client.PostAsJsonAsync("/api/v1/scans", scanRequest);
        var scan = await response.Content.ReadFromJsonAsync<ScanResponse>();

        // Get proof bundle
        var proofsResponse = await _client.GetAsync($"/api/v1/scans/{scan!.ScanId}/proofs");

        // Assert
        proofsResponse.StatusCode.Should().Be(HttpStatusCode.OK);

        var proofs = await proofsResponse.Content.ReadFromJsonAsync<ProofsListResponse>();
        proofs.Should().NotBeNull();
        proofs!.Items.Should().NotBeEmpty();

        var proof = proofs.Items.First();
        proof.RootHash.Should().StartWith("sha256:");
        proof.DsseEnvelopeValid.Should().BeTrue();
    }

    #endregion

    #region T1-AC4: Test proof verification succeeds for valid bundles

    [Fact]
    public async Task ProofVerification_Succeeds_ForValidBundle()
    {
        // Arrange
        var sbomContent = CreateMinimalSbom();
        var scanRequest = new { sbom = sbomContent, policyId = "default" };

        var response = await _client.PostAsJsonAsync("/api/v1/scans", scanRequest);
        var scan = await response.Content.ReadFromJsonAsync<ScanResponse>();

        var proofsResponse = await _client.GetAsync($"/api/v1/scans/{scan!.ScanId}/proofs");
        var proofs = await proofsResponse.Content.ReadFromJsonAsync<ProofsListResponse>();
        var rootHash = proofs!.Items.First().RootHash;

        // Act
        var verifyResponse = await _client.PostAsJsonAsync(
            $"/api/v1/scans/{scan.ScanId}/proofs/{rootHash}/verify",
            new { });

        // Assert
        verifyResponse.StatusCode.Should().Be(HttpStatusCode.OK);

        var verifyResult = await verifyResponse.Content.ReadFromJsonAsync<VerifyResponse>();
        verifyResult.Should().NotBeNull();
        verifyResult!.Valid.Should().BeTrue();
        verifyResult.Checks.Should().Contain(c => c.Name == "dsse_signature" && c.Passed);
        verifyResult.Checks.Should().Contain(c => c.Name == "merkle_root" && c.Passed);
    }

    #endregion

    #region T1-AC5: Test verification fails for tampered bundles

    [Fact]
    public async Task ProofVerification_Fails_ForTamperedBundle()
    {
        // Arrange
        var sbomContent = CreateMinimalSbom();
        var scanRequest = new { sbom = sbomContent, policyId = "default" };

        var response = await _client.PostAsJsonAsync("/api/v1/scans", scanRequest);
        var scan = await response.Content.ReadFromJsonAsync<ScanResponse>();

        // Get a valid proof then tamper with the hash
        var proofsResponse = await _client.GetAsync($"/api/v1/scans/{scan!.ScanId}/proofs");
        var proofs = await proofsResponse.Content.ReadFromJsonAsync<ProofsListResponse>();
        var originalHash = proofs!.Items.First().RootHash;
        var tamperedHash = "sha256:" + new string('0', 64); // Tampered hash

        // Act
        var verifyResponse = await _client.PostAsJsonAsync(
            $"/api/v1/scans/{scan.ScanId}/proofs/{tamperedHash}/verify",
            new { });

        // Assert
        verifyResponse.StatusCode.Should().Be(HttpStatusCode.NotFound);
    }

    #endregion

    #region T1-AC6: Test replay produces identical scores

    [Fact]
    public async Task ScoreReplay_ProducesIdenticalScore_WithSameManifest()
    {
        // Arrange
        var sbomContent = CreateSbomWithVulnerability("CVE-2024-99999");
        var scanRequest = new { sbom = sbomContent, policyId = "default" };

        var response = await _client.PostAsJsonAsync("/api/v1/scans", scanRequest);
        var scan = await response.Content.ReadFromJsonAsync<ScanResponse>();

        var manifest = await GetManifestAsync(scan!.ScanId);
        var originalProofs = await GetProofsAsync(scan.ScanId);
        var originalRootHash = originalProofs.Items.First().RootHash;

        // Act - Replay the score computation
        var replayResponse = await _client.PostAsJsonAsync(
            $"/api/v1/scans/{scan.ScanId}/score/replay",
            new { manifestHash = manifest.ManifestHash });

        // Assert
        replayResponse.StatusCode.Should().Be(HttpStatusCode.OK);

        var replayResult = await replayResponse.Content.ReadFromJsonAsync<ReplayResponse>();
        replayResult.Should().NotBeNull();
        replayResult!.RootHash.Should().Be(originalRootHash);
        replayResult.Deterministic.Should().BeTrue();
    }

    #endregion

    #region Helper Methods

    private static string CreateMinimalSbom()
    {
        return JsonSerializer.Serialize(new
        {
            bomFormat = "CycloneDX",
            specVersion = "1.5",
            version = 1,
            metadata = new
            {
                timestamp = DateTimeOffset.UtcNow.ToString("O"),
                component = new
                {
                    type = "application",
                    name = "integration-test-app",
                    version = "1.0.0"
                }
            },
            components = Array.Empty<object>()
        });
    }

    private static string CreateSbomWithVulnerability(string cveId)
    {
        return JsonSerializer.Serialize(new
        {
            bomFormat = "CycloneDX",
            specVersion = "1.5",
            version = 1,
            metadata = new
            {
                timestamp = DateTimeOffset.UtcNow.ToString("O"),
                component = new
                {
                    type = "application",
                    name = "vuln-test-app",
                    version = "1.0.0"
                }
            },
            components = new[]
            {
                new
                {
                    type = "library",
                    name = "vulnerable-package",
                    version = "1.0.0",
                    purl = "pkg:npm/vulnerable-package@1.0.0"
                }
            },
            vulnerabilities = new[]
            {
                new
                {
                    id = cveId,
                    source = new { name = "NVD" },
                    ratings = new[]
                    {
                        new { severity = "high", score = 7.5, method = "CVSSv31" }
                    },
                    affects = new[]
                    {
                        new { @ref = "pkg:npm/vulnerable-package@1.0.0" }
                    }
                }
            }
        });
    }

    private async Task<ManifestResponse> GetManifestAsync(string scanId)
    {
        var response = await _client.GetAsync($"/api/v1/scans/{scanId}/manifest");
        response.EnsureSuccessStatusCode();
        return (await response.Content.ReadFromJsonAsync<ManifestResponse>())!;
    }

    private async Task<ProofsListResponse> GetProofsAsync(string scanId)
    {
        var response = await _client.GetAsync($"/api/v1/scans/{scanId}/proofs");
        response.EnsureSuccessStatusCode();
        return (await response.Content.ReadFromJsonAsync<ProofsListResponse>())!;
    }

    #endregion

    #region DTOs

    private sealed record ScanResponse(
        string ScanId,
        string Status,
        DateTimeOffset CreatedAt);

    private sealed record ManifestResponse(
        string ManifestHash,
        string SbomHash,
        string RulesHash,
        string FeedHash,
        string PolicyHash,
        DateTimeOffset CreatedAt);

    private sealed record ProofsListResponse(
        IReadOnlyList<ProofItem> Items);

    private sealed record ProofItem(
        string RootHash,
        string BundleUri,
        bool DsseEnvelopeValid,
        DateTimeOffset CreatedAt);

    private sealed record VerifyResponse(
        bool Valid,
        string RootHash,
        IReadOnlyList<VerifyCheck> Checks);

    private sealed record VerifyCheck(
        string Name,
        bool Passed,
        string? Message);

    private sealed record ReplayResponse(
        string RootHash,
        double Score,
        bool Deterministic,
        DateTimeOffset ReplayedAt);

    #endregion
}

/// <summary>
/// Collection definition for proof chain integration tests.
/// </summary>
[CollectionDefinition("ProofChainIntegration")]
public class ProofChainIntegrationCollection : ICollectionFixture<ProofChainTestFixture>
{
}