using System.Security.Cryptography;
using FluentAssertions;
using Microsoft.Extensions.Logging.Abstractions;
using StellaOps.AirGap.Importer.Contracts;
using StellaOps.AirGap.Importer.Quarantine;
using StellaOps.AirGap.Importer.Validation;
using StellaOps.AirGap.Importer.Versioning;

namespace StellaOps.AirGap.Importer.Tests;

public sealed class ImportValidatorTests
{
    [Fact]
    public async Task ValidateAsync_WhenTufInvalid_ShouldFailAndQuarantine()
    {
        var quarantine = new CapturingQuarantineService();
        var monotonicity = new CapturingMonotonicityChecker();

        var validator = new ImportValidator(
            new DsseVerifier(),
            new TufMetadataValidator(),
            new MerkleRootCalculator(),
            new RootRotationPolicy(),
            monotonicity,
            quarantine,
            NullLogger<ImportValidator>.Instance);

        var tempRoot = Path.Combine(Path.GetTempPath(), "stellaops-airgap-tests", Guid.NewGuid().ToString("N"));
        Directory.CreateDirectory(tempRoot);
        var bundlePath = Path.Combine(tempRoot, "bundle.tar.zst");
        await File.WriteAllTextAsync(bundlePath, "bundle-bytes");

        try
        {
            var request = BuildRequest(bundlePath, rootJson: "{}", snapshotJson: "{}", timestampJson: "{}");
            var result = await validator.ValidateAsync(request);

            result.IsValid.Should().BeFalse();
            result.Reason.Should().StartWith("tuf:");

            quarantine.Requests.Should().HaveCount(1);
            quarantine.Requests[0].TenantId.Should().Be("tenant-a");
        }
        finally
        {
            try
            {
                Directory.Delete(tempRoot, recursive: true);
            }
            catch
            {
                // best-effort cleanup
            }
        }
    }

    [Fact]
    public async Task ValidateAsync_WhenAllChecksPass_ShouldSucceedAndRecordActivation()
    {
        var root = "{\"version\":1,\"expiresUtc\":\"2030-01-01T00:00:00Z\"}";
        var snapshot = "{\"version\":1,\"expiresUtc\":\"2030-01-01T00:00:00Z\",\"meta\":{\"snapshot\":{\"hashes\":{\"sha256\":\"abc\"}}}}";
        var timestamp = "{\"version\":1,\"expiresUtc\":\"2030-01-01T00:00:00Z\",\"snapshot\":{\"meta\":{\"hashes\":{\"sha256\":\"abc\"}}}}";

        using var rsa = RSA.Create(2048);
        var pub = rsa.ExportSubjectPublicKeyInfo();

        var payload = "bundle-body";
        var payloadType = "application/vnd.stella.bundle";
        var pae = BuildPae(payloadType, payload);
        var sig = rsa.SignData(pae, HashAlgorithmName.SHA256, RSASignaturePadding.Pss);

        var envelope = new DsseEnvelope(payloadType, Convert.ToBase64String(System.Text.Encoding.UTF8.GetBytes(payload)), new[]
        {
            new DsseSignature("k1", Convert.ToBase64String(sig))
        });

        var trustStore = new TrustStore();
        trustStore.LoadActive(new Dictionary<string, byte[]> { ["k1"] = pub });
        trustStore.StagePending(new Dictionary<string, byte[]> { ["k2"] = pub });

        var quarantine = new CapturingQuarantineService();
        var monotonicity = new CapturingMonotonicityChecker();

        var validator = new ImportValidator(
            new DsseVerifier(),
            new TufMetadataValidator(),
            new MerkleRootCalculator(),
            new RootRotationPolicy(),
            monotonicity,
            quarantine,
            NullLogger<ImportValidator>.Instance);

        var tempRoot = Path.Combine(Path.GetTempPath(), "stellaops-airgap-tests", Guid.NewGuid().ToString("N"));
        Directory.CreateDirectory(tempRoot);
        var bundlePath = Path.Combine(tempRoot, "bundle.tar.zst");
        await File.WriteAllTextAsync(bundlePath, "bundle-bytes");

        try
        {
            var request = new ImportValidationRequest(
                TenantId: "tenant-a",
                BundleType: "offline-kit",
                BundleDigest: "sha256:bundle",
                BundlePath: bundlePath,
                ManifestJson: "{\"version\":\"1.0.0\"}",
                ManifestVersion: "1.0.0",
                ManifestCreatedAt: DateTimeOffset.Parse("2025-12-15T00:00:00Z"),
                ForceActivate: false,
                ForceActivateReason: null,
                Envelope: envelope,
                TrustRoots: new TrustRootConfig("/tmp/root.json", new[] { Fingerprint(pub) }, new[] { "rsassa-pss-sha256" }, null, null, new Dictionary<string, byte[]> { ["k1"] = pub }),
                RootJson: root,
                SnapshotJson: snapshot,
                TimestampJson: timestamp,
                PayloadEntries: new List<NamedStream> { new("a.txt", new MemoryStream("data"u8.ToArray())) },
                TrustStore: trustStore,
                ApproverIds: new[] { "approver-1", "approver-2" });

            var result = await validator.ValidateAsync(request);

            result.IsValid.Should().BeTrue();
            result.Reason.Should().Be("import-validated");

            monotonicity.RecordedActivations.Should().HaveCount(1);
            monotonicity.RecordedActivations[0].BundleDigest.Should().Be("sha256:bundle");
            monotonicity.RecordedActivations[0].Version.SemVer.Should().Be("1.0.0");

            quarantine.Requests.Should().BeEmpty();
        }
        finally
        {
            try
            {
                Directory.Delete(tempRoot, recursive: true);
            }
            catch
            {
                // best-effort cleanup
            }
        }
    }

    private static byte[] BuildPae(string payloadType, string payload)
    {
        var parts = new[] { "DSSEv1", payloadType, payload };
        var paeBuilder = new System.Text.StringBuilder();
        paeBuilder.Append("PAE:");
        paeBuilder.Append(parts.Length);
        foreach (var part in parts)
        {
            paeBuilder.Append(' ');
            paeBuilder.Append(part.Length);
            paeBuilder.Append(' ');
            paeBuilder.Append(part);
        }

        return System.Text.Encoding.UTF8.GetBytes(paeBuilder.ToString());
    }

    private static string Fingerprint(byte[] pub) => Convert.ToHexString(SHA256.HashData(pub)).ToLowerInvariant();

    private static ImportValidationRequest BuildRequest(string bundlePath, string rootJson, string snapshotJson, string timestampJson)
    {
        var envelope = new DsseEnvelope("text/plain", Convert.ToBase64String("hi"u8), Array.Empty<DsseSignature>());
        var trustRoot = TrustRootConfig.Empty("/tmp");
        var trustStore = new TrustStore();
        return new ImportValidationRequest(
            TenantId: "tenant-a",
            BundleType: "offline-kit",
            BundleDigest: "sha256:bundle",
            BundlePath: bundlePath,
            ManifestJson: null,
            ManifestVersion: "1.0.0",
            ManifestCreatedAt: DateTimeOffset.Parse("2025-12-15T00:00:00Z"),
            ForceActivate: false,
            ForceActivateReason: null,
            Envelope: envelope,
            TrustRoots: trustRoot,
            RootJson: rootJson,
            SnapshotJson: snapshotJson,
            TimestampJson: timestampJson,
            PayloadEntries: Array.Empty<NamedStream>(),
            TrustStore: trustStore,
            ApproverIds: Array.Empty<string>());
    }

    private sealed class CapturingMonotonicityChecker : IVersionMonotonicityChecker
    {
        public List<(BundleVersion Version, string BundleDigest)> RecordedActivations { get; } = new();

        public Task<MonotonicityCheckResult> CheckAsync(string tenantId, string bundleType, BundleVersion incomingVersion, CancellationToken cancellationToken = default)
        {
            return Task.FromResult(new MonotonicityCheckResult(
                IsMonotonic: true,
                CurrentVersion: null,
                CurrentBundleDigest: null,
                CurrentActivatedAt: null,
                ReasonCode: "FIRST_ACTIVATION"));
        }

        public Task RecordActivationAsync(
            string tenantId,
            string bundleType,
            BundleVersion version,
            string bundleDigest,
            bool wasForceActivated = false,
            string? forceActivateReason = null,
            CancellationToken cancellationToken = default)
        {
            RecordedActivations.Add((version, bundleDigest));
            return Task.CompletedTask;
        }
    }

    private sealed class CapturingQuarantineService : IQuarantineService
    {
        public List<QuarantineRequest> Requests { get; } = new();

        public Task<QuarantineResult> QuarantineAsync(QuarantineRequest request, CancellationToken cancellationToken = default)
        {
            Requests.Add(request);
            return Task.FromResult(new QuarantineResult(
                Success: true,
                QuarantineId: "test",
                QuarantinePath: "(memory)",
                QuarantinedAt: DateTimeOffset.UnixEpoch));
        }

        public Task<IReadOnlyList<QuarantineEntry>> ListAsync(string tenantId, QuarantineListOptions? options = null, CancellationToken cancellationToken = default) =>
            Task.FromResult<IReadOnlyList<QuarantineEntry>>(Array.Empty<QuarantineEntry>());

        public Task<bool> RemoveAsync(string tenantId, string quarantineId, string removalReason, CancellationToken cancellationToken = default) =>
            Task.FromResult(false);

        public Task<int> CleanupExpiredAsync(TimeSpan retentionPeriod, CancellationToken cancellationToken = default) =>
            Task.FromResult(0);
    }
}