using Microsoft.Extensions.Logging.Abstractions;
using Microsoft.Extensions.Options;
using StellaOps.AirGap.Time.Models;
using StellaOps.AirGap.Time.Services;
using StellaOps.AirGap.Time.Stores;

namespace StellaOps.AirGap.Time.Tests;

/// <summary>
/// Tests for TimeAnchorPolicyService.
/// Per AIRGAP-TIME-57-001: Time-anchor policy enforcement.
/// </summary>
public class TimeAnchorPolicyServiceTests
{
    private readonly TimeProvider _fixedTimeProvider;
    private readonly InMemoryTimeAnchorStore _store;
    private readonly StalenessCalculator _calculator;
    private readonly TimeTelemetry _telemetry;
    private readonly TimeStatusService _statusService;
    private readonly AirGapOptions _airGapOptions;

    public TimeAnchorPolicyServiceTests()
    {
        _fixedTimeProvider = new FakeTimeProvider(new DateTimeOffset(2025, 1, 15, 12, 0, 0, TimeSpan.Zero));
        _store = new InMemoryTimeAnchorStore();
        _calculator = new StalenessCalculator();
        _telemetry = new TimeTelemetry();
        _airGapOptions = new AirGapOptions
        {
            Staleness = new AirGapOptions.StalenessOptions { WarningSeconds = 3600, BreachSeconds = 7200 },
            ContentBudgets = new Dictionary<string, AirGapOptions.StalenessOptions>()
        };
        _statusService = new TimeStatusService(_store, _calculator, _telemetry, Options.Create(_airGapOptions));
    }

    private TimeAnchorPolicyService CreateService(TimeAnchorPolicyOptions? options = null)
    {
        return new TimeAnchorPolicyService(
            _statusService,
            Options.Create(options ?? new TimeAnchorPolicyOptions()),
            NullLogger<TimeAnchorPolicyService>.Instance,
            _fixedTimeProvider);
    }

    [Fact]
    public async Task ValidateTimeAnchorAsync_ReturnsFailure_WhenNoAnchor()
    {
        var service = CreateService();

        var result = await service.ValidateTimeAnchorAsync("tenant-1");

        Assert.False(result.Allowed);
        Assert.Equal(TimeAnchorPolicyErrorCodes.AnchorMissing, result.ErrorCode);
        Assert.NotNull(result.Remediation);
    }

    [Fact]
    public async Task ValidateTimeAnchorAsync_ReturnsSuccess_WhenAnchorValid()
    {
        var service = CreateService();
        var anchor = new TimeAnchor(
            _fixedTimeProvider.GetUtcNow().AddMinutes(-30),
            "test-source",
            "Roughtime",
            "fingerprint",
            "digest123");
        var budget = new StalenessBudget(3600, 7200);

        await _store.SetAsync("tenant-1", anchor, budget, CancellationToken.None);

        var result = await service.ValidateTimeAnchorAsync("tenant-1");

        Assert.True(result.Allowed);
        Assert.Null(result.ErrorCode);
        Assert.NotNull(result.Staleness);
        Assert.False(result.Staleness.IsBreach);
    }

    [Fact]
    public async Task ValidateTimeAnchorAsync_ReturnsWarning_WhenAnchorStale()
    {
        var service = CreateService();
        var anchor = new TimeAnchor(
            _fixedTimeProvider.GetUtcNow().AddSeconds(-5000), // Past warning threshold
            "test-source",
            "Roughtime",
            "fingerprint",
            "digest123");
        var budget = new StalenessBudget(3600, 7200);

        await _store.SetAsync("tenant-1", anchor, budget, CancellationToken.None);

        var result = await service.ValidateTimeAnchorAsync("tenant-1");

        Assert.True(result.Allowed); // Allowed but with warning
        Assert.NotNull(result.Staleness);
        Assert.True(result.Staleness.IsWarning);
        Assert.Contains("warning", result.Reason, StringComparison.OrdinalIgnoreCase);
    }

    [Fact]
    public async Task ValidateTimeAnchorAsync_ReturnsFailure_WhenAnchorBreached()
    {
        var service = CreateService();
        var anchor = new TimeAnchor(
            _fixedTimeProvider.GetUtcNow().AddSeconds(-8000), // Past breach threshold
            "test-source",
            "Roughtime",
            "fingerprint",
            "digest123");
        var budget = new StalenessBudget(3600, 7200);

        await _store.SetAsync("tenant-1", anchor, budget, CancellationToken.None);

        var result = await service.ValidateTimeAnchorAsync("tenant-1");

        Assert.False(result.Allowed);
        Assert.Equal(TimeAnchorPolicyErrorCodes.AnchorBreached, result.ErrorCode);
        Assert.NotNull(result.Staleness);
        Assert.True(result.Staleness.IsBreach);
    }

    [Fact]
    public async Task EnforceBundleImportPolicyAsync_AllowsImport_WhenAnchorValid()
    {
        var service = CreateService();
        var anchor = new TimeAnchor(
            _fixedTimeProvider.GetUtcNow().AddMinutes(-30),
            "test-source",
            "Roughtime",
            "fingerprint",
            "digest123");
        var budget = new StalenessBudget(3600, 7200);

        await _store.SetAsync("tenant-1", anchor, budget, CancellationToken.None);

        var result = await service.EnforceBundleImportPolicyAsync(
            "tenant-1",
            "bundle-123",
            _fixedTimeProvider.GetUtcNow().AddMinutes(-15));

        Assert.True(result.Allowed);
    }

    [Fact]
    public async Task EnforceBundleImportPolicyAsync_BlocksImport_WhenDriftExceeded()
    {
        var options = new TimeAnchorPolicyOptions { MaxDriftSeconds = 3600 }; // 1 hour max
        var service = CreateService(options);
        var anchor = new TimeAnchor(
            _fixedTimeProvider.GetUtcNow().AddMinutes(-30),
            "test-source",
            "Roughtime",
            "fingerprint",
            "digest123");
        var budget = new StalenessBudget(86400, 172800); // Large budget

        await _store.SetAsync("tenant-1", anchor, budget, CancellationToken.None);

        var bundleTimestamp = _fixedTimeProvider.GetUtcNow().AddDays(-2); // 2 days ago

        var result = await service.EnforceBundleImportPolicyAsync(
            "tenant-1",
            "bundle-123",
            bundleTimestamp);

        Assert.False(result.Allowed);
        Assert.Equal(TimeAnchorPolicyErrorCodes.DriftExceeded, result.ErrorCode);
    }

    [Fact]
    public async Task EnforceOperationPolicyAsync_BlocksStrictOperations_WhenNoAnchor()
    {
        var options = new TimeAnchorPolicyOptions
        {
            StrictOperations = new[] { "attestation.sign" }
        };
        var service = CreateService(options);

        var result = await service.EnforceOperationPolicyAsync("tenant-1", "attestation.sign");

        Assert.False(result.Allowed);
        Assert.Equal(TimeAnchorPolicyErrorCodes.AnchorMissing, result.ErrorCode);
    }

    [Fact]
    public async Task EnforceOperationPolicyAsync_AllowsNonStrictOperations_InNonStrictMode()
    {
        var options = new TimeAnchorPolicyOptions
        {
            StrictEnforcement = false,
            StrictOperations = new[] { "attestation.sign" }
        };
        var service = CreateService(options);

        var result = await service.EnforceOperationPolicyAsync("tenant-1", "some.other.operation");

        Assert.True(result.Allowed);
    }

    [Fact]
    public async Task CalculateDriftAsync_ReturnsNoDrift_WhenNoAnchor()
    {
        var service = CreateService();

        var result = await service.CalculateDriftAsync("tenant-1", _fixedTimeProvider.GetUtcNow());

        Assert.False(result.HasAnchor);
        Assert.Equal(TimeSpan.Zero, result.Drift);
        Assert.Null(result.AnchorTime);
    }

    [Fact]
    public async Task CalculateDriftAsync_ReturnsDrift_WhenAnchorExists()
    {
        var service = CreateService(new TimeAnchorPolicyOptions { MaxDriftSeconds = 3600 });
        var anchorTime = _fixedTimeProvider.GetUtcNow().AddMinutes(-30);
        var anchor = new TimeAnchor(anchorTime, "test", "Roughtime", "fp", "digest");
        var budget = new StalenessBudget(3600, 7200);

        await _store.SetAsync("tenant-1", anchor, budget, CancellationToken.None);

        var targetTime = _fixedTimeProvider.GetUtcNow().AddMinutes(15);
        var result = await service.CalculateDriftAsync("tenant-1", targetTime);

        Assert.True(result.HasAnchor);
        Assert.Equal(anchorTime, result.AnchorTime);
        Assert.Equal(45, (int)result.Drift.TotalMinutes); // 30 min + 15 min
        Assert.False(result.DriftExceedsThreshold);
    }

    [Fact]
    public async Task CalculateDriftAsync_DetectsExcessiveDrift()
    {
        var service = CreateService(new TimeAnchorPolicyOptions { MaxDriftSeconds = 60 }); // 1 minute max
        var anchor = new TimeAnchor(
            _fixedTimeProvider.GetUtcNow(),
            "test",
            "Roughtime",
            "fp",
            "digest");
        var budget = new StalenessBudget(3600, 7200);

        await _store.SetAsync("tenant-1", anchor, budget, CancellationToken.None);

        var targetTime = _fixedTimeProvider.GetUtcNow().AddMinutes(5); // 5 minutes drift
        var result = await service.CalculateDriftAsync("tenant-1", targetTime);

        Assert.True(result.HasAnchor);
        Assert.True(result.DriftExceedsThreshold);
    }

    private sealed class FakeTimeProvider : TimeProvider
    {
        private readonly DateTimeOffset _now;

        public FakeTimeProvider(DateTimeOffset now) => _now = now;

        public override DateTimeOffset GetUtcNow() => _now;
    }
}