using FluentAssertions;
using Microsoft.Extensions.Logging.Abstractions;
using Microsoft.Extensions.Options;
using Moq;
using StellaOps.Gateway.WebService.Authorization;
using StellaOps.Router.Common.Models;
using Xunit;

namespace StellaOps.Gateway.WebService.Tests;

/// <summary>
/// Unit tests for <see cref="AuthorityClaimsRefreshService"/>.
/// </summary>
public sealed class AuthorityClaimsRefreshServiceTests
{
    private readonly Mock<IAuthorityClaimsProvider> _claimsProviderMock;
    private readonly Mock<IEffectiveClaimsStore> _claimsStoreMock;
    private readonly AuthorityConnectionOptions _options;

    public AuthorityClaimsRefreshServiceTests()
    {
        _claimsProviderMock = new Mock<IAuthorityClaimsProvider>();
        _claimsStoreMock = new Mock<IEffectiveClaimsStore>();
        _options = new AuthorityConnectionOptions
        {
            AuthorityUrl = "http://authority.local",
            Enabled = true,
            RefreshInterval = TimeSpan.FromMilliseconds(100),
            WaitForAuthorityOnStartup = false,
            StartupTimeout = TimeSpan.FromSeconds(1)
        };

        _claimsProviderMock.Setup(p => p.GetOverridesAsync(It.IsAny<CancellationToken>()))
            .ReturnsAsync(new Dictionary<EndpointKey, IReadOnlyList<ClaimRequirement>>());
    }

    private AuthorityClaimsRefreshService CreateService()
    {
        return new AuthorityClaimsRefreshService(
            _claimsProviderMock.Object,
            _claimsStoreMock.Object,
            Options.Create(_options),
            NullLogger<AuthorityClaimsRefreshService>.Instance);
    }

    #region ExecuteAsync Tests - Disabled

    [Fact]
    public async Task ExecuteAsync_WhenDisabled_DoesNotFetchClaims()
    {
        // Arrange
        _options.Enabled = false;
        var service = CreateService();
        using var cts = new CancellationTokenSource();

        // Act
        await service.StartAsync(cts.Token);
        await Task.Delay(50);
        await service.StopAsync(cts.Token);

        // Assert
        _claimsProviderMock.Verify(
            p => p.GetOverridesAsync(It.IsAny<CancellationToken>()),
            Times.Never);
    }

    [Fact]
    public async Task ExecuteAsync_WhenNoAuthorityUrl_DoesNotFetchClaims()
    {
        // Arrange
        _options.AuthorityUrl = string.Empty;
        var service = CreateService();
        using var cts = new CancellationTokenSource();

        // Act
        await service.StartAsync(cts.Token);
        await Task.Delay(50);
        await service.StopAsync(cts.Token);

        // Assert
        _claimsProviderMock.Verify(
            p => p.GetOverridesAsync(It.IsAny<CancellationToken>()),
            Times.Never);
    }

    #endregion

    #region ExecuteAsync Tests - Enabled

    [Fact]
    public async Task ExecuteAsync_WhenEnabled_FetchesClaims()
    {
        // Arrange
        var service = CreateService();
        using var cts = new CancellationTokenSource();

        // Act
        await service.StartAsync(cts.Token);
        await Task.Delay(50);
        await cts.CancelAsync();
        await service.StopAsync(CancellationToken.None);

        // Assert
        _claimsProviderMock.Verify(
            p => p.GetOverridesAsync(It.IsAny<CancellationToken>()),
            Times.AtLeastOnce);
    }

    [Fact]
    public async Task ExecuteAsync_UpdatesStoreWithOverrides()
    {
        // Arrange
        var key = EndpointKey.Create("service", "GET", "/api/test");
        var overrides = new Dictionary<EndpointKey, IReadOnlyList<ClaimRequirement>>
        {
            [key] = [new ClaimRequirement { Type = "role", Value = "admin" }]
        };
        _claimsProviderMock.Setup(p => p.GetOverridesAsync(It.IsAny<CancellationToken>()))
            .ReturnsAsync(overrides);

        var service = CreateService();
        using var cts = new CancellationTokenSource();

        // Act
        await service.StartAsync(cts.Token);
        await Task.Delay(50);
        await cts.CancelAsync();
        await service.StopAsync(CancellationToken.None);

        // Assert
        _claimsStoreMock.Verify(
            s => s.UpdateFromAuthority(It.Is<IReadOnlyDictionary<EndpointKey, IReadOnlyList<ClaimRequirement>>>(
                d => d.ContainsKey(key))),
            Times.AtLeastOnce);
    }

    #endregion

    #region ExecuteAsync Tests - Wait for Authority

    [Fact]
    public async Task ExecuteAsync_WaitForAuthority_FetchesOnStartup()
    {
        // Arrange
        _options.WaitForAuthorityOnStartup = true;
        _options.StartupTimeout = TimeSpan.FromMilliseconds(500);

        // Authority is immediately available
        _claimsProviderMock.Setup(p => p.IsAvailable).Returns(true);

        var fetchCalled = false;
        _claimsProviderMock.Setup(p => p.GetOverridesAsync(It.IsAny<CancellationToken>()))
            .Callback(() => fetchCalled = true)
            .ReturnsAsync(new Dictionary<EndpointKey, IReadOnlyList<ClaimRequirement>>());

        var service = CreateService();
        using var cts = new CancellationTokenSource();

        // Act
        await service.StartAsync(cts.Token);
        await Task.Delay(100);
        await cts.CancelAsync();
        await service.StopAsync(CancellationToken.None);

        // Assert - fetch was called during startup
        fetchCalled.Should().BeTrue();
    }

    [Fact]
    public async Task ExecuteAsync_WaitForAuthority_StopsAfterTimeout()
    {
        // Arrange
        _options.WaitForAuthorityOnStartup = true;
        _options.StartupTimeout = TimeSpan.FromMilliseconds(100);

        _claimsProviderMock.Setup(p => p.IsAvailable).Returns(false);

        var service = CreateService();
        using var cts = new CancellationTokenSource();

        // Act - should not block forever
        var startTask = service.StartAsync(cts.Token);
        await Task.Delay(300);
        await cts.CancelAsync();
        await service.StopAsync(CancellationToken.None);

        // Assert - should complete even if Authority never becomes available
        startTask.IsCompleted.Should().BeTrue();
    }

    #endregion

    #region Push Notification Tests

    [Fact]
    public async Task ExecuteAsync_WithPushNotifications_SubscribesToEvent()
    {
        // Arrange
        _options.UseAuthorityPushNotifications = true;
        var service = CreateService();
        using var cts = new CancellationTokenSource();

        // Act
        await service.StartAsync(cts.Token);
        await Task.Delay(50);
        await cts.CancelAsync();
        await service.StopAsync(CancellationToken.None);

        // Assert - verify event subscription by checking it doesn't throw
        _claimsProviderMock.VerifyAdd(
            p => p.OverridesChanged += It.IsAny<EventHandler<ClaimsOverrideChangedEventArgs>>(),
            Times.Once);
    }

    [Fact]
    public async Task Dispose_WithPushNotifications_UnsubscribesFromEvent()
    {
        // Arrange
        _options.UseAuthorityPushNotifications = true;
        var service = CreateService();
        using var cts = new CancellationTokenSource();

        await service.StartAsync(cts.Token);
        await Task.Delay(50);

        // Act
        await cts.CancelAsync();
        service.Dispose();

        // Assert
        _claimsProviderMock.VerifyRemove(
            p => p.OverridesChanged -= It.IsAny<EventHandler<ClaimsOverrideChangedEventArgs>>(),
            Times.Once);
    }

    #endregion

    #region Error Handling Tests

    [Fact]
    public async Task ExecuteAsync_ProviderThrows_ContinuesRefreshLoop()
    {
        // Arrange
        var callCount = 0;
        _claimsProviderMock.Setup(p => p.GetOverridesAsync(It.IsAny<CancellationToken>()))
            .ReturnsAsync(() =>
            {
                callCount++;
                if (callCount == 1)
                {
                    throw new HttpRequestException("Test error");
                }
                return new Dictionary<EndpointKey, IReadOnlyList<ClaimRequirement>>();
            });

        var service = CreateService();
        using var cts = new CancellationTokenSource();

        // Act
        await service.StartAsync(cts.Token);
        await Task.Delay(250); // Wait for at least 2 refresh cycles
        await cts.CancelAsync();
        await service.StopAsync(CancellationToken.None);

        // Assert - should have continued after error
        callCount.Should().BeGreaterThan(1);
    }

    #endregion
}