using StellaOps.Router.Common.Models;

using StellaOps.TestKit;
namespace StellaOps.Router.Config.Tests;

/// <summary>
/// Unit tests for <see cref="RouterConfig"/>.
/// </summary>
public sealed class RouterConfigTests
{
    #region Default Values Tests

    [Trait("Category", TestCategories.Unit)]
        [Fact]
    public void Constructor_PayloadLimits_DefaultsToNewInstance()
    {
        // Arrange & Act
        var config = new RouterConfig();

        // Assert
        config.PayloadLimits.Should().NotBeNull();
    }

    [Trait("Category", TestCategories.Unit)]
        [Fact]
    public void Constructor_Routing_DefaultsToNewInstance()
    {
        // Arrange & Act
        var config = new RouterConfig();

        // Assert
        config.Routing.Should().NotBeNull();
    }

    [Trait("Category", TestCategories.Unit)]
        [Fact]
    public void Constructor_Services_DefaultsToEmptyList()
    {
        // Arrange & Act
        var config = new RouterConfig();

        // Assert
        config.Services.Should().NotBeNull();
        config.Services.Should().BeEmpty();
    }

    [Trait("Category", TestCategories.Unit)]
        [Fact]
    public void Constructor_StaticInstances_DefaultsToEmptyList()
    {
        // Arrange & Act
        var config = new RouterConfig();

        // Assert
        config.StaticInstances.Should().NotBeNull();
        config.StaticInstances.Should().BeEmpty();
    }

    #endregion

    #region PayloadLimits Tests

    [Trait("Category", TestCategories.Unit)]
        [Fact]
    public void PayloadLimits_HasDefaultValues()
    {
        // Arrange & Act
        var config = new RouterConfig();

        // Assert
        config.PayloadLimits.MaxRequestBytesPerCall.Should().Be(10 * 1024 * 1024); // 10 MB
        config.PayloadLimits.MaxRequestBytesPerConnection.Should().Be(100 * 1024 * 1024); // 100 MB
        config.PayloadLimits.MaxAggregateInflightBytes.Should().Be(1024 * 1024 * 1024); // 1 GB
    }

    [Trait("Category", TestCategories.Unit)]
        [Fact]
    public void PayloadLimits_CanBeSet()
    {
        // Arrange
        var config = new RouterConfig();

        // Act
        config.PayloadLimits = new PayloadLimits
        {
            MaxRequestBytesPerCall = 5 * 1024 * 1024,
            MaxRequestBytesPerConnection = 50 * 1024 * 1024,
            MaxAggregateInflightBytes = 500 * 1024 * 1024
        };

        // Assert
        config.PayloadLimits.MaxRequestBytesPerCall.Should().Be(5 * 1024 * 1024);
        config.PayloadLimits.MaxRequestBytesPerConnection.Should().Be(50 * 1024 * 1024);
        config.PayloadLimits.MaxAggregateInflightBytes.Should().Be(500 * 1024 * 1024);
    }

    #endregion

    #region Routing Tests

    [Trait("Category", TestCategories.Unit)]
        [Fact]
    public void Routing_HasDefaultValues()
    {
        // Arrange & Act
        var config = new RouterConfig();

        // Assert
        config.Routing.LocalRegion.Should().Be("default");
        config.Routing.TieBreaker.Should().Be(TieBreakerStrategy.RoundRobin);
        config.Routing.PreferLocalRegion.Should().BeTrue();
        config.Routing.DefaultTimeout.Should().Be(TimeSpan.FromSeconds(30));
    }

    [Trait("Category", TestCategories.Unit)]
        [Fact]
    public void Routing_CanBeSet()
    {
        // Arrange
        var config = new RouterConfig();

        // Act
        config.Routing = new RoutingOptions
        {
            LocalRegion = "us-east-1",
            TieBreaker = TieBreakerStrategy.LeastLoaded,
            PreferLocalRegion = false,
            DefaultTimeout = TimeSpan.FromMinutes(2),
            NeighborRegions = ["us-west-1", "eu-west-1"]
        };

        // Assert
        config.Routing.LocalRegion.Should().Be("us-east-1");
        config.Routing.TieBreaker.Should().Be(TieBreakerStrategy.LeastLoaded);
        config.Routing.PreferLocalRegion.Should().BeFalse();
        config.Routing.DefaultTimeout.Should().Be(TimeSpan.FromMinutes(2));
        config.Routing.NeighborRegions.Should().HaveCount(2);
    }

    #endregion

    #region Services Tests

    [Trait("Category", TestCategories.Unit)]
        [Fact]
    public void Services_CanAddServices()
    {
        // Arrange
        var config = new RouterConfig();

        // Act
        config.Services.Add(new ServiceConfig { ServiceName = "service-a" });
        config.Services.Add(new ServiceConfig { ServiceName = "service-b" });

        // Assert
        config.Services.Should().HaveCount(2);
        config.Services[0].ServiceName.Should().Be("service-a");
        config.Services[1].ServiceName.Should().Be("service-b");
    }

    [Trait("Category", TestCategories.Unit)]
        [Fact]
    public void Services_CanBeInitialized()
    {
        // Arrange & Act
        var config = new RouterConfig
        {
            Services =
            [
                new ServiceConfig { ServiceName = "auth" },
                new ServiceConfig { ServiceName = "users" },
                new ServiceConfig { ServiceName = "orders" }
            ]
        };

        // Assert
        config.Services.Should().HaveCount(3);
    }

    #endregion

    #region StaticInstances Tests

    [Trait("Category", TestCategories.Unit)]
        [Fact]
    public void StaticInstances_CanAddInstances()
    {
        // Arrange
        var config = new RouterConfig();

        // Act
        config.StaticInstances.Add(new StaticInstanceConfig
        {
            ServiceName = "legacy-service",
            Version = "1.0",
            Host = "legacy.internal",
            Port = 9000
        });

        // Assert
        config.StaticInstances.Should().HaveCount(1);
        config.StaticInstances[0].ServiceName.Should().Be("legacy-service");
    }

    [Trait("Category", TestCategories.Unit)]
        [Fact]
    public void StaticInstances_CanBeInitialized()
    {
        // Arrange & Act
        var config = new RouterConfig
        {
            StaticInstances =
            [
                new StaticInstanceConfig
                {
                    ServiceName = "db-proxy",
                    Version = "2.0",
                    Host = "db-proxy-1.internal",
                    Port = 5432
                },
                new StaticInstanceConfig
                {
                    ServiceName = "db-proxy",
                    Version = "2.0",
                    Host = "db-proxy-2.internal",
                    Port = 5432
                }
            ]
        };

        // Assert
        config.StaticInstances.Should().HaveCount(2);
    }

    #endregion

    #region Complete Configuration Tests

    [Trait("Category", TestCategories.Unit)]
        [Fact]
    public void CompleteConfiguration_Works()
    {
        // Arrange & Act
        var config = new RouterConfig
        {
            PayloadLimits = new PayloadLimits
            {
                MaxRequestBytesPerCall = 1024 * 1024,
                MaxRequestBytesPerConnection = 10 * 1024 * 1024,
                MaxAggregateInflightBytes = 100 * 1024 * 1024
            },
            Routing = new RoutingOptions
            {
                LocalRegion = "us-east-1",
                NeighborRegions = ["us-west-1"],
                TieBreaker = TieBreakerStrategy.ConsistentHash,
                PreferLocalRegion = true,
                DefaultTimeout = TimeSpan.FromSeconds(60)
            },
            Services =
            [
                new ServiceConfig
                {
                    ServiceName = "api-gateway",
                    DefaultVersion = "1.0.0",
                    Endpoints =
                    [
                        new EndpointConfig { Method = "GET", Path = "/health" }
                    ]
                }
            ],
            StaticInstances =
            [
                new StaticInstanceConfig
                {
                    ServiceName = "api-gateway",
                    Version = "1.0.0",
                    Host = "api-1.internal",
                    Port = 8080,
                    Weight = 100
                }
            ]
        };

        // Assert
        config.PayloadLimits.MaxRequestBytesPerCall.Should().Be(1024 * 1024);
        config.Routing.LocalRegion.Should().Be("us-east-1");
        config.Services.Should().HaveCount(1);
        config.StaticInstances.Should().HaveCount(1);
    }

    #endregion
}