using System;
using Shouldly;
using Xunit;
using ZB.MOM.WW.LmxOpcUa.Host.Domain;
using ZB.MOM.WW.LmxOpcUa.Host.Metrics;
using ZB.MOM.WW.LmxOpcUa.Host.Status;

namespace ZB.MOM.WW.LmxOpcUa.Tests.Status
{
    /// <summary>
    /// Verifies how the dashboard health service classifies bridge health from connection state and metrics.
    /// </summary>
    public class HealthCheckServiceTests
    {
        private readonly HealthCheckService _sut = new();

        /// <summary>
        /// Confirms that a disconnected runtime is reported as unhealthy.
        /// </summary>
        [Fact]
        public void NotConnected_ReturnsUnhealthy()
        {
            var result = _sut.CheckHealth(ConnectionState.Disconnected, null);
            result.Status.ShouldBe("Unhealthy");
            result.Color.ShouldBe("red");
            result.Message.ShouldContain("not connected");
        }

        /// <summary>
        /// Confirms that a connected runtime with no metrics history is still considered healthy.
        /// </summary>
        [Fact]
        public void Connected_NoMetrics_ReturnsHealthy()
        {
            var result = _sut.CheckHealth(ConnectionState.Connected, null);
            result.Status.ShouldBe("Healthy");
            result.Color.ShouldBe("green");
        }

        /// <summary>
        /// Confirms that good success-rate metrics keep the service in a healthy state.
        /// </summary>
        [Fact]
        public void Connected_GoodMetrics_ReturnsHealthy()
        {
            using var metrics = new PerformanceMetrics();
            for (int i = 0; i < 200; i++)
                metrics.RecordOperation("Read", TimeSpan.FromMilliseconds(10), true);

            var result = _sut.CheckHealth(ConnectionState.Connected, metrics);
            result.Status.ShouldBe("Healthy");
        }

        /// <summary>
        /// Confirms that poor operation success rates degrade the reported health state.
        /// </summary>
        [Fact]
        public void Connected_LowSuccessRate_ReturnsDegraded()
        {
            using var metrics = new PerformanceMetrics();
            for (int i = 0; i < 40; i++)
                metrics.RecordOperation("Read", TimeSpan.FromMilliseconds(10), true);
            for (int i = 0; i < 80; i++)
                metrics.RecordOperation("Read", TimeSpan.FromMilliseconds(10), false);

            var result = _sut.CheckHealth(ConnectionState.Connected, metrics);
            result.Status.ShouldBe("Degraded");
            result.Color.ShouldBe("yellow");
        }

        /// <summary>
        /// Confirms that the boolean health helper reports true when the runtime is connected.
        /// </summary>
        [Fact]
        public void IsHealthy_Connected_ReturnsTrue()
        {
            _sut.IsHealthy(ConnectionState.Connected, null).ShouldBe(true);
        }

        /// <summary>
        /// Confirms that the boolean health helper reports false when the runtime is disconnected.
        /// </summary>
        [Fact]
        public void IsHealthy_Disconnected_ReturnsFalse()
        {
            _sut.IsHealthy(ConnectionState.Disconnected, null).ShouldBe(false);
        }

        /// <summary>
        /// Confirms that the error connection state is treated as unhealthy.
        /// </summary>
        [Fact]
        public void Error_ReturnsUnhealthy()
        {
            var result = _sut.CheckHealth(ConnectionState.Error, null);
            result.Status.ShouldBe("Unhealthy");
        }

        /// <summary>
        /// Confirms that the reconnecting state is treated as unhealthy while recovery is in progress.
        /// </summary>
        [Fact]
        public void Reconnecting_ReturnsUnhealthy()
        {
            var result = _sut.CheckHealth(ConnectionState.Reconnecting, null);
            result.Status.ShouldBe("Unhealthy");
        }
    }
}