using System.Reflection;
using Shouldly;
using Xunit;
using ZB.MOM.WW.OtOpcUa.Core.Abstractions;

namespace ZB.MOM.WW.OtOpcUa.Core.Abstractions.Tests.Historian;

/// <summary>
///     Structural contract tests for the historian data-source surface added in PR 1.1.
///     Asserts the type shape — implementations are tested in their own projects.
/// </summary>
public sealed class IHistorianDataSourceContractTests
{
    [Fact]
    public void Interface_LivesInRootNamespace()
    {
        typeof(IHistorianDataSource).Namespace
            .ShouldBe("ZB.MOM.WW.OtOpcUa.Core.Abstractions");
    }

    [Fact]
    public void Interface_IsPublic()
    {
        typeof(IHistorianDataSource).IsPublic.ShouldBeTrue();
        typeof(IHistorianDataSource).IsInterface.ShouldBeTrue();
    }

    [Fact]
    public void Interface_ExtendsIDisposable()
    {
        typeof(IDisposable).IsAssignableFrom(typeof(IHistorianDataSource))
            .ShouldBeTrue("data sources own backend connections; the server disposes them on shutdown");
    }

    [Theory]
    [InlineData("ReadRawAsync", typeof(Task<HistoryReadResult>))]
    [InlineData("ReadProcessedAsync", typeof(Task<HistoryReadResult>))]
    [InlineData("ReadAtTimeAsync", typeof(Task<HistoryReadResult>))]
    [InlineData("ReadEventsAsync", typeof(Task<HistoricalEventsResult>))]
    public void ReadMethods_ReturnExpectedTaskShape(string methodName, Type expectedReturnType)
    {
        var method = typeof(IHistorianDataSource).GetMethod(methodName);
        method.ShouldNotBeNull();
        method!.ReturnType.ShouldBe(expectedReturnType);
    }

    [Fact]
    public void GetHealthSnapshot_IsSynchronous()
    {
        var method = typeof(IHistorianDataSource).GetMethod("GetHealthSnapshot");
        method.ShouldNotBeNull();
        method!.ReturnType.ShouldBe(typeof(HistorianHealthSnapshot));
    }

    [Fact]
    public void HealthSnapshot_AcceptsEmptyClusterNodeList()
    {
        var snapshot = new HistorianHealthSnapshot(
            TotalQueries: 0,
            TotalSuccesses: 0,
            TotalFailures: 0,
            ConsecutiveFailures: 0,
            LastSuccessTime: null,
            LastFailureTime: null,
            LastError: null,
            ProcessConnectionOpen: false,
            EventConnectionOpen: false,
            ActiveProcessNode: null,
            ActiveEventNode: null,
            Nodes: Array.Empty<HistorianClusterNodeState>());

        snapshot.Nodes.ShouldBeEmpty();
    }

    [Fact]
    public void HealthSnapshot_PreservesClusterNodes()
    {
        var node = new HistorianClusterNodeState(
            Name: "hist-01",
            IsHealthy: true,
            CooldownUntil: null,
            FailureCount: 0,
            LastError: null,
            LastFailureTime: null);

        var snapshot = new HistorianHealthSnapshot(
            TotalQueries: 5,
            TotalSuccesses: 5,
            TotalFailures: 0,
            ConsecutiveFailures: 0,
            LastSuccessTime: new DateTime(2026, 4, 29, 12, 0, 0, DateTimeKind.Utc),
            LastFailureTime: null,
            LastError: null,
            ProcessConnectionOpen: true,
            EventConnectionOpen: true,
            ActiveProcessNode: "hist-01",
            ActiveEventNode: "hist-01",
            Nodes: new[] { node });

        snapshot.Nodes.Count.ShouldBe(1);
        snapshot.Nodes[0].ShouldBe(node);
    }

    [Fact]
    public void ClusterNodeState_RecordEqualityByValue()
    {
        var a = new HistorianClusterNodeState("hist-01", true, null, 0, null, null);
        var b = new HistorianClusterNodeState("hist-01", true, null, 0, null, null);

        a.ShouldBe(b);
    }

    [Fact]
    public void ClusterNodeState_DistinctByAnyField()
    {
        var healthy = new HistorianClusterNodeState("hist-01", true, null, 0, null, null);
        var unhealthy = new HistorianClusterNodeState("hist-01", false, null, 1, "boom", null);

        healthy.ShouldNotBe(unhealthy);
    }
}