using Shouldly;
using Xunit;
using ZB.MOM.WW.OtOpcUa.Core.Abstractions;
using ZB.MOM.WW.OtOpcUa.Server.History;

namespace ZB.MOM.WW.OtOpcUa.Server.Tests.History;

/// <summary>
///     Tests for <see cref="HistoryRouter"/> registration + resolution semantics added
///     in PR 1.2. The router is the only seam between OPC UA HistoryRead service calls
///     and registered <see cref="IHistorianDataSource"/> implementations, so the
///     resolution rules (case-insensitive prefix, longest-match wins, no source =>
///     null) need explicit coverage.
/// </summary>
public sealed class HistoryRouterTests
{
    [Fact]
    public void Resolve_ReturnsNull_WhenNoSourceRegistered()
    {
        using var router = new HistoryRouter();
        router.Resolve("anything").ShouldBeNull();
    }

    [Fact]
    public void Resolve_ReturnsRegisteredSource_WhenPrefixMatches()
    {
        using var router = new HistoryRouter();
        var source = new FakeSource("galaxy");
        router.Register("galaxy", source);

        router.Resolve("galaxy.TankFarm.Tank1.Level").ShouldBe(source);
    }

    [Fact]
    public void Resolve_ReturnsNull_WhenPrefixDoesNotMatch()
    {
        using var router = new HistoryRouter();
        router.Register("galaxy", new FakeSource("galaxy"));

        router.Resolve("modbus.MyDevice.Tag1").ShouldBeNull();
    }

    [Fact]
    public void Resolve_LongestPrefixWins_WhenMultipleRegistered()
    {
        using var router = new HistoryRouter();
        var generic = new FakeSource("generic");
        var specific = new FakeSource("specific");

        router.Register("galaxy", generic);
        router.Register("galaxy.HighRate", specific);

        router.Resolve("galaxy.HighRate.Sensor1").ShouldBe(specific);
        router.Resolve("galaxy.LowRate.Sensor2").ShouldBe(generic);
    }

    [Fact]
    public void Resolve_IsCaseInsensitive_OnPrefixMatch()
    {
        using var router = new HistoryRouter();
        var source = new FakeSource("galaxy");
        router.Register("Galaxy", source);

        router.Resolve("galaxy.foo").ShouldBe(source);
        router.Resolve("GALAXY.foo").ShouldBe(source);
    }

    [Fact]
    public void Register_Throws_WhenPrefixAlreadyRegistered()
    {
        using var router = new HistoryRouter();
        router.Register("galaxy", new FakeSource("first"));

        Should.Throw<InvalidOperationException>(
            () => router.Register("galaxy", new FakeSource("second")));
    }

    [Fact]
    public void Dispose_DisposesAllRegisteredSources()
    {
        var router = new HistoryRouter();
        var a = new FakeSource("a");
        var b = new FakeSource("b");
        router.Register("ns_a", a);
        router.Register("ns_b", b);

        router.Dispose();

        a.IsDisposed.ShouldBeTrue();
        b.IsDisposed.ShouldBeTrue();
    }

    [Fact]
    public void Dispose_SwallowsExceptionsFromMisbehavingSource()
    {
        var router = new HistoryRouter();
        var throwing = new ThrowingFakeSource();
        var clean = new FakeSource("clean");
        router.Register("bad", throwing);
        router.Register("good", clean);

        // Even when one source's Dispose throws, the router must finish disposing the
        // remaining sources (server shutdown invariant).
        Should.NotThrow(() => router.Dispose());
        clean.IsDisposed.ShouldBeTrue();
    }

    [Fact]
    public void Resolve_Throws_AfterDisposal()
    {
        var router = new HistoryRouter();
        router.Dispose();

        Should.Throw<ObjectDisposedException>(() => router.Resolve("anything"));
    }

    [Fact]
    public void Register_Throws_AfterDisposal()
    {
        var router = new HistoryRouter();
        router.Dispose();

        Should.Throw<ObjectDisposedException>(
            () => router.Register("ns", new FakeSource("x")));
    }

    private sealed class FakeSource(string name) : IHistorianDataSource
    {
        public string Name { get; } = name;
        public bool IsDisposed { get; private set; }

        public void Dispose() => IsDisposed = true;

        public Task<HistoryReadResult> ReadRawAsync(string fullReference, DateTime startUtc, DateTime endUtc, uint maxValuesPerNode, CancellationToken cancellationToken)
            => throw new NotImplementedException();

        public Task<HistoryReadResult> ReadProcessedAsync(string fullReference, DateTime startUtc, DateTime endUtc, TimeSpan interval, HistoryAggregateType aggregate, CancellationToken cancellationToken)
            => throw new NotImplementedException();

        public Task<HistoryReadResult> ReadAtTimeAsync(string fullReference, IReadOnlyList<DateTime> timestampsUtc, CancellationToken cancellationToken)
            => throw new NotImplementedException();

        public Task<HistoricalEventsResult> ReadEventsAsync(string? sourceName, DateTime startUtc, DateTime endUtc, int maxEvents, CancellationToken cancellationToken)
            => throw new NotImplementedException();

        public HistorianHealthSnapshot GetHealthSnapshot()
            => new(0, 0, 0, 0, null, null, null, false, false, null, null, []);
    }

    private sealed class ThrowingFakeSource : IHistorianDataSource
    {
        public void Dispose() => throw new InvalidOperationException("boom");

        public Task<HistoryReadResult> ReadRawAsync(string fullReference, DateTime startUtc, DateTime endUtc, uint maxValuesPerNode, CancellationToken cancellationToken)
            => throw new NotImplementedException();

        public Task<HistoryReadResult> ReadProcessedAsync(string fullReference, DateTime startUtc, DateTime endUtc, TimeSpan interval, HistoryAggregateType aggregate, CancellationToken cancellationToken)
            => throw new NotImplementedException();

        public Task<HistoryReadResult> ReadAtTimeAsync(string fullReference, IReadOnlyList<DateTime> timestampsUtc, CancellationToken cancellationToken)
            => throw new NotImplementedException();

        public Task<HistoricalEventsResult> ReadEventsAsync(string? sourceName, DateTime startUtc, DateTime endUtc, int maxEvents, CancellationToken cancellationToken)
            => throw new NotImplementedException();

        public HistorianHealthSnapshot GetHealthSnapshot()
            => new(0, 0, 0, 0, null, null, null, false, false, null, null, []);
    }
}