using Shouldly;
using Xunit;
using ZB.MOM.WW.OtOpcUa.Core.Abstractions;
using ZB.MOM.WW.OtOpcUa.Driver.AbLegacy;

namespace ZB.MOM.WW.OtOpcUa.Driver.AbLegacy.Tests;

/// <summary>
///     PR 8 — per-tag deadband / change filter tests. The driver layers the deadband on top of
///     <see cref="PollGroupEngine"/>'s built-in change-detection: the engine fires its callback
///     whenever value or status differs from its own last snapshot; the driver then applies the
///     per-tag absolute / percent / type-aware filter before raising <c>OnDataChange</c>.
/// </summary>
[Trait("Category", "Unit")]
public sealed class AbLegacyDeadbandTests
{
    private const uint Good = 0x00000000u;
    private const uint BadCommunication = 0x80050000u;

    private static async Task<AbLegacyDriver> BuildDriverAsync(params AbLegacyTagDefinition[] tags)
    {
        var drv = new AbLegacyDriver(new AbLegacyDriverOptions
        {
            Devices = [], // ShouldPublish only inspects the tag-by-name map; no device is needed.
            Tags = tags,
            Probe = new AbLegacyProbeOptions { Enabled = false, ProbeAddress = null },
        }, "drv-deadband", new FakeAbLegacyTagFactory());
        await drv.InitializeAsync("{}", CancellationToken.None);
        return drv;
    }

    private static DataValueSnapshot Snap(object? v, uint status = Good) =>
        new(v, status, DateTime.UtcNow, DateTime.UtcNow);

    [Fact]
    public async Task Absolute_deadband_suppresses_changes_below_threshold()
    {
        var tag = new AbLegacyTagDefinition("t", "ab://h/", "F8:0", AbLegacyDataType.Float,
            AbsoluteDeadband: 1.0);
        await using var drv = await BuildDriverAsync(tag);

        // Walk the published flag for each sample — the asserted sequence is [10.0, 11.5].
        drv.ShouldPublish("t", Snap(10.0)).ShouldBeTrue();   // first-seen
        drv.ShouldPublish("t", Snap(10.5)).ShouldBeFalse();  // 0.5 < 1.0
        drv.ShouldPublish("t", Snap(11.5)).ShouldBeTrue();   // 1.5 from last published 10.0
        drv.ShouldPublish("t", Snap(11.6)).ShouldBeFalse();  // 0.1 from last published 11.5
    }

    [Fact]
    public async Task Percent_deadband_suppresses_changes_below_threshold()
    {
        var tag = new AbLegacyTagDefinition("t", "ab://h/", "F8:0", AbLegacyDataType.Float,
            PercentDeadband: 10.0);
        await using var drv = await BuildDriverAsync(tag);

        drv.ShouldPublish("t", Snap(100.0)).ShouldBeTrue(); // first-seen
        drv.ShouldPublish("t", Snap(105.0)).ShouldBeFalse(); // 5% < 10%
        drv.ShouldPublish("t", Snap(115.0)).ShouldBeTrue();  // |115-100|=15 >= 10% of 100
    }

    [Fact]
    public async Task Percent_deadband_with_zero_prev_always_publishes_on_change()
    {
        var tag = new AbLegacyTagDefinition("t", "ab://h/", "F8:0", AbLegacyDataType.Float,
            PercentDeadband: 50.0);
        await using var drv = await BuildDriverAsync(tag);

        drv.ShouldPublish("t", Snap(0.0)).ShouldBeTrue();   // first-seen
        drv.ShouldPublish("t", Snap(0.001)).ShouldBeTrue(); // prev=0 short-circuit
    }

    [Fact]
    public async Task Boolean_publishes_every_transition_and_suppresses_no_op()
    {
        var tag = new AbLegacyTagDefinition("t", "ab://h/", "B3:0/0", AbLegacyDataType.Bit,
            AbsoluteDeadband: 1.0);
        await using var drv = await BuildDriverAsync(tag);

        // Edge sequence false -> true -> false -> true => 4 publishes.
        drv.ShouldPublish("t", Snap(false)).ShouldBeTrue();
        drv.ShouldPublish("t", Snap(true)).ShouldBeTrue();
        drv.ShouldPublish("t", Snap(false)).ShouldBeTrue();
        drv.ShouldPublish("t", Snap(true)).ShouldBeTrue();

        // No-op (true -> true) suppressed.
        drv.ShouldPublish("t", Snap(true)).ShouldBeFalse();
    }

    [Fact]
    public async Task Status_change_always_publishes_even_within_deadband()
    {
        var tag = new AbLegacyTagDefinition("t", "ab://h/", "F8:0", AbLegacyDataType.Float,
            AbsoluteDeadband: 100.0); // ridiculously large — would normally suppress everything
        await using var drv = await BuildDriverAsync(tag);

        drv.ShouldPublish("t", Snap(10.0, Good)).ShouldBeTrue();             // first-seen
        drv.ShouldPublish("t", Snap(10.5, Good)).ShouldBeFalse();            // within deadband
        drv.ShouldPublish("t", Snap(10.5, BadCommunication)).ShouldBeTrue(); // status flip
        drv.ShouldPublish("t", Snap(10.5, Good)).ShouldBeTrue();             // status flip back
    }

    [Fact]
    public async Task String_publishes_on_value_change_and_suppresses_no_op()
    {
        var tag = new AbLegacyTagDefinition("t", "ab://h/", "ST20:0", AbLegacyDataType.String,
            AbsoluteDeadband: 1.0); // deadband meaningless on strings — should be ignored
        await using var drv = await BuildDriverAsync(tag);

        drv.ShouldPublish("t", Snap("alpha")).ShouldBeTrue();   // first-seen
        drv.ShouldPublish("t", Snap("alpha")).ShouldBeFalse();  // identical
        drv.ShouldPublish("t", Snap("beta")).ShouldBeTrue();    // change
    }

    [Fact]
    public async Task Both_deadbands_set_either_triggers_publish()
    {
        // 1.0 absolute OR 50% percent — picking deltas where one passes, the other does not.
        var tag = new AbLegacyTagDefinition("t", "ab://h/", "F8:0", AbLegacyDataType.Float,
            AbsoluteDeadband: 1.0, PercentDeadband: 50.0);
        await using var drv = await BuildDriverAsync(tag);

        drv.ShouldPublish("t", Snap(2.0)).ShouldBeTrue();   // first-seen
        // |3.0 - 2.0| = 1.0 -> absolute passes (>= 1.0); percent test 50% of 2.0 = 1.0 -> 1.0 >= 1.0 also passes.
        drv.ShouldPublish("t", Snap(3.0)).ShouldBeTrue();
        // After last-publish=3.0: small delta of 0.6, absolute fails (0.6 < 1.0), percent fails (0.6 < 1.5).
        drv.ShouldPublish("t", Snap(3.6)).ShouldBeFalse();
        // |5.0 - 3.0| = 2.0; absolute passes (>= 1.0).
        drv.ShouldPublish("t", Snap(5.0)).ShouldBeTrue();
    }

    [Fact]
    public async Task First_seen_always_publishes_even_with_huge_deadband()
    {
        var tag = new AbLegacyTagDefinition("t", "ab://h/", "F8:0", AbLegacyDataType.Float,
            AbsoluteDeadband: 1e9);
        await using var drv = await BuildDriverAsync(tag);

        drv.ShouldPublish("t", Snap(1.0)).ShouldBeTrue();
    }

    [Fact]
    public async Task ReinitializeAsync_clears_last_published_cache()
    {
        var tag = new AbLegacyTagDefinition("t", "ab://h/", "F8:0", AbLegacyDataType.Float,
            AbsoluteDeadband: 1.0);
        var drv = new AbLegacyDriver(new AbLegacyDriverOptions
        {
            Devices = [],
            Tags = [tag],
            Probe = new AbLegacyProbeOptions { Enabled = false, ProbeAddress = null },
        }, "drv-reinit", new FakeAbLegacyTagFactory());

        await drv.InitializeAsync("{}", CancellationToken.None);
        drv.ShouldPublish("t", Snap(10.0)).ShouldBeTrue();
        drv.ShouldPublish("t", Snap(10.2)).ShouldBeFalse();

        await drv.ReinitializeAsync("{}", CancellationToken.None);

        // After reinit the cache is empty — the very next sample is treated as first-seen and
        // publishes regardless of how close it is to the pre-reinit last-published value.
        drv.ShouldPublish("t", Snap(10.2)).ShouldBeTrue();

        await drv.ShutdownAsync(CancellationToken.None);
    }

    [Fact]
    public async Task Tag_without_deadband_publishes_every_sample_reaching_dispatcher()
    {
        // No deadband fields set — the driver passes through whatever the engine gives it.
        // (PollGroupEngine itself filters by value-equality, so any sample reaching ShouldPublish
        // is already a real change.)
        var tag = new AbLegacyTagDefinition("t", "ab://h/", "F8:0", AbLegacyDataType.Float);
        await using var drv = await BuildDriverAsync(tag);

        drv.ShouldPublish("t", Snap(1.0)).ShouldBeTrue();
        drv.ShouldPublish("t", Snap(1.001)).ShouldBeTrue();
        drv.ShouldPublish("t", Snap(1.002)).ShouldBeTrue();
    }

    [Fact]
    public async Task Dto_round_trip_preserves_deadband_fields()
    {
        const string json = """
            {
              "Devices": [
                { "HostAddress": "ab://10.0.0.5/1,0", "PlcFamily": "Slc500" }
              ],
              "Tags": [
                {
                  "Name": "T1",
                  "DeviceHostAddress": "ab://10.0.0.5/1,0",
                  "Address": "F8:0",
                  "DataType": "Float",
                  "AbsoluteDeadband": 0.5,
                  "PercentDeadband": 5.0
                }
              ]
            }
            """;

        var drv = AbLegacyDriverFactoryExtensions.CreateInstance("drv-json", json);
        try
        {
            await drv.InitializeAsync(json, CancellationToken.None);
            // ShouldPublish exercises the deadband — confirms the DTO values landed on the
            // AbLegacyTagDefinition.
            drv.ShouldPublish("T1", Snap(100.0)).ShouldBeTrue();   // first-seen
            drv.ShouldPublish("T1", Snap(100.4)).ShouldBeFalse();  // 0.4 < 0.5 absolute
            drv.ShouldPublish("T1", Snap(101.0)).ShouldBeTrue();   // 1.0 >= 0.5 absolute
        }
        finally
        {
            await drv.DisposeAsync();
        }
    }
}