using ZB.MOM.WW.ScadaBridge.Commons.Messages.Streaming;
using ZB.MOM.WW.ScadaBridge.Commons.Types.Alarms;
using ZB.MOM.WW.ScadaBridge.Commons.Types.Enums;

namespace ZB.MOM.WW.ScadaBridge.Commons.Tests.Messages;

public class AlarmStateChangedEnrichmentTests
{
    /// <summary>Verifies that a default alarm state change is of the computed kind with auto-acknowledge.</summary>
    [Fact]
    public void Defaults_AreComputedKind_WithAutoAck()
    {
        var m = new AlarmStateChanged("inst", "HiAlarm", AlarmState.Active, 700, DateTimeOffset.UnixEpoch);
        Assert.Equal(AlarmKind.Computed, m.Kind);
        Assert.True(m.Condition.Acknowledged);          // computed = auto-acked
        Assert.Equal(700, m.Condition.Severity);        // severity defaults to Priority
        Assert.True(m.Condition.Active);                // derived from State
        Assert.Equal("", m.SourceReference);
    }

    /// <summary>Verifies that the computed factory maps priority and state onto the message.</summary>
    [Fact]
    public void Factory_ForComputed_MapsPriorityAndState()
    {
        var c = AlarmConditionStateFactory.ForComputed(AlarmState.Normal, priority: 250);
        Assert.False(c.Active);
        Assert.True(c.Acknowledged);
        Assert.Equal(250, c.Severity);
    }

    // ── MES alarm-status API §6.4: additive AckTime ──

    /// <summary>Verifies that the acknowledge time defaults to null when using the positional constructor.</summary>
    [Fact]
    public void AckTime_DefaultsToNull_OnThePositionalConstructor()
    {
        // Additive-only evolution: every existing positional construction stays valid and
        // reports no ack time. A computed alarm is auto-acked but has no operator ack
        // event, so null (not the timestamp) is the honest value.
        var m = new AlarmStateChanged("inst", "HiAlarm", AlarmState.Active, 700, DateTimeOffset.UnixEpoch);

        Assert.True(m.Condition.Acknowledged);   // computed = auto-acked…
        Assert.Null(m.AckTime);                  // …yet still no ack instant
    }

    /// <summary>Verifies that the acknowledge time round-trips through its init property.</summary>
    [Fact]
    public void AckTime_RoundTripsThroughTheInitProperty()
    {
        var ackedAt = new DateTimeOffset(2026, 8, 1, 12, 0, 0, TimeSpan.Zero);

        var m = new AlarmStateChanged("inst", "Tank01.Level.HiHi", AlarmState.Active, 900, DateTimeOffset.UnixEpoch)
        {
            Kind = AlarmKind.NativeOpcUa,
            AckTime = ackedAt
        };

        Assert.Equal(ackedAt, m.AckTime);
        // `with` (used by the mirror to synthesise a return-to-normal) preserves it.
        Assert.Equal(ackedAt, (m with { State = AlarmState.Normal }).AckTime);
    }
}