using ZB.MOM.WW.ScadaBridge.Commons.Types.Kpi;

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

/// <summary>
/// Tests for <see cref="KpiMetricAggregationCatalog"/> — the gauge-vs-rate
/// classification the hourly rollup fold consults. Covers totality over every
/// metric the four <c>IKpiSampleSource</c> implementations actually emit, the
/// specific Rate set, a gauge sampling, and the unknown-metric default.
/// </summary>
public class KpiMetricAggregationTests
{
    // Every (source, metric) pair emitted by the four sample sources, transcribed
    // from the source code. The catalog must classify all of them (totality).
    public static readonly (string Source, string Metric)[] AllEmittedMetrics =
    {
        // NotificationOutboxKpiSampleSource
        (KpiSources.NotificationOutbox, "queueDepth"),
        (KpiSources.NotificationOutbox, "stuckCount"),
        (KpiSources.NotificationOutbox, "parkedCount"),
        (KpiSources.NotificationOutbox, "deliveredLastInterval"),
        (KpiSources.NotificationOutbox, "oldestPendingAgeSeconds"),

        // SiteCallAuditKpiSampleSource
        (KpiSources.SiteCallAudit, "buffered"),
        (KpiSources.SiteCallAudit, "parked"),
        (KpiSources.SiteCallAudit, "failedLastInterval"),
        (KpiSources.SiteCallAudit, "deliveredLastInterval"),
        (KpiSources.SiteCallAudit, "stuck"),
        (KpiSources.SiteCallAudit, "oldestPendingAgeSeconds"),

        // AuditLogKpiSampleSource
        (KpiSources.AuditLog, "totalEventsLastHour"),
        (KpiSources.AuditLog, "errorEventsLastHour"),
        (KpiSources.AuditLog, "backlogTotal"),

        // SiteHealthKpiSampleSource
        (KpiSources.SiteHealth, "connectionsUp"),
        (KpiSources.SiteHealth, "connectionsDown"),
        (KpiSources.SiteHealth, "scriptErrors"),
        (KpiSources.SiteHealth, "alarmEvalErrors"),
        (KpiSources.SiteHealth, "sfBufferDepth"),
        (KpiSources.SiteHealth, "deadLetters"),
        (KpiSources.SiteHealth, "parkedMessages"),
        (KpiSources.SiteHealth, "deployedInstances"),
        (KpiSources.SiteHealth, "enabledInstances"),
        (KpiSources.SiteHealth, "disabledInstances"),
        (KpiSources.SiteHealth, "auditBacklogPending"),
        (KpiSources.SiteHealth, "eventLogWriteFailures"),
        // Register row 33. Both are instantaneous readings, so both fold as Gauge (the
        // default) — summing an oplog depth per hour would be meaningless, and summing a
        // 0/1 link flag doubly so. Both are CONDITIONALLY emitted: a site that reports no
        // reading writes no sample rather than a fabricated 0.
        (KpiSources.SiteHealth, "localDbOplogBacklog"),
        (KpiSources.SiteHealth, "localDbReplicationConnected"),
    };

    // The (source, metric) pairs that must fold as Rate (sum-per-hour).
    public static readonly (string Source, string Metric)[] RateMetrics =
    {
        (KpiSources.NotificationOutbox, "deliveredLastInterval"),
        (KpiSources.SiteCallAudit, "failedLastInterval"),
        (KpiSources.SiteCallAudit, "deliveredLastInterval"),
        (KpiSources.SiteHealth, "scriptErrors"),
        (KpiSources.SiteHealth, "alarmEvalErrors"),
        (KpiSources.SiteHealth, "deadLetters"),
        (KpiSources.SiteHealth, "eventLogWriteFailures"),
    };

    // A representative sampling of gauges — including the two *LastHour audit
    // metrics that are rolling last-hour gauges, NOT rates (deliberate override).
    public static readonly (string Source, string Metric)[] GaugeSampling =
    {
        (KpiSources.NotificationOutbox, "queueDepth"),
        (KpiSources.NotificationOutbox, "oldestPendingAgeSeconds"),
        (KpiSources.SiteCallAudit, "buffered"),
        (KpiSources.SiteCallAudit, "stuck"),
        (KpiSources.AuditLog, "backlogTotal"),
        (KpiSources.AuditLog, "totalEventsLastHour"),
        (KpiSources.AuditLog, "errorEventsLastHour"),
        (KpiSources.SiteHealth, "connectionsUp"),
        (KpiSources.SiteHealth, "connectionsDown"),
        (KpiSources.SiteHealth, "sfBufferDepth"),
        (KpiSources.SiteHealth, "deployedInstances"),
        (KpiSources.SiteHealth, "localDbOplogBacklog"),
        (KpiSources.SiteHealth, "localDbReplicationConnected"),
    };

    /// <summary>Supplies every emitted source and metric pair as theory data.</summary>
    /// <returns>The theory data rows of source and metric names.</returns>
    public static IEnumerable<object[]> AllEmittedCases() =>
        AllEmittedMetrics.Select(m => new object[] { m.Source, m.Metric });

    /// <summary>Supplies the rate metric source and metric pairs as theory data.</summary>
    /// <returns>The theory data rows of source and metric names.</returns>
    public static IEnumerable<object[]> RateCases() =>
        RateMetrics.Select(m => new object[] { m.Source, m.Metric });

    /// <summary>Supplies the gauge-sampled source and metric pairs as theory data.</summary>
    /// <returns>The theory data rows of source and metric names.</returns>
    public static IEnumerable<object[]> GaugeCases() =>
        GaugeSampling.Select(m => new object[] { m.Source, m.Metric });

    /// <summary>Verifies that every emitted metric resolves to a defined aggregation.</summary>
    /// <param name="source">The KPI source name.</param>
    /// <param name="metric">The metric name.</param>
    [Theory]
    [MemberData(nameof(AllEmittedCases))]
    public void Resolve_EveryEmittedMetric_ReturnsDefinedAggregation(string source, string metric)
    {
        var result = KpiMetricAggregationCatalog.Resolve(source, metric);

        Assert.True(
            result is KpiRollupAggregation.Gauge or KpiRollupAggregation.Rate,
            $"({source}, {metric}) resolved to an undefined aggregation: {result}");
    }

    /// <summary>Verifies that rate metrics are classified as rate.</summary>
    /// <param name="source">The KPI source name.</param>
    /// <param name="metric">The metric name.</param>
    [Theory]
    [MemberData(nameof(RateCases))]
    public void Resolve_RateMetrics_ClassifiedAsRate(string source, string metric)
    {
        Assert.Equal(KpiRollupAggregation.Rate, KpiMetricAggregationCatalog.Resolve(source, metric));
    }

    /// <summary>Verifies that gauge-sampled metrics are classified as gauge.</summary>
    /// <param name="source">The KPI source name.</param>
    /// <param name="metric">The metric name.</param>
    [Theory]
    [MemberData(nameof(GaugeCases))]
    public void Resolve_GaugeSampling_ClassifiedAsGauge(string source, string metric)
    {
        Assert.Equal(KpiRollupAggregation.Gauge, KpiMetricAggregationCatalog.Resolve(source, metric));
    }

    /// <summary>Verifies that last-hour audit metrics resolve as gauges rather than rates.</summary>
    [Fact]
    public void Resolve_LastHourAuditMetrics_AreGaugeNotRate()
    {
        // Rolling trailing-one-hour counts: last-value-per-hour is correct; summing
        // 60 overlapping minute samples would ~60x over-count. Guard the decision.
        Assert.Equal(
            KpiRollupAggregation.Gauge,
            KpiMetricAggregationCatalog.Resolve(KpiSources.AuditLog, "totalEventsLastHour"));
        Assert.Equal(
            KpiRollupAggregation.Gauge,
            KpiMetricAggregationCatalog.Resolve(KpiSources.AuditLog, "errorEventsLastHour"));
    }

    /// <summary>Verifies that an unknown metric defaults to a gauge.</summary>
    /// <param name="source">The KPI source name.</param>
    /// <param name="metric">The metric name.</param>
    [Theory]
    [InlineData(KpiSources.NotificationOutbox, "someBrandNewMetricAddedLater")]
    [InlineData("AnEntirelyNewSource", "anyMetric")]
    [InlineData(KpiSources.SiteHealth, "")]
    public void Resolve_UnknownMetric_DefaultsToGauge(string source, string metric)
    {
        // The fold must never crash on a metric added after this catalog was updated;
        // Gauge (last-value) is the safe, non-fabricating default.
        Assert.Equal(KpiRollupAggregation.Gauge, KpiMetricAggregationCatalog.Resolve(source, metric));
    }

    /// <summary>Verifies that the same metric name under a different source is keyed on the source and metric pair.</summary>
    [Fact]
    public void Resolve_SameMetricNameDifferentSource_KeysOnSourcePair()
    {
        // deliveredLastInterval is Rate under both sources here, but the point is the
        // API keys on (source, metric) rather than metric alone — both resolve.
        Assert.Equal(
            KpiRollupAggregation.Rate,
            KpiMetricAggregationCatalog.Resolve(KpiSources.NotificationOutbox, "deliveredLastInterval"));
        Assert.Equal(
            KpiRollupAggregation.Rate,
            KpiMetricAggregationCatalog.Resolve(KpiSources.SiteCallAudit, "deliveredLastInterval"));
    }

    // ---- Catalog metric literals promoted to shared KpiMetrics constants (R4) ----

    /// <summary>Verifies that the promoted metric constants lock the historical persisted values.</summary>
    [Fact]
    public void PromotedMetricConstants_LockHistoricalPersistedValues()
    {
        // Persisted data contract — these are symbol promotions, NOT renames.
        Assert.Equal("deliveredLastInterval", KpiMetrics.SiteCallAudit.DeliveredLastInterval);
        Assert.Equal("alarmEvalErrors", KpiMetrics.SiteHealth.AlarmEvalErrors);
        Assert.Equal("eventLogWriteFailures", KpiMetrics.SiteHealth.EventLogWriteFailures);
    }

    /// <summary>Verifies that the promoted rate pairs still classify as rate.</summary>
    /// <param name="source">The KPI source name.</param>
    /// <param name="metric">The metric name.</param>
    [Theory]
    [InlineData(KpiSources.SiteCallAudit, KpiMetrics.SiteCallAudit.DeliveredLastInterval)]
    [InlineData(KpiSources.SiteHealth, KpiMetrics.SiteHealth.AlarmEvalErrors)]
    [InlineData(KpiSources.SiteHealth, KpiMetrics.SiteHealth.EventLogWriteFailures)]
    public void Resolve_PromotedRatePairs_StillClassifyAsRate(string source, string metric)
        => Assert.Equal(KpiRollupAggregation.Rate, KpiMetricAggregationCatalog.Resolve(source, metric));
}