using ZB.MOM.WW.Audit;
using ZB.MOM.WW.ScadaBridge.Commons.Types.Audit;
using ZB.MOM.WW.ScadaBridge.Commons.Types.Debugging;
using ZB.MOM.WW.ScadaBridge.Commons.Types.Enums;

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

/// <summary>
/// Flow Debugger design 2026-09-05 §7.2: lane/edge/boundary rules over a Delmia-shaped
/// event list, truncation pass-through, and total-ness on unknown kinds.
/// </summary>
public class FlowGraphBuilderTests
{
    private static readonly DateTime T0 = new(2026, 9, 5, 12, 0, 0, DateTimeKind.Utc);
    private static readonly Guid Root = Guid.NewGuid();
    private static readonly Guid SiteRun = Guid.NewGuid();
    private static readonly Guid Cascade = Guid.NewGuid();

    /// <summary>Inbound → RouteCall → site ScriptRun → write → wait → write, plus a value-change ScriptRun spawned by the second write.</summary>
    private static List<AuditEvent> DelmiaShaped()
    {
        var inbound = ScadaBridgeAuditEventFactory.Create(AuditChannel.ApiInbound, AuditKind.InboundRequest, AuditStatus.Delivered,
            occurredAtUtc: T0, actor: "delmia-key", target: "DelmiaRecipeDownload", sourceNode: "central-a",
            executionId: Root, durationMs: 900, requestSummary: "{\"MachineCode\":\"M1\"}", responseSummary: "{\"ok\":true}");
        var route = ScadaBridgeAuditEventFactory.Create(AuditChannel.ScriptTrace, AuditKind.RouteCall, AuditStatus.Delivered,
            occurredAtUtc: T0.AddMilliseconds(10), actor: "inbound-api", target: "M1.ProcessRecipeDownload", sourceNode: "central-a",
            executionId: Root, durationMs: 850, extra: new ScriptTraceExtra { ChildExecutionId = SiteRun }.ToJson());
        var run = ScadaBridgeAuditEventFactory.Create(AuditChannel.ScriptTrace, AuditKind.ScriptRun, AuditStatus.Delivered,
            occurredAtUtc: T0.AddMilliseconds(20), actor: "ProcessRecipeDownload", target: "ProcessRecipeDownload", sourceNode: "node-a",
            executionId: SiteRun, parentExecutionId: Root, sourceSiteId: "site-a", sourceInstanceId: "M1", durationMs: 800,
            extra: new ScriptTraceExtra { TriggerKind = "call" }.ToJson());
        var write1 = ScadaBridgeAuditEventFactory.Create(AuditChannel.ScriptTrace, AuditKind.AttributeWrite, AuditStatus.Delivered,
            occurredAtUtc: T0.AddMilliseconds(30), actor: "ProcessRecipeDownload", target: "DelmiaReceiver.RecipePath", sourceNode: "node-a",
            executionId: SiteRun, parentExecutionId: Root, sourceSiteId: "site-a", sourceInstanceId: "M1", durationMs: 5,
            extra: new ScriptTraceExtra { Writes = [new AttributeWriteDetail("DelmiaReceiver.RecipePath", "C:\\r.nc", true, null)] }.ToJson());
        var wait = ScadaBridgeAuditEventFactory.Create(AuditChannel.ScriptTrace, AuditKind.AttributeWait, AuditStatus.Delivered,
            occurredAtUtc: T0.AddMilliseconds(40), actor: "ProcessRecipeDownload", target: "DelmiaReceiver.Processed", sourceNode: "node-a",
            executionId: SiteRun, parentExecutionId: Root, sourceSiteId: "site-a", sourceInstanceId: "M1", durationMs: 700,
            extra: new ScriptTraceExtra { WaitAttribute = "DelmiaReceiver.Processed", WaitOutcome = "satisfied", ObservedValue = "true" }.ToJson());
        var write2 = ScadaBridgeAuditEventFactory.Create(AuditChannel.ScriptTrace, AuditKind.AttributeWrite, AuditStatus.Delivered,
            occurredAtUtc: T0.AddMilliseconds(750), actor: "ProcessRecipeDownload", target: "DelmiaReceiver.Trigger", sourceNode: "node-a",
            executionId: SiteRun, parentExecutionId: Root, sourceSiteId: "site-a", sourceInstanceId: "M1", durationMs: 3,
            extra: new ScriptTraceExtra { Writes = [new AttributeWriteDetail("DelmiaReceiver.Trigger", "false", true, null)] }.ToJson());
        var cascade = ScadaBridgeAuditEventFactory.Create(AuditChannel.ScriptTrace, AuditKind.ScriptRun, AuditStatus.Delivered,
            occurredAtUtc: T0.AddMilliseconds(760), actor: "OnTriggerReset", target: "OnTriggerReset", sourceNode: "node-a",
            executionId: Cascade, parentExecutionId: SiteRun, sourceSiteId: "site-a", sourceInstanceId: "M1", durationMs: 10,
            extra: new ScriptTraceExtra { TriggerKind = "valuechange", TriggerAttribute = "DelmiaReceiver.Trigger", TriggerValue = "false" }.ToJson());

        // Deliberately shuffled WITHIN each execution: the builder must order by time inside one execution.
        // The executions themselves are given in emission order (root, site run, cascade) — since arch-review
        // F5 that is what fixes their relative order, because they do not share a clock.
        return [inbound, route, wait, run, write2, write1, cascade];
    }

    [Fact]
    public void DelmiaShape_ProjectsLanes_Edges_AndSynthesizedResponse()
    {
        var graph = FlowGraphBuilder.Build(DelmiaShaped());

        Assert.False(graph.Predicted);
        Assert.False(graph.Truncated);
        Assert.Equal(8, graph.Steps.Count); // 7 events + synthesized Response

        var kinds = graph.Steps.Select(s => s.Kind).ToArray();
        Assert.Equal(
            new[]
            {
                FlowStepKind.InboundRequest, FlowStepKind.RouteCall, FlowStepKind.ScriptRun, FlowStepKind.AttributeWrite,
                FlowStepKind.AttributeWait, FlowStepKind.AttributeWrite, FlowStepKind.ScriptRun, FlowStepKind.Response,
            },
            kinds);

        Assert.Equal(FlowLane.Central, graph.Steps[0].Lane);
        Assert.Equal(FlowLane.Central, graph.Steps[1].Lane);
        Assert.Equal(FlowLane.Site, graph.Steps[2].Lane);
        Assert.Equal(FlowLane.Tags, graph.Steps[3].Lane);
        Assert.Equal(FlowLane.Site, graph.Steps[4].Lane);
        Assert.Equal(FlowLane.Tags, graph.Steps[5].Lane);
        Assert.Equal(FlowLane.Site, graph.Steps[6].Lane);
        Assert.Equal(FlowLane.Central, graph.Steps[7].Lane);

        // Exactly one boundary crossing: route → site run. The Response links from the RouteCall (D9), Central → Central.
        var crossing = Assert.Single(graph.Edges, e => e.CrossesBoundary);
        Assert.Equal(graph.Steps[1].EventId, crossing.FromEventId);
        Assert.Equal(graph.Steps[2].EventId, crossing.ToEventId);
        Assert.Contains(graph.Edges, e => e.FromEventId == graph.Steps[1].EventId && e.ToEventId == graph.Steps[7].EventId && !e.CrossesBoundary);
        Assert.DoesNotContain(graph.Edges, e => e.FromEventId == graph.Steps[6].EventId && e.ToEventId == graph.Steps[7].EventId);

        // One inferred echo edge: first write → satisfied wait.
        var external = Assert.Single(graph.Edges, e => e.External);
        Assert.Equal(graph.Steps[3].EventId, external.FromEventId);
        Assert.Equal(graph.Steps[4].EventId, external.ToEventId);

        // The cascade run hangs off the write that spawned it (same site, no boundary) — a Spawn edge (D9);
        // the route → run edge and every in-chain edge are not.
        var spawn = Assert.Single(graph.Edges, e => e.Spawn);
        Assert.Equal(graph.Steps[5].EventId, spawn.FromEventId);
        Assert.Equal(graph.Steps[6].EventId, spawn.ToEventId);
        Assert.False(spawn.CrossesBoundary);
        Assert.Contains(graph.Edges, e => e.FromEventId == graph.Steps[1].EventId && e.ToEventId == graph.Steps[2].EventId && !e.Spawn);
        Assert.DoesNotContain(graph.Edges, e => e.Async);

        // Inbound → route call chained inside the root execution.
        Assert.Contains(graph.Edges, e => e.FromEventId == graph.Steps[0].EventId && e.ToEventId == graph.Steps[1].EventId);

        // Projection detail.
        Assert.Equal("→ " + SiteRun.ToString("D")[..8], graph.Steps[1].Subtitle);
        Assert.Equal("M1 · call", graph.Steps[2].Subtitle);
        Assert.Equal("DelmiaReceiver.RecipePath = C:\\r.nc", graph.Steps[3].Subtitle);
        Assert.Equal("satisfied · true", graph.Steps[4].Subtitle);
        Assert.Equal("{\"ok\":true}", graph.Steps[7].OutputJson);
        Assert.All(graph.Steps, s => Assert.Equal(FlowStepOutcome.Ok, s.Outcome));
    }

    [Fact]
    public void Build_IsDeterministic_ResponseIdIsStable()
    {
        var events = DelmiaShaped();
        var a = FlowGraphBuilder.Build(events);
        var b = FlowGraphBuilder.Build(events);
        Assert.Equal(a.Steps.Select(s => s.EventId), b.Steps.Select(s => s.EventId));
        Assert.Equal(a.Edges, b.Edges);
    }

    [Fact]
    public void Truncated_PassesThrough()
    {
        Assert.True(FlowGraphBuilder.Build(DelmiaShaped(), truncated: true).Truncated);
        Assert.True(FlowGraphBuilder.Build(Array.Empty<AuditEvent>(), truncated: true).Truncated);
        Assert.Empty(FlowGraphBuilder.Build(Array.Empty<AuditEvent>()).Steps);
    }

    [Fact]
    public void UnknownKind_ProjectsToUnknown_NeverThrows()
    {
        var weird = new AuditEvent
        {
            EventId = Guid.NewGuid(),
            OccurredAtUtc = T0,
            Actor = "x",
            Action = "Future.Thing",
            Outcome = AuditOutcome.Success,
            DetailsJson = "{\"channel\":\"Future\",\"kind\":\"Thing\",\"extra\":\"not json at all\"}",
        };
        var garbage = new AuditEvent
        {
            EventId = Guid.NewGuid(),
            OccurredAtUtc = T0,
            Actor = "x",
            Action = "?",
            Outcome = AuditOutcome.Failure,
            DetailsJson = "{{{",
        };

        var graph = FlowGraphBuilder.Build([weird, garbage]);

        Assert.Equal(2, graph.Steps.Count);
        Assert.All(graph.Steps, s => Assert.Equal(FlowStepKind.Unknown, s.Kind));
        Assert.All(graph.Steps, s => Assert.Null(s.Extra));
        Assert.Empty(graph.Edges);
    }

    [Fact]
    public void FailedScriptRun_WithTimeoutMessage_IsTimedOut()
    {
        var run = ScadaBridgeAuditEventFactory.Create(AuditChannel.ScriptTrace, AuditKind.ScriptRun, AuditStatus.Failed,
            occurredAtUtc: T0, target: "S", executionId: SiteRun, errorMessage: "Script timed out after 30s");
        var write = ScadaBridgeAuditEventFactory.Create(AuditChannel.ScriptTrace, AuditKind.AttributeWrite, AuditStatus.Failed,
            occurredAtUtc: T0.AddMilliseconds(1), target: "A", executionId: SiteRun, errorMessage: "rejected");

        var graph = FlowGraphBuilder.Build([run, write]);

        Assert.Equal(FlowStepOutcome.TimedOut, graph.Steps[0].Outcome);
        Assert.Equal(FlowStepOutcome.Failed, graph.Steps[1].Outcome);
        Assert.Single(graph.Edges);
    }

    [Fact]
    public void ScriptTraceExtra_RoundTrips_CamelCase_AndIgnoresUnknownMembers()
    {
        var extra = new ScriptTraceExtra { ChildExecutionId = SiteRun, WaitTimeoutMs = 1500, Source = "flow-debugger" };
        var json = extra.ToJson();
        Assert.Contains("\"childExecutionId\"", json);
        Assert.DoesNotContain("triggerKind", json);

        var back = ScriptTraceExtra.TryParse(json.Insert(1, "\"futureField\":1,"));
        Assert.Equal(extra, back);
        Assert.Null(ScriptTraceExtra.TryParse(null));
        Assert.Null(ScriptTraceExtra.TryParse("nope"));
    }

    // ---- Outbound calls (2026-09-06 plan, Task 2) --------------------------------------------

    private static AuditEvent SiteRunRow(int ms, Guid executionId = default) => ScadaBridgeAuditEventFactory.Create(
        AuditChannel.ScriptTrace, AuditKind.ScriptRun, AuditStatus.Delivered,
        occurredAtUtc: T0.AddMilliseconds(ms), actor: "S", target: "S", sourceNode: "node-a",
        executionId: executionId == default ? SiteRun : executionId, sourceSiteId: "site-a", sourceInstanceId: "M1", durationMs: 800,
        extra: new ScriptTraceExtra { TriggerKind = "call" }.ToJson());

    private static AuditEvent WriteRow(int ms, string attr) => ScadaBridgeAuditEventFactory.Create(
        AuditChannel.ScriptTrace, AuditKind.AttributeWrite, AuditStatus.Delivered,
        occurredAtUtc: T0.AddMilliseconds(ms), actor: "S", target: attr, sourceNode: "node-a",
        executionId: SiteRun, sourceSiteId: "site-a", sourceInstanceId: "M1", durationMs: 2,
        extra: new ScriptTraceExtra { Writes = [new AttributeWriteDetail(attr, "1", true, null)] }.ToJson());

    private static AuditEvent Outbound(AuditChannel channel, AuditKind kind, AuditStatus status, int ms, Guid? correlation, string target,
        string node = "node-a", string? error = null, int? durationMs = null, string? request = null, string? response = null)
        => ScadaBridgeAuditEventFactory.Create(channel, kind, status,
            occurredAtUtc: T0.AddMilliseconds(ms), actor: "S", target: target, sourceNode: node, correlationId: correlation,
            executionId: SiteRun, sourceSiteId: "site-a", sourceInstanceId: "M1", errorMessage: error, durationMs: durationMs,
            requestSummary: request, responseSummary: response);

    [Fact]
    public void CachedApiCall_FourRows_FoldIntoOneAsyncNode()
    {
        var corr = Guid.NewGuid();
        var events = new List<AuditEvent>
        {
            SiteRunRow(20),
            WriteRow(30, "A"),
            Outbound(AuditChannel.ApiOutbound, AuditKind.CachedSubmit, AuditStatus.Submitted, 35, corr, "Delmia.AckRecipe", request: "{\"id\":1}"),
            WriteRow(40, "B"),
            Outbound(AuditChannel.ApiOutbound, AuditKind.ApiCallCached, AuditStatus.Forwarded, 2000, corr, "Delmia.AckRecipe"),
            Outbound(AuditChannel.ApiOutbound, AuditKind.ApiCallCached, AuditStatus.Attempted, 3000, corr, "Delmia.AckRecipe", error: "503", durationMs: 40),
            Outbound(AuditChannel.ApiOutbound, AuditKind.CachedResolve, AuditStatus.Delivered, 4135, corr, "Delmia.AckRecipe", response: "{\"ok\":true}"),
        };

        var graph = FlowGraphBuilder.Build(events);

        Assert.Equal(4, graph.Steps.Count);
        var api = Assert.Single(graph.Steps, s => s.Kind == FlowStepKind.ApiCall);
        Assert.Equal(FlowLane.External, api.Lane);
        Assert.Equal(events[2].EventId, api.EventId);
        Assert.Equal(T0.AddMilliseconds(35), api.OccurredAtUtc.UtcDateTime);
        Assert.Equal(4, api.Lifecycle!.Count);
        Assert.Equal(new[] { "CachedSubmit", "ApiCallCached", "ApiCallCached", "CachedResolve" }, api.Lifecycle.Select(r => r.Kind));
        Assert.Equal(corr, api.CorrelationId);
        Assert.Equal("503", api.Lifecycle[2].ErrorMessage);
        Assert.Equal(FlowStepOutcome.Ok, api.Outcome);
        Assert.Equal(4100, api.DurationMs);
        Assert.Equal("{\"id\":1}", api.InputJson);
        Assert.Equal("{\"ok\":true}", api.OutputJson);
        Assert.Equal("Delivered · cached", api.Subtitle);
        Assert.Null(api.ErrorMessage);
        Assert.Equal(SiteRun, api.ExecutionId);

        var run = graph.Steps[0]; var w1 = graph.Steps[1]; var w2 = graph.Steps[3];
        Assert.Equal(new[] { FlowStepKind.ScriptRun, FlowStepKind.AttributeWrite, FlowStepKind.ApiCall, FlowStepKind.AttributeWrite },
            graph.Steps.Select(s => s.Kind));
        var async = Assert.Single(graph.Edges, e => e.Async);
        Assert.Equal(w1.EventId, async.FromEventId);
        Assert.Equal(api.EventId, async.ToEventId);
        Assert.Contains(graph.Edges, e => e.FromEventId == run.EventId && e.ToEventId == w1.EventId && !e.Async);
        Assert.Contains(graph.Edges, e => e.FromEventId == w1.EventId && e.ToEventId == w2.EventId && !e.Async);
        Assert.DoesNotContain(graph.Edges, e => e.FromEventId == api.EventId);
        Assert.Equal(3, graph.Edges.Count);
    }

    [Fact]
    public void SyncApiCall_SitsInChain_NoAsyncEdge()
    {
        var events = new List<AuditEvent>
        {
            SiteRunRow(20),
            WriteRow(30, "A"),
            Outbound(AuditChannel.ApiOutbound, AuditKind.ApiCall, AuditStatus.Delivered, 35, null, "Delmia.AckRecipe", durationMs: 212),
            WriteRow(40, "B"),
        };

        var graph = FlowGraphBuilder.Build(events);

        var api = Assert.Single(graph.Steps, s => s.Kind == FlowStepKind.ApiCall);
        Assert.Equal(212, api.DurationMs);
        Assert.Single(api.Lifecycle!);
        Assert.Equal("Delivered · sync", api.Subtitle);
        Assert.DoesNotContain(graph.Edges, e => e.Async);
        Assert.Contains(graph.Edges, e => e.FromEventId == graph.Steps[1].EventId && e.ToEventId == api.EventId);
        Assert.Contains(graph.Edges, e => e.FromEventId == api.EventId && e.ToEventId == graph.Steps[3].EventId);
        Assert.DoesNotContain(graph.Edges, e => e.FromEventId == graph.Steps[1].EventId && e.ToEventId == graph.Steps[3].EventId);
    }

    [Fact]
    public void TwoSyncCalls_NullCorrelation_AreNotFoldedTogether()
    {
        var events = new List<AuditEvent>
        {
            SiteRunRow(20),
            Outbound(AuditChannel.DbOutbound, AuditKind.DbWrite, AuditStatus.Delivered, 30, null, "MesDb"),
            Outbound(AuditChannel.DbOutbound, AuditKind.DbWrite, AuditStatus.Failed, 40, null, "MesDb", error: "deadlock"),
        };

        var graph = FlowGraphBuilder.Build(events);

        Assert.Equal(2, graph.Steps.Count(s => s.Kind == FlowStepKind.DbCall));
        Assert.Equal(FlowStepOutcome.Failed, graph.Steps[2].Outcome);
        Assert.Equal(2, graph.Edges.Count);
    }

    [Fact]
    public void NotifySend_PlusCentralDeliverParked_FoldsIntoOneParkedNotifyNode()
    {
        var notificationId = Guid.NewGuid();
        var events = new List<AuditEvent>
        {
            SiteRunRow(20),
            WriteRow(30, "A"),
            Outbound(AuditChannel.Notification, AuditKind.NotifySend, AuditStatus.Submitted, 35, notificationId, "Planners", request: "{\"subject\":\"hi\"}"),
            Outbound(AuditChannel.Notification, AuditKind.NotifyDeliver, AuditStatus.Attempted, 5000, notificationId, "Planners", node: "central-a", error: "smtp down", durationMs: 30),
            Outbound(AuditChannel.Notification, AuditKind.NotifyDeliver, AuditStatus.Parked, 9000, notificationId, "Planners", node: "central-a", error: "retries exhausted"),
        };

        var graph = FlowGraphBuilder.Build(events);

        var notify = Assert.Single(graph.Steps, s => s.Kind == FlowStepKind.Notify);
        Assert.Equal(FlowStepOutcome.Parked, notify.Outcome);
        Assert.Equal(3, notify.Lifecycle!.Count);
        Assert.Equal("central-a", notify.Lifecycle[2].Node);
        Assert.Equal("retries exhausted", notify.ErrorMessage);
        Assert.Equal(8965, notify.DurationMs);
        Assert.Equal("Parked", notify.Subtitle);
        Assert.Equal("node-a", notify.Node);
        var async = Assert.Single(graph.Edges, e => e.Async);
        Assert.Equal(graph.Steps[1].EventId, async.FromEventId);
        Assert.Equal(notify.EventId, async.ToEventId);
    }

    [Fact]
    public void CachedSubmitOnly_IsPending_WithNoDuration()
    {
        var events = new List<AuditEvent>
        {
            SiteRunRow(20),
            Outbound(AuditChannel.DbOutbound, AuditKind.CachedSubmit, AuditStatus.Submitted, 35, Guid.NewGuid(), "MesDb"),
        };

        var graph = FlowGraphBuilder.Build(events);

        var db = Assert.Single(graph.Steps, s => s.Kind == FlowStepKind.DbCall);
        Assert.Equal(FlowStepOutcome.Pending, db.Outcome);
        Assert.Null(db.DurationMs);
        Assert.Single(db.Lifecycle!);
        var async = Assert.Single(graph.Edges);
        Assert.True(async.Async);
        Assert.Equal(graph.Steps[0].EventId, async.FromEventId);
    }

    [Fact]
    public void ResponseLinksFromTheInboundExecutionsLastStep_NotTheLastCascadedStep()
    {
        var events = DelmiaShaped();
        var graph = FlowGraphBuilder.Build(events);
        var response = Assert.Single(graph.Steps, s => s.Kind == FlowStepKind.Response);
        var into = Assert.Single(graph.Edges, e => e.ToEventId == response.EventId);
        Assert.Equal(graph.Steps[1].EventId, into.FromEventId);
        Assert.Equal(FlowStepKind.RouteCall, graph.Steps[1].Kind);
    }

    [Fact]
    public void ResponseFallsBackToTheInboundRow_WhenNothingElseSharesItsExecution()
    {
        var inbound = ScadaBridgeAuditEventFactory.Create(AuditChannel.ApiInbound, AuditKind.InboundRequest, AuditStatus.Delivered,
            occurredAtUtc: T0, actor: "k", target: "Ping", sourceNode: "central-a", executionId: Root, durationMs: 5, responseSummary: "{}");
        var graph = FlowGraphBuilder.Build([inbound]);
        Assert.Equal(2, graph.Steps.Count);
        var edge = Assert.Single(graph.Edges);
        Assert.Equal(graph.Steps[0].EventId, edge.FromEventId);
        Assert.Equal(graph.Steps[1].EventId, edge.ToEventId);
    }

    // ---- Arch-review F5: emission order between executions, timestamps within one ------------

    /// <summary>
    /// Central and site clocks differ. The four rows are given in EMISSION order (the Live path's
    /// collector order); the graph must keep the executions in that order whichever way the skew runs.
    /// </summary>
    private static List<AuditEvent> SkewedRouteShape(int siteSkewMs)
    {
        var inbound = ScadaBridgeAuditEventFactory.Create(AuditChannel.ApiInbound, AuditKind.InboundRequest, AuditStatus.Delivered,
            occurredAtUtc: T0, actor: "k", target: "M", sourceNode: "central-a", executionId: Root, durationMs: 900,
            requestSummary: "{}", responseSummary: "{\"ok\":true}");
        var route = ScadaBridgeAuditEventFactory.Create(AuditChannel.ScriptTrace, AuditKind.RouteCall, AuditStatus.Delivered,
            occurredAtUtc: T0.AddMilliseconds(50), target: "M1.S", sourceNode: "central-a", executionId: Root,
            extra: new ScriptTraceExtra { ChildExecutionId = SiteRun }.ToJson());
        var run = ScadaBridgeAuditEventFactory.Create(AuditChannel.ScriptTrace, AuditKind.ScriptRun, AuditStatus.Delivered,
            occurredAtUtc: T0.AddMilliseconds(siteSkewMs), actor: "S", target: "S", sourceNode: "node-a",
            executionId: SiteRun, parentExecutionId: Root, sourceSiteId: "site-a", sourceInstanceId: "M1", durationMs: 20,
            extra: new ScriptTraceExtra { TriggerKind = "call" }.ToJson());
        var write = ScadaBridgeAuditEventFactory.Create(AuditChannel.ScriptTrace, AuditKind.AttributeWrite, AuditStatus.Delivered,
            occurredAtUtc: T0.AddMilliseconds(siteSkewMs + 10), actor: "S", target: "A", sourceNode: "node-a",
            executionId: SiteRun, parentExecutionId: Root, sourceSiteId: "site-a", sourceInstanceId: "M1", durationMs: 2,
            extra: new ScriptTraceExtra { Writes = [new AttributeWriteDetail("A", "1", true, null)] }.ToJson());
        return [inbound, route, run, write];
    }

    [Fact]
    public void SiteClockAhead_SiteStepsStillFollowTheirRouteCall_AndPrecedeResponse()
    {
        var events = SkewedRouteShape(siteSkewMs: 2000); // site 2 s ahead of central
        var graph = FlowGraphBuilder.Build(events);

        Assert.Equal(
            new[]
            {
                FlowStepKind.InboundRequest, FlowStepKind.RouteCall, FlowStepKind.ScriptRun,
                FlowStepKind.AttributeWrite, FlowStepKind.Response,
            },
            graph.Steps.Select(s => s.Kind));
        Assert.Equal(events.Select(e => e.EventId), graph.Steps.Take(4).Select(s => s.EventId));
        // The Response time still comes off the inbound row's own clock (inbound + DurationMs).
        Assert.Equal(T0.AddMilliseconds(900), graph.Steps[4].OccurredAtUtc.UtcDateTime);
    }

    [Fact]
    public void SiteClockBehind_SiteStepsDoNotSortAheadOfTheInboundRequest()
    {
        var events = SkewedRouteShape(siteSkewMs: -2000); // site 2 s behind central
        var graph = FlowGraphBuilder.Build(events);

        Assert.Equal(
            new[]
            {
                FlowStepKind.InboundRequest, FlowStepKind.RouteCall, FlowStepKind.ScriptRun,
                FlowStepKind.AttributeWrite, FlowStepKind.Response,
            },
            graph.Steps.Select(s => s.Kind));
        Assert.Equal(events.Select(e => e.EventId), graph.Steps.Take(4).Select(s => s.EventId));
    }

    [Fact]
    public void SiteClockBehind_TriggerCascade_SpawnsFromTheLastParentStep_NotTheFirst()
    {
        // Mixed-version shape: no RouteCall row, so the spawner is found by position, and a site
        // clock behind central used to push every parent step "after" the child → parentChain[0].
        var inbound = ScadaBridgeAuditEventFactory.Create(AuditChannel.ApiInbound, AuditKind.InboundRequest, AuditStatus.Delivered,
            occurredAtUtc: T0, actor: "k", target: "M", sourceNode: "central-a", executionId: Root, durationMs: 900);
        var centralDb = ScadaBridgeAuditEventFactory.Create(AuditChannel.DbOutbound, AuditKind.DbWrite, AuditStatus.Delivered,
            occurredAtUtc: T0.AddMilliseconds(10), actor: "api:M", target: "CfgDb", sourceNode: "central-a", executionId: Root);
        var run = ScadaBridgeAuditEventFactory.Create(AuditChannel.ScriptTrace, AuditKind.ScriptRun, AuditStatus.Delivered,
            occurredAtUtc: T0.AddMilliseconds(-2000), actor: "S", target: "S", sourceNode: "node-a",
            executionId: SiteRun, parentExecutionId: Root, sourceSiteId: "site-a", sourceInstanceId: "M1", durationMs: 20,
            extra: new ScriptTraceExtra { TriggerKind = "call" }.ToJson());

        var graph = FlowGraphBuilder.Build([inbound, centralDb, run]);

        var spawn = Assert.Single(graph.Edges, e => e.Spawn);
        Assert.Equal(centralDb.EventId, spawn.FromEventId); // the LAST parent step, not the inbound row
        Assert.Equal(run.EventId, spawn.ToEventId);
    }

    [Fact]
    public void SameClock_TriggerCascade_SpawnsFromTheWriteThatFiredIt_NotTheParentsLastStep()
    {
        // Review follow-up: executions are contiguous blocks, so "the last parent step BEFORE the child
        // in display order" is always the parent's last step. Parent and child of a cascade share the
        // SITE clock, so the write that fired the trigger is the last parent step at or before the child.
        var run = SiteRunRow(0);
        var writeA = WriteRow(10, "DelmiaReceiver.Trigger");
        var wait = ScadaBridgeAuditEventFactory.Create(AuditChannel.ScriptTrace, AuditKind.AttributeWait, AuditStatus.Delivered,
            occurredAtUtc: T0.AddMilliseconds(20), actor: "S", target: "DelmiaReceiver.Processed", sourceNode: "node-a",
            executionId: SiteRun, sourceSiteId: "site-a", sourceInstanceId: "M1", durationMs: 5,
            extra: new ScriptTraceExtra { WaitAttribute = "DelmiaReceiver.Processed", WaitOutcome = "satisfied" }.ToJson());
        var writeB = WriteRow(30, "DelmiaReceiver.Ack");
        var cascade = ScadaBridgeAuditEventFactory.Create(AuditChannel.ScriptTrace, AuditKind.ScriptRun, AuditStatus.Delivered,
            occurredAtUtc: T0.AddMilliseconds(15), actor: "OnTrigger", target: "OnTrigger", sourceNode: "node-a",
            executionId: Cascade, parentExecutionId: SiteRun, sourceSiteId: "site-a", sourceInstanceId: "M1", durationMs: 4,
            extra: new ScriptTraceExtra { TriggerKind = "valuechange", TriggerAttribute = "DelmiaReceiver.Trigger" }.ToJson());

        var graph = FlowGraphBuilder.Build([run, writeA, wait, writeB, cascade]);

        var spawn = Assert.Single(graph.Edges, e => e.Spawn);
        Assert.Equal(writeA.EventId, spawn.FromEventId);
        Assert.Equal(cascade.EventId, spawn.ToEventId);
    }

    [Fact]
    public void SimultaneousWrites_TriggerCascade_SpawnsFromTheWriteOfTheTriggerAttribute_NotTheLastWrite()
    {
        // Rig 2026-09-08: a run wrote Result, ResultText, Flag=false and Processed inside the same millisecond,
        // and the value-change child (trigger attribute Flag) was drawn spawning from Processed — the last write
        // at or before the child. The child names its trigger attribute, so that write wins outright.
        var run = SiteRunRow(0);
        var result = WriteRow(10, "DelmiaReceiver.Result");
        var flag = WriteRow(10, "DelmiaReceiver.Flag");
        var processed = WriteRow(10, "DelmiaReceiver.Processed");
        var cascade = ScadaBridgeAuditEventFactory.Create(AuditChannel.ScriptTrace, AuditKind.ScriptRun, AuditStatus.Delivered,
            occurredAtUtc: T0.AddMilliseconds(10), actor: "OnFlag", target: "OnFlag", sourceNode: "node-a",
            executionId: Cascade, parentExecutionId: SiteRun, sourceSiteId: "site-a", sourceInstanceId: "M1", durationMs: 3,
            extra: new ScriptTraceExtra { TriggerKind = "valuechange", TriggerAttribute = "delmiareceiver.flag" }.ToJson());

        var graph = FlowGraphBuilder.Build([run, result, flag, processed, cascade]);

        var spawn = Assert.Single(graph.Edges, e => e.Spawn);
        Assert.Equal(flag.EventId, spawn.FromEventId);
        Assert.Equal(cascade.EventId, spawn.ToEventId);
    }

    [Fact]
    public void TriggerCascade_WhoseAttributeTheParentNeverWrote_FallsBackToTheTimeRule()
    {
        // The device echo of a DCL-sourced change, or a trace from an older site that names an attribute
        // the parent chain has no write for: the attribute rule finds nothing and the time rule still applies.
        var run = SiteRunRow(0);
        var writeA = WriteRow(10, "DelmiaReceiver.A");
        var writeB = WriteRow(30, "DelmiaReceiver.B");
        var cascade = ScadaBridgeAuditEventFactory.Create(AuditChannel.ScriptTrace, AuditKind.ScriptRun, AuditStatus.Delivered,
            occurredAtUtc: T0.AddMilliseconds(15), actor: "OnX", target: "OnX", sourceNode: "node-a",
            executionId: Cascade, parentExecutionId: SiteRun, sourceSiteId: "site-a", sourceInstanceId: "M1", durationMs: 3,
            extra: new ScriptTraceExtra { TriggerKind = "valuechange", TriggerAttribute = "DelmiaReceiver.X" }.ToJson());

        var graph = FlowGraphBuilder.Build([run, writeA, writeB, cascade]);

        var spawn = Assert.Single(graph.Edges, e => e.Spawn);
        Assert.Equal(writeA.EventId, spawn.FromEventId);
    }

    [Fact]
    public void FoldedNode_TakesTheEmissionIndexOfItsEarliestEmittedRow()
    {
        // The folded step keeps the earliest-by-TIME row's id (the resolve here is emitted first),
        // so its sequence must be the minimum input index over the rows folded into it.
        var corr = Guid.NewGuid();
        var resolve = Outbound(AuditChannel.ApiOutbound, AuditKind.CachedResolve, AuditStatus.Delivered, 4000, corr, "Delmia.Ack", response: "res");
        var submit = Outbound(AuditChannel.ApiOutbound, AuditKind.CachedSubmit, AuditStatus.Submitted, 35, corr, "Delmia.Ack", request: "req");
        var run = SiteRunRow(20, Cascade);

        // Emission order interleaves the executions: the folded node's earliest row is index 0, so
        // its execution leads — even though the id the folded step keeps (the submit) is index 2.
        var graph = FlowGraphBuilder.Build([resolve, run, submit]);

        var api = Assert.Single(graph.Steps, s => s.Kind == FlowStepKind.ApiCall);
        Assert.Equal(submit.EventId, api.EventId);
        Assert.Equal(new[] { FlowStepKind.ApiCall, FlowStepKind.ScriptRun }, graph.Steps.Select(s => s.Kind));
    }

    // ---- Review findings on Task 2 (2026-09-06) --------------------------------------------

    [Fact]
    public void LeadingAsyncSteps_HangOffTheSpawner_NeverOrphaned()
    {
        // A routed run whose ScriptTrace rows are absent (TraceAllCalls off / older site): only its outbound rows survive.
        var route = ScadaBridgeAuditEventFactory.Create(AuditChannel.ScriptTrace, AuditKind.RouteCall, AuditStatus.Delivered,
            occurredAtUtc: T0.AddMilliseconds(10), target: "M1.S", sourceNode: "central-a", executionId: Root,
            extra: new ScriptTraceExtra { ChildExecutionId = SiteRun }.ToJson());
        var cached = ScadaBridgeAuditEventFactory.Create(AuditChannel.ApiOutbound, AuditKind.CachedSubmit, AuditStatus.Submitted,
            occurredAtUtc: T0.AddMilliseconds(20), target: "Delmia.Ack", correlationId: Guid.NewGuid(), executionId: SiteRun, parentExecutionId: Root, sourceSiteId: "site-a");
        var notify = ScadaBridgeAuditEventFactory.Create(AuditChannel.Notification, AuditKind.NotifySend, AuditStatus.Submitted,
            occurredAtUtc: T0.AddMilliseconds(30), target: "Planners", correlationId: Guid.NewGuid(), executionId: SiteRun, parentExecutionId: Root, sourceSiteId: "site-a");
        var sync = ScadaBridgeAuditEventFactory.Create(AuditChannel.DbOutbound, AuditKind.DbWrite, AuditStatus.Delivered,
            occurredAtUtc: T0.AddMilliseconds(40), target: "MesDb", executionId: SiteRun, parentExecutionId: Root, sourceSiteId: "site-a");

        var graph = FlowGraphBuilder.Build([route, cached, notify, sync]);

        var routeStep = graph.Steps[0];
        var reached = graph.Edges.Select(e => e.ToEventId).ToHashSet();
        Assert.All(graph.Steps.Skip(1), s => Assert.Contains(s.EventId, reached));
        Assert.Equal(2, graph.Edges.Count(e => e.Async && e.FromEventId == routeStep.EventId));
        var syncEdge = Assert.Single(graph.Edges, e => e.ToEventId == graph.Steps[3].EventId);
        Assert.Equal(routeStep.EventId, syncEdge.FromEventId);
        Assert.False(syncEdge.Async);
        Assert.False(syncEdge.Spawn);
        Assert.Equal(3, graph.Edges.Count);
    }

    [Fact]
    public void OnlyNotifyRows_InAnExecution_AllLinkFromTheSpawner()
    {
        var run = SiteRunRow(20);
        var n1 = ScadaBridgeAuditEventFactory.Create(AuditChannel.Notification, AuditKind.NotifySend, AuditStatus.Submitted,
            occurredAtUtc: T0.AddMilliseconds(30), target: "A", correlationId: Guid.NewGuid(), executionId: Cascade, parentExecutionId: SiteRun, sourceSiteId: "site-a");
        var n2 = ScadaBridgeAuditEventFactory.Create(AuditChannel.Notification, AuditKind.NotifySend, AuditStatus.Submitted,
            occurredAtUtc: T0.AddMilliseconds(31), target: "B", correlationId: Guid.NewGuid(), executionId: Cascade, parentExecutionId: SiteRun, sourceSiteId: "site-a");

        var graph = FlowGraphBuilder.Build([run, n1, n2]);

        Assert.Equal(2, graph.Edges.Count);
        Assert.All(graph.Edges, e => { Assert.True(e.Async); Assert.True(e.Spawn); Assert.Equal(graph.Steps[0].EventId, e.FromEventId); });
    }

    [Fact]
    public void Fold_IsOrderIndependent_AndTiesBreakByLifecycleRank()
    {
        var corr = Guid.NewGuid();
        var submit = Outbound(AuditChannel.ApiOutbound, AuditKind.CachedSubmit, AuditStatus.Submitted, 35, corr, "Delmia.Ack", request: "req");
        var resolve = Outbound(AuditChannel.ApiOutbound, AuditKind.CachedResolve, AuditStatus.Delivered, 35, corr, "Delmia.Ack", response: "res");

        var a = FlowGraphBuilder.Build([SiteRunRow(20), resolve, submit]);
        var b = FlowGraphBuilder.Build([SiteRunRow(20), submit, resolve]);

        var sa = Assert.Single(a.Steps, s => s.Kind == FlowStepKind.ApiCall);
        var sb = Assert.Single(b.Steps, s => s.Kind == FlowStepKind.ApiCall);
        Assert.Equal(submit.EventId, sa.EventId);
        Assert.Equal(sa.EventId, sb.EventId);
        Assert.Equal("req", sa.InputJson);
        Assert.Equal("res", sa.OutputJson);
        Assert.Equal(FlowStepOutcome.Ok, sa.Outcome);
        Assert.Equal(0, sa.DurationMs);
        Assert.True(FlowGraphBuilder.IsAsync(sa));
        Assert.Equal(sa.Lifecycle!.Select(r => r.Kind), sb.Lifecycle!.Select(r => r.Kind));
    }

    [Fact]
    public void CachedStep_WhoseSubmitRowIsMissing_IsStillAsync()
    {
        var corr = Guid.NewGuid();
        var graph = FlowGraphBuilder.Build([
            SiteRunRow(20),
            Outbound(AuditChannel.ApiOutbound, AuditKind.ApiCallCached, AuditStatus.Attempted, 3000, corr, "Delmia.Ack"),
            Outbound(AuditChannel.ApiOutbound, AuditKind.CachedResolve, AuditStatus.Delivered, 4000, corr, "Delmia.Ack"),
        ]);
        var api = Assert.Single(graph.Steps, s => s.Kind == FlowStepKind.ApiCall);
        Assert.True(FlowGraphBuilder.IsAsync(api));
        Assert.Single(graph.Edges, e => e.Async && e.ToEventId == api.EventId);
    }

    [Fact]
    public void ExternalLaneEdges_NeverCountAsClusterBoundaryCrossings()
    {
        var inbound = ScadaBridgeAuditEventFactory.Create(AuditChannel.ApiInbound, AuditKind.InboundRequest, AuditStatus.Delivered,
            occurredAtUtc: T0, target: "M", sourceNode: "central-a", executionId: Root, durationMs: 50, responseSummary: "{}");
        var centralDb = ScadaBridgeAuditEventFactory.Create(AuditChannel.DbOutbound, AuditKind.DbWrite, AuditStatus.Delivered,
            occurredAtUtc: T0.AddMilliseconds(5), actor: "api:M", target: "CfgDb", sourceNode: "central-a", executionId: Root,
            extra: "{\"op\":\"read\",\"rowsReturned\":2}");

        var graph = FlowGraphBuilder.Build([inbound, centralDb]);

        Assert.DoesNotContain(graph.Edges, e => e.CrossesBoundary);
        Assert.Equal("read · 2 rows", graph.Steps[1].Subtitle);
        // Response links from the DB call — the inbound execution's last sync step.
        var into = Assert.Single(graph.Edges, e => e.ToEventId == graph.Steps[2].EventId);
        Assert.Equal(graph.Steps[1].EventId, into.FromEventId);
    }

    // ---- Script entry point (2026-09-08 plan, Task 6) -----------------------------------------

    [Fact]
    public void RouteCallRoot_WithoutInboundRow_BuildsCentralToSite_AndNoResponse()
    {
        // Flow Debugger script entry (design 2026-09-08 §4): a direct script call's root is an
        // operator-attributed RouteCall row — there is no InboundRequest and no Response.
        var root = Guid.NewGuid();
        var run = Guid.NewGuid();
        var events = new List<AuditEvent>
        {
            ScadaBridgeAuditEventFactory.Create(AuditChannel.ScriptTrace, AuditKind.RouteCall, AuditStatus.Delivered,
                occurredAtUtc: T0, actor: "ops", target: "M1.Manual", sourceNode: "central-a", executionId: root,
                sourceSiteId: "site-a", sourceInstanceId: "M1", durationMs: 50, requestSummary: "{\"n\":3}", responseSummary: "42",
                extra: new ScriptTraceExtra { Source = "flow-debugger", ChildExecutionId = run }.ToJson()),
            ScadaBridgeAuditEventFactory.Create(AuditChannel.ScriptTrace, AuditKind.ScriptRun, AuditStatus.Delivered,
                occurredAtUtc: T0.AddMilliseconds(5), actor: "Manual", target: "Manual", sourceNode: "node-a",
                executionId: run, parentExecutionId: root, sourceSiteId: "site-a", sourceInstanceId: "M1", durationMs: 40,
                extra: new ScriptTraceExtra { TriggerKind = "call" }.ToJson()),
        };

        var graph = FlowGraphBuilder.Build(events);

        Assert.Equal([FlowStepKind.RouteCall, FlowStepKind.ScriptRun], graph.Steps.Select(s => s.Kind).ToList());
        Assert.Equal([FlowLane.Central, FlowLane.Site], graph.Steps.Select(s => s.Lane).ToList());
        var edge = Assert.Single(graph.Edges);
        Assert.Equal((graph.Steps[0].EventId, graph.Steps[1].EventId, true), (edge.FromEventId, edge.ToEventId, edge.CrossesBoundary));
        Assert.DoesNotContain(graph.Steps, s => s.Kind == FlowStepKind.Response);
    }
}