OpenNest/OpenNest.Engine/CuttingPlanning/CuttingPlanBatch.cs

using System;
using System.Collections.Generic;
using System.Globalization;
using System.Linq;
using System.Threading;
using OpenNest.CNC.CuttingPlanning;
using OpenNest.CNC.CuttingStrategy;
using OpenNest.Diagnostics;

namespace OpenNest.Engine.CuttingPlanning;

/// <summary>What a batch is doing for one plate, reported from the worker.</summary>
public enum CuttingPlanPhase
{
    /// <summary>Searching for a new whole-part order.</summary>
    Reordering,

    /// <summary>Planning with the plate's current part order.</summary>
    KeepingOrder,

    /// <summary>Checking the plate's clean part material for overlaps.</summary>
    CheckingOverlap,

    /// <summary>No route passed every check within the search limit: finding the safest one.</summary>
    SafestRoute,
}

/// <summary>Worker progress: zero-based position in the batch, the plate's display number and phase.</summary>
public sealed record CuttingPlanProgress(int PlateIndex, int PlateCount, int PlateNumber, CuttingPlanPhase Phase);

/// <summary>
/// One desktop planning attempt over one or more plates with caller-confirmed cutting parameters.
/// Capture on the thread that owns the plates, <see cref="Plan"/> on a worker, then apply the
/// returned proposal back on the owner thread. Every plate goes through
/// <see cref="CuttingPlanService"/>; nothing here installs programs or reorders parts itself.
/// </summary>
public sealed class CuttingPlanBatch
{
    /// <summary>The smallest budget a plate gets, the service default.</summary>
    public const int MinimumExpansionBudget = 20000;

    /// <summary>
    /// Expansions allowed per part, whether or not the order is kept: both still choose contour
    /// order and entries for every part. Dense grids measured near 260 per part with a new order
    /// and 210 when kept; the margin keeps 100-150 part plates inside the budget.
    /// </summary>
    public const int ExpansionsPerPart = 400;

    /// <summary>The planning-effort multiplier that gives today's budgets.</summary>
    public const double DefaultBudgetMultiplier = 1.0;

    /// <summary>The smallest planning-effort multiplier; it still leaves the first pass room to run.</summary>
    public const double MinimumBudgetMultiplier = 0.5;

    /// <summary>The largest planning-effort multiplier, a bound on one plate's planning time.</summary>
    public const double MaximumBudgetMultiplier = 10.0;

    // Extra bounded work on hard/refused plates; the full-cap search still gets its whole budget.
    // Not scaled by the multiplier: it is a fixed-cost probe for easy plates, so raising the
    // effort spends more only where the full search runs and leaves easy plates' plans unchanged.
    internal const int FirstPassBudget = 1000;
    internal const int FirstPassEntries = 8;

    private readonly Entry[] entries;
    private readonly CuttingParameters ownedParameters;

    private CuttingPlanBatch(Entry[] entries, CuttingParameters ownedParameters)
    {
        this.entries = entries;
        this.ownedParameters = ownedParameters;
    }

    public int PlateCount => entries.Length;

    /// <summary>
    /// Captures every plate's exact state with an owned copy of <paramref name="confirmedParameters"/>,
    /// and its clean part material for the overlap check. When the order may change, the
    /// current-order request is captured too, so a free search that runs out of budget can be
    /// retried on the worker without reading live plates again.
    /// </summary>
    /// <param name="budgetMultiplier">
    /// Scales both searches' <see cref="PlateBudget"/>, between <see cref="MinimumBudgetMultiplier"/>
    /// and <see cref="MaximumBudgetMultiplier"/>. The caller passes the operator's setting; the
    /// worker never reads it.
    /// </param>
    public static CuttingPlanBatch Capture(IReadOnlyList<Plate> plates, CuttingParameters confirmedParameters,
        bool preservePartOrder, IReadOnlyList<int> plateNumbers = null, CancellationToken token = default,
        double budgetMultiplier = DefaultBudgetMultiplier) =>
        Capture(plates, confirmedParameters, preservePartOrder, plateNumbers, null, token, budgetMultiplier);

    /// <param name="reorderBudget">Overrides the new-order budget (tests); null gives <see cref="PlateBudget"/>.</param>
    internal static CuttingPlanBatch Capture(IReadOnlyList<Plate> plates, CuttingParameters confirmedParameters,
        bool preservePartOrder, IReadOnlyList<int> plateNumbers, int? reorderBudget, CancellationToken token,
        double budgetMultiplier = DefaultBudgetMultiplier)
    {
        ArgumentNullException.ThrowIfNull(plates);
        ArgumentNullException.ThrowIfNull(confirmedParameters);
        if (!(budgetMultiplier >= MinimumBudgetMultiplier && budgetMultiplier <= MaximumBudgetMultiplier))
            throw new ArgumentOutOfRangeException(nameof(budgetMultiplier), budgetMultiplier,
                $"The budget multiplier must be between {MinimumBudgetMultiplier} and {MaximumBudgetMultiplier}.");
        if (plates.Count == 0)
            throw new ArgumentException("At least one plate is required.", nameof(plates));
        if (plates.Any(plate => plate == null)
            || plates.Distinct(ReferenceEqualityComparer.Instance).Count() != plates.Count)
            throw new ArgumentException("Plates must be distinct and not null.", nameof(plates));
        if (plateNumbers != null && plateNumbers.Count != plates.Count)
            throw new ArgumentException("Give one display number per plate.", nameof(plateNumbers));

        CuttingParameters owned;
        try
        {
            owned = OwnedCuttingParameters.Copy(confirmedParameters);
        }
        catch (NotSupportedException)
        {
            owned = null; // Each plate's capture reports the unsupported settings itself.
        }

        var entries = new Entry[plates.Count];
        for (var index = 0; index < plates.Count; index++)
        {
            var plate = plates[index];
            var budget = PlateBudget(plate.Parts.Count, budgetMultiplier);
            // One capture serves both searches: the order flag and budget are search settings
            // over the same owned geometry, programs and freshness record.
            var captured = CuttingPlanService.Capture(CuttingPlanRequest.ForPlate(plate,
                expansionBudget: budget, confirmedParameters: confirmedParameters,
                preservePartOrder: preservePartOrder), token);
            var keepOrder = preservePartOrder ? captured : captured.WithPreservedOrder();
            var reorder = preservePartOrder ? null
                : reorderBudget is { } reorderLimit ? captured.WithSearchLimits(reorderLimit, captured.MaxEntries) : captured;
            var overlap = PlateOverlapAnalyzer.Capture(plate.Parts.ToArray(), token);
            var fallback = reorder ?? keepOrder;
            if (fallback.Failure == CuttingPlanStatus.UnsupportedGeometry)
                fallback = CuttingPlanService.Capture(CuttingPlanRequest.ForPlate(plate,
                    confirmedParameters: confirmedParameters, preservePartOrder: preservePartOrder), token, bestEffort: true);
            entries[index] = new(plate, plateNumbers?[index] ?? index + 1, reorder, keepOrder, overlap, fallback);
        }
        return new(entries, owned);
    }

    /// <summary>A plate's expansion budget: <see cref="ExpansionsPerPart"/> per part, at least
    /// <see cref="MinimumExpansionBudget"/>, times the multiplier.</summary>
    internal static int PlateBudget(int partCount, double multiplier = DefaultBudgetMultiplier)
    {
        var budget = System.Math.Max((double)MinimumExpansionBudget, (double)partCount * ExpansionsPerPart);
        return (int)System.Math.Min(int.MaxValue, System.Math.Round(budget * multiplier));
    }

    /// <summary>
    /// Brings a stored planning-effort value inside the supported range; a non-finite value gives
    /// <see cref="DefaultBudgetMultiplier"/>.
    /// </summary>
    public static double ClampBudgetMultiplier(double multiplier) => double.IsFinite(multiplier)
        ? System.Math.Clamp(multiplier, MinimumBudgetMultiplier, MaximumBudgetMultiplier)
        : DefaultBudgetMultiplier;

    /// <summary>
    /// Checks and plans every plate from its captured snapshots. Safe on a worker: live plates are
    /// not read. Overlapping material blocks a plate whatever its route. A free search that ends
    /// without a complete plan within its budget is retried with the current order; the proposal
    /// reports that it kept the order. Incomplete geometry also gets a separately labeled,
    /// unverified fallback when supported closed contours can still be emitted.
    /// </summary>
    public CuttingPlanProposal Plan(IProgress<CuttingPlanProgress> progress = null,
        CancellationToken token = default)
    {
        var plans = new CuttingPlanPlateResult[entries.Length];
        for (var index = 0; index < entries.Length; index++)
        {
            var entry = entries[index];
            progress?.Report(new(index, entries.Length, entry.Number, CuttingPlanPhase.CheckingOverlap));
            PlateOverlapReport overlap;
            try
            {
                overlap = PlateOverlapAnalyzer.Analyze(entry.Overlap, token);
            }
            catch (OperationCanceledException)
            {
                plans[index] = new(entry.Plate, entry.Number, new(CuttingPlanStatus.Canceled), null, null);
                continue;
            }

            CuttingPlanResult reorder = null;
            if (entry.Reorder != null)
            {
                progress?.Report(new(index, entries.Length, entry.Number, CuttingPlanPhase.Reordering));
                reorder = PlanReorder(entry.Reorder, token);
                if (reorder.Status != CuttingPlanStatus.NoSolutionWithinBudget)
                {
                    plans[index] = new(entry.Plate, entry.Number, WithFallback(entry, reorder, token), null, overlap);
                    continue;
                }
            }
            progress?.Report(new(index, entries.Length, entry.Number, CuttingPlanPhase.KeepingOrder));
            var kept = WithFallback(entry, CuttingPlanService.Plan(entry.KeepOrder, token), token);
            if (SearchLimited(kept, reorder))
            {
                progress?.Report(new(index, entries.Length, entry.Number, CuttingPlanPhase.SafestRoute));
                if (SafestRoute(entry, token) is var (safest, freeOrder))
                {
                    plans[index] = new(entry.Plate, entry.Number, safest, freeOrder ? null : reorder, overlap);
                    continue;
                }
            }
            plans[index] = new(entry.Plate, entry.Number, kept, reorder, overlap);
        }
        return new(plans, ownedParameters);
    }

    // The strict search stopped at its limit: no complete plan, and no other reason to refuse.
    private static bool SearchLimited(CuttingPlanResult kept, CuttingPlanResult reorder) =>
        kept.Status == CuttingPlanStatus.NoSolutionWithinBudget
        || reorder?.Status == CuttingPlanStatus.NoSolutionWithinBudget && kept.Status == CuttingPlanStatus.ConstraintConflict;

    /// <summary>
    /// Safest first, then fastest: the replayed safest route from the free order and from the
    /// current order, whichever breaks fewer checks (most severe first), then raises the head
    /// fewer times, then has less rapid travel. A route whose planner-chosen motions pass every
    /// check head-down is taken at once, even when fixed lead-ins still warn. Null when neither
    /// walk finds a route.
    /// </summary>
    private static (CuttingPlanResult Result, bool FreeOrder)? SafestRoute(Entry entry, CancellationToken token)
    {
        (CuttingPlanResult Result, bool FreeOrder)? best = null;
        try
        {
            foreach (var (snapshot, freeOrder) in new[] { (entry.Reorder, true), (entry.KeepOrder, false) })
            {
                if (CuttingPlanService.PlanSafestRoute(snapshot, token) is not { } candidate)
                    continue;
                if (!candidate.IsSafestRouteFallback && candidate.HeadRaises == 0)
                    return (candidate, freeOrder);
                if (best is not { } known || Safer(candidate, known.Result))
                    best = (candidate, freeOrder);
            }
        }
        catch (OperationCanceledException)
        {
            return (new(CuttingPlanStatus.Canceled), true);
        }
        return best;
    }

    // Fewer broken checks (a route that breaks none first), then fewer head raises, then less travel.
    private static bool Safer(CuttingPlanResult candidate, CuttingPlanResult known)
    {
        var severity = (candidate.SafestRoute ?? default).CompareTo(known.SafestRoute ?? default);
        if (severity != 0)
            return severity < 0;
        if (candidate.HeadRaises != known.HeadRaises)
            return candidate.HeadRaises < known.HeadRaises;
        return candidate.RapidDistance < known.RapidDistance;
    }

    internal static CuttingPlanResult PlanReorder(CuttingPlanSnapshot snapshot, CancellationToken token,
        int firstPassBudget = FirstPassBudget)
    {
        // A failed first pass is not a proof of impossibility: retain all original
        // full-cap alternatives and the complete original budget for the retry.
        if (snapshot.Failure == null && snapshot.Regeneration && snapshot.MaxEntries > FirstPassEntries
            && snapshot.ExpansionBudget > firstPassBudget)
        {
            var first = CuttingPlanService.Plan(snapshot.WithSearchLimits(firstPassBudget, FirstPassEntries), token);
            // A replayed proposal whose only warnings are fixed emissions passed every strict
            // check; fixed emissions never steer the search, so the full pass cannot improve it.
            if (first.IndependentlyReplayed && first.Status is CuttingPlanStatus.Ready or CuttingPlanStatus.BestEffort
                || first.Status == CuttingPlanStatus.Canceled)
                return first;
        }
        return CuttingPlanService.Plan(snapshot, token);
    }

    private static CuttingPlanResult WithFallback(Entry entry, CuttingPlanResult strict, CancellationToken token)
    {
        if (strict.Status != CuttingPlanStatus.UnsupportedGeometry || entry.Fallback.Failure != null)
            return strict;
        var fallback = BestEffortCuttingPlan.Plan(entry.Fallback, token);
        if (fallback.Status != CuttingPlanStatus.BestEffort)
            return fallback.Status == CuttingPlanStatus.Canceled ? fallback : strict;
        return new(CuttingPlanStatus.BestEffort, fallback.ProposedOrder,
            strict.Findings.Concat(fallback.Findings).Distinct(), rapidDistance: fallback.RapidDistance)
        { Snapshot = entry.Fallback };
    }

    private sealed record Entry(Plate Plate, int Number, CuttingPlanSnapshot Reorder, CuttingPlanSnapshot KeepOrder,
        PlateOverlapSnapshot Overlap, CuttingPlanSnapshot Fallback);
}

/// <summary>One plate's outcome inside a <see cref="CuttingPlanProposal"/>.</summary>
public sealed class CuttingPlanPlateResult
{
    internal CuttingPlanPlateResult(Plate plate, int plateNumber, CuttingPlanResult result,
        CuttingPlanResult reorderAttempt, PlateOverlapReport overlap)
    {
        Plate = plate;
        PlateNumber = plateNumber;
        Result = result;
        ReorderAttempt = reorderAttempt;
        Overlap = overlap;
    }

    /// <summary>The live plate. Read it only on the thread that owns it.</summary>
    public Plate Plate { get; }
    public int PlateNumber { get; }

    /// <summary>The result that would be applied.</summary>
    public CuttingPlanResult Result { get; }

    /// <summary>The free-order attempt that ran out of budget before the current order was kept; else null.</summary>
    public CuttingPlanResult ReorderAttempt { get; }

    /// <summary>The clean-material overlap check (part ids are current part positions); null if canceled first.</summary>
    public PlateOverlapReport Overlap { get; }

    public bool KeptCurrentOrder => ReorderAttempt != null;

    /// <summary>The route was replayed and the overlap check completed without overlaps.</summary>
    public bool IsRouteReady => Result.Status == CuttingPlanStatus.Ready && Result.IndependentlyReplayed;

    public bool IsOverlapClear => Overlap is { IsComplete: true } && Overlap.Pairs.Count == 0;
    public bool IsReady => IsRouteReady && IsOverlapClear;

    /// <summary>Owned readable output is available, but not all geometric checks passed.</summary>
    public bool CanApplyWithWarnings => Overlap != null && Overlap.Pairs.Count == 0
        && (IsRouteReady || Result.Status == CuttingPlanStatus.BestEffort);

    /// <summary>
    /// Refused after a search ran out of its expansion budget: this plan, or the free-order attempt
    /// before the current order was kept. A higher planning effort searches further, without a promise.
    /// </summary>
    public bool SearchLimitReached => !CanApplyWithWarnings && !IsRouteReady
        && (Result.Status == CuttingPlanStatus.NoSolutionWithinBudget || KeptCurrentOrder
            && Result.Status is not (CuttingPlanStatus.Canceled or CuttingPlanStatus.UnsupportedGeometry
                or CuttingPlanStatus.InvalidInput));

    /// <summary>
    /// The route was replayed and passed every strict check; only fixed emissions (locked or
    /// pinned leads) carry warnings, so the proposal is UNVERIFIED and needs acceptance.
    /// </summary>
    public bool HasOnlyFixedLeadWarnings => Result.Status == CuttingPlanStatus.BestEffort
        && Result.IndependentlyReplayed && IsOverlapClear;
    public int PartCount => Result.ProposedOrder.Count;
    public int RegeneratedCount => Result.ProposedOrder.Count(p => p.IsRegenerated);

    /// <summary>Head-locked far-edge cutoff segments the plan cuts the other way.</summary>
    public int ReversedCutOffCount => Result.ProposedOrder.Count(p => p.ReversesCutOff);

    public bool OrderChanged =>
        Result.ProposedOrder.Select((proposal, index) => proposal.SourceOrdinal != index).Any(changed => changed);
}

/// <summary>A diagnostic tied to captured plate and source part positions, not display text.</summary>
public sealed record CuttingPlanDiagnosticRow(int PlateIndex, int PlateNumber, int? PartNumber,
    int? OtherPartNumber, string Message)
{
    /// <summary>World-coordinate markers for the problem (overlap area, rapid, contacts); null when none.</summary>
    public PostVerificationFinding Witness { get; init; }
}

/// <summary>
/// The outcome of a batch. Apply is all-or-nothing. Unverified output needs explicit acceptance.
/// </summary>
public sealed class CuttingPlanProposal
{
    private const int FindingsPerPlate = 5;
    private readonly CuttingParameters ownedParameters;

    internal CuttingPlanProposal(IReadOnlyList<CuttingPlanPlateResult> plates, CuttingParameters ownedParameters)
    {
        Plates = plates;
        this.ownedParameters = ownedParameters;
    }

    public IReadOnlyList<CuttingPlanPlateResult> Plates { get; }

    public bool IsCanceled => Plates.Any(p => p.Result.Status == CuttingPlanStatus.Canceled);

    public bool CanApply => Plates.Count > 0 && !IsCanceled && ownedParameters != null
        && Plates.All(p => p.IsReady);

    /// <summary>All plates have usable output, possibly requiring explicit warning acceptance.</summary>
    public bool CanApplyWithWarnings => Plates.Count > 0 && !IsCanceled && ownedParameters != null
        && Plates.All(p => p.CanApplyWithWarnings);

    public bool RequiresWarningAcceptance => CanApplyWithWarnings && !CanApply;

    /// <summary>All findings, including ones hidden by a blocked plate's abbreviated summary.</summary>
    public IReadOnlyList<CuttingPlanDiagnosticRow> DiagnosticRows()
    {
        var rows = new List<CuttingPlanDiagnosticRow>();
        for (var index = 0; index < Plates.Count; index++)
        {
            var plate = Plates[index];
            if (plate.Overlap != null)
            {
                foreach (var pair in plate.Overlap.Pairs)
                {
                    var message = $"Part {pair.PartAId + 1}{Name(pair.PartAName)} overlaps part "
                        + $"{pair.PartBId + 1}{Name(pair.PartBName)}.";
                    rows.Add(new(index, plate.PlateNumber, pair.PartAId + 1, pair.PartBId + 1, message)
                    {
                        Witness = new(PostVerificationKind.Overlap, plate.PlateNumber, pair.PartAId + 1,
                            pair.PartBId + 1, message)
                        { Location = pair.Marker, Overlap = pair }
                    });
                }
                foreach (var issue in plate.Overlap.Issues)
                    rows.Add(new(index, plate.PlateNumber, issue.PartAId + 1,
                        issue.PartBId is int other ? other + 1 : null,
                        $"Overlap check incomplete for part {issue.PartAId + 1}"
                        + (issue.PartBId is int second ? $" and part {second + 1}" : string.Empty)
                        + $": {issue.Message}"));
            }
            foreach (var finding in plate.Result.Findings)
                rows.Add(new(index, plate.PlateNumber,
                    finding.SourceOrdinal is int part ? part + 1 : null,
                    finding.OtherSourceOrdinal is int other ? other + 1 : null,
                    DescribeFinding(finding))
                { Witness = finding.Witness });
        }
        return rows;
    }

    /// <summary>
    /// Installs every plate's replayed proposal through <see cref="CuttingPlanService.Apply"/>, on the
    /// thread that owns the plates. Only after every plate is applied does each one keep an owned copy
    /// of the confirmed parameters as its cutting settings; any other status changes nothing.
    /// </summary>
    public CuttingCommitResult Apply(CancellationToken token = default) => Apply(false, token);

    /// <summary>Explicit per-proposal acceptance; never grants consent to post CNC output.</summary>
    public CuttingCommitResult Apply(bool acceptWarnings, CancellationToken token = default)
    {
        if (!(CanApply || acceptWarnings && CanApplyWithWarnings))
            return new(CuttingCommitStatus.InvalidInput,
                "Every plate must have a ready plan before anything is applied.");
        var commit = CuttingPlanService.Apply(Plates.Select(p => p.Result), token, null, acceptWarnings);
        if (commit.Status == CuttingCommitStatus.Applied)
            foreach (var plate in Plates)
                plate.Plate.CuttingParameters = OwnedCuttingParameters.Copy(ownedParameters);
        return commit;
    }

    /// <summary>
    /// A detached copy of a ready or explicitly unverified proposal for display, or null.
    /// Refused graphs are never cloned. Changed plates are not previewed at uncaptured poses.
    /// The copy has quantity zero, so drawing quantities stay put.
    /// Call it on the thread that owns the plates.
    /// </summary>
    public Plate BuildPreview(int index)
    {
        var planned = Plates[index];
        if (!planned.CanApplyWithWarnings || planned.Result.Snapshot?.PlateState?.IsCurrent() != true)
            return null;
        // Unchanged since capture: graphs are supported and the preview uses the exact proposal.
        var source = planned.Plate;
        var preview = new Plate(source.Size)
        {
            Quantity = 0,
            Quadrant = source.Quadrant,
            PartSpacing = source.PartSpacing,
            EdgeSpacing = source.EdgeSpacing,
            // View > Draw Support shows the proposal on the same bed.
            SupportBed = source.SupportBed,
        };
        // Machine clamps stay visible while inspecting the proposal; zones are immutable.
        foreach (var zone in source.ClampZones)
            preview.ClampZones.Add(zone);
        foreach (var proposal in planned.Result.ProposedOrder)
        {
            var part = (Part)proposal.SourcePart.Clone();
            part.RestoreLeadInProgram(proposal.CopyProgram(), proposal.LeadInsLocked);
            preview.Parts.Add(part);
        }
        return preview;
    }

    /// <summary>Operator-facing summary: one overall line, then each plate and its findings.</summary>
    /// <param name="changeSettings">How this front end changes the settings, completed by
    /// "a lead-in type other than None..." in the missing lead-in advice.</param>
    public IReadOnlyList<string> Describe(string unit, string changeSettings = "Open Cutting Settings... and select")
    {
        var lines = new List<string>();
        var blocked = Plates.Count(p => !p.CanApplyWithWarnings);
        if (IsCanceled)
            lines.Add("Planning was canceled. Nothing has changed.");
        else if (CanApply)
            lines.Add($"Ready to apply to {Count(Plates.Count, "plate")}: "
                + $"{Count(Plates.Count(p => p.OrderChanged), "plate")} with a new part order, "
                + $"{Count(Plates.Sum(p => p.RegeneratedCount), "part program")} regenerated.");
        else if (RequiresWarningAcceptance)
            lines.Add((Plates.All(p => p.IsReady || p.HasOnlyFixedLeadWarnings)
                    ? "Unverified plan available: " + Unverified(Plates.Where(p => !p.IsReady)).Headline + " "
                    : Plates.Any(p => p.Result.IsSafestRouteFallback)
                        ? "Safest-route plan available: no route passed every check within the search limit. "
                        : "Best-effort plan available. ")
                + "Review the warnings and accept the unverified plan to apply. "
                + "Posting CNC output still requires its own review and approval.");
        else
            lines.Add($"Apply is unavailable: {blocked} of {Count(Plates.Count, "plate")} could not "
                + "be planned. No plate changes until every plate is ready.");

        foreach (var plate in Plates)
        {
            lines.Add(string.Empty);
            lines.AddRange(DescribePlate(plate, unit, changeSettings));
        }
        return lines;
    }

    // What an unverified plan whose motions all passed asks the operator to review: its fixed
    // lead-ins, parts its support bed cannot hold level, or both.
    private static (string Headline, string Plate) Unverified(IEnumerable<CuttingPlanPlateResult> plates)
    {
        var kinds = plates.SelectMany(p => p.Result.Findings).Select(f => f.Kind).Where(k => k != null).ToHashSet();
        return kinds.Count == 1 && kinds.Contains(PostVerificationKind.PartSupport)
            ? ("a part may tip once cut free.", "a part may tip once cut free.")
            : kinds.Contains(PostVerificationKind.PartSupport)
                ? ("fixed lead-ins could not be certified, and a part may tip once cut free.",
                    "fixed lead-ins need review, and a part may tip once cut free.")
                : ("fixed lead-ins could not be certified.", "fixed lead-ins need review.");
    }

    private static IEnumerable<string> DescribePlate(CuttingPlanPlateResult plate, string unit, string changeSettings)
    {
        var heading = $"Plate {plate.PlateNumber}: ";
        var result = plate.Result;
        if (plate.IsReady && plate.PartCount == 0)
        {
            yield return heading + "no parts.";
            yield break;
        }
        if (plate.IsReady)
        {
            var kept = plate.PartCount - plate.RegeneratedCount;
            var order = plate.KeptCurrentOrder
                ? "No new part order was found within the search limit, so the current order is kept."
                : plate.OrderChanged ? "The part order changes." : "The part order is unchanged.";
            yield return heading + $"ready. {Count(plate.PartCount, "part")}, {plate.RegeneratedCount} "
                + $"regenerated, {kept} kept as is; rapid travel "
                + $"{result.RapidDistance.ToString("0.##", CultureInfo.CurrentCulture)} {unit}. {order}"
                + (plate.ReversedCutOffCount == 0 ? ""
                    : $" {Count(plate.ReversedCutOffCount, "cutoff segment")} at the far edge change direction.")
                + (result.HeadRaises == 0 ? ""
                    : $" No route found keeps the head down over every cut part, so {Count(result.HeadRaises, "rapid")} "
                        + $"{(result.HeadRaises == 1 ? "raises" : "raise")} the head; each is listed below.");
            // A ready plan's findings are advisory notes (head raises, support tabs that may not hold a part level).
            foreach (var line in Limit(result.Findings.Select(DescribeFinding)))
                yield return line;
            yield break;
        }

        if (plate.CanApplyWithWarnings)
        {
            yield return heading + (plate.HasOnlyFixedLeadWarnings
                ? $"unverified: {Unverified([plate]).Plate} {Count(plate.PartCount, "part")}, "
                    + $"{plate.RegeneratedCount} regenerated; every planned motion passed its checks."
                : result.SafestRoute is { } severity
                ? $"safest route found, unverified. No route passed every check within the search limit; "
                    + $"this one breaks {Count(severity.Count, "check")}, listed below. {Count(plate.PartCount, "part")}, "
                    + $"{plate.RegeneratedCount} regenerated; rapid travel "
                    + $"{result.RapidDistance.ToString("0.##", CultureInfo.CurrentCulture)} {unit}."
                : $"best-effort, unverified. {Count(plate.PartCount, "part")}, "
                    + $"{plate.RegeneratedCount} regenerated; review lead-ins and cutting order.");
            // Unverified Apply requires the operator to see every finding, not just a
            // bounded diagnostic summary that hides later parts behind "... and N more".
            foreach (var line in DescribeOverlap(plate.Overlap).Concat(result.Findings.Select(DescribeFinding)))
                yield return "  - " + line;
            yield break;
        }

        var missingLead = !plate.IsRouteReady && result.Status != CuttingPlanStatus.Canceled
            && result.Findings.Any(f => f.Kind == PostVerificationKind.MissingLeadIn);
        yield return heading + (plate.IsRouteReady
            ? "blocked: parts overlap or could not be checked for overlap."
            : missingLead ? "blocked: missing or zero-length lead-in." : StatusText(result.Status));
        foreach (var line in Limit(DescribeOverlap(plate.Overlap)))
            yield return line;
        if (plate.IsRouteReady)
            yield break;
        if (missingLead)
        {
            yield return $"  {changeSettings} a lead-in type other than None with "
                + "nonzero length for the affected contour (External, Internal, or Arc / Circle), then replan.";
            yield return "  If the affected part is locked, edit its lead-ins or unlock it before replanning.";
        }
        else if (plate.KeptCurrentOrder)
            yield return "  No new part order was found within the search limit, and planning with the "
                + "current order was refused:";
        foreach (var line in Limit(result.Findings.Select(DescribeFinding)))
            yield return line;
        if (!missingLead && plate.SearchLimitReached)
            yield return "  " + SearchLimitHint;
    }

    /// <summary>Hint for a plate refused at the search limit (console and MCP; the desktop panel names its effort setting).</summary>
    public const string SearchLimitHint = "The planner stopped at its search limit; a longer search might help, "
        + "but it may still find no plan.";

    private static IEnumerable<string> Limit(IEnumerable<string> lines)
    {
        var all = lines.ToList();
        foreach (var line in all.Take(FindingsPerPlate))
            yield return "  - " + line;
        if (all.Count > FindingsPerPlate)
            yield return $"  ... and {all.Count - FindingsPerPlate} more.";
    }

    private static IEnumerable<string> DescribeOverlap(PlateOverlapReport overlap)
    {
        if (overlap == null)
            yield break;
        foreach (var pair in overlap.Pairs)
            yield return $"Part {pair.PartAId + 1}{Name(pair.PartAName)} overlaps part "
                + $"{pair.PartBId + 1}{Name(pair.PartBName)}.";
        foreach (var issue in overlap.Issues)
            yield return $"Overlap check incomplete for part {issue.PartAId + 1}"
                + (issue.PartBId is int other ? $" and part {other + 1}" : string.Empty) + $": {issue.Message}";
    }

    private static string StatusText(CuttingPlanStatus status) => status switch
    {
        CuttingPlanStatus.Ready => "ready, but the plan was not independently replayed.",
        CuttingPlanStatus.ConstraintConflict => "blocked: the fixed programs or required cut order conflict.",
        CuttingPlanStatus.UnsupportedGeometry => "blocked: unsupported geometry or an incomplete check.",
        CuttingPlanStatus.InvalidInput => "blocked: invalid input.",
        CuttingPlanStatus.NoSolutionWithinBudget => "no complete plan was found within the search limit.",
        CuttingPlanStatus.Canceled => "canceled.",
        _ => status.ToString(),
    };

    private static string DescribeFinding(CuttingPlanFinding finding)
    {
        var text = finding.SourceOrdinal is int ordinal
            ? $"Part {ordinal + 1}{Name(finding.SourcePart)}: {finding.Message}"
            : finding.Message;
        if (finding.OtherSourceOrdinal is int other)
            text += $" (with part {other + 1}{Name(finding.OtherSourcePart)})";
        return text;
    }

    private static string Name(Part part) => Name(part?.BaseDrawing?.Name);

    private static string Name(string name) => string.IsNullOrWhiteSpace(name) ? string.Empty : $" ({name})";

    private static string Count(int count, string noun) => $"{count} {noun}{(count == 1 ? string.Empty : "s")}";
}