using System.Text.Json;
using Microsoft.AspNetCore.Mvc.Rendering;
using PlotLine.Data;
using PlotLine.Models;
using PlotLine.ViewModels;

namespace PlotLine.Services;

public interface IStoryIntelligenceNarrativeReviewService
{
    Task<StoryIntelligenceNarrativeReviewViewModel> GetReviewAsync(OnboardingStoryIntelligenceBatch batch);
    Task<StoryIntelligenceImportCommitResult> ImportAsync(OnboardingStoryIntelligenceBatch batch, StoryIntelligenceNarrativeImportForm form, int userId);
    Task<StoryIntelligenceNarrativeImportResultViewModel?> GetResultAsync(OnboardingStoryIntelligenceBatch batch);
}

public sealed class StoryIntelligenceNarrativeReviewService(
    IStoryIntelligenceNarrativeCandidateRepository candidates,
    IStoryIntelligenceResultRepository runs,
    ISceneRepository scenes,
    IPlotRepository plots,
    IStoryIntelligencePipelineStateService pipelineState) : IStoryIntelligenceNarrativeReviewService
{
    private static readonly JsonSerializerOptions JsonOptions = new()
    {
        PropertyNamingPolicy = JsonNamingPolicy.CamelCase,
        PropertyNameCaseInsensitive = true
    };

    public async Task<StoryIntelligenceNarrativeReviewViewModel> GetReviewAsync(OnboardingStoryIntelligenceBatch batch)
    {
        await EnsureCandidatesAsync(batch);
        var rows = await candidates.ListByBookAsync(batch.BookID);
        var pending = rows
            .Where(candidate => string.Equals(candidate.Status, StoryIntelligenceNarrativeCandidateStatuses.Pending, StringComparison.OrdinalIgnoreCase))
            .ToList();
        var plotLines = await plots.ListPlotLinesAsync(batch.ProjectID);

        return new StoryIntelligenceNarrativeReviewViewModel
        {
            HasCommittedScenes = await HasCommittedScenesAsync(batch),
            CanImport = pending.Count > 0,
            IsComplete = rows.Count > 0 && pending.Count == 0,
            PlotLineOptions = plotLines
                .OrderBy(plotLine => plotLine.SortOrder)
                .ThenBy(plotLine => plotLine.PlotLineName)
                .Select(plotLine => new SelectListItem(plotLine.PlotLineName, plotLine.PlotLineID.ToString()))
                .ToList(),
            Candidates = pending.Select(ToViewModel).ToList()
        };
    }

    public async Task<StoryIntelligenceImportCommitResult> ImportAsync(OnboardingStoryIntelligenceBatch batch, StoryIntelligenceNarrativeImportForm form, int userId)
    {
        await EnsureCandidatesAsync(batch);
        var rows = (await candidates.ListByBookAsync(batch.BookID)).ToDictionary(candidate => candidate.NarrativeCandidateID);
        var lookups = await plots.GetLookupsAsync();
        var plotLineTypeId = lookups.PlotLineTypes.FirstOrDefault(type => string.Equals(type.TypeName, "Main Plot", StringComparison.OrdinalIgnoreCase))?.PlotLineTypeID
            ?? lookups.PlotLineTypes.FirstOrDefault()?.PlotLineTypeID
            ?? 0;
        var plotImportanceId = lookups.PlotImportance.FirstOrDefault(importance => string.Equals(importance.ImportanceName, "Primary", StringComparison.OrdinalIgnoreCase))?.PlotImportanceID
            ?? lookups.PlotImportance.FirstOrDefault()?.PlotImportanceID
            ?? 0;
        var threadTypeId = lookups.ThreadTypes.FirstOrDefault(type => string.Equals(type.TypeName, "Question", StringComparison.OrdinalIgnoreCase))?.ThreadTypeID
            ?? lookups.ThreadTypes.FirstOrDefault()?.ThreadTypeID
            ?? 0;
        var threadStatusId = lookups.ThreadStatuses.FirstOrDefault(status => string.Equals(status.StatusName, "Open", StringComparison.OrdinalIgnoreCase))?.ThreadStatusID
            ?? lookups.ThreadStatuses.FirstOrDefault()?.ThreadStatusID
            ?? 0;
        var threadEventTypeId = lookups.ThreadEventTypes.FirstOrDefault(type => string.Equals(type.TypeName, "Raised", StringComparison.OrdinalIgnoreCase))?.ThreadEventTypeID
            ?? lookups.ThreadEventTypes.FirstOrDefault()?.ThreadEventTypeID
            ?? 0;
        var plotEventTypeId = lookups.PlotEventTypes.FirstOrDefault(type => string.Equals(type.TypeName, "Progress", StringComparison.OrdinalIgnoreCase))?.PlotEventTypeID
            ?? lookups.PlotEventTypes.FirstOrDefault()?.PlotEventTypeID
            ?? 0;

        var plotLinesCreated = 0;
        var plotLinesMerged = 0;
        var threadsCreated = 0;
        var rejected = 0;

        foreach (var choice in form.Candidates.Where(choice => choice.NarrativeCandidateID > 0))
        {
            if (!rows.TryGetValue(choice.NarrativeCandidateID, out var candidate)
                || !string.Equals(candidate.Status, StoryIntelligenceNarrativeCandidateStatuses.Pending, StringComparison.OrdinalIgnoreCase))
            {
                continue;
            }

            var action = string.IsNullOrWhiteSpace(choice.Action) ? StoryIntelligenceNarrativeReviewActions.AcceptNew : choice.Action;
            if (string.Equals(action, StoryIntelligenceNarrativeReviewActions.Reject, StringComparison.OrdinalIgnoreCase))
            {
                await candidates.MarkReviewedAsync(candidate.NarrativeCandidateID, StoryIntelligenceNarrativeCandidateStatuses.Rejected, action, userId, null, null);
                rejected++;
                continue;
            }

            if (string.Equals(candidate.CandidateType, StoryIntelligenceNarrativeCandidateTypes.PlotLine, StringComparison.OrdinalIgnoreCase))
            {
                if (string.Equals(action, StoryIntelligenceNarrativeReviewActions.MergeExisting, StringComparison.OrdinalIgnoreCase) && choice.ExistingPlotLineID is > 0)
                {
                    await candidates.MarkReviewedAsync(candidate.NarrativeCandidateID, StoryIntelligenceNarrativeCandidateStatuses.Merged, action, userId, choice.ExistingPlotLineID, null);
                    plotLinesMerged++;
                    continue;
                }

                var plotLineId = await plots.SavePlotLineAsync(new PlotLineItem
                {
                    ProjectID = batch.ProjectID,
                    BookID = batch.BookID,
                    PlotLineName = CleanTitle(choice.Title, candidate.ProposedTitle),
                    Description = CleanNullable(choice.Description) ?? candidate.ProposedDescription,
                    PlotLineTypeID = plotLineTypeId,
                    PlotImportanceID = plotImportanceId,
                    SortOrder = 0,
                    Colour = "#2f6f63",
                    IsVisibleOnTimeline = true
                });
                await candidates.MarkReviewedAsync(candidate.NarrativeCandidateID, StoryIntelligenceNarrativeCandidateStatuses.Accepted, action, userId, plotLineId, null);
                plotLinesCreated++;
                continue;
            }

            var relatedPlotLineId = choice.RelatedPlotLineID ?? candidate.RelatedPlotLineID ?? choice.ExistingPlotLineID;
            if (relatedPlotLineId is not > 0)
            {
                await candidates.MarkReviewedAsync(candidate.NarrativeCandidateID, StoryIntelligenceNarrativeCandidateStatuses.Rejected, StoryIntelligenceNarrativeReviewActions.Reject, userId, null, null);
                rejected++;
                continue;
            }

            var firstSceneId = candidate.Evidence.OrderBy(evidence => evidence.SortOrder).FirstOrDefault()?.SceneID;
            var threadId = await plots.SavePlotThreadAsync(new PlotThread
            {
                PlotLineID = relatedPlotLineId.Value,
                ThreadTitle = CleanTitle(choice.Title, candidate.ProposedTitle),
                Summary = CleanNullable(choice.Description) ?? candidate.ProposedDescription,
                ThreadTypeID = threadTypeId,
                ThreadStatusID = threadStatusId,
                Importance = 5,
                IntroducedSceneID = firstSceneId
            });

            foreach (var evidence in candidate.Evidence.Where(evidence => evidence.SceneID > 0))
            {
                await plots.SaveThreadEventAsync(new ThreadEvent
                {
                    PlotThreadID = threadId,
                    SceneID = evidence.SceneID,
                    EventTypeID = threadEventTypeId,
                    PlotEventTypeID = plotEventTypeId,
                    EventTitle = string.IsNullOrWhiteSpace(evidence.ContributionType) ? candidate.ProposedTitle : evidence.ContributionType,
                    EventDescription = evidence.Evidence
                });
            }

            await candidates.MarkReviewedAsync(candidate.NarrativeCandidateID, StoryIntelligenceNarrativeCandidateStatuses.Accepted, action, userId, null, threadId);
            threadsCreated++;
        }

        batch.LastNarrativeImportResult = new StoryIntelligenceNarrativeImportBatchResult
        {
            PlotLinesCreated = plotLinesCreated,
            PlotLinesMerged = plotLinesMerged,
            ThreadsCreated = threadsCreated,
            CandidatesRejected = rejected
        };
        batch.NarrativeStageComplete = true;
        await pipelineState.RecordNarrativeImportAsync(batch.ProjectID, batch.BookID);

        return new StoryIntelligenceImportCommitResult
        {
            Success = true,
            Message = $"Narrative review applied. {plotLinesCreated:N0} Plot Line(s) created, {threadsCreated:N0} Thread(s) created, {plotLinesMerged:N0} merged, {rejected:N0} rejected."
        };
    }

    public Task<StoryIntelligenceNarrativeImportResultViewModel?> GetResultAsync(OnboardingStoryIntelligenceBatch batch)
        => Task.FromResult<StoryIntelligenceNarrativeImportResultViewModel?>(new StoryIntelligenceNarrativeImportResultViewModel
        {
            BatchID = batch.BatchID,
            ProjectID = batch.ProjectID,
            BookID = batch.BookID,
            PlotLinesCreated = batch.LastNarrativeImportResult?.PlotLinesCreated ?? 0,
            PlotLinesMerged = batch.LastNarrativeImportResult?.PlotLinesMerged ?? 0,
            ThreadsCreated = batch.LastNarrativeImportResult?.ThreadsCreated ?? 0,
            CandidatesRejected = batch.LastNarrativeImportResult?.CandidatesRejected ?? 0
        });

    private async Task EnsureCandidatesAsync(OnboardingStoryIntelligenceBatch batch)
    {
        var existingPlotLines = await plots.ListPlotLinesAsync(batch.ProjectID);
        var existingThreads = await plots.ListPlotThreadsByProjectAsync(batch.ProjectID);
        var existingThreadByKey = existingThreads
            .GroupBy(thread => Key(thread.ThreadTitle), StringComparer.OrdinalIgnoreCase)
            .ToDictionary(group => group.Key, group => group.First(), StringComparer.OrdinalIgnoreCase);
        var signalInputs = new List<StoryIntelligenceNarrativeSignalInput>();

        foreach (var item in batch.Items)
        {
            var commit = await runs.GetImportCommitAsync(item.RunID);
            if (commit is null || !string.Equals(commit.Status, StoryIntelligenceImportCommitStatuses.Completed, StringComparison.OrdinalIgnoreCase))
            {
                continue;
            }

            var importedScenes = (await scenes.ListByChapterAsync(item.ChapterID))
                .Where(scene => scene.ImportRunID == item.RunID)
                .ToList();
            var importedByRange = importedScenes
                .Where(scene => scene.SourceStartParagraph.HasValue && scene.SourceEndParagraph.HasValue)
                .ToDictionary(scene => $"{scene.SourceStartParagraph}-{scene.SourceEndParagraph}", scene => scene, StringComparer.OrdinalIgnoreCase);
            var importedByNumber = importedScenes.ToDictionary(scene => Convert.ToInt32(scene.SceneNumber), scene => scene);
            var sceneResults = await runs.ListSceneResultsAsync(item.RunID);

            foreach (var sceneResult in sceneResults)
            {
                var importedScene = ResolveImportedScene(sceneResult, importedByRange, importedByNumber);
                var parsed = TryReadScene(sceneResult);
                if (importedScene is null || parsed is null)
                {
                    continue;
                }

                foreach (var arc in parsed.NarrativeArcs ?? [])
                {
                    var category = string.Equals(arc.Scale, "thread", StringComparison.OrdinalIgnoreCase)
                        ? "Thread"
                        : "Plot Line";
                    signalInputs.Add(new StoryIntelligenceNarrativeSignalInput(
                        importedScene.SceneID,
                        CleanNullable(arc.Title),
                        CleanNullable(arc.Description),
                        category,
                        CleanNullable(arc.ArcType) ?? "Narrative arc",
                        arc.Confidence,
                        arc.MatchingExistingPlotLineId,
                        arc.Evidence));
                }

                foreach (var question in parsed.QuestionsRaised ?? [])
                {
                    signalInputs.Add(new StoryIntelligenceNarrativeSignalInput(
                        importedScene.SceneID,
                        CleanNullable(question.Question),
                        null,
                        "Thread",
                        "Open",
                        question.Confidence,
                        null,
                        question.Evidence));
                }

                foreach (var clue in parsed.TimelineClues ?? [])
                {
                    signalInputs.Add(new StoryIntelligenceNarrativeSignalInput(
                        importedScene.SceneID,
                        CleanNullable(clue.Clue),
                        null,
                        "Thread",
                        "Introduced",
                        clue.Confidence,
                        null,
                        clue.Evidence));
                }
            }
        }

        var signals = StoryIntelligenceNarrativeSignalConsolidator.Consolidate(signalInputs, existingPlotLines);
        foreach (var signal in signals.Where(signal => signal.SceneIds.Count > 1).OrderBy(signal => signal.Title))
        {
            var existingThread = existingThreadByKey.GetValueOrDefault(Key(signal.Title));
            var candidateType = string.Equals(signal.Category, "Plot Line", StringComparison.OrdinalIgnoreCase) || (signal.ExistingPlotLineID.HasValue && existingThread is null)
                ? StoryIntelligenceNarrativeCandidateTypes.PlotLine
                : StoryIntelligenceNarrativeCandidateTypes.Thread;
            var candidateId = await candidates.SaveAsync(new StoryIntelligenceNarrativeCandidateSeed
            {
                ProjectID = batch.ProjectID,
                BookID = batch.BookID,
                CandidateType = candidateType,
                CandidateKey = $"{candidateType}:{Key(signal.Title)}",
                ProposedTitle = signal.Title,
                ProposedDescription = signal.Description,
                Category = signal.Category,
                InferredState = signal.State,
                ExistingPlotLineID = signal.ExistingPlotLineID,
                ExistingPlotThreadID = existingThread?.PlotThreadID,
                RelatedPlotLineID = existingThread?.PlotLineID,
                Confidence = signal.Confidence
            });

            var sortOrder = 0;
            foreach (var item in signal.Evidence.OrderBy(item => item.SceneID))
            {
                await candidates.SaveEvidenceAsync(candidateId, item.SceneID, item.ContributionType, item.Evidence, sortOrder++);
            }
        }
    }

    private async Task<bool> HasCommittedScenesAsync(OnboardingStoryIntelligenceBatch batch)
    {
        foreach (var item in batch.Items)
        {
            var commit = await runs.GetImportCommitAsync(item.RunID);
            if (commit is not null && string.Equals(commit.Status, StoryIntelligenceImportCommitStatuses.Completed, StringComparison.OrdinalIgnoreCase))
            {
                return true;
            }
        }

        return false;
    }

    private static StoryIntelligenceNarrativeReviewCandidateViewModel ToViewModel(StoryIntelligenceNarrativeCandidate candidate)
        => new()
        {
            NarrativeCandidateID = candidate.NarrativeCandidateID,
            CandidateType = candidate.CandidateType,
            ProposedTitle = candidate.ProposedTitle,
            ProposedDescription = candidate.ProposedDescription ?? string.Empty,
            Category = candidate.Category ?? string.Empty,
            InferredState = candidate.InferredState ?? string.Empty,
            Confidence = candidate.Confidence.HasValue ? $"{candidate.Confidence.Value:P0}" : "Unknown",
            ExistingPlotLineID = candidate.ExistingPlotLineID,
            RelatedPlotLineID = candidate.RelatedPlotLineID,
            RelatedPlotLineName = candidate.RelatedPlotLineName,
            DefaultAction = candidate.ExistingPlotLineID.HasValue || candidate.ExistingPlotThreadID.HasValue
                ? StoryIntelligenceNarrativeReviewActions.MergeExisting
                : StoryIntelligenceNarrativeReviewActions.AcceptNew,
            Evidence = candidate.Evidence.Select(evidence => new StoryIntelligenceNarrativeEvidenceViewModel
            {
                SceneID = evidence.SceneID,
                SceneLabel = $"Chapter {evidence.ChapterNumber:0.##}, Scene {evidence.SceneNumber:0.##}: {evidence.SceneTitle}",
                ContributionType = evidence.ContributionType ?? string.Empty,
                Evidence = evidence.Evidence ?? string.Empty
            }).ToList()
        };

    private static Scene? ResolveImportedScene(
        StoryIntelligenceSavedSceneResult sceneResult,
        IReadOnlyDictionary<string, Scene> importedByRange,
        IReadOnlyDictionary<int, Scene> importedByNumber)
    {
        if (sceneResult.StartParagraph.HasValue
            && sceneResult.EndParagraph.HasValue
            && importedByRange.TryGetValue($"{sceneResult.StartParagraph}-{sceneResult.EndParagraph}", out var byRange))
        {
            return byRange;
        }

        return importedByNumber.TryGetValue(sceneResult.TemporarySceneNumber, out var byNumber) ? byNumber : null;
    }

    private static SceneIntelligenceScene? TryReadScene(StoryIntelligenceSavedSceneResult result)
    {
        foreach (var json in new[] { result.ParsedJson, result.OutputTextJson })
        {
            if (string.IsNullOrWhiteSpace(json))
            {
                continue;
            }

            try
            {
                var direct = JsonSerializer.Deserialize<SceneIntelligenceScene>(json, JsonOptions);
                if (direct?.Summary is not null)
                {
                    return direct;
                }

                using var document = JsonDocument.Parse(json);
                if (document.RootElement.TryGetProperty("parsedScene", out var parsedScene))
                {
                    return parsedScene.Deserialize<SceneIntelligenceScene>(JsonOptions);
                }
            }
            catch (JsonException)
            {
                // Try the next persisted JSON form.
            }
        }

        return null;
    }

    private static string CleanTitle(string? preferred, string fallback)
        => string.IsNullOrWhiteSpace(preferred) ? fallback.Trim() : preferred.Trim();

    private static string? CleanNullable(string? value)
        => string.IsNullOrWhiteSpace(value) ? null : value.Trim();

    private static string Key(string? value)
        => StoryIntelligenceNarrativeSignalConsolidator.Key(value);
}

public sealed record StoryIntelligenceNarrativeSignalInput(
    int SceneID,
    string? Title,
    string? Description,
    string Category,
    string State,
    decimal? Confidence,
    int? MatchingExistingPlotLineID,
    string? Evidence);

public sealed record StoryIntelligenceNarrativeSignalEvidence(int SceneID, string ContributionType, string? Evidence);

public sealed record StoryIntelligenceNarrativeConsolidatedSignal(
    string Title,
    string Description,
    string Category,
    string State,
    int? ExistingPlotLineID,
    decimal? Confidence,
    IReadOnlyCollection<int> SceneIds,
    IReadOnlyList<StoryIntelligenceNarrativeSignalEvidence> Evidence);

public static class StoryIntelligenceNarrativeSignalConsolidator
{
    private static readonly HashSet<string> StopWords = new(StringComparer.OrdinalIgnoreCase)
    {
        "a", "an", "and", "are", "as", "at", "be", "by", "for", "from", "has", "have", "her", "his", "how", "in", "into",
        "is", "it", "its", "of", "on", "or", "she", "he", "that", "the", "their", "them", "they", "this", "to", "what",
        "when", "where", "who", "why", "with", "about", "after", "before", "looks", "looking", "case", "plot", "line",
        "story", "arc"
    };

    private static readonly Dictionary<string, string> ArcFamilies = new(StringComparer.OrdinalIgnoreCase)
    {
        ["absence"] = "disappearance",
        ["absent"] = "disappearance",
        ["clue"] = "disappearance",
        ["clues"] = "disappearance",
        ["disappear"] = "disappearance",
        ["disappearance"] = "disappearance",
        ["disappeared"] = "disappearance",
        ["disappears"] = "disappearance",
        ["find"] = "disappearance",
        ["finding"] = "disappearance",
        ["found"] = "disappearance",
        ["investigate"] = "disappearance",
        ["investigates"] = "disappearance",
        ["investigation"] = "disappearance",
        ["lead"] = "disappearance",
        ["leads"] = "disappearance",
        ["missing"] = "disappearance",
        ["search"] = "disappearance",
        ["searches"] = "disappearance",
        ["searching"] = "disappearance",
        ["suspect"] = "disappearance",
        ["suspects"] = "disappearance",
        ["gone"] = "disappearance",
        ["went"] = "disappearance",
        ["conspiracy"] = "conspiracy",
        ["quest"] = "quest",
        ["romance"] = "romance",
        ["secret"] = "secret",
        ["secrets"] = "secret",
        ["revenge"] = "revenge",
        ["rivalry"] = "rivalry"
    };

    public static IReadOnlyList<StoryIntelligenceNarrativeConsolidatedSignal> Consolidate(
        IEnumerable<StoryIntelligenceNarrativeSignalInput> inputs,
        IReadOnlyList<PlotLineItem> existingPlotLines)
    {
        var groups = new Dictionary<string, NarrativeSignal>(StringComparer.OrdinalIgnoreCase);
        var plotLinesById = existingPlotLines.Where(plotLine => plotLine.PlotLineID > 0).ToDictionary(plotLine => plotLine.PlotLineID);

        foreach (var input in inputs)
        {
            if (string.IsNullOrWhiteSpace(input.Title) || input.Title.Trim().Length < 8)
            {
                continue;
            }

            var matchingPlotLine = ResolveExistingPlotLine(input, existingPlotLines, plotLinesById);
            var key = matchingPlotLine is not null
                ? $"existing:{matchingPlotLine.PlotLineID}"
                : FindSimilarGroupKey(groups, input) ?? ArcKey(input.Title, input.Description);

            if (!groups.TryGetValue(key, out var signal))
            {
                var terms = Terms($"{input.Title} {input.Description}");
                signal = new NarrativeSignal(
                    input.Title.Trim(),
                    string.IsNullOrWhiteSpace(input.Description) ? $"{input.Category} recurring across scenes." : input.Description.Trim(),
                    matchingPlotLine is not null ? "Plot Line" : input.Category,
                    input.State,
                    matchingPlotLine?.PlotLineID,
                    ArcFamily(terms),
                    terms.ToHashSet(StringComparer.OrdinalIgnoreCase));
                groups[key] = signal;
            }

            signal.SceneIds.Add(input.SceneID);
            signal.Confidence = input.Confidence.HasValue
                ? Math.Max(signal.Confidence ?? 0m, input.Confidence.Value)
                : signal.Confidence;
            signal.Evidence.Add(new StoryIntelligenceNarrativeSignalEvidence(input.SceneID, input.Category, input.Evidence));
        }

        return groups.Values
            .Select(signal => new StoryIntelligenceNarrativeConsolidatedSignal(
                signal.Title,
                signal.Description,
                signal.Category,
                signal.State,
                signal.ExistingPlotLineID,
                signal.Confidence,
                signal.SceneIds,
                signal.Evidence))
            .ToList();
    }

    public static string Key(string? value)
        => new((value ?? string.Empty).Where(char.IsLetterOrDigit).Select(char.ToLowerInvariant).ToArray());

    private static PlotLineItem? ResolveExistingPlotLine(
        StoryIntelligenceNarrativeSignalInput input,
        IReadOnlyList<PlotLineItem> existingPlotLines,
        IReadOnlyDictionary<int, PlotLineItem> plotLinesById)
    {
        if (input.MatchingExistingPlotLineID is > 0 && plotLinesById.TryGetValue(input.MatchingExistingPlotLineID.Value, out var suppliedMatch))
        {
            return suppliedMatch;
        }

        return existingPlotLines.FirstOrDefault(plotLine => HasSharedArcIdentity(input, plotLine));
    }

    private static bool HasSharedArcIdentity(StoryIntelligenceNarrativeSignalInput input, PlotLineItem plotLine)
    {
        var signalTerms = Terms($"{input.Title} {input.Description}");
        var plotLineTerms = Terms($"{plotLine.PlotLineName} {plotLine.Description}");
        if (signalTerms.Count == 0 || plotLineTerms.Count == 0)
        {
            return false;
        }

        var shared = signalTerms.Intersect(plotLineTerms, StringComparer.OrdinalIgnoreCase).Count();
        var smaller = Math.Min(signalTerms.Count, plotLineTerms.Count);
        if (shared >= 2 && shared / (decimal)smaller >= 0.5m)
        {
            return true;
        }

        if (ArcFamily(signalTerms) == ArcFamily(plotLineTerms)
            && signalTerms.Intersect(plotLineTerms, StringComparer.OrdinalIgnoreCase).Any())
        {
            return true;
        }

        return ArcKey(input.Title, input.Description) == ArcKey(plotLine.PlotLineName, plotLine.Description);
    }

    private static string? FindSimilarGroupKey(
        IReadOnlyDictionary<string, NarrativeSignal> groups,
        StoryIntelligenceNarrativeSignalInput input)
    {
        var terms = Terms($"{input.Title} {input.Description}");
        var family = ArcFamily(terms);
        if (terms.Count == 0)
        {
            return null;
        }

        foreach (var group in groups)
        {
            if (group.Value.ExistingPlotLineID.HasValue || !string.Equals(group.Value.Family, family, StringComparison.OrdinalIgnoreCase))
            {
                continue;
            }

            if (group.Value.Terms.Intersect(terms, StringComparer.OrdinalIgnoreCase).Any())
            {
                return group.Key;
            }
        }

        return null;
    }

    private static string ArcKey(string? title, string? description)
    {
        var terms = Terms($"{title} {description}");
        var family = ArcFamily(terms);
        var anchors = terms
            .Where(term => !ArcFamilies.ContainsKey(term))
            .Distinct(StringComparer.OrdinalIgnoreCase)
            .OrderBy(term => term)
            .Take(3)
            .ToList();

        if (anchors.Count == 0)
        {
            anchors = terms.Distinct(StringComparer.OrdinalIgnoreCase).OrderBy(term => term).Take(3).ToList();
        }

        return $"{family}:{string.Join('-', anchors)}";
    }

    private static string ArcFamily(IEnumerable<string> terms)
        => terms.Select(term => ArcFamilies.GetValueOrDefault(term)).FirstOrDefault(value => !string.IsNullOrWhiteSpace(value)) ?? "general";

    private static List<string> Terms(string? value)
        => (value ?? string.Empty)
            .Split((char[]?)null, StringSplitOptions.RemoveEmptyEntries | StringSplitOptions.TrimEntries)
            .Select(NormalizeTerm)
            .Where(term => term.Length > 2 && !StopWords.Contains(term))
            .ToList();

    private static string NormalizeTerm(string value)
    {
        var term = new string(value.Where(char.IsLetterOrDigit).Select(char.ToLowerInvariant).ToArray());
        return term.EndsWith('s') && term.Length > 4 ? term[..^1] : term;
    }

    private sealed record NarrativeSignal(
        string Title,
        string Description,
        string Category,
        string State,
        int? ExistingPlotLineID,
        string Family,
        HashSet<string> Terms)
    {
        public HashSet<int> SceneIds { get; } = [];
        public List<StoryIntelligenceNarrativeSignalEvidence> Evidence { get; } = [];
        public decimal? Confidence { get; set; }
    }
}