using PlotLine.Data;
using PlotLine.Models;
using PlotLine.ViewModels;

namespace PlotLine.Services;

public sealed class StoryPointInputs
{
    public TimelineData Timeline { get; init; } = new();
    public IReadOnlyList<Character> Characters { get; init; } = [];
    public IReadOnlyList<SceneCharacter> Appearances { get; init; } = [];
    public IReadOnlyList<StoryAsset> Assets { get; init; } = [];
    public IReadOnlyList<AssetEvent> AssetEvents { get; init; } = [];
    public IReadOnlyList<LocationItem> Locations { get; init; } = [];
    public RelationshipMapData Relationships { get; init; } = new();
    public StoryPointHistory History { get; init; } = new();
    public IReadOnlyList<ContinuityWarningAcknowledgement> Acknowledgements { get; init; } = [];
}

public interface IStoryPointContextService
{
    Task<StoryPointViewModel?> GetAsync(int projectId, int? sceneId);
}

public sealed class StoryPointContextService(IProjectAccessService access, ITimelineRepository timelineRepository,
    ICharacterRepository characters, IAssetRepository assets, ILocationRepository locations,
    IStoryPointRepository history, IContinuityWarningAcknowledgementRepository acknowledgements) : IStoryPointContextService
{
    public async Task<StoryPointViewModel?> GetAsync(int projectId, int? sceneId)
    {
        if (!await access.CanAccessProjectAsync(projectId)) return null;
        var timeline = await timelineRepository.GetByProjectAsync(projectId, null, false, [], false);
        if (timeline.Project is null) return null;
        var ordered = StoryStateService.OrderScenes(timeline).ToList();
        if (sceneId.HasValue && ordered.All(x => x.SceneID != sceneId)) return null;
        sceneId ??= ordered.FirstOrDefault()?.SceneID;
        StoryPointSnapshot? snapshot = null;
        if (sceneId.HasValue)
        {
            // Each repository uses its own connection; batch count is independent of scene/entity count.
            var peopleTask = characters.GetTimelineAsync(projectId, null);
            var assetsTask = assets.GetTimelineAsync(projectId, null);
            var locationsTask = locations.ListByProjectAsync(projectId);
            var relationshipsTask = characters.GetRelationshipMapAsync(projectId);
            var historyTask = history.GetHistoryAsync(projectId, sceneId.Value);
            var acknowledgementsTask = acknowledgements.ListByProjectAsync(projectId);
            await Task.WhenAll(peopleTask, assetsTask, locationsTask, relationshipsTask, historyTask, acknowledgementsTask);
            snapshot = Compose(new StoryPointInputs
            {
                Timeline = timeline, Characters = peopleTask.Result.Characters, Appearances = peopleTask.Result.Appearances,
                Assets = assetsTask.Result.Assets, AssetEvents = assetsTask.Result.Events,
                Locations = locationsTask.Result, Relationships = relationshipsTask.Result,
                History = historyTask.Result, Acknowledgements = acknowledgementsTask.Result
            }, sceneId.Value);
        }
        return new StoryPointViewModel { Project = timeline.Project, Books = timeline.Books.OrderBy(x => x.SortOrder).ThenBy(x => x.BookNumber).ToList(),
            Chapters = timeline.Chapters.OrderBy(x => x.SortOrder).ThenBy(x => x.ChapterNumber).ToList(), Scenes = ordered, Snapshot = snapshot };
    }

    public static StoryPointSnapshot? Compose(StoryPointInputs input, int sceneId)
    {
        var ordered = StoryStateService.OrderScenes(input.Timeline).ToList();
        var maximum = ordered.FindIndex(x => x.SceneID == sceneId);
        if (maximum < 0 || input.Timeline.Project is null) return null;
        var scene = ordered[maximum];
        var chapter = input.Timeline.Chapters.Single(x => x.ChapterID == scene.ChapterID);
        var book = input.Timeline.Books.Single(x => x.BookID == chapter.BookID);
        var indexes = ordered.Select((x, i) => (x.SceneID, i)).ToDictionary(x => x.SceneID, x => x.i);
        var allowed = ordered.Take(maximum + 1).Select(x => x.SceneID).ToHashSet();
        var chaptersById = input.Timeline.Chapters.ToDictionary(x => x.ChapterID);
        var booksById = input.Timeline.Books.ToDictionary(x => x.BookID);
        var sources = ordered.Take(maximum + 1).ToDictionary(x => x.SceneID, x =>
        {
            var ch = chaptersById[x.ChapterID];
            return new StoryPointSource(x.SceneID, $"{booksById[ch.BookID].BookDisplayTitle} · Ch {ch.ChapterNumber:0.##} · Scene {x.SceneNumber:0.##}");
        });
        var present = input.Appearances.Where(x => x.SceneID == sceneId).GroupBy(x => x.CharacterID)
            .Select(x => x.OrderByDescending(y => y.UpdatedDate).First()).OrderBy(x => x.CharacterName).ToList();
        var presentIds = present.Select(x => x.CharacterID).ToHashSet();
        var state = StoryStateService.BuildAtScene(input, sceneId);
        var knowledge = StoryStateService.KnowledgeAtScene(input.History.Knowledge, indexes, sceneId).ToLookup(x => x.CharacterID);
        var previous = input.Appearances.Where(x => allowed.Contains(x.SceneID) && x.SceneID != sceneId)
            .GroupBy(x => x.CharacterID).ToDictionary(x => x.Key, x => x.OrderBy(y => indexes[y.SceneID]).Last().SceneID);
        var characterModels = input.Characters.ToDictionary(x => x.CharacterID);
        var people = present.Select(x => new StoryPointCharacter(x,
            characterModels.TryGetValue(x.CharacterID, out var character)
                ? CharacterAgeDisplayService.GetAgeForScene(character, scene.TimeModeName, scene.StartDateTime)
                : CharacterAgeDisplayService.GetAgeForScene(x, scene.TimeModeName, scene.StartDateTime),
            state.Characters.FirstOrDefault(y => y.CharacterID == x.CharacterID),
            previous.TryGetValue(x.CharacterID, out var previousId) ? sources[previousId] : null, knowledge[x.CharacterID].ToList())).ToList();
        var custodyIds = input.History.Custodians.Where(x => x.CharacterID.HasValue && presentIds.Contains(x.CharacterID.Value))
            .Select(x => x.AssetCustodyEventID).ToHashSet();
        var pointAssets = state.Assets.Where(x => x.LastConfirmedSceneID == sceneId
            || (scene.PrimaryLocationID.HasValue && x.LocationID == scene.PrimaryLocationID)
            || (x.CustodyEventID.HasValue && custodyIds.Contains(x.CustodyEventID.Value))).ToList();
        var relevantCharacters = presentIds.Concat(state.Characters.Where(x => scene.PrimaryLocationID.HasValue && x.LocationID == scene.PrimaryLocationID).Select(x => x.CharacterID)).ToHashSet();
        var location = scene.PrimaryLocationID.HasValue
            ? state.Locations.FirstOrDefault(x => x.LocationID == scene.PrimaryLocationID) ?? input.Locations.Where(x => x.LocationID == scene.PrimaryLocationID)
                .Select(x => new LocationStoryStateViewModel { LocationID = x.LocationID, LocationName = x.LocationName, LocationPath = x.LocationPath }).FirstOrDefault()
            : null;
        var lastLocationScene = ordered.Take(maximum).LastOrDefault(x => scene.PrimaryLocationID.HasValue && x.PrimaryLocationID == scene.PrimaryLocationID);
        return new StoryPointSnapshot
        {
            ProjectID = input.Timeline.Project.ProjectID, Book = book, Chapter = chapter, Scene = scene, Characters = people,
            PovName = scene.POVCharacterID.HasValue ? characterModels.GetValueOrDefault(scene.POVCharacterID.Value)?.CharacterName ?? scene.POVCharacterName : scene.POVCharacterName,
            Relationships = RelationshipMapService.BuildAtScene(input.Relationships, indexes, sceneId)
                .Where(x => presentIds.Contains(x.CharacterAID) || presentIds.Contains(x.CharacterBID)).ToList(),
            Assets = pointAssets, Location = location, PreviousLocationUse = lastLocationScene is null ? null : sources[lastLocationScene.SceneID],
            Threads = BuildThreads(input.History, allowed, indexes, sources),
            Warnings = StoryStateService.WarningsAtScene(input, sceneId, relevantCharacters, pointAssets.Select(x => x.StoryAssetID).ToHashSet()), Sources = sources
        };
    }

    private static IReadOnlyList<StoryPointThread> BuildThreads(StoryPointHistory history, HashSet<int> allowed,
        IReadOnlyDictionary<int, int> indexes, IReadOnlyDictionary<int, StoryPointSource> sources)
    {
        var events = history.ThreadEvents.Where(x => allowed.Contains(x.SceneID)).ToLookup(x => x.PlotThreadID);
        var result = new List<StoryPointThread>();
        foreach (var thread in history.Threads.Where(x => !x.IsArchived))
        {
            var threadEvents = events[thread.PlotThreadID].OrderBy(x => indexes[x.SceneID]).ThenBy(x => x.ThreadEventID).ToList();
            if (thread.IntroducedSceneID.HasValue ? !allowed.Contains(thread.IntroducedSceneID.Value) : threadEvents.Count == 0) continue;
            if (thread.ActualResolutionSceneID.HasValue && allowed.Contains(thread.ActualResolutionSceneID.Value)) continue;
            var latestLifecycle = threadEvents.LastOrDefault(x => x.EventTypeName is "Resolved" or "Payoff" or "Introduced");
            if (latestLifecycle?.EventTypeName is "Resolved" or "Payoff") continue;
            var last = threadEvents.LastOrDefault();
            var sourceId = last?.SceneID ?? thread.IntroducedSceneID;
            result.Add(new StoryPointThread(thread.PlotThreadID, thread.ThreadTitle, thread.ThreadTypeName, thread.PlotLineName,
                sourceId.HasValue ? sources.GetValueOrDefault(sourceId.Value) : null, last?.EventTypeName ?? "Introduced"));
        }
        return result.OrderBy(x => x.Title).ToList();
    }
}