using Dalamud.Game.ClientState.Objects.SubKinds;
using Dalamud.Plugin.Services;
using LightlessSync.API.Dto.User;
using LightlessSync.LightlessConfiguration;
using LightlessSync.Services.Mediator;
using Microsoft.Extensions.Logging;
using System.Collections.Concurrent;

namespace LightlessSync.Services;

public class BroadcastScannerService : DisposableMediatorSubscriberBase, IDisposable
{
    private readonly ILogger<BroadcastScannerService> _logger;
    private readonly IObjectTable _objectTable;
    private readonly IFramework _framework;

    private readonly BroadcastService _broadcastService;
    private readonly NameplateHandler _nameplateHandler;

    private readonly ConcurrentDictionary<string, BroadcastEntry> _broadcastCache = new();
    private readonly Queue<string> _lookupQueue = new();
    private readonly HashSet<string> _lookupQueuedCids = new();
    private readonly HashSet<string> _syncshellCids = new();

    private static readonly TimeSpan MaxAllowedTtl = TimeSpan.FromMinutes(4);
    private static readonly TimeSpan RetryDelay = TimeSpan.FromMinutes(1);

    private readonly CancellationTokenSource _cleanupCts = new();
    private Task? _cleanupTask;

    private readonly int _checkEveryFrames = 20;
    private int _frameCounter = 0;
    private int _lookupsThisFrame = 0;
    private const int MaxLookupsPerFrame = 30;
    private const int MaxQueueSize = 100;

    private volatile bool _batchRunning = false;

    public IReadOnlyDictionary<string, BroadcastEntry> BroadcastCache => _broadcastCache;
    public readonly record struct BroadcastEntry(bool IsBroadcasting, DateTime ExpiryTime, string? GID);

    public BroadcastScannerService(ILogger<BroadcastScannerService> logger,
        IClientState clientState,
        IObjectTable objectTable,
        IFramework framework,
        BroadcastService broadcastService,
        LightlessMediator mediator,
        NameplateHandler nameplateHandler,
        DalamudUtilService dalamudUtil,
        LightlessConfigService configService) : base(logger, mediator)
    {
        _logger = logger;
        _objectTable = objectTable;
        _broadcastService = broadcastService;
        _nameplateHandler = nameplateHandler;

        _logger = logger;
        _framework = framework;
        _framework.Update += OnFrameworkUpdate;

        Mediator.Subscribe<BroadcastStatusChangedMessage>(this, OnBroadcastStatusChanged);
        _cleanupTask = Task.Run(ExpiredBroadcastCleanupLoop);

        _nameplateHandler.Init();
    }

    private void OnFrameworkUpdate(IFramework framework) => Update();

    public void Update()
    {
        _frameCounter++;
        _lookupsThisFrame = 0;

        if (!_broadcastService.IsBroadcasting)
            return;

        var now = DateTime.UtcNow;

        foreach (var obj in _objectTable)
        {
            if (obj is not IPlayerCharacter player || player.Address == IntPtr.Zero)
                continue;

            var cid = DalamudUtilService.GetHashedCIDFromPlayerPointer(player.Address);
            var isStale = !_broadcastCache.TryGetValue(cid, out var entry) || entry.ExpiryTime <= now;

            if (isStale && _lookupQueuedCids.Add(cid) && _lookupQueue.Count < MaxQueueSize)
                _lookupQueue.Enqueue(cid);
        }

        if (_frameCounter % _checkEveryFrames == 0 && _lookupQueue.Count > 0)
        {
            var cidsToLookup = new List<string>();
            while (_lookupQueue.Count > 0 && _lookupsThisFrame < MaxLookupsPerFrame)
            {
                var cid = _lookupQueue.Dequeue();
                _lookupQueuedCids.Remove(cid);
                cidsToLookup.Add(cid);
                _lookupsThisFrame++;
            }

            if (cidsToLookup.Count > 0 && !_batchRunning)
            {
                _batchRunning = true;
                _ = BatchUpdateBroadcastCacheAsync(cidsToLookup).ContinueWith(_ => _batchRunning = false);
            }
        }
    }

    private async Task BatchUpdateBroadcastCacheAsync(List<string> cids)
    {
        var results = await _broadcastService.AreUsersBroadcastingAsync(cids).ConfigureAwait(false);
        var now = DateTime.UtcNow;

        foreach (var (cid, info) in results)
        {
            if (string.IsNullOrWhiteSpace(cid) || info == null)
                continue;

            var ttl = info.IsBroadcasting && info.TTL.HasValue
                ? TimeSpan.FromTicks(Math.Min(info.TTL.Value.Ticks, MaxAllowedTtl.Ticks))
                : RetryDelay;

            var expiry = now + ttl;

            _broadcastCache.AddOrUpdate(cid,
                new BroadcastEntry(info.IsBroadcasting, expiry, info.GID),
                (_, old) => new BroadcastEntry(info.IsBroadcasting, expiry, info.GID));
        }

        var activeCids = _broadcastCache
            .Where(e => e.Value.IsBroadcasting && e.Value.ExpiryTime > now)
            .Select(e => e.Key)
            .ToList();

        _nameplateHandler.UpdateBroadcastingCids(activeCids);
        UpdateSyncshellBroadcasts();
    }

    private void OnBroadcastStatusChanged(BroadcastStatusChangedMessage msg)
    {
        if (!msg.Enabled)
        {
            _broadcastCache.Clear();
            _lookupQueue.Clear();
            _lookupQueuedCids.Clear();
            _syncshellCids.Clear();

            _nameplateHandler.UpdateBroadcastingCids(Enumerable.Empty<string>());
        }
    }

    private void UpdateSyncshellBroadcasts()
    {
        var now = DateTime.UtcNow;
        var newSet = _broadcastCache
            .Where(e => e.Value.IsBroadcasting && e.Value.ExpiryTime > now && !string.IsNullOrEmpty(e.Value.GID))
            .Select(e => e.Key)
            .ToHashSet();

        if (!_syncshellCids.SetEquals(newSet))
        {
            _syncshellCids.Clear();
            foreach (var cid in newSet)
                _syncshellCids.Add(cid);

            Mediator.Publish(new SyncshellBroadcastsUpdatedMessage());
        }
    }

    public List<BroadcastStatusInfoDto> GetActiveSyncshellBroadcasts()
    {
        var now = DateTime.UtcNow;

        return _broadcastCache
            .Where(e => e.Value.IsBroadcasting && e.Value.ExpiryTime > now && !string.IsNullOrEmpty(e.Value.GID))
            .Select(e => new BroadcastStatusInfoDto
            {
                HashedCID = e.Key,
                IsBroadcasting = true,
                TTL = e.Value.ExpiryTime - now,
                GID = e.Value.GID
            })
            .ToList();
    }

    private async Task ExpiredBroadcastCleanupLoop()
    {
        var token = _cleanupCts.Token;

        try
        {
            while (!token.IsCancellationRequested)
            {
                await Task.Delay(TimeSpan.FromSeconds(10), token);

                var now = DateTime.UtcNow;
                foreach (var (cid, entry) in _broadcastCache.ToArray())
                {
                    if (entry.ExpiryTime <= now)
                        _broadcastCache.TryRemove(cid, out _);
                }
            }
        }
        catch (OperationCanceledException) { }
        catch (Exception ex)
        {
            _logger.LogError(ex, "Broadcast cleanup loop crashed");
        }

        UpdateSyncshellBroadcasts();
    }

    public int CountActiveBroadcasts(string? excludeHashedCid = null)
    {
        var now = DateTime.UtcNow;
        var comparer = StringComparer.Ordinal;
        return _broadcastCache.Count(entry =>
            entry.Value.IsBroadcasting &&
            entry.Value.ExpiryTime > now &&
            (excludeHashedCid is null || !comparer.Equals(entry.Key, excludeHashedCid)));
    }

    public List<KeyValuePair<string, BroadcastEntry>> GetActiveBroadcasts(string? excludeHashedCid = null)
    {
        var now = DateTime.UtcNow;
        var comparer = StringComparer.Ordinal;
        return [.. _broadcastCache.Where(entry =>
            entry.Value.IsBroadcasting &&
            entry.Value.ExpiryTime > now &&
            (excludeHashedCid is null || !comparer.Equals(entry.Key, excludeHashedCid)))];
    }

    protected override void Dispose(bool disposing)
    {
        base.Dispose(disposing);
        _framework.Update -= OnFrameworkUpdate;
        _cleanupCts.Cancel();
        _cleanupTask?.Wait(100);
        _nameplateHandler.Uninit();
    }
}