using AcDream.App.Physics;
using AcDream.Core.Physics;

namespace AcDream.App.World;

/// <summary>
/// Applies the presentation/collision side effects of accepted retail
/// PhysicsState transitions after the canonical live owner is ready.
/// Logical ownership stays in <see cref="LiveEntityRuntime"/>; Hidden never
/// unregisters scripts, particles, lights, meshes, or the live record.
/// </summary>
/// <remarks>
/// Ports <c>CPhysicsObj::set_state</c> (<c>0x00514DD0</c>),
/// <c>set_nodraw</c> (<c>0x0050FCA0</c>), and <c>set_hidden</c>
/// (<c>0x00514C60</c>). Typed script ids are retail
/// <c>PS_UnHide=0x75</c> and <c>PS_Hidden=0x76</c> from <c>acclient.h</c>.
/// </remarks>
public sealed class LiveEntityPresentationController : IDisposable
{
    public const uint UnHideScriptType = 0x75u;
    public const uint HiddenScriptType = 0x76u;

    private readonly LiveEntityRuntime _liveEntities;
    private readonly ShadowObjectRegistry _shadows;
    private readonly Func<uint, uint, float, bool> _playTyped;
    private readonly Action<uint, bool> _setDirectChildrenNoDraw;
    private readonly Action<uint> _clearInvalidTarget;
    private readonly Func<(int X, int Y)> _liveCenter;
    private readonly Action<uint>? _onShadowRestored;
    private readonly Dictionary<uint, ushort> _readyGenerationByGuid = new();
    private readonly Dictionary<uint, ushort> _suspendedShadowGenerationByGuid = new();
    private readonly Dictionary<uint, ushort> _activePlacementGenerationByGuid = new();
    private bool _disposed;

    public LiveEntityPresentationController(
        LiveEntityRuntime liveEntities,
        ShadowObjectRegistry shadows,
        Func<uint, uint, float, bool> playTyped,
        Action<uint, bool>? setDirectChildrenNoDraw = null,
        Action<uint>? clearInvalidTarget = null,
        Func<(int X, int Y)>? liveCenter = null,
        Action<uint>? onShadowRestored = null)
    {
        _liveEntities = liveEntities ?? throw new ArgumentNullException(nameof(liveEntities));
        _shadows = shadows ?? throw new ArgumentNullException(nameof(shadows));
        _playTyped = playTyped ?? throw new ArgumentNullException(nameof(playTyped));
        _setDirectChildrenNoDraw = setDirectChildrenNoDraw ?? ((_, _) => { });
        _clearInvalidTarget = clearInvalidTarget ?? (_ => { });
        _liveCenter = liveCenter ?? (() => (0, 0));
        _onShadowRestored = onShadowRestored;
        _liveEntities.ProjectionVisibilityChanged += OnProjectionVisibilityChanged;
    }

    /// <summary>
    /// Opens the state-side-effect barrier after render/effect owners have
    /// registered, then drains constructor and pre-materialization transitions
    /// exactly once in accepted order.
    /// </summary>
    public bool OnLiveEntityReady(uint serverGuid)
    {
        if (!_liveEntities.TryGetRecord(serverGuid, out LiveEntityRecord record)
            || record.WorldEntity is null
            || !record.ResourcesRegistered)
        {
            return false;
        }

        _readyGenerationByGuid[serverGuid] = record.Generation;
        ApplyPendingTransitions(record);
        return true;
    }

    /// <summary>Drains a newly accepted SetState when this incarnation is ready.</summary>
    public bool OnStateAccepted(uint serverGuid)
    {
        if (!_liveEntities.TryGetRecord(serverGuid, out LiveEntityRecord record)
            || !_readyGenerationByGuid.TryGetValue(serverGuid, out ushort generation)
            || generation != record.Generation)
        {
            return false;
        }

        ApplyPendingTransitions(record);
        return true;
    }

    /// <summary>
    /// Retains ownership of a collision shadow that another retail transition
    /// suspended while this incarnation's spatial projection is unavailable.
    /// Hidden/UnHide and teleport rollback intentionally converge on this one
    /// generation-scoped restoration marker.
    /// </summary>
    public bool DeferShadowRestore(uint serverGuid, ushort generation)
        => CompleteAuthoritativePlacement(serverGuid, generation, deferShadowRestore: true);

    /// <summary>
    /// Completes active placement ownership after its final frame/cell is
    /// known, either returning a stable deferred restore to presentation or
    /// clearing the suspension for an immediate controller-owned restore.
    /// </summary>
    public bool CompleteAuthoritativePlacement(
        uint serverGuid,
        ushort generation,
        bool deferShadowRestore)
    {
        if (!_liveEntities.TryGetRecord(serverGuid, out LiveEntityRecord record)
            || record.Generation != generation
            || record.WorldEntity is null)
        {
            return false;
        }

        if (_activePlacementGenerationByGuid.TryGetValue(
                serverGuid,
                out ushort activeGeneration)
            && activeGeneration == generation)
        {
            _activePlacementGenerationByGuid.Remove(serverGuid);
        }

        if (deferShadowRestore)
            _suspendedShadowGenerationByGuid[serverGuid] = generation;
        else if (_suspendedShadowGenerationByGuid.TryGetValue(
                     serverGuid,
                     out ushort deferredGeneration)
                 && deferredGeneration == generation)
            _suspendedShadowGenerationByGuid.Remove(serverGuid);
        return true;
    }

    /// <summary>
    /// Transfers a deferred restore to a newer authoritative placement before
    /// that placement rebuckets and can become visible. The placement hands
    /// ownership back after it reaches a stable Hidden destination/rollback;
    /// this prevents an intervening UnHide from restoring an unresolved pose.
    /// </summary>
    public bool BeginAuthoritativePlacement(uint serverGuid, ushort generation)
    {
        if (!_liveEntities.TryGetRecord(serverGuid, out LiveEntityRecord record)
            || record.Generation != generation)
        {
            return false;
        }

        _activePlacementGenerationByGuid[serverGuid] = generation;
        if (_suspendedShadowGenerationByGuid.TryGetValue(
                serverGuid,
                out ushort deferredGeneration)
            && deferredGeneration == generation)
        {
            _suspendedShadowGenerationByGuid.Remove(serverGuid);
        }
        return true;
    }

    internal bool HasDeferredShadowRestore(uint serverGuid) =>
        _suspendedShadowGenerationByGuid.ContainsKey(serverGuid);

    internal bool HasActivePlacement(uint serverGuid) =>
        _activePlacementGenerationByGuid.ContainsKey(serverGuid);

    public void Forget(LiveEntityRecord record)
    {
        ArgumentNullException.ThrowIfNull(record);
        if (_readyGenerationByGuid.TryGetValue(record.ServerGuid, out ushort generation)
            && generation == record.Generation)
        {
            _readyGenerationByGuid.Remove(record.ServerGuid);
        }
        if (_suspendedShadowGenerationByGuid.TryGetValue(
                record.ServerGuid,
                out ushort suspendedGeneration)
            && suspendedGeneration == record.Generation)
        {
            _suspendedShadowGenerationByGuid.Remove(record.ServerGuid);
        }
        if (_activePlacementGenerationByGuid.TryGetValue(
                record.ServerGuid,
                out ushort activeGeneration)
            && activeGeneration == record.Generation)
        {
            _activePlacementGenerationByGuid.Remove(record.ServerGuid);
        }
    }

    public void Clear()
    {
        _readyGenerationByGuid.Clear();
        _suspendedShadowGenerationByGuid.Clear();
        _activePlacementGenerationByGuid.Clear();
    }

    public void Dispose()
    {
        if (_disposed)
            return;
        _disposed = true;
        _liveEntities.ProjectionVisibilityChanged -= OnProjectionVisibilityChanged;
        Clear();
    }

    private void ApplyPendingTransitions(LiveEntityRecord record)
    {
        while (record.TryDequeueStateTransition(out RetailPhysicsStateTransition transition))
        {
            if (record.WorldEntity is not { } entity)
                return;

            // set_state writes the final state before any PartArray/cell side
            // effect. Retained shadow registrations must see those same bits
            // even while their cell rows are suspended.
            _shadows.UpdatePhysicsState(entity.Id, (uint)transition.FinalState);

            switch (transition.HiddenTransition)
            {
                case RetailHiddenTransition.BecameHidden:
                    _playTyped(entity.Id, HiddenScriptType, 1f);
                    _setDirectChildrenNoDraw(record.ServerGuid, true);
                    _shadows.Suspend(entity.Id);
                    if (!IsPlacementActive(record))
                        _suspendedShadowGenerationByGuid[record.ServerGuid] = record.Generation;
                    _clearInvalidTarget(record.ServerGuid);
                    break;

                case RetailHiddenTransition.BecameVisible:
                    _playTyped(entity.Id, UnHideScriptType, 1f);
                    _setDirectChildrenNoDraw(record.ServerGuid, false);
                    if (!IsPlacementActive(record) && RestoreShadow(record, entity))
                        _suspendedShadowGenerationByGuid.Remove(record.ServerGuid);
                    break;
            }
        }
    }

    private bool RestoreShadow(LiveEntityRecord record, AcDream.Core.World.WorldEntity entity)
    {
        if (!record.IsSpatiallyProjected
            || !record.IsSpatiallyVisible
            || record.FullCellId == 0)
        {
            return false;
        }

        (int centerX, int centerY) = _liveCenter();
        ShadowPositionSynchronizer.Sync(
            _shadows,
            entity.Id,
            entity.Position,
            entity.Rotation,
            record.FullCellId,
            centerX,
            centerY);
        _onShadowRestored?.Invoke(record.ServerGuid);
        return true;
    }

    private void OnProjectionVisibilityChanged(LiveEntityRecord record, bool visible)
    {
        if (!visible
            || record.WorldEntity is not { } entity
            || (record.FinalPhysicsState & PhysicsStateFlags.Hidden) != 0
            || IsPlacementActive(record)
            || !_readyGenerationByGuid.TryGetValue(record.ServerGuid, out ushort readyGeneration)
            || readyGeneration != record.Generation
            || !_suspendedShadowGenerationByGuid.TryGetValue(
                record.ServerGuid,
                out ushort suspendedGeneration)
            || suspendedGeneration != record.Generation)
        {
            return;
        }

        if (RestoreShadow(record, entity))
            _suspendedShadowGenerationByGuid.Remove(record.ServerGuid);
    }

    private bool IsPlacementActive(LiveEntityRecord record) =>
        _activePlacementGenerationByGuid.TryGetValue(
            record.ServerGuid,
            out ushort generation)
        && generation == record.Generation;
}