using System.Collections.Generic;
using BrewMonster.Scripts;

namespace BrewMonster
{
    public sealed class FadeOutGfx
    {
        public int m_dwTotalTTL;
        public int m_dwTTL;
        public GFX_BINDING m_pGfx;
        public float m_fAlpha;
    }

    /// <summary>
    /// Queues skill/combined-action GFX for delayed stop (fade-out window), aligned with A3DGFXExMan::UpdateFadeOutGfxLst.
    /// </summary>
    public class A3DGfxMan : IAutoInitialize, ITickable
    {
        public const int DefaultFadeOutMs = 1000;

        private static A3DGfxMan _instance;

        readonly Dictionary<int, List<GFX_BINDING>> _releaseByModel = new Dictionary<int, List<GFX_BINDING>>();
        readonly List<FadeOutGfx> _fadeOutList = new List<FadeOutGfx>();
        readonly List<GFX_BINDING> _flushBuffer = new List<GFX_BINDING>();

        public static A3DGfxMan Instance => _instance ??= new A3DGfxMan();

        public void Initialize()
        {
            _instance = this;
            TickInvoker.Instance.RegisterTickable(this);
        }

        public bool Tick(uint dwDeltaTime)
        {
            if (_fadeOutList.Count == 0)
                return true;

            int deltaTime = (int)dwDeltaTime;

            for (int i = _fadeOutList.Count - 1; i >= 0; i--)
            {
                FadeOutGfx entry = _fadeOutList[i];
                GFX_BINDING gfx = entry.m_pGfx;

                if (gfx == null)
                {
                    _fadeOutList.RemoveAt(i);
                    continue;
                }

                entry.m_dwTTL -= deltaTime;
                if (entry.m_dwTTL > 0)
                {
                    _fadeOutList[i] = entry;
                    continue;
                }

                gfx.Stop();
                _fadeOutList.RemoveAt(i);
            }

            return true;
        }

        public void Dispose()
        {
            _fadeOutList.Clear();
            _releaseByModel.Clear();
            _flushBuffer.Clear();
        }

        public void AddReleaseGfx(int modelId, GFX_BINDING gfx)
        {
            if (gfx == null)
                return;

            if (!_releaseByModel.TryGetValue(modelId, out List<GFX_BINDING> list))
            {
                list = new List<GFX_BINDING>(4);
                _releaseByModel[modelId] = list;
            }

            list.Add(gfx);
        }

        public int GetPendingReleaseCount(int modelId)
        {
            return _releaseByModel.TryGetValue(modelId, out List<GFX_BINDING> list) ? list.Count : 0;
        }

        /// <summary>
        /// Fade out the oldest <paramref name="maxCount"/> pending GFX for a model (cast/chant phase snapshot).
        /// 淡出该模型最早注册的 maxCount 个待释放特效（吟唱阶段快照）。
        /// </summary>
        public void FadeOutReleaseUpTo(int modelId, int maxCount, int fadeMs = DefaultFadeOutMs)
        {
            if (maxCount <= 0
                || !_releaseByModel.TryGetValue(modelId, out List<GFX_BINDING> releaseList)
                || releaseList.Count == 0)
                return;

            int count = maxCount < releaseList.Count ? maxCount : releaseList.Count;
            QueueFadeOutFromReleaseList(releaseList, count, fadeMs);

            if (releaseList.Count == 0)
                _releaseByModel.Remove(modelId);
        }

        /// <summary>
        /// Fade out every pending combined-action GFX registered for a model.
        /// 淡出该模型所有待释放的组合动作特效。
        /// </summary>
        public void FadeOutGfx(int modelId, int fadeMs = DefaultFadeOutMs)
        {
            if (!_releaseByModel.TryGetValue(modelId, out List<GFX_BINDING> releaseList)
                || releaseList.Count == 0)
                return;

            QueueFadeOutFromReleaseList(releaseList, releaseList.Count, fadeMs);
            _releaseByModel.Remove(modelId);
        }

        void QueueFadeOutFromReleaseList(List<GFX_BINDING> releaseList, int count, int fadeMs)
        {
            _flushBuffer.Clear();

            for (int i = 0; i < count; i++)
            {
                GFX_BINDING gfx = releaseList[i];
                if (gfx != null)
                    _flushBuffer.Add(gfx);
            }

            releaseList.RemoveRange(0, count);

            for (int i = 0; i < _flushBuffer.Count; i++)
            {
                GFX_BINDING gfx = _flushBuffer[i];
                if (gfx == null)
                    continue;

                _fadeOutList.Add(new FadeOutGfx
                {
                    m_dwTotalTTL = fadeMs,
                    m_dwTTL = fadeMs,
                    m_pGfx = gfx,
                    m_fAlpha = 1f,
                });
            }

            _flushBuffer.Clear();
        }
    }
}