using System;
using System.Collections.Generic;
using System.Reflection;
using UnityEngine;
using Object = UnityEngine.Object;

namespace Coffee.UIParticleExtensions
{
    internal static class SpriteExtensions
    {
#if UNITY_EDITOR
        private static Type tSpriteEditorExtension =
            Type.GetType("UnityEditor.Experimental.U2D.SpriteEditorExtension, UnityEditor")
            ?? Type.GetType("UnityEditor.U2D.SpriteEditorExtension, UnityEditor");

        private static MethodInfo miGetActiveAtlasTexture = tSpriteEditorExtension
            .GetMethod("GetActiveAtlasTexture", BindingFlags.Static | BindingFlags.NonPublic);

        public static Texture2D GetActualTexture(this Sprite self)
        {
            if (!self) return null;

            if (Application.isPlaying) return self.texture;
            var ret = miGetActiveAtlasTexture.Invoke(null, new[] {self}) as Texture2D;
            return ret ? ret : self.texture;
        }
#else
        internal static Texture2D GetActualTexture(this Sprite self)
        {
            return self ? self.texture : null;
        }
#endif
    }

    internal static class ListExtensions
    {
        public static bool SequenceEqualFast(this List<bool> self, List<bool> value)
        {
            if (self.Count != value.Count) return false;
            for (var i = 0; i < self.Count; ++i)
            {
                if (self[i] != value[i]) return false;
            }

            return true;
        }

        public static int CountFast(this List<bool> self)
        {
            var count = 0;
            for (var i = 0; i < self.Count; ++i)
            {
                if (self[i]) count++;
            }

            return count;
        }

        public static bool AnyFast<T>(this List<T> self) where T : Object
        {
            for (var i = 0; i < self.Count; ++i)
            {
                if (self[i]) return true;
            }

            return false;
        }
    }

    internal static class MeshExtensions
    {
        static readonly List<Color32> s_Colors = new List<Color32>();

        public static void ModifyColorSpaceToLinear(this Mesh self)
        {
            self.GetColors(s_Colors);

            for (var i = 0; i < s_Colors.Count; i++)
                s_Colors[i] = ((Color) s_Colors[i]).gamma;

            self.SetColors(s_Colors);
            s_Colors.Clear();
        }

        public static void Clear(this CombineInstance[] self)
        {
            for (var i = 0; i < self.Length; i++)
            {
                MeshPool.Return(self[i].mesh);
                self[i].mesh = null;
            }
        }
    }

    internal static class MeshPool
    {
        private static readonly Stack<Mesh> s_Pool = new Stack<Mesh>();

        public static void Init()
        {
        }

        static MeshPool()
        {
            for (var i = 0; i < 32; i++)
            {
                var m = new Mesh();
                m.MarkDynamic();
                s_Pool.Push(m);
            }
        }

        public static Mesh Rent()
        {
            Mesh m;
            while (0 < s_Pool.Count)
            {
                m = s_Pool.Pop();
                if (m) return m;
            }

            m = new Mesh();
            m.MarkDynamic();
            return m;
        }

        public static void Return(Mesh mesh)
        {
            if (!mesh || s_Pool.Contains(mesh)) return;
            mesh.Clear(false);
            s_Pool.Push(mesh);
        }
    }

    internal static class CombineInstanceArrayPool
    {
        private static readonly Dictionary<int, CombineInstance[]> s_Pool;

        public static void Init()
        {
            s_Pool.Clear();
        }

        static CombineInstanceArrayPool()
        {
            s_Pool = new Dictionary<int, CombineInstance[]>();
        }

        public static CombineInstance[] Get(List<CombineInstance> src)
        {
            CombineInstance[] dst;
            var count = src.Count;
            if (!s_Pool.TryGetValue(count, out dst))
            {
                dst = new CombineInstance[count];
                s_Pool.Add(count, dst);
            }

            for (var i = 0; i < src.Count; i++)
            {
                dst[i].mesh = src[i].mesh;
                dst[i].transform = src[i].transform;
            }

            return dst;
        }

        public static CombineInstance[] Get(List<CombineInstanceEx> src, int count)
        {
            CombineInstance[] dst;
            if (!s_Pool.TryGetValue(count, out dst))
            {
                dst = new CombineInstance[count];
                s_Pool.Add(count, dst);
            }

            for (var i = 0; i < count; i++)
            {
                dst[i].mesh = src[i].mesh;
                dst[i].transform = src[i].transform;
            }

            return dst;
        }
    }

    internal static class ParticleSystemExtensions
    {
        public static void SortForRendering(this List<ParticleSystem> self, Transform transform, bool sortByMaterial)
        {
            self.Sort((a, b) =>
            {
                var tr = transform;
                var aRenderer = a.GetComponent<ParticleSystemRenderer>();
                var bRenderer = b.GetComponent<ParticleSystemRenderer>();

                // Render queue: ascending
                var aMat = aRenderer.sharedMaterial ?? aRenderer.trailMaterial;
                var bMat = bRenderer.sharedMaterial ?? bRenderer.trailMaterial;
                if (!aMat && !bMat) return 0;
                if (!aMat) return -1;
                if (!bMat) return 1;

                if (sortByMaterial)
                    return aMat.GetInstanceID() - bMat.GetInstanceID();

                if (aMat.renderQueue != bMat.renderQueue)
                    return aMat.renderQueue - bMat.renderQueue;

                // Sorting layer: ascending
                if (aRenderer.sortingLayerID != bRenderer.sortingLayerID)
                    return aRenderer.sortingLayerID - bRenderer.sortingLayerID;

                // Sorting order: ascending
                if (aRenderer.sortingOrder != bRenderer.sortingOrder)
                    return aRenderer.sortingOrder - bRenderer.sortingOrder;

                // Z position & sortingFudge: descending
                var aTransform = a.transform;
                var bTransform = b.transform;
                var aPos = tr.InverseTransformPoint(aTransform.position).z + aRenderer.sortingFudge;
                var bPos = tr.InverseTransformPoint(bTransform.position).z + bRenderer.sortingFudge;
                if (!Mathf.Approximately(aPos, bPos))
                    return (int) Mathf.Sign(bPos - aPos);

                return (int) Mathf.Sign(GetIndex(self, a) - GetIndex(self, b));

                // Material instance ID: match
                // if (aMat.GetInstanceID() == bMat.GetInstanceID())
                // return 0;

                // Transform: ascending
                // return TransformCompare(aTransform, bTransform);
            });
        }

        private static int GetIndex(IReadOnlyList<ParticleSystem> list, Object ps)
        {
            for (var i = 0; i < list.Count; i++)
            {
                if (list[i].GetInstanceID() == ps.GetInstanceID()) return i;
            }

            return 0;
        }

        // private static int TransformCompare(Transform a, Transform b)
        // {
        //     while (true)
        //     {
        //         if (!a && !b) return 0;
        //         if (!a) return -1;
        //         if (!b) return 1;
        //         if (a.parent == b.parent) return a.GetSiblingIndex() - b.GetSiblingIndex();
        //
        //         a = a.parent;
        //         b = b.parent;
        //     }
        // }

        public static long GetMaterialHash(this ParticleSystem self, bool trail)
        {
            if (!self) return 0;

            var r = self.GetComponent<ParticleSystemRenderer>();
            var mat = trail ? r.trailMaterial : r.sharedMaterial;

            if (!mat) return 0;

            var tex = trail ? null : self.GetTextureForSprite();
            return ((long) mat.GetHashCode() << 32) + (tex ? tex.GetHashCode() : 0);
        }

        public static Texture2D GetTextureForSprite(this ParticleSystem self)
        {
            if (!self) return null;

            // Get sprite's texture.
            var tsaModule = self.textureSheetAnimation;
            if (!tsaModule.enabled || tsaModule.mode != ParticleSystemAnimationMode.Sprites) return null;

            for (var i = 0; i < tsaModule.spriteCount; i++)
            {
                var sprite = tsaModule.GetSprite(i);
                if (!sprite) continue;

                return sprite.GetActualTexture();
            }

            return null;
        }

        public static void Exec(this List<ParticleSystem> self, Action<ParticleSystem> action)
        {
            self.RemoveAll(p => !p);
            self.ForEach(action);
        }
    }
}