using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using UnityEngine.Profiling;
using UnityEngine.Rendering;
using UnityEngine.UI;
using ShaderPropertyType = Coffee.UIExtensions.UIParticle.AnimatableProperty.ShaderPropertyType;


namespace Coffee.UIExtensions
{
    /// <summary>
    /// Render maskable and sortable particle effect ,without Camera, RenderTexture or Canvas.
    /// </summary>
    [ExecuteInEditMode]
    [RequireComponent(typeof(CanvasRenderer))]
    public class UIParticle : MaskableGraphic
    {
        //################################
        // Constant or Readonly Static Members.
        //################################
        static readonly int s_IdMainTex = Shader.PropertyToID("_MainTex");
        static readonly List<Vector3> s_Vertices = new List<Vector3>();
        static readonly List<Color32> s_Colors = new List<Color32>();
        static readonly List<UIParticle> s_TempRelatables = new List<UIParticle>();
        static readonly List<UIParticle> s_ActiveParticles = new List<UIParticle>();


        //################################
        // Serialize Members.
        //################################
        [Tooltip("The ParticleSystem rendered by CanvasRenderer")]
        [SerializeField] ParticleSystem m_ParticleSystem;
        [Tooltip("The UIParticle to render trail effect")]
        [SerializeField] UIParticle m_TrailParticle;
        [HideInInspector] [SerializeField] bool m_IsTrail = false;
        [Tooltip("Particle effect scale")]
        [SerializeField] float m_Scale = 1;
        [Tooltip("Ignore parent scale")]
        [SerializeField] bool m_IgnoreParent = false;

        [Tooltip("Animatable material properties. AnimationでParticleSystemのマテリアルプロパティを変更する場合、有効にしてください。")]
        [SerializeField] AnimatableProperty[] m_AnimatableProperties = new AnimatableProperty[0];

        static MaterialPropertyBlock s_Mpb;

        [System.Serializable]
        public class AnimatableProperty : ISerializationCallbackReceiver
        {
            public enum ShaderPropertyType
            {
                Color,
                Vector,
                Float,
                Range,
                Texture,
            };

            [SerializeField]
            string m_Name = "";
            [SerializeField]
            ShaderPropertyType m_Type = ShaderPropertyType.Vector;
            public int id { get; private set; }
            public ShaderPropertyType type { get { return m_Type; } }


            public void OnBeforeSerialize()
            {
            }

            public void OnAfterDeserialize()
            {
                id = Shader.PropertyToID(m_Name);
            }
        }



        //################################
        // Public/Protected Members.
        //################################
        public override Texture mainTexture
        {
            get
            {
                Texture tex = null;
                if (!m_IsTrail && cachedParticleSystem)
                {
                    Profiler.BeginSample("Check TextureSheetAnimation module");
                    var textureSheet = cachedParticleSystem.textureSheetAnimation;
                    if (textureSheet.enabled && textureSheet.mode == ParticleSystemAnimationMode.Sprites && 0 < textureSheet.spriteCount)
                    {
                        var sprite = textureSheet.GetSprite(0);
                        textureSheet.uvChannelMask = (UVChannelFlags) (sprite && sprite.packed ? -1 : 0);
                        tex = sprite ? sprite.texture : null;
                    }
                    Profiler.EndSample();
                }
                if (!tex && _renderer)
                {
                    Profiler.BeginSample("Check material");
                    var mat = material;
                    if (mat && mat.HasProperty(s_IdMainTex))
                    {
                        tex = mat.mainTexture;
                    }
                    Profiler.EndSample();
                }
                return tex ?? s_WhiteTexture;
            }
        }

        public override Material material
        {
            get
            {
                return _renderer
                        ? m_IsTrail
                            ? _renderer.trailMaterial
                            : _renderer.sharedMaterial
                        : null;
            }

            set
            {
                if (!_renderer)
                {
                }
                else if (m_IsTrail && _renderer.trailMaterial != value)
                {
                    _renderer.trailMaterial = value;
                    SetMaterialDirty();
                }
                else if (!m_IsTrail && _renderer.sharedMaterial != value)
                {
                    _renderer.sharedMaterial = value;
                    SetMaterialDirty();
                }
            }
        }

        /// <summary>
        /// Particle effect scale.
        /// </summary>
        public float scale { get { return _parent ? _parent.scale : m_Scale; } set { m_Scale = value; } }

        /// <summary>
        /// Should the soft mask ignore parent soft masks?
        /// </summary>
        /// <value>If set to true the soft mask will ignore any parent soft mask settings.</value>
        public bool ignoreParent
        {
            get { return m_IgnoreParent; }
            set
            {
                if (m_IgnoreParent != value)
                {
                    m_IgnoreParent = value;
                    OnTransformParentChanged();
                }
            }
        }

        /// <summary>
        /// Is this the root UIParticle?
        /// </summary>
        public bool isRoot
        {
            get { return !_parent; }
        }

        /// <summary>
        /// Should this graphic be considered a target for raycasting?
        /// </summary>
        public override bool raycastTarget { get { return false; } set { base.raycastTarget = value; } }

        /// <summary>
        /// ParticleSystem.
        /// </summary>
        public ParticleSystem cachedParticleSystem { get { return m_ParticleSystem ? m_ParticleSystem : (m_ParticleSystem = GetComponent<ParticleSystem>()); } }

        /// <summary>
        /// Perform material modification in this function.
        /// </summary>
        /// <returns>Modified material.</returns>
        /// <param name="baseMaterial">Configured Material.</param>
        public override Material GetModifiedMaterial(Material baseMaterial)
        {
            Material mat = null;
            if (!_renderer)
                mat = baseMaterial;
            else if (m_AnimatableProperties.Length == 0)
                mat = _renderer.sharedMaterial;
            else
                mat = new Material(material);

            return base.GetModifiedMaterial(mat);
        }

        /// <summary>
        /// This function is called when the object becomes enabled and active.
        /// </summary>
        protected override void OnEnable()
        {
            // Register.
            if (s_ActiveParticles.Count == 0)
            {
                Canvas.willRenderCanvases += UpdateMeshes;
                s_Mpb = new MaterialPropertyBlock();
            }
            s_ActiveParticles.Add(this);

            // Reset the parent-child relation.
            GetComponentsInChildren<UIParticle>(false, s_TempRelatables);
            for (int i = s_TempRelatables.Count - 1; 0 <= i; i--)
            {
                s_TempRelatables[i].OnTransformParentChanged();
            }
            s_TempRelatables.Clear();

            _renderer = cachedParticleSystem ? cachedParticleSystem.GetComponent<ParticleSystemRenderer>() : null;
            if (_renderer && Application.isPlaying)
            {
                _renderer.enabled = false;
            }

            // Create objects.
            _mesh = new Mesh();
            _mesh.MarkDynamic();
            CheckTrail();

            if (cachedParticleSystem)
            {
                _oldPos = cachedParticleSystem.main.scalingMode == ParticleSystemScalingMode.Local
                    ? rectTransform.localPosition
                    : rectTransform.position;
            }

            base.OnEnable();
        }

        /// <summary>
        /// This function is called when the behaviour becomes disabled.
        /// </summary>
        protected override void OnDisable()
        {
            // Unregister.
            s_ActiveParticles.Remove(this);
            if (s_ActiveParticles.Count == 0)
            {
                Canvas.willRenderCanvases -= UpdateMeshes;
            }

            // Reset the parent-child relation.
            for (int i = _children.Count - 1; 0 <= i; i--)
            {
                _children[i].SetParent(_parent);
            }
            _children.Clear();
            SetParent(null);

            // Destroy objects.
            DestroyImmediate(_mesh);
            _mesh = null;
            CheckTrail();

            base.OnDisable();
        }

#if UNITY_EDITOR
        /// <summary>
        /// Reset to default values.
        /// </summary>
        protected override void Reset()
        {
            // Disable ParticleSystemRenderer on reset.
            if (cachedParticleSystem)
            {
                cachedParticleSystem.GetComponent<ParticleSystemRenderer>().enabled = false;
            }
            base.Reset();
        }
#endif

        /// <summary>
        /// Call to update the geometry of the Graphic onto the CanvasRenderer.
        /// </summary>
        protected override void UpdateGeometry()
        {
        }

        /// <summary>
        /// This function is called when the parent property of the transform of the GameObject has changed.
        /// </summary>
        protected override void OnTransformParentChanged()
        {
            UIParticle newParent = null;
            if (isActiveAndEnabled && !m_IgnoreParent)
            {
                var parentTransform = transform.parent;
                while (parentTransform && (!newParent || !newParent.enabled))
                {
                    newParent = parentTransform.GetComponent<UIParticle>();
                    parentTransform = parentTransform.parent;
                }
            }
            SetParent(newParent);

            base.OnTransformParentChanged();
        }

        /// <summary>
        /// Callback for when properties have been changed by animation.
        /// </summary>
        protected override void OnDidApplyAnimationProperties()
        {
        }

#if UNITY_EDITOR
        /// <summary>
        /// This function is called when the script is loaded or a value is changed in the inspector(Called in the editor only).
        /// </summary>
        protected override void OnValidate()
        {
            OnTransformParentChanged();
            base.OnValidate();
        }
#endif


        //################################
        // Private Members.
        //################################
        Mesh _mesh;
        ParticleSystemRenderer _renderer;
        UIParticle _parent;
        List<UIParticle> _children = new List<UIParticle>();
        Matrix4x4 scaleaMatrix = default(Matrix4x4);
        Vector3 _oldPos;
        static readonly Vector3 minimumVec3 = new Vector3(0.0000001f, 0.0000001f, 0.0000001f);
        static ParticleSystem.Particle[] s_Particles = new ParticleSystem.Particle[4096];

        /// <summary>
        /// Update meshes.
        /// </summary>
        static void UpdateMeshes()
        {
            for (int i = 0; i < s_ActiveParticles.Count; i++)
            {
                if (s_ActiveParticles[i])
                {
                    s_ActiveParticles[i].UpdateMesh();
                }
            }
        }

        /// <summary>
        /// Update meshe.
        /// </summary>
        void UpdateMesh()
        {
            try
            {
                Profiler.BeginSample("CheckTrail");
                CheckTrail();
                Profiler.EndSample();

                if (m_ParticleSystem && canvas)
                {
                    // I do not know why, but it worked fine when setting `transform.localPosition.z` to `0.01`. (#34, #39)
                    {
                        Vector3 pos = rectTransform.localPosition;
                        if (Mathf.Abs(pos.z) < 0.01f)
                        {
                            pos.z = 0.01f;
                            rectTransform.localPosition = pos;
                        }
                    }

                    var rootCanvas = canvas.rootCanvas;
                    Profiler.BeginSample("Disable ParticleSystemRenderer");
                    if (Application.isPlaying)
                    {
                        _renderer.enabled = false;
                    }
                    Profiler.EndSample();

                    // #69: Editor crashes when mesh is set to null when ParticleSystem.RenderMode=Mesh
                    if (_renderer.renderMode == ParticleSystemRenderMode.Mesh && !_renderer.mesh)
                        return;

                    // #61: When ParticleSystem.RenderMode=None, an error occurs
                    if (_renderer.renderMode == ParticleSystemRenderMode.None)
                        return;

                    Profiler.BeginSample("Make Matrix");
                    ParticleSystem.MainModule main = m_ParticleSystem.main;
                    scaleaMatrix = main.scalingMode == ParticleSystemScalingMode.Hierarchy
                                                   ? Matrix4x4.Scale(scale * Vector3.one)
                                                   : Matrix4x4.Scale(scale * rootCanvas.transform.localScale);
                    Matrix4x4 matrix = default(Matrix4x4);
                    switch (main.simulationSpace)
                    {
                        case ParticleSystemSimulationSpace.Local:
                            matrix =
                                scaleaMatrix
                                * Matrix4x4.Rotate(rectTransform.rotation).inverse
                                * Matrix4x4.Scale(rectTransform.lossyScale + minimumVec3).inverse;
                            break;
                        case ParticleSystemSimulationSpace.World:
                            matrix =
                                scaleaMatrix
                                * rectTransform.worldToLocalMatrix;

                            bool isLocalScaling = main.scalingMode == ParticleSystemScalingMode.Local;
                            Vector3 newPos = rectTransform.position;
                            Vector3 delta = (newPos - _oldPos);
                            _oldPos = newPos;

                            if (!Mathf.Approximately(scale, 0) && 0 < delta.sqrMagnitude)
                            {
                                if (isLocalScaling)
                                {
                                    var s = rootCanvas.transform.localScale * scale;
                                    delta.x *= 1f - 1f / s.x;
                                    delta.y *= 1f - 1f / s.y;
                                    delta.z *= 1f - 1f / s.z;
                                }
                                else
                                {
                                    delta = delta * (1 - 1 / scale);
                                }

                                int count = m_ParticleSystem.particleCount;
                                if (s_Particles.Length < count)
                                {
                                    s_Particles = new ParticleSystem.Particle[s_Particles.Length * 2];
                                }

                                m_ParticleSystem.GetParticles(s_Particles);
                                for (int i = 0; i < count; i++)
                                {
                                    var p = s_Particles[i];
                                    p.position = p.position + delta;
                                    s_Particles[i] = p;
                                }
                                m_ParticleSystem.SetParticles(s_Particles, count);
                            }
                            break;
                        case ParticleSystemSimulationSpace.Custom:
                            break;
                    }
                    Profiler.EndSample();

                    _mesh.Clear();
                    if (0 < m_ParticleSystem.particleCount)
                    {
                        Profiler.BeginSample("Bake Mesh");
                        var cam = rootCanvas.renderMode == RenderMode.ScreenSpaceOverlay
                            ? UIParticleOverlayCamera.GetCameraForOvrelay(rootCanvas)
                            : canvas.worldCamera ?? Camera.main;

                        if (!cam)
                        {
                            Profiler.EndSample();
                            return;
                        }
                        if (m_IsTrail)
                        {
                            _renderer.BakeTrailsMesh(_mesh, cam, true);
                        }
                        else
                        {
                            _renderer.BakeMesh(_mesh, cam, true);
                        }
                        Profiler.EndSample();

                        // Apply matrix.
                        Profiler.BeginSample("Apply matrix to position");

                        if (QualitySettings.activeColorSpace == ColorSpace.Linear)
                        {
                            _mesh.GetColors(s_Colors);
                            var count_c = s_Colors.Count;
                            for (int i = 0; i < count_c; i++)
                            {
                                s_Colors[i] = ((Color)s_Colors[i]).gamma;
                            }
                            _mesh.SetColors(s_Colors);
                        }

                        _mesh.GetVertices(s_Vertices);
                        var count = s_Vertices.Count;
                        for (int i = 0; i < count; i++)
                        {
                            s_Vertices[i] = matrix.MultiplyPoint3x4(s_Vertices[i]);
                        }
                        _mesh.SetVertices(s_Vertices);
                        _mesh.RecalculateBounds();
                        s_Vertices.Clear();
                        s_Colors.Clear();
                        Profiler.EndSample();
                    }


                    // Set mesh to CanvasRenderer.
                    Profiler.BeginSample("Set mesh and texture to CanvasRenderer");
                    canvasRenderer.SetMesh(_mesh);
                    canvasRenderer.SetTexture(mainTexture);

                    // Copy the value from MaterialPropertyBlock to CanvasRenderer (#41)
                    UpdateAnimatableMaterialProperties();

                    Profiler.EndSample();
                }
            }
            catch (System.Exception e)
            {
                Debug.LogException(e);
            }
        }

        /// <summary>
        /// Checks the trail.
        /// </summary>
        void CheckTrail()
        {
            if (isActiveAndEnabled && !m_IsTrail && m_ParticleSystem && m_ParticleSystem.trails.enabled)
            {
                if (!m_TrailParticle)
                {
                    m_TrailParticle = new GameObject("[UIParticle] Trail").AddComponent<UIParticle>();
                    var trans = m_TrailParticle.transform;
                    trans.SetParent(transform);
                    trans.localPosition = Vector3.zero;
                    trans.localRotation = Quaternion.identity;
                    trans.localScale = Vector3.one;

                    m_TrailParticle._renderer = GetComponent<ParticleSystemRenderer>();
                    m_TrailParticle.m_ParticleSystem = GetComponent<ParticleSystem>();
                    m_TrailParticle.m_IsTrail = true;
                }
                m_TrailParticle.enabled = true;
            }
            else if (m_TrailParticle)
            {
                m_TrailParticle.enabled = false;
            }
        }

        /// <summary>
        /// Set the parent of the soft mask.
        /// </summary>
        /// <param name="newParent">The parent soft mask to use.</param>
        void SetParent(UIParticle newParent)
        {
            if (_parent != newParent && this != newParent)
            {
                if (_parent && _parent._children.Contains(this))
                {
                    _parent._children.Remove(this);
                    _parent._children.RemoveAll(x => x == null);
                }
                _parent = newParent;
            }

            if (_parent && !_parent._children.Contains(this))
            {
                _parent._children.Add(this);
            }
        }

        /// <summary>
        /// Copy the value from MaterialPropertyBlock to CanvasRenderer (#41)
        /// </summary>
        void UpdateAnimatableMaterialProperties()
        {
#if UNITY_EDITOR
            if (!Application.isPlaying)
                return;
#endif
            if (0 == m_AnimatableProperties.Length)
                return;

            _renderer.GetPropertyBlock(s_Mpb);
            for (int i = 0; i < canvasRenderer.materialCount; i++)
            {
                var mat = canvasRenderer.GetMaterial(i);
                foreach (var ap in m_AnimatableProperties)
                {
                    switch (ap.type)
                    {
                        case ShaderPropertyType.Color:
                            mat.SetColor(ap.id, s_Mpb.GetColor(ap.id));
                            break;
                        case ShaderPropertyType.Vector:
                            mat.SetVector(ap.id, s_Mpb.GetVector(ap.id));
                            break;
                        case ShaderPropertyType.Float:
                        case ShaderPropertyType.Range:
                            mat.SetFloat(ap.id, s_Mpb.GetFloat(ap.id));
                            break;
                        case ShaderPropertyType.Texture:
                            mat.SetTexture(ap.id, s_Mpb.GetTexture(ap.id));
                            break;
                    }
                }
            }
        }
    }
}