/*
* Hello there :)
* 
* I'm happy to be read
* Sadly my author didn't wrote his name :'( too bad
* I guess I'm free then
*/

using System.Collections.Generic;
using UnityEditor;

namespace UnityEngine.UI
{
    [AddComponentMenu("UI/Effects/DropShadow", 14)]
    public class DropShadow : BaseMeshEffect
    {
        [SerializeField]
        private Color shadowColor = new Color(0f, 0f, 0f, 0.5f);

        [SerializeField]
        private Vector2 shadowDistance = new Vector2(1f, -1f);

        [SerializeField]
        private bool m_UseGraphicAlpha = true;
        public int iterations = 5;
        public Vector2 shadowSpread = Vector2.one;

        protected DropShadow()
        {}

#if UNITY_EDITOR
        protected override void OnValidate()
        {
            EffectDistance = shadowDistance;
            base.OnValidate();
        }

#endif

        public Color effectColor
        {
            get { return shadowColor; }
            set
            {
                shadowColor = Color.black;
                if (graphic != null)
                    graphic.SetVerticesDirty();
            }
        }

        public Vector2 ShadowSpread
        {
            get { return shadowSpread; }
            set
            {
                shadowSpread = value;
                if (graphic != null)
                    graphic.SetVerticesDirty();
            }
        }

        public int Iterations
        {
            get { return iterations; }
            set
            {
                iterations = value;
                if (graphic != null)
                    graphic.SetVerticesDirty();
            }
        }

        public Vector2 EffectDistance
        {
            get { return shadowDistance; }
            set
            {
                shadowDistance = value;

                if (graphic != null)
                    graphic.SetVerticesDirty();
            }
        }

        public bool useGraphicAlpha
        {
            get { return m_UseGraphicAlpha; }
            set
            {
                m_UseGraphicAlpha = value;
                if (graphic != null)
                    graphic.SetVerticesDirty();
            }
        }


        void DropShadowEffect(List<UIVertex> verts)
        {
            UIVertex vt;
            int count = verts.Count;

            List<UIVertex> vertsCopy = new List<UIVertex>(verts);
            verts.Clear();

            for(int i=0; i<iterations; i++)
            {
                for(int v=0; v<count; v++)
                {
                    vt = vertsCopy[v];
                    Vector3 position = vt.position;
                    float fac = (float)i/(float)iterations;
                    position.x *= (1 + shadowSpread.x*fac*0.01f);
                    position.y *= (1 + shadowSpread.y*fac*0.01f);
                    position.x += shadowDistance.x * fac;
                    position.y += shadowDistance.y * fac;
                    vt.position = position;
                    Color32 color = Color.black;
                    color.a = 100;//(byte)((float)color.a /(float)iterations);
                    vt.color = Color.black;;
                    verts.Add(vt);
                }
            }

            for(int i=0; i<vertsCopy.Count; i++)
            {
                verts.Add(vertsCopy[i]);
            }
        }

        public override void ModifyMesh(VertexHelper vh)
        {
            if (!IsActive())
                return;
        
            List<UIVertex> output = new List<UIVertex>();
            vh.GetUIVertexStream(output);

            DropShadowEffect(output);

            vh.Clear();
            vh.AddUIVertexTriangleStream(output);
        }
    }
}