using UnityEngine;
using System.Collections;
using System.Collections.Generic;
using UnityEngine.UI;

[AddComponentMenu("UI/Effects/VerticalColorGradual")]
public class VerticalColorGradual:BaseMeshEffect {

    [SerializeField]
    private Color32 m_TopColor = Color.white;
    public Color32 topColor {
        get {
            return m_TopColor;
        }
        set {
            m_TopColor = value;
            this.graphic.SetVerticesDirty();
        }
    }

    [SerializeField]
    private Color32 m_BottomColor = Color.black;
    public Color32 bottomColor {
        get {
            return m_BottomColor;
        }
        set {
            m_BottomColor = value;
            this.graphic.SetVerticesDirty();
        }
    }

    [Range(-1,1)]
    [SerializeField]
    private float m_Center = 0f;
    public float center {
        get {
            return m_Center;
        }
        set {
            m_Center = value;
            this.graphic.SetVerticesDirty();
        }
    }

    public override void ModifyMesh(VertexHelper vh) {
        var vertexList = new List<UIVertex>();
        vh.GetUIVertexStream(vertexList);

        int count = vertexList.Count;
        if(count > 0) {
            var bottomY = vertexList[0].position.y;
            var topY = vertexList[0].position.y;

            for(int i = 1;i < count;i++) {
                var y = vertexList[i].position.y;
                if(y > topY) {
                    topY = y;
                }
                else if(y < bottomY) {
                    bottomY = y;
                }
            }

            var height = topY - bottomY;
            for(int i = 0;i < count;i++) {
                var uiVertex = vertexList[i];
                uiVertex.color = Color32.Lerp(bottomColor,topColor,Mathf.Clamp01((uiVertex.position.y - (bottomY + height * center)) / height));
                vertexList[i] = uiVertex;
            }
        }

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



}