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

[RequireComponent(typeof(Image))]
public class DivideImage : BaseMeshEffect, ICanvasRaycastFilter
{
    [SerializeField]
    int m_Divide = 5;
    public int Divide { get { return m_Divide; } }

    [SerializeField]
    int m_CurrentDivide = 1;
    public int CurrenDivide { get { return m_CurrentDivide; } }

    [Range(0, 1)]
    [SerializeField]
    float m_FillPercent = 1f;
    public float fillPercent { get { return m_FillPercent; } }

    [Range(4, 128)]
    [SerializeField]
    int m_Segements = 30;
    public int segements { get { return m_Segements; } }

    private Image m_Image;
    public Image image { get { return m_Image ?? (m_Image = this.AddMissingComponent<Image>()); } }

    private List<Vector3> outterVertices;

    protected override void Awake()
    {
        outterVertices = new List<Vector3>();
    }

    public override void ModifyMesh(VertexHelper vh)
    {
        vh.Clear();
        outterVertices.Clear();
        var degreeDelta = (float)(2 * Mathf.PI / segements);
        var realSegements = (int)(segements * fillPercent);
        var width = image.rectTransform.rect.width;
        var height = image.rectTransform.rect.height;
        var uv = image.overrideSprite != null ? DataUtility.GetOuterUV(image.overrideSprite) : Vector4.zero;
        var uvCenterX = (uv.x + uv.z) * 0.5f;
        var uvCenterY = (uv.y + uv.w) * 0.5f;
        var uvScaleX = (uv.z - uv.x) / width;
        var uvScaleY = (uv.w - uv.y) / height;
        var outerArea = new Vector2(0.5f * width, 0.5f * height);
        UIVertex uiVertex;
        var position = Vector2.zero;
        var uv0 = new Vector2(position.x * uvScaleX + uvCenterX, position.y * uvScaleY + uvCenterY);
        uiVertex = UIUtility.PackageUIVertex(position, uv0, image.color);
        vh.AddVert(uiVertex);
        var everyRad = (float)(2 * Mathf.PI / Divide);
        var currentRad = everyRad*CurrenDivide - Mathf.PI*0.1f;
        var verticeCount = 0;
        var triangleCount = 0;
        verticeCount = realSegements + 1;
        uv0 = new Vector2(position.x * uvScaleX + uvCenterX, position.y * uvScaleY + uvCenterY);
        uiVertex = UIUtility.PackageUIVertex(position, uv0, image.color);
        vh.AddVert(uiVertex);

        for (int i = 1; i < verticeCount; i++)
        {
            var cosA = Mathf.Cos(currentRad);
            var sinA = Mathf.Sin(currentRad);
            currentRad = currentRad - degreeDelta;
            position = new Vector2(cosA * outerArea.x, sinA * outerArea.y);
            uv0 = new Vector2(position.x * uvScaleX + uvCenterX, position.y * uvScaleY + uvCenterY);
            uiVertex = UIUtility.PackageUIVertex(position, uv0, image.color);
            vh.AddVert(uiVertex);
            outterVertices.Add(position);
        }

        triangleCount = realSegements * 3;
        for (int i = 0, vIdx = 1; i < triangleCount - 3; i += 3, vIdx++)
        {
            vh.AddTriangle(vIdx, 0, vIdx + 1);
        }
        if (fillPercent == 1)
        {
            vh.AddTriangle(verticeCount - 1, 0, 1);
        }
    }

    public virtual bool IsRaycastLocationValid(Vector2 screenPoint, Camera eventCamera)
    {
        var sprite = image.overrideSprite;
        if (sprite == null)
        {
            return true;
        }

        Vector2 local;
        RectTransformUtility.ScreenPointToLocalPointInRectangle(image.rectTransform, screenPoint, eventCamera, out local);
        return Contains(local, outterVertices);
    }

    private bool Contains(Vector2 p, List<Vector3> outterVertices)
    {
        var crossNumber = 0;
        crossNumber += UIUtility.RayCrossingCount(p, outterVertices);
        return (crossNumber & 1) == 1;
    }
}