using System.Collections;
using System.Collections.Generic;
using System.Linq;
using UnityEngine;
using static EZXR.Glass.UI.HorizontalLayoutGroup;

namespace EZXR.Glass.UI
{
    [ExecuteInEditMode]
    public class GridLayoutGroup : LayoutGroup
    {
        public List<SpatialUIElement> children = new List<SpatialUIElement>();
        float prevChildCount;
        Vector3 prevSize;
        [Tooltip("单位是m")]
        public float horizontalSpace = 0.001f;
        float prevHorizontalSpace;
        [Tooltip("单位是m")]
        public float verticalSpace = 0.001f;
        float prevVerticalSpace;
        Vector3 anchor;
        public enum HoriAlignment
        {
            Left,
            Middle,
            Right
        }
        public HoriAlignment horiAlignment;
        HoriAlignment prevHoriAlignment;
        public enum VertAlignment
        {
            Top,
            Middle,
            Bottom
        }
        public VertAlignment vertAlignment;
        VertAlignment prevVertAlignment;

        public override void OnValidate()
        {
            if (!Application.isPlaying)
            {
                base.OnValidate();

                GetSpatialUIElement();

                if (horizontalSpace != prevHorizontalSpace || verticalSpace != prevVerticalSpace || spatialUIElement.size != prevSize || children.Count != prevChildCount)
                {
                    prevHorizontalSpace = horizontalSpace;
                    prevVerticalSpace = verticalSpace;
                    prevSize = spatialUIElement.size;
                    prevChildCount = children.Count;

                    needReLayout = true;
                }
            }
        }

        public void AddChild(SpatialUIElement child)
        {
            if (!children.Contains(child))
            {
                children.Add(child);
                needReLayout = true;
            }
        }

        // Update is called once per frame
        void Update()
        {
            if (startLayout)
            {
                if (needReLayout)
                {
                    needReLayout = false;

                    if (transform.childCount > 0)
                    {
                        children = new List<SpatialUIElement>();
                        for (int i = 0; i < transform.childCount; i++)
                        {
                            SpatialUIElement temp = transform.GetChild(i).GetComponent<SpatialUIElement>();
                            if (temp != null && temp.gameObject.activeInHierarchy)
                            {
                                children.Add(temp);
                            }
                        }

                        int numPerRow = Mathf.FloorToInt((spatialUIElement.size.x + horizontalSpace) / (children[0].size.x + horizontalSpace));
                        int numPerCol = Mathf.FloorToInt((spatialUIElement.size.y + verticalSpace) / (children[0].size.y + verticalSpace));

                        float horiOffset = 0.0f;
                        float vertOffset = 0.0f;

                        switch (horiAlignment)
                        {
                            case HoriAlignment.Left:
                                horiOffset = 0;
                                break;
                            case HoriAlignment.Middle:
                                horiOffset = (spatialUIElement.size.x - (children[0].size.x * numPerRow + horizontalSpace * (numPerRow - 1))) / 2.0f;
                                break;
                            case HoriAlignment.Right:
                                horiOffset = 0;
                                break;
                        }

                        switch (vertAlignment)
                        {
                            case VertAlignment.Top:
                                vertOffset = 0.0f;
                                break;
                            case VertAlignment.Middle:
                                vertOffset = (spatialUIElement.size.y - (children[0].size.y * numPerCol + verticalSpace * (numPerCol - 1))) / 2.0f;
                                break;
                            case VertAlignment.Bottom:

                                break;
                        }

                        anchor = spatialUIElement.size / 2.0f - new Vector3(horiOffset, vertOffset, 0);
                        Vector3 curPos = Vector3.zero;
                        for (int i = 0; i < children.Count; i++)
                        {
                            if (children[i] != null)
                            {
                                //下面的0.0000001f是为了解决float判定相等的bug
                                if ((curPos.x + children[i].size.x <= spatialUIElement.size.x + 0.0000001f) && (curPos.y + children[i].size.y <= spatialUIElement.size.y + 0.0000001f))
                                {
                                    children[i].transform.localPosition = new Vector3(anchor.x - curPos.x - children[i].size.x / 2.0f, anchor.y - curPos.y - children[i].size.y / 2.0f, 0);
                                    curPos = new Vector3(curPos.x + children[i].size.x + horizontalSpace, curPos.y, curPos.z);
                                }
                                else if (curPos.x + children[i].size.x > spatialUIElement.size.x && curPos.y + 2.0 * children[i].size.y + verticalSpace <= spatialUIElement.size.y + 0.0000001f)
                                {
                                    children[i].transform.localPosition = new Vector3(anchor.x - children[i].size.x / 2.0f, anchor.y - (curPos.y + children[i - 1].size.y + verticalSpace) - children[i].size.y / 2.0f, 0);
                                    curPos = new Vector3(0 + children[i].size.x + horizontalSpace, curPos.y + children[i - 1].size.y + verticalSpace, curPos.z);
                                }
                                else
                                {
                                    Debug.LogError($"GridLayoutGroup: No enough space for {children[i].name}");
                                }
                            }
                        }
                    }
                }
            }
        }
    }
}