using System;
using UnityEngine;
using Random = UnityEngine.Random;

public class HexGrid : MonoBehaviour
{
    /// <summary>
    /// 格子宽度
    /// </summary>
    public int width = 6;

    /// <summary>
    /// 格子高度
    /// </summary>
    public int height = 6;

    /// <summary>
    /// 格子实例预制体（用于实际角色放入交互，也有可能会删掉改用判断位置的方式处理交互）
    /// </summary>
    public HexCell cellPrefab;

    /// <summary>
    /// 六边形渲染mesh
    /// </summary>
    HexMesh hexMesh;

    /// <summary>
    /// 格子存储
    /// </summary>
    HexCell[] cells;

    public Color defaultColor = Color.white;
    public Color touchedColor = Color.magenta;

    void Awake()
    {
        hexMesh = GetComponentInChildren<HexMesh>();
        cells = new HexCell[height * width];

        for (int z = 0, i = 0; z < height; z++)
        {
            for (int x = 0; x < width; x++)
            {
                CreateCell(x, z, i++);
            }
        }
    }

    private void Start()
    {
        // 渲染mesh
        hexMesh.Triangulate(cells);
    }

    /// <summary>
    /// 创建格子以及实例
    /// </summary>
    /// <param name="x"></param>
    /// <param name="z"></param>
    /// <param name="i"></param>
    void CreateCell(int x, int z, int i)
    {
        Vector3 position;
        position.x = (x + z * 0.5f - z / 2) * (HexMetrics.innerRadius * 2f);
        position.y = 0f;
        position.z = HexMetrics.offset * z;

        HexCell cell = cells[i] = Instantiate<HexCell>(cellPrefab);
        cell.transform.SetParent(transform, false);
        cell.transform.localPosition = position;
        cell.coordinates = HexCoordinates.FromOffsetCoordinates(x, z);
        cell.color = new Color(Random.Range(0, 1f), Random.Range(0, 1f), Random.Range(0, 1f), 1);
    }

    private void Update()
    {
        if (Input.GetMouseButtonDown(0))
        {
            HandleInput();
        }
    }

    /// <summary>
    /// 射线检测拿到射线点，然后传递给TouchCell进行实际位置判断
    /// </summary>
    void HandleInput()
    {
        Ray inputRay = Camera.main.ScreenPointToRay(Input.mousePosition);
        RaycastHit hit;
        if (Physics.Raycast(inputRay, out hit))
        {
            TouchCell(hit.point);
        }
    }

    /// <summary>
    /// 判断点击的哪个格子
    /// </summary>
    /// <param name="position"></param>
    public void TouchCell(Vector3 position)
    {
        // 将 position 从世界空间变换到本地空间
        position = transform.InverseTransformPoint(position);
        HexCoordinates coordinates = HexCoordinates.FromPosition(position);
        int index = coordinates.X + coordinates.Z * width + coordinates.Z / 2;
        HexCell cell = cells[index];
        cell.color = touchedColor;
        hexMesh.Triangulate(cells);
    }
}