using UnityEngine;

/// <summary>
/// 部署网格的几何参数与坐标换算。
/// 阵型编排场景和战斗场景共用同一份参数，保证两边的格位完全对齐。
/// </summary>
public static class DeployGrid
{
    public const int Cols = 6;
    public const int Rows = 5;
    public const float ColStep = 2.8f;
    public const float RowStep = 3.0f;
    public const float BackZ = 2.5f;        // 最靠后一排的中心 Z（让部署区落在底部卡片栏上方）
    public const float CellWidth = 2.5f;
    public const float CellDepth = 2.7f;
    public const float CellHeight = 0.03f;
    public const float GridY = 0.12f;       // 格位可视块的中心高度
    public const float UnitY = 0.16f;       // 单位落点高度（与 NavMesh 高度一致）

    public const int CellCount = Cols * Rows;

    public static int ToIndex(int row, int col) => row * Cols + col;
    public static int RowOf(int index) => index / Cols;
    public static int ColOf(int index) => index % Cols;
    public static bool IsValidIndex(int index) => index >= 0 && index < CellCount;

    /// <summary>格位中心的世界坐标（单位落点高度）。</summary>
    public static Vector3 CellPosition(int index)
    {
        int r = RowOf(index);
        int c = ColOf(index);
        float x = (c - (Cols - 1) * 0.5f) * ColStep;
        float z = BackZ + r * RowStep;
        return new Vector3(x, UnitY, z);
    }

    /// <summary>把地面上的世界坐标吸附到最近格位；不在网格范围内返回 -1。</summary>
    public static int SnapToCell(Vector3 world)
    {
        int c = Mathf.RoundToInt(world.x / ColStep + (Cols - 1) * 0.5f);
        int r = Mathf.RoundToInt((world.z - BackZ) / RowStep);
        if (c < 0 || c >= Cols || r < 0 || r >= Rows)
        {
            return -1;
        }

        Vector3 center = CellPosition(ToIndex(r, c));
        if (Mathf.Abs(center.x - world.x) > ColStep * 0.5f) return -1;
        if (Mathf.Abs(center.z - world.z) > RowStep * 0.5f) return -1;
        return ToIndex(r, c);
    }

    /// <summary>把一组单位在网格宽度内均匀铺开，返回列号。</summary>
    public static int SpreadColumn(int indexInGroup, int groupCount)
    {
        if (groupCount <= 1) return Cols / 2;
        if (groupCount >= Cols) return indexInGroup % Cols;

        float step = (Cols - 1f) / (groupCount + 1f);
        return Mathf.RoundToInt(step * (indexInGroup + 1));
    }

    /// <summary>默认阵型格位：近战在最前排（靠近敌人），远程在最后排。</summary>
    public static int DefaultCell(bool isMelee, int indexInGroup, int groupCount)
    {
        int row = isMelee ? Rows - 1 : 0;
        return ToIndex(row, SpreadColumn(indexInGroup, groupCount));
    }
}