using UnityEngine;

namespace Ashwild.GrassClearer
{
    public class GrassClearer : MonoBehaviour
    {
        // Singleton pour un accès direct sans FindObjectOfType
        public static GrassClearer Instance { get; private set; }

        void Awake()
        {
            Instance = this;
        }

        // Appelle ça quand un bâtiment est posé.
        // worldCenter = centre du sol, sizeWorld = (largeur, profondeur) en mètres
        public void ClearGrassRect(Vector3 worldCenter, Vector2 sizeWorld)
        {
            Terrain terrain = GetTerrainAt(worldCenter);
            if (terrain == null) return;

            TerrainData data = terrain.terrainData;
            int detailW = data.detailWidth;
            int detailH = data.detailHeight;

            // Position relative au terrain, normalisée 0-1
            Vector3 local = worldCenter - terrain.transform.position;
            float normX = local.x / data.size.x;
            float normZ = local.z / data.size.z;

            int cx = Mathf.RoundToInt(normX * detailW);
            int cz = Mathf.RoundToInt(normZ * detailH);

            // Demi-taille en cellules de detail
            int radX = Mathf.CeilToInt((sizeWorld.x * 0.5f / data.size.x) * detailW);
            int radZ = Mathf.CeilToInt((sizeWorld.y * 0.5f / data.size.z) * detailH);

            int xMin = Mathf.Clamp(cx - radX, 0, detailW - 1);
            int xMax = Mathf.Clamp(cx + radX, 0, detailW - 1);
            int zMin = Mathf.Clamp(cz - radZ, 0, detailH - 1);
            int zMax = Mathf.Clamp(cz + radZ, 0, detailH - 1);

            int w = xMax - xMin + 1;
            int h = zMax - zMin + 1;
            if (w <= 0 || h <= 0) return;

            // On vide TOUTES les couches de details (herbe + fleurs) dans la zone
            int numLayers = data.detailPrototypes.Length;
            for (int layer = 0; layer < numLayers; layer++)
            {
                int[,] block = data.GetDetailLayer(xMin, zMin, w, h, layer);
                for (int y = 0; y < h; y++)
                    for (int x = 0; x < w; x++)
                        block[y, x] = 0;
                data.SetDetailLayer(xMin, zMin, layer, block);
            }
        }

        // Trouve le terrain qui contient cette position (gère le multi-terrain)
        Terrain GetTerrainAt(Vector3 worldPos)
        {
            foreach (var t in Terrain.activeTerrains)
            {
                Vector3 l = worldPos - t.transform.position;
                TerrainData d = t.terrainData;
                if (l.x >= 0 && l.x <= d.size.x && l.z >= 0 && l.z <= d.size.z)
                    return t;
            }
            return null;
        }
    }
}