using System;
using UnityEngine;

[RequireComponent(typeof(MeshRenderer)), RequireComponent(typeof(MeshFilter))]
public class GrassChunk : MonoBehaviour {
    [Header("LOD 0")]
    public Material grassMaterialLOD0;
    [Header("LOD 1")]
    public Material grassMaterialLOD1;
    [Header("LOD 2")]
    public Material grassMaterialLOD2;

    private int lod = -1;
    [SerializeField]
    public int LOD {
        get { return lod; }
        set {
            if (lod == value) return;

            lod = value;
            var meshRenderer = GetComponent<MeshRenderer>();
            switch (lod) {
                case 0: meshRenderer.sharedMaterial = grassMaterialLOD0; break;
                case 1: meshRenderer.sharedMaterial = grassMaterialLOD1; break;
                case 2: meshRenderer.sharedMaterial = grassMaterialLOD2; break;
            }
        }
    }

    private void Update() {
        UpdateLOD();
    }

    public void UpdateLOD() {
        var meshRenderer = GetComponent<MeshRenderer>();
        if (Camera.main) {
            var sqrCamDist = meshRenderer.bounds.SqrDistance(Camera.main.transform.position);
            if (sqrCamDist > 20f * 20f) {
                LOD = 2;
            }
            else if (sqrCamDist > 5f * 5f) {
                LOD = 1;
            }
            else {
                LOD = 0;
            }
        }
    }

    private void OnDrawGizmos() {
        Gizmos.color = new Color(1f, 0.7f, 0f, 0.5f);
        var meshRenderer = GetComponent<MeshRenderer>();
        var bounds = meshRenderer.bounds;
        Gizmos.DrawWireCube(bounds.center, bounds.size);
    }
}