TowerDefenseGame/Assets/_GAME_/Player/Scripts/BuildHandler.cs

using NUnit.Framework.Constraints;
using System;
using System.Collections;
using System.Collections.Generic;
using System.Linq;
using UnityEngine;
using UnityEngine.EventSystems;
using UnityEngine.Tilemaps;
using UnityEngine.UI;
using static Unity.Cinemachine.IInputAxisOwner.AxisDescriptor;
using static UnityEngine.RuleTile.TilingRuleOutput;

[CreateAssetMenu(menuName = "Custom/BuilderHandler", fileName = "NewBuilderHandler")]
public class BuildHandler : ScriptableObject {
  [Header("Build Dependencies")]
  public GameObject PrefabToSpawn;
  public GameObject PrefabToSpawnPreviewAsset;

  [Header("VFX Dependencies")]
  public GameObject VfxExplosion;
  private GameObject VfxExplosionParentInstance;
  private List<ParticleSystem> VfxExplosionParticles = new List<ParticleSystem>();

  private GameObject PreviewObj;
  private Vector3 SnappedPosition;
  private bool BuildMode = false;
  private Vector2 SpriteSize;
  private CapsuleDirection2D CapsuleDirection = CapsuleDirection2D.Vertical;
  private bool Initialized = false;

  void Awake() {
    Debug.Log(PreviewObj.name);
  }

  public void Initialize() {
    PreviewObj = Instantiate(PrefabToSpawnPreviewAsset, new Vector3(), Quaternion.identity);
    SpriteRenderer sprite = PreviewObj.GetComponent<SpriteRenderer>();
    Sprite s = PreviewObj.GetComponent<SpriteRenderer>().sprite;
    Vector2 pivot = s.pivot / s.pixelsPerUnit;
    SpriteSize = s.rect.size / s.pixelsPerUnit;
    if (SpriteSize.x > SpriteSize.y)
      CapsuleDirection = CapsuleDirection2D.Horizontal;

    VfxExplosionParticles.Clear();
    if (VfxExplosion) {
      VfxExplosionParentInstance = Instantiate(VfxExplosion, Vector3.one, Quaternion.identity);
      var foundParticleSystems = VfxExplosionParentInstance.GetComponentsInChildren<ParticleSystem>();
      VfxExplosionParticles.AddRange(foundParticleSystems);
      VfxExplosionParticles.ForEach((x) => x.transform.localScale = Vector3.one);
    }

    Initialized = true;
  }

  public void SetBuildMode(bool mode) {
    //if (!PreviewObj)
    //  CreatePreviewObj();
    PreviewObj.SetActive(mode);
    BuildMode = mode;
    if (mode) Debug.Log("BuildMode ON");
  }

  Vector3 GetSnappedPosition(Vector3 worldPos, float gridSize) {
    float x = Mathf.Round(worldPos.x / gridSize) * gridSize;
    float y = Mathf.Round(worldPos.y / gridSize) * gridSize;
    //Debug.Log($"{x}, {y}");
    return new Vector3(x, y, 0);
  }

  public void UpdatePreview(float gridSize) {
    if (!BuildMode) return;
    Vector3 mousePos = Camera.main.ScreenToWorldPoint(Input.mousePosition);
    Vector3 offset = new Vector3(0, 0, 3);
    mousePos += offset;
    SnappedPosition = GetSnappedPosition(mousePos, gridSize / 2);
    PreviewObj.transform.position = SnappedPosition;
  }


  public void PlaceObject() {
    if (!BuildMode) return;
    if (!IsTileUnderMouse()) return;

    Collider2D[] hits = Physics2D.OverlapCapsuleAll(SnappedPosition, SpriteSize * 0.8f, CapsuleDirection, 0);
    foreach (var hit in hits) {
      if (hit.CompareTag("Structural")) {
        Debug.Log("Hit building object");
        return;
      } else {
        Debug.Log($"Tag:{hit.tag}");
      }
    }

    hits = Physics2D.OverlapCapsuleAll(SnappedPosition, SpriteSize, CapsuleDirection, 0);
    foreach (var hit in hits) {
      if (hit.GetComponent<TilemapCollider2D>()) {
        Debug.Log("Hit terrain tile");
        return;
      }
    }

    if (VfxExplosionParentInstance) {
      VfxExplosionParentInstance.transform.position = SnappedPosition;
      VfxExplosionParticles.ForEach((x) => x.Play());
    }
    GameObject newObj = Instantiate(PrefabToSpawn, SnappedPosition, Quaternion.identity);
    SpriteRenderer image = newObj.GetComponent<SpriteRenderer>();
  }

  public bool IsTileUnderMouse() {
    Vector3 worldPos = Camera.main.ScreenToWorldPoint(Input.mousePosition);
    worldPos.z = 0f;

    GameObject groundGO = GameObject.FindGameObjectWithTag("Ground");
    if (!groundGO) return false;

    Tilemap tilemap = groundGO.GetComponent<Tilemap>();
    if (!tilemap) return false;

    Vector3Int cellPos = tilemap.WorldToCell(worldPos);
    TileBase tile = tilemap.GetTile(cellPos);
    if (!tile) return false;
    return tile;
    //Bounds tileBounds = tilemap.GetBoundsLocal(cellPos);
    //Collider2D[] hits = Physics2D.OverlapBoxAll(tilemap.GetCellCenterWorld(cellPos), tilemap.cellSize * 0.9f, 0f);

    //return (hits.Length == 0);
  }


  public void DrawGizmos() {
    if (!Initialized) return;

    Vector2 center = SnappedPosition;
    Vector2 size = SpriteSize;
    float radius = size.x / 2 * 0.8f;
    float height = size.y / 2 * 0.8f;

    if (SpriteSize.x != SpriteSize.y) {
      Vector2 top = center + Vector2.up * (height / 2 - radius);
      Vector2 bottom = center + Vector2.down * (height / 2 - radius);

      Gizmos.color = Color.green;
      Gizmos.DrawWireCube(center, new Vector2(size.x, height - 2 * radius));
      Gizmos.DrawWireSphere(top, radius);
      Gizmos.DrawWireSphere(bottom, radius);
    } else {
      Gizmos.color = Color.green;
      Gizmos.DrawWireSphere(center, radius);
    }
  }
}