using System.Collections;
using System.Collections.Generic;
using UnityEngine;

namespace MoreMountains.Tools
{
    /// <summary>
    /// Add this class to an empty object, bind a few prefabs into its RandomPool slots, and it'll instantiate one of them at its position/rotation on Start or Awake
    /// You can also call its InstantiateRandomObject method at any time, and it'll instantiate another random object on demand, 
    /// potentially destroying the previous one if you decide so
    /// </summary>
    public class MMRandomInstantiator : MonoBehaviour
    {
        /// the possible start modes
        public enum StartModes { Awake, Start, None }

        [Header("Random instantiation")]
        /// whether this instantiator should auto trigger on Awake, Start, or never
        public StartModes StartMode = StartModes.Awake;
        /// the name to give to the instantiated object
        public string InstantiatedObjectName = "RandomInstantiated";
        /// if this is true, the instantiated object will be parented to the spawner
        public bool ParentInstantiatedToThisObject = true;
        /// if this is true, every time InstantiateRandomObject is called, any previously instantiated object will be destroyed
        public bool DestroyPreviouslyInstantiatedObject = true;
        /// the list containing all the objects that can potentially be instantiated
        public List<GameObject> RandomPool;

        [Header("Test")]
        /// a test button for your inspector
        [MMInspectorButton("InstantiateRandomObject")]
        public bool InstantiateButton;

        protected GameObject _instantiatedGameObject;

        /// <summary>
        /// On awake we instantiate if needed
        /// </summary>
        protected virtual void Awake()
        {
            if (StartMode == StartModes.Awake)
            {
                InstantiateRandomObject();
            }
        }

        /// <summary>
        /// On Start we instantiate if needed
        /// </summary>
        protected virtual void Start()
        {
            if (StartMode == StartModes.Start)
            {
                InstantiateRandomObject();
            }
        }

        /// <summary>
        /// Spawns a random object from the pool of choices
        /// </summary>
        public virtual void InstantiateRandomObject()
        {
            // if the pool is empty we do nothing and exit
            if (RandomPool.Count == 0)
            {
                return;
            }

            // we destroy our previous object if needed
            if (DestroyPreviouslyInstantiatedObject)
            {
                if (_instantiatedGameObject != null)
                {
                    DestroyImmediate(_instantiatedGameObject);
                }
            }

            // pick a random object and instantiates it
            int randomIndex = Random.Range(0, RandomPool.Count);
            _instantiatedGameObject = Instantiate(RandomPool[randomIndex], this.transform.position, this.transform.rotation);
            _instantiatedGameObject.name = InstantiatedObjectName;
            if (ParentInstantiatedToThisObject)
            {
                _instantiatedGameObject.transform.SetParent(this.transform);
            }
        }
    }
}