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

public class WaypointSystemManager : MonoBehaviour
{
    public static WaypointSystemManager Instance;

    [SerializeField] private float WaypointRadiusTolerence = 0.01f;
    [SerializeField] private List<Transform> Waypoints;

    [SerializeField] public List<WaypointEntityData> activeEntities = new();

    public GameObject DebugPrefab;

    private void OnEnable()
    {
        if (Instance != null)
            Destroy(Instance);
        Instance = this;
    }

    private void Start()
    {
        var data = new WaypointEntityData();
        data.Entity = Instantiate(DebugPrefab).transform;
        data.MoveSpeed = 1;

        AddObjectToPath(data);
    }

    private void Update()
    {
        for (int i = 0; i < activeEntities.Count; i++)
        {
            var data = activeEntities[i];

            // Check if entity still exists
            if (data.Entity == null)
            {
                activeEntities.RemoveAt(i);
                continue;
            }

            // Set target if no target
            if (data.NextTargetPosition == null)
                data.NextTargetPosition = Waypoints[0];

            // Changes target if within tolerence
            if (Vector3.Distance(data.Entity.position, data.NextTargetPosition.position) < WaypointRadiusTolerence)
            {
                int index = Waypoints.IndexOf(data.NextTargetPosition);
                
                if (index + 1 >= Waypoints.Count)
                {
                    Destroy(data.Entity.gameObject); // Destroy object when finish waypoints
                }
                else
                {
                    data.NextTargetPosition = Waypoints[index + 1];
                }
            }

            // Move object by speed
            Vector3 targetDirection = data.NextTargetPosition.position - data.Entity.position;
            Vector3 normTargetDir = targetDirection.normalized;

            float dist = Vector3.Distance(data.Entity.position, data.NextTargetPosition.position);
            float minDist = Math.Min(dist, data.MoveSpeed * Time.deltaTime);

            data.Entity.position += normTargetDir * minDist;
        }
    }

    public void AddObjectToPath(WaypointEntityData data)
    {
        activeEntities.Add(data);
    }
}

public class WaypointEntityData
{
    public Transform Entity;
    public Transform NextTargetPosition;
    public float MoveSpeed;
}