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

public class ItemGrabber : MonoBehaviour
{
    public static ItemGrabber instance;
    void Awake()
    {
        instance = this;
    }
    public float pickupDistance;
    public Pickable currentTarget;
    public Pickable grabbingItem;
    public Transform holdingPoint;
    public Transform scanningItem;
    public Transform arm;
    void Update()
    {
        ScanForTarget();
        CalculateHoldingPointVelocity();

        arm.transform.localRotation = arm.transform.localRotation.with(x: Camera.main.transform.localRotation.x);

        if (currentTarget != null && Input.GetMouseButtonDown(0))
        {
            currentTarget.Grab();

            grabbingItem = currentTarget;
            currentTarget = null;
            return;
        }

        if (grabbingItem != null && Input.GetMouseButtonUp(0))
        {
            grabbingItem.LetGo(holdingPointVelocity);
            grabbingItem = null;
        }
    }

    Vector3 m_lastHoldingPointPos;
    public Vector3 holdingPointVelocity;
    void CalculateHoldingPointVelocity(){
        holdingPointVelocity = holdingPoint.position - m_lastHoldingPointPos;
        m_lastHoldingPointPos = holdingPoint.position;
    }
    void ScanForTarget()
    {
        if (grabbingItem != null) { return; }

        RaycastHit hit = new RaycastHit();
        Ray ray = Camera.main.ScreenPointToRay(new Vector3(Screen.width / 2, Screen.height / 2, 0));
        if (Physics.Raycast(ray, out hit, pickupDistance))
        {
            scanningItem = hit.transform;
            Pickable pick = hit.transform.GetComponent<Pickable>();
            if (pick != null)
            {
                currentTarget = pick.isGrabbing ? null : pick;
                Debug.DrawRay(transform.position, hit.point, Color.green);

            }
            else
            {
                currentTarget = null;
                Debug.DrawRay(transform.position, hit.point, Color.red);

            }
        }
    }
}