using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using Valve.VR;

public class Hand : MonoBehaviour
{
    public SteamVR_Action_Boolean GrabAction = null;

    private SteamVR_Behaviour_Pose Pose = null;
    private FixedJoint Joint = null;

    private Interactable currentInteractable = null;
    public List<Interactable> contactInteractables = new List<Interactable>();

    private void Awake()
    {
        Pose = GetComponent<SteamVR_Behaviour_Pose>();
        Joint = GetComponent<FixedJoint>();
    }

    void Update()
    {
        // Down
        if (GrabAction.GetStateDown(Pose.inputSource))
        {
            print(Pose.inputSource + "TriggerDown");
            Pickup();
        }

        // Up
        if (GrabAction.GetStateUp(Pose.inputSource))
        {
            print(Pose.inputSource + "TriggerUp");
            Drop();
        }

    }

    private void OnTriggerEnter(Collider other)
    {
        if (!other.gameObject.CompareTag("Interactable"))
        {
            return;
        }

        contactInteractables.Add(other.gameObject.GetComponent<Interactable>());
    }


    private void OnTriggerExit(Collider other)
    {
        if (!other.gameObject.CompareTag("Interactable"))
        {
            return;
        }

        contactInteractables.Remove(other.gameObject.GetComponent<Interactable>());
    }

    private void Pickup()
    {
        // Get nearest
        currentInteractable = GetNearestInteractable();

        // Null check
        if (!currentInteractable)
        {
            return;
        }

        // Already held, check
        if (currentInteractable.ActiveHand)
        {
            currentInteractable.ActiveHand.Drop();
        }

        // Position
        currentInteractable.transform.position = transform.position;

        // Attach
        Rigidbody targetBody = currentInteractable.GetComponent<Rigidbody>();
        Joint.connectedBody = targetBody;

        // Set active hand
        currentInteractable.ActiveHand = this;

    }

    private void Drop()
    {
        // Null check
        if (!currentInteractable)
        {
            return;
        }

        // Apply velocity
        Rigidbody targetBody = currentInteractable.GetComponent<Rigidbody>();
        targetBody.velocity = Pose.GetVelocity();
        targetBody.angularVelocity = Pose.GetAngularVelocity();

        // Detach
        Joint.connectedBody = null;

        // Clear
        currentInteractable.ActiveHand = null;
        currentInteractable = null;
    }


    private Interactable GetNearestInteractable()
    {
        Interactable nearest = null;
        float minDistance = float.MaxValue;
        float distance = 0.0f;

        foreach (Interactable interactable in contactInteractables)
        {
            distance = (interactable.transform.position - transform.position).sqrMagnitude;

            if (distance<minDistance)
            {
                minDistance = distance;
                nearest = interactable;
            }
        }

        return nearest;
    }
}