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

public class AutoFlip : MonoBehaviour {
    [SerializeField]
    bool autoFlipX = false;

    [SerializeField]
    bool autoFlipY = false;

    [SerializeField]
    Camera referenceCamera;

    Vector2 screenPointOld;
    Vector2 direction = Vector2.zero;
    Vector2 directionOld = Vector2.zero;

    // Use this for initialization
    void Start () {
        if (referenceCamera == null)
            referenceCamera = FindObjectOfType<Canvas>().GetComponent<Canvas>().worldCamera;

        screenPointOld = referenceCamera.WorldToScreenPoint(transform.position);
    }

    int flipCounterX = 0;
    int flipCounterY = 0;

    // Update is called once per frame
    void Update () {
        if (referenceCamera == null)
            return;

        Vector2 screenPoint = referenceCamera.WorldToScreenPoint(transform.position);
        direction = screenPoint - screenPointOld;
        if (direction.x == 0)
            direction.x = directionOld.x;

        if (direction.y == 0)
            direction.y = directionOld.y;

        Quaternion rotation = transform.rotation;

        { //flip X
            if (direction.x * directionOld.x < 0)
            {
                flipCounterX = 1;
            }

            if (direction.x * directionOld.x > 0 && flipCounterX != 0)
            {
                flipCounterX += 1;
            }


            if (autoFlipX && flipCounterX >= 4)
            {
                rotation *= Quaternion.Euler(0, 180, 0);
                flipCounterX = 0;
            }
        }

        { //flip Y
            if (direction.y * directionOld.y < 0)
            {
                flipCounterY = 1;
            }

            if (direction.y * directionOld.y > 0 && flipCounterY != 0)
            {
                flipCounterY += 1;
            }

            if (autoFlipY && flipCounterY >= 4)
            {
                rotation *= Quaternion.Euler(180, 0, 0);
                flipCounterY = 0;
            }
        }

        transform.rotation = rotation;

        screenPointOld = screenPoint;

        directionOld = direction;
        /*
        if (direction.x != 0)
            directionOld.x = direction.x;

        if (direction.y != 0)
            directionOld.y = direction.y;
            */
    }
}