using UnityEngine;

public class SinTwoWay2D : MonoBehaviour
{
    public float distance = 5.0f;
    public float frequency = 5.0f;
    public float speed = 0.1f;
    public float yMax = 1.0f; 
    bool facingRight = true;
    Vector3 pos;
    Vector3 move;
    Vector3 localScale;

    void Start()
    {
        pos = transform.position;
        move = transform.position;
        localScale = transform.localScale;
    }

    void FixedUpdate()
    {
        CheckWhereToFace();

        if (facingRight)
        {
            MoveRight();
        }
        else
        {
            MoveLeft();
        }
    }

    void CheckWhereToFace()
    {
        if (transform.position.x < pos.x - distance)
        {
            facingRight = true;
        }
        else if (transform.position.x > pos.x + distance)
        {
            facingRight = false;
        }

        if ((facingRight && localScale.x < 0) || (!facingRight && localScale.x > 0))
        {
            localScale.x *= -1;
        }

        transform.localScale = localScale;
    }

    void MoveRight()
    {
        move += transform.right * speed;
        transform.position = move + transform.up * Mathf.Sin(Time.time * frequency) * yMax;
    }

    void MoveLeft()
    {
        move -= transform.right * speed;
        transform.position = move + transform.up * Mathf.Sin(Time.time * frequency) * yMax;
    }
}