using UnityEngine;

public class IntroParallaxLayer : MonoBehaviour
{
    [Header("Reference")]
    public Transform cameraTransform;

    [Header("Parallax Strength")]
    public float parallaxX = 0.02f;
    public float parallaxY = 0.01f;

    [Header("Smoothing")]
    public float smoothSpeed = 4f;

    private Vector3 startLocalPosition;
    private Quaternion startCameraRotation;

    private void Start()
    {
        startLocalPosition = transform.localPosition;

        if (cameraTransform == null && Camera.main != null)
        {
            cameraTransform = Camera.main.transform;
        }

        if (cameraTransform != null)
        {
            startCameraRotation = cameraTransform.rotation;
        }
    }

    private void Update()
    {
        if (cameraTransform == null)
            return;

        Quaternion deltaRotation = Quaternion.Inverse(startCameraRotation) * cameraTransform.rotation;
        Vector3 deltaEuler = deltaRotation.eulerAngles;

        float yaw = NormalizeAngle(deltaEuler.y);
        float pitch = NormalizeAngle(deltaEuler.x);

        Vector3 targetPosition = startLocalPosition + new Vector3(
            -yaw * parallaxX,
            pitch * parallaxY,
            0f
        );

        transform.localPosition = Vector3.Lerp(
            transform.localPosition,
            targetPosition,
            Time.deltaTime * smoothSpeed
        );
    }

    private float NormalizeAngle(float angle)
    {
        if (angle > 180f)
            angle -= 360f;

        return angle;
    }
}