using UnityEngine;

public class BallShooter : MonoBehaviour
{
    public GameObject ballPrefab;
    public Transform spawnPoint;
    public float arcHeight = 2f;

    void Update()
    {
        if (Input.GetMouseButtonDown(0))
        {
            Ray ray = Camera.main.ScreenPointToRay(Input.mousePosition);
            Vector3 target;

            if (Physics.Raycast(ray, out RaycastHit hit))
            {
                target = hit.point;
            }
            else
            {
                target = ray.GetPoint(10f); // fallback
            }

            if (Vector3.Distance(spawnPoint.position, target) < 0.1f)
                return; // avoid NaN if click too close

            GameObject ball = Instantiate(ballPrefab, spawnPoint.position, Quaternion.identity);
            Rigidbody rb = ball.GetComponent<Rigidbody>();
            rb.useGravity = true;

            Vector3 velocity = CalculateArcVelocity(spawnPoint.position, target, arcHeight);
            if (float.IsNaN(velocity.x) || float.IsNaN(velocity.y) || float.IsNaN(velocity.z))
            {
                Destroy(ball); // safety: don't throw broken ball
                return;
            }

            rb.velocity = velocity;
        }
    }

    Vector3 CalculateArcVelocity(Vector3 start, Vector3 end, float height)
    {
        float gravity = Mathf.Abs(Physics.gravity.y);

        Vector3 displacementXZ = new Vector3(end.x - start.x, 0, end.z - start.z);
        float horizontalDist = displacementXZ.magnitude;

        if (horizontalDist < 0.01f) horizontalDist = 0.01f; // prevent divide-by-zero

        float heightDifference = end.y - start.y;
        height = Mathf.Max(height, heightDifference + 0.1f); // ensure height is enough

        float timeUp = Mathf.Sqrt(2 * height / gravity);
        float timeDown = Mathf.Sqrt(2 * (height - heightDifference) / gravity);
        float totalTime = timeUp + timeDown;

        Vector3 velocityY = Vector3.up * Mathf.Sqrt(2 * gravity * height);
        Vector3 velocityXZ = displacementXZ / totalTime;

        return velocityXZ + velocityY;
    }
}