using UnityEngine;

namespace UnityAgent
{
    /// <summary>
    /// Smooth third-person camera with collision handling. Attach to a Camera
    /// GameObject and assign the target transform in the inspector.
    /// </summary>
    public class ThirdPersonCamera : MonoBehaviour
    {
        [Header("Target")]
        public Transform target;

        [Header("Positioning")]
        public Vector3 pivotOffset = new Vector3(0f, 1.5f, 0f);
        public float distance = 5f;
        public float minDistance = 1.5f;
        public float maxDistance = 8f;
        public float height = 1.2f;

        [Header("Smoothing")]
        public float positionSmooth = 10f;
        public float rotationSmooth = 10f;

        [Header("Collision")]
        public LayerMask collisionMask = ~0;
        public float collisionRadius = 0.3f;

        [Header("Input")]
        public bool useMouseOrbit = true;
        public float mouseSensitivity = 3f;
        public float minPitch = -30f;
        public float maxPitch = 75f;

        private float _yaw;
        private float _pitch = 15f;
        private float _currentDistance;

        private void Start()
        {
            _currentDistance = distance;
            if (target != null)
            {
                Vector3 e = transform.eulerAngles;
                _yaw = e.y; _pitch = e.x;
            }
            Cursor.lockState = CursorLockMode.Locked;
        }

        private void LateUpdate()
        {
            if (target == null) return;

            if (useMouseOrbit)
            {
                _yaw += Input.GetAxis("Mouse X") * mouseSensitivity;
                _pitch -= Input.GetAxis("Mouse Y") * mouseSensitivity;
                _pitch = Mathf.Clamp(_pitch, minPitch, maxPitch);
            }

            Quaternion rotation = Quaternion.Euler(_pitch, _yaw, 0f);
            Vector3 pivot = target.position + pivotOffset;

            // Desired camera position.
            Vector3 desired = pivot + rotation * new Vector3(0f, height, -distance);

            // Collision: shrink the distance if there's an obstacle.
            if (Physics.SphereCast(
                pivot, collisionRadius, (desired - pivot).normalized,
                out RaycastHit hit, distance, collisionMask, QueryTriggerInteraction.Ignore))
            {
                _currentDistance = Mathf.Clamp(hit.distance, minDistance, distance);
            }
            else
            {
                _currentDistance = Mathf.Lerp(_currentDistance, distance, Time.deltaTime * 4f);
            }

            Vector3 finalPos = pivot + rotation * new Vector3(0f, height, -_currentDistance);
            transform.position = Vector3.Lerp(transform.position, finalPos, positionSmooth * Time.deltaTime);
            transform.rotation = Quaternion.Slerp(
                transform.rotation, rotation, rotationSmooth * Time.deltaTime);
        }
    }
}