// From: http://wiki.unity3d.com/index.php/SmoothFollowWithCameraBumper
// (Created CSharp Version) 10/2010: Daniel P. Rossi (DR9885) 
// Pixel Crushers changes:
// 1. Moved to PixelCrushers.DialogueSystem.Examples namespace to prevent conflicts.
// 2. Exposed target so wizard can set it.
// 3. Added adjustQuaternion so SimpleController can adjust the angle without
//    directly changing the camera's rotation. Changing the camera's rotation
//    in multiple scripts can cause flickering on objects that position themselves
//    in Update() based on the current rotation, since there's no guarantee
//    that Update() is called in the same order on each frame update.
// 4. Set default values for private fields to address compiler warnings.
// 5. To work with the new prefab system (Unity 2018.3+), no longer childs to target.
//    Assign the child manually at design time.

using UnityEngine;

namespace PixelCrushers.DialogueSystem.Demo
{

    [AddComponentMenu("")] // Use wrapper.
    public class SmoothCameraWithBumper : MonoBehaviour
    {
        public Transform target = null;
        [SerializeField] private float distance = 3.0f;
        [SerializeField] private float height = 1.0f;
        [SerializeField] private float damping = 5.0f;
        [SerializeField] private bool smoothRotation = true;
        [SerializeField] private float rotationDamping = 10.0f;

        [SerializeField] private Vector3 targetLookAtOffset = Vector3.zero; // allows offsetting of camera lookAt, very useful for low bumper heights

        [SerializeField] private float bumperDistanceCheck = 2.5f; // length of bumper ray
        [SerializeField] private float bumperCameraHeight = 1.0f; // adjust camera height while bumping
        [SerializeField] private Vector3 bumperRayOffset = Vector3.zero; // allows offset of the bumper ray from target origin

        public Quaternion adjustQuaternion { get; set; }
        private Quaternion originalRotation;

        /// <Summary>
        /// If the target moves, the camera should child the target to allow for smoother movement. DR
        /// </Summary>
        private void Awake()
        {
            // For compatibility with the new prefab system, no longer childs to target:
            //UnityEngine.Camera myCamera = GetComponent<UnityEngine.Camera>();
            //if (myCamera != null) myCamera.transform.parent = target;
            adjustQuaternion = Quaternion.identity;
        }

        private void Start()
        {
            originalRotation = transform.localRotation;
        }

        private void FixedUpdate()
        {
            Vector3 wantedPosition = target.TransformPoint(0, height, -distance);

            // check to see if there is anything behind the target
            RaycastHit hit;
            Vector3 back = target.transform.TransformDirection(-1 * Vector3.forward);

            // cast the bumper ray out from rear and check to see if there is anything behind
            if (Physics.Raycast(target.TransformPoint(bumperRayOffset), back, out hit, bumperDistanceCheck)
                && hit.transform != target) // ignore ray-casts that hit the user. DR
            {
                // clamp wanted position to hit position
                wantedPosition.x = hit.point.x;
                wantedPosition.z = hit.point.z;
                wantedPosition.y = Mathf.Lerp(hit.point.y + bumperCameraHeight, wantedPosition.y, Time.deltaTime * damping);
            }

            transform.position = Vector3.Lerp(transform.position, wantedPosition, Time.deltaTime * damping);

            Vector3 lookPosition = target.TransformPoint(targetLookAtOffset);

            if (smoothRotation)
            {
                Quaternion wantedRotation = Quaternion.LookRotation(lookPosition - transform.position, target.up);
                transform.rotation = Quaternion.Slerp(transform.rotation, wantedRotation, Time.deltaTime * rotationDamping);
            }
            else
            {
                transform.rotation = Quaternion.LookRotation(lookPosition - transform.position, target.up);
            }

            transform.localRotation = originalRotation * adjustQuaternion;
        }

    }

}