using UnityEngine;

namespace SC.XR.Unity.Module_Keyboard
{
    public class KeyboardFollower : FollowerBase
    {
        [Header("Following Settings")]
        public bool LinearFollowing;//Whether is linear movement.

        public Vector2 border_x; //x-axis boundary
        public Vector2 border_y; //y-axis boundary
        private Transform _slamHead;
        Vector2 initViewPoint;//The midpoint of the camera frame, the coordinates are (0.5f, 0.5f).
        Vector3 viewPoint = Vector3.zero;// Panel coordinates are relative to the coordinates of the camera screen.
        private Vector3 velocity = Vector3.zero;
        bool isFollower = false;

        Vector3 originPos = Vector3.zero;
        Vector3 desPos = Vector3.zero;
        float journeyLength = 0f;

        Vector3 offsetPos;
        Quaternion offsetRotation;
        protected override void OnEnable()
        {
            base.OnEnable();
        }

        private void Start()
        {
            InitTrans();
        }

        protected override void LateUpdate()
        {          
            if (StopFollower == false)
            {
                if (IsFollower())
                {
                    if (LinearFollowing)
                    {
                        LinearFollow();
                    }
                    else
                    {
                        Follow();
                    }
                }
            }
        }

        void InitTrans()
        {
            if (!this.StopFollower && (Camera.main != null))
            {
                _slamHead = Camera.main.transform;
                transform.position = CalculateWindowPosition(Camera.main.transform);
                transform.rotation = CalculateWindowRotation(Camera.main.transform);
                initViewPoint = Camera.main.WorldToViewportPoint(_slamHead.position + (_slamHead.forward * WindowDistance));//The coordinates of the midpoint of the camera screen.
            }
        }

        protected bool IsFollower()
        {
            if ( Camera.main == null)
            {
                return false;
            }
            viewPoint = Camera.main.WorldToViewportPoint(transform.position);// The coordinates of the panel on the camera screen.

            if (viewPoint.x > initViewPoint.x + border_x.x + CalculateWindowOffsetX() || viewPoint.x < initViewPoint.x + border_x.y + CalculateWindowOffsetX() || viewPoint.y < initViewPoint.y + border_y.y + CalculateWindowOffsetY() || viewPoint.y > initViewPoint.y + border_y.x + CalculateWindowOffsetY())// Boundary judgment
            {
                isFollower = true;
            }
            else if (Mathf.Abs(viewPoint.x - initViewPoint.x - CalculateWindowOffsetX()) < 0.05f && Mathf.Abs(viewPoint.y - initViewPoint.y - CalculateWindowOffsetY()) < 0.09f)
            {
                isFollower = false;
            }
            return isFollower;
        }

        //Nonlinear Following by default
        protected override void Follow()
        {
            transform.position = Vector3.Lerp(transform.position, CalculateWindowPosition(Camera.main.transform), WindowFollowSpeed * Time.deltaTime);
            //transform.position = Vector3.SmoothDamp(transform.position, CalculateWindowPosition(Camera.main.transform), ref velocity, WindowFollowSpeed);
            transform.rotation = Quaternion.Slerp(transform.rotation, CalculateWindowRotation(Camera.main.transform), WindowFollowSpeed * Time.deltaTime);
        }

        //For Linear Following, turn down the WindowFollowSpeed to around 0.5 at distance = 1 for best experience
        protected void LinearFollow()
        {
            originPos = transform.position;
            desPos = CalculateWindowPosition(Camera.main.transform);
            journeyLength = Vector3.Distance(originPos, desPos);
            transform.position = Vector3.Lerp(originPos, desPos, (Time.fixedDeltaTime) / journeyLength * WindowFollowSpeed);
            transform.rotation = Quaternion.Slerp(transform.rotation, CalculateWindowRotation(Camera.main.transform), (Time.fixedDeltaTime) / journeyLength * WindowFollowSpeed);
        }

        protected override Vector3 CalculateWindowPosition(Transform cameraTransform)
        {

            Vector3 position = cameraTransform.position + (Vector3.ProjectOnPlane(cameraTransform.forward, Vector3.up).normalized * WindowDistance);
            Vector3 horizontalOffset = cameraTransform.right * windowOffset.x;
            Vector3 verticalOffset = cameraTransform.up * windowOffset.y;

            switch (windowAnchor)
            {
                case TextAnchor.UpperLeft: position += verticalOffset - horizontalOffset; break;
                case TextAnchor.UpperCenter: position += verticalOffset; break;
                case TextAnchor.UpperRight: position += verticalOffset + horizontalOffset; break;
                case TextAnchor.MiddleLeft: position -= horizontalOffset; break;
                case TextAnchor.MiddleRight: position += horizontalOffset; break;

                case TextAnchor.MiddleCenter: position += horizontalOffset + verticalOffset; break;

                case TextAnchor.LowerLeft: position -= verticalOffset + horizontalOffset; break;
                case TextAnchor.LowerCenter: position -= verticalOffset; break;
                case TextAnchor.LowerRight: position -= verticalOffset - horizontalOffset; break;
            }

            return position;
        }

        protected override Quaternion CalculateWindowRotation(Transform cameraTransform)
        {
            Quaternion rotation = Quaternion.Euler(0, cameraTransform.rotation.eulerAngles.y, 0);

            switch (windowAnchor)
            {

                case TextAnchor.UpperLeft: rotation *= windowHorizontalRotationInverse * windowVerticalRotationInverse; break;
                case TextAnchor.UpperCenter: rotation *= windowHorizontalRotationInverse; break;
                case TextAnchor.UpperRight: rotation *= windowHorizontalRotationInverse * windowVerticalRotation; break;
                case TextAnchor.MiddleLeft: rotation *= windowVerticalRotationInverse; break;
                case TextAnchor.MiddleRight: rotation *= windowVerticalRotation; break;
                case TextAnchor.LowerLeft: rotation *= windowHorizontalRotation * windowVerticalRotationInverse; break;
                case TextAnchor.LowerCenter: rotation *= windowHorizontalRotation; break;
                case TextAnchor.LowerRight: rotation *= windowHorizontalRotation * windowVerticalRotation; break;
            }

            return rotation;
        }
        
    }

}