////////////////////////////////////////////////////////////////////////////////
//
//  Copyright (C) 2007-2020 , Inc.  All Rights Reserved.
//
////////////////////////////////////////////////////////////////////////////////

using UnityEngine;
using UnityEngine.EventSystems;

using GCSeries.Core.EventSystems;
using GCSeries.Core.Input;

namespace GCSeries.Core.Samples
{
    public class DraggableCustomPlane :
        ZPointerInteractable, IBeginDragHandler, IDragHandler, IEndDragHandler
    {
        ////////////////////////////////////////////////////////////////////////
        // Inspector Fields
        ////////////////////////////////////////////////////////////////////////

        /// <summary>
        /// A transform from which to base planar movement on. Forward (Z) is 
        /// normal to the plane, and the object will drag along its X and Y 
        /// coordinates.
        /// </summary>
        [Tooltip(
            "A transform from which to base planar movement on. Forward (Z) " +
            "is normal to the plane, and the object will drag along its X " +
            "and Y coordinates.")]
        public Transform PlaneQuadTransform;

        ////////////////////////////////////////////////////////////////////////
        // Public Methods
        ////////////////////////////////////////////////////////////////////////

        public override ZPointer.DragPolicy GetDragPolicy(ZPointer pointer)
        {
            return ZPointer.DragPolicy.LockToCustomPlane;
        }

        public override Plane GetDragPlane(ZPointer pointer)
        {
            if (PlaneQuadTransform != null)
            {
                return new Plane(
                    PlaneQuadTransform.forward,
                    PlaneQuadTransform.position);
            }

            return base.GetDragPlane(pointer);
        }

        public void OnBeginDrag(PointerEventData eventData)
        {
            ZPointerEventData pointerEventData = eventData as ZPointerEventData;
            if (pointerEventData == null ||
                pointerEventData.button != PointerEventData.InputButton.Left)
            {
                return;
            }

            Pose pose = pointerEventData.Pointer.EndPointWorldPose;

            // Cache the initial grab state.
            this._initialGrabOffset =
                Quaternion.Inverse(this.transform.rotation) *
                (this.transform.position - pose.position);

            // commenting out rotation from the original draggable script
            // to maintain a fixed orientation relative to the drag plane
            //
            //this._initialGrabRotation =
            //    Quaternion.Inverse(pose.rotation) *
            //    this.transform.rotation;

            // If the grabbable object has a rigidbody component,
            // mark it as kinematic during the grab.
            var rigidbody = this.GetComponent<Rigidbody>();
            if (rigidbody != null)
            {
                this._isKinematic = rigidbody.isKinematic;
                rigidbody.isKinematic = true;
            }

            // Capture pointer events.
            pointerEventData.Pointer.CapturePointer(this.gameObject);
        }

        public void OnDrag(PointerEventData eventData)
        {
            ZPointerEventData pointerEventData = eventData as ZPointerEventData;
            if (pointerEventData == null ||
                pointerEventData.button != PointerEventData.InputButton.Left)
            {
                return;
            }

            Pose pose = pointerEventData.Pointer.EndPointWorldPose;

            // commenting out rotation from the original draggable script
            // to maintain a fixed orientation relative to the drag plane
            //
            // Update the grab object's rotation.
            //this.transform.rotation =
            //    pose.rotation * this._initialGrabRotation;

            // Update the grab object's position.
            this.transform.position =
                pose.position +
                (this.transform.rotation * this._initialGrabOffset);
        }

        public void OnEndDrag(PointerEventData eventData)
        {
            ZPointerEventData pointerEventData = eventData as ZPointerEventData;
            if (pointerEventData == null ||
                pointerEventData.button != PointerEventData.InputButton.Left)
            {
                return;
            }

            // Release the pointer.
            pointerEventData.Pointer.CapturePointer(null);

            // If the grabbable object has a rigidbody component,
            // restore its original isKinematic state.
            var rigidbody = this.GetComponent<Rigidbody>();
            if (rigidbody != null)
            {
                rigidbody.isKinematic = this._isKinematic;
            }
        }

        ////////////////////////////////////////////////////////////////////////
        // Private Members
        ////////////////////////////////////////////////////////////////////////

        private Vector3 _initialGrabOffset = Vector3.zero;
        //private Quaternion _initialGrabRotation = Quaternion.identity;
        private bool _isKinematic = false;
    }
}