// Animancer // Copyright 2020 Kybernetik //

using UnityEngine;

namespace Animancer.Examples
{
    /// <summary>
    /// Simple mouse controls for orbiting the camera around a focal point.
    /// </summary>
    [AddComponentMenu(Strings.MenuPrefix + "Examples/Orbit Controls")]
    public sealed class OrbitControls : MonoBehaviour
    {
        /************************************************************************************************************************/

        [SerializeField]
        private Vector3 _FocalPoint = new Vector3(0, 1, 0);

        [SerializeField]
        [Range(-1, 2)]
        private int _MouseButton = 1;

        [SerializeField]
        private Vector3 _Sensitivity = new Vector3(15, -10, -0.1f);

        private float _Distance;

        /************************************************************************************************************************/

        private void Awake()
        {
            _Distance = Vector3.Distance(_FocalPoint, transform.position);

            transform.LookAt(_FocalPoint);
        }

        /************************************************************************************************************************/

        private void Update()
        {
#if UNITY_EDITOR
            if (!UnityEditor.EditorApplication.isPlayingOrWillChangePlaymode)
            {
                transform.LookAt(_FocalPoint);
                return;
            }
#endif

            if (_MouseButton < 0 || Input.GetMouseButton(_MouseButton))
            {
                var movement = new Vector2(
                    Input.GetAxis("Mouse X"),
                    Input.GetAxis("Mouse Y"));

                if (movement != Vector2.zero)
                {
                    var euler = transform.localEulerAngles;
                    euler.y += movement.x * _Sensitivity.x;
                    euler.x += movement.y * _Sensitivity.y;
                    if (euler.x > 180)
                        euler.x -= 360;
                    euler.x = Mathf.Clamp(euler.x, -80, 80);
                    transform.localEulerAngles = euler;
                }
            }

            var zoom = Input.mouseScrollDelta.y * _Sensitivity.z;
            if (zoom != 0 &&
                Input.mousePosition.x >= 0 && Input.mousePosition.x <= Screen.width &&
                Input.mousePosition.y >= 0 && Input.mousePosition.y <= Screen.height)
            {
                _Distance *= 1 + zoom;
            }

            // Always update position even with no input in case the target is moving.
            UpdatePosition();
        }

        /************************************************************************************************************************/

        private void UpdatePosition()
        {
            transform.position = _FocalPoint - transform.forward * _Distance;
        }

        /************************************************************************************************************************/

        private void OnDrawGizmosSelected()
        {
            Gizmos.color = new Color(0.5f, 1, 0.5f, 1);
            Gizmos.DrawLine(transform.position, _FocalPoint);
        }

        /************************************************************************************************************************/
    }
}