using UnityEngine;
using UnityEngine.EventSystems;
using UnityEngine.UI;

namespace Unity.VRTemplate
{
    /// <summary>
    /// Controls the visual states of a boolean toggle switch UI
    /// </summary>
    [RequireComponent(typeof(Toggle))]
    public class BooleanToggleVisualsController : MonoBehaviour, IPointerEnterHandler, IPointerExitHandler
    {
        const float k_TargetPositionX = 17f;

#pragma warning disable 649
        [SerializeField, Tooltip("The boolean toggle knob.")]
        RectTransform m_Knob;

        [SerializeField, Tooltip("How much to translate the button imagery on the z on hover.")]
        float m_ZTranslation = 5f;
#pragma warning restore 649

        Toggle m_Toggle;
        float m_InitialBackground;
        Coroutine m_ColorFade;
        Coroutine m_LocalMove;

        void Awake()
        {
            m_Toggle = gameObject.GetComponent<Toggle>();

            //Add listener for when the state of the Toggle changes, to take action
            m_Toggle.onValueChanged.AddListener(ToggleValueChanged);

            if (m_Knob != null)
            {
                m_InitialBackground = m_Knob.localPosition.z;
            }
        }

        void OnEnable()
        {
            ToggleValueChanged(m_Toggle.isOn);
        }

        /// <inheritdoc />
        void IPointerEnterHandler.OnPointerEnter(PointerEventData eventData)
        {
            PerformEntranceActions();
        }

        /// <inheritdoc />
        void IPointerExitHandler.OnPointerExit(PointerEventData eventData)
        {
            PerformExitActions();
        }

        void ToggleValueChanged(bool value)
        {
            if (value)
            {
                m_Knob.localPosition = new Vector3(k_TargetPositionX, m_Knob.localPosition.y, m_Knob.localPosition.z);
            }
            else
            {
                m_Knob.localPosition = new Vector3(-k_TargetPositionX, m_Knob.localPosition.y, m_Knob.localPosition.z);
            }
        }

        void PerformEntranceActions()
        {
            if (m_Knob != null)
            {
                var backgroundLocalPosition = m_Knob.localPosition;
                backgroundLocalPosition.z = m_InitialBackground - m_ZTranslation;
                m_Knob.localPosition = backgroundLocalPosition;
            }
        }

        void PerformExitActions()
        {
            if (m_Knob != null)
            {
                var backgroundLocalPosition = m_Knob.localPosition;
                backgroundLocalPosition.z = m_InitialBackground;
                m_Knob.localPosition = backgroundLocalPosition;
                m_Knob.localScale = Vector3.one;
            }
        }
    }
}