#if MM_UI
using System;
using UnityEngine;
using UnityEngine.Events;
using UnityEngine.EventSystems;

namespace MoreMountains.Tools
{
    [Serializable]
    public class AxisEvent : UnityEvent<float>
    {
    }

    /// <summary>
    ///     Add this component to a GUI Image to have it act as an axis.
    ///     Bind pressed down, pressed continually and released actions to it from the inspector
    ///     Handles mouse and multi touch
    /// </summary>
    [RequireComponent(typeof(Rect))]
    [RequireComponent(typeof(CanvasGroup))]
    [AddComponentMenu("More Mountains/Tools/Controls/MM Touch Axis")]
    public class MMTouchAxis : MonoBehaviour, IPointerDownHandler, IPointerUpHandler, IPointerExitHandler,
        IPointerEnterHandler
    {
        public enum ButtonStates
        {
            Off,
            ButtonDown,
            ButtonPressed,
            ButtonUp
        }

        [Header("Binding")]
        /// The method(s) to call when the axis gets pressed down
        [Tooltip("The method(s) to call when the axis gets pressed down")]
        public UnityEvent AxisPressedFirstTime;

        /// The method(s) to call when the axis gets released
        [Tooltip("The method(s) to call when the axis gets released")]
        public UnityEvent AxisReleased;

        /// The method(s) to call while the axis is being pressed
        [Tooltip("The method(s) to call while the axis is being pressed")]
        public AxisEvent AxisPressed;

        [Header("Pressed Behaviour")]
        [MMInformation("Here you can set the opacity of the button when it's pressed. Useful for visual feedback.",
            MMInformationAttribute.InformationType.Info, false)]
        /// the new opacity to apply to the canvas group when the axis is pressed
        [Tooltip("the new opacity to apply to the canvas group when the axis is pressed")]
        public float PressedOpacity = 0.5f;

        /// the value to send the bound method when the axis is pressed
        [Tooltip("the value to send the bound method when the axis is pressed")]
        public float AxisValue;

        [Header("Mouse Mode")]
        [MMInformation(
            "If you set this to true, you'll need to actually press the axis for it to be triggered, otherwise a simple hover will trigger it (better for touch input).",
            MMInformationAttribute.InformationType.Info, false)]
        /// If you set this to true, you'll need to actually press the axis for it to be triggered, otherwise a simple hover will trigger it (better for touch input).
        [Tooltip(
            "If you set this to true, you'll need to actually press the axis for it to be triggered, otherwise a simple hover will trigger it (better for touch input).")]
        public bool MouseMode;

        protected CanvasGroup _canvasGroup;
        protected float _initialOpacity;

        public virtual ButtonStates CurrentState { get; protected set; }

        /// <summary>
        ///     On Start, we get our canvasgroup and set our initial alpha
        /// </summary>
        protected virtual void Awake()
        {
            _canvasGroup = GetComponent<CanvasGroup>();
            if (_canvasGroup != null) _initialOpacity = _canvasGroup.alpha;
            ResetButton();
        }

        /// <summary>
        ///     Every frame, if the touch zone is pressed, we trigger the bound method if it exists
        /// </summary>
        protected virtual void Update()
        {
            if (AxisPressed != null)
                if (CurrentState == ButtonStates.ButtonPressed)
                    AxisPressed.Invoke(AxisValue);
        }

        /// <summary>
        ///     At the end of every frame, we change our button's state if needed
        /// </summary>
        protected virtual void LateUpdate()
        {
            if (CurrentState == ButtonStates.ButtonUp) CurrentState = ButtonStates.Off;
            if (CurrentState == ButtonStates.ButtonDown) CurrentState = ButtonStates.ButtonPressed;
        }

        /// <summary>
        ///     OnEnable, we reset our button state
        /// </summary>
        protected virtual void OnEnable()
        {
            ResetButton();
        }

        /// <summary>
        ///     Triggers the bound pointer down action
        /// </summary>
        public virtual void OnPointerDown(PointerEventData data)
        {
            if (CurrentState != ButtonStates.Off) return;

            CurrentState = ButtonStates.ButtonDown;
            if (_canvasGroup != null) _canvasGroup.alpha = PressedOpacity;
            if (AxisPressedFirstTime != null) AxisPressedFirstTime.Invoke();
        }

        /// <summary>
        ///     Triggers the bound pointer enter action when touch enters zone
        /// </summary>
        public virtual void OnPointerEnter(PointerEventData data)
        {
            if (!MouseMode) OnPointerDown(data);
        }

        /// <summary>
        ///     Triggers the bound pointer exit action when touch is out of zone
        /// </summary>
        public virtual void OnPointerExit(PointerEventData data)
        {
            if (!MouseMode) OnPointerUp(data);
        }

        /// <summary>
        ///     Triggers the bound pointer up action
        /// </summary>
        public virtual void OnPointerUp(PointerEventData data)
        {
            if (CurrentState != ButtonStates.ButtonPressed && CurrentState != ButtonStates.ButtonDown) return;

            CurrentState = ButtonStates.ButtonUp;
            if (_canvasGroup != null) _canvasGroup.alpha = _initialOpacity;
            if (AxisReleased != null) AxisReleased.Invoke();
            AxisPressed.Invoke(0);
        }

        /// <summary>
        ///     Resets the button's state and opacity
        /// </summary>
        protected virtual void ResetButton()
        {
            CurrentState = ButtonStates.Off;
            _canvasGroup.alpha = _initialOpacity;
            CurrentState = ButtonStates.Off;
        }
    }
}
#endif