using UnityEngine;
using UnityEngine.Events;
using UnityEngine.Serialization;
using Lean.Common;
using FSA = UnityEngine.Serialization.FormerlySerializedAsAttribute;

namespace Lean.Touch
{
	/// <summary>This component calls OnDown when a finger begins touching the screen on top of this UI element.
	/// NOTE: This requires you to enable the RaycastTarget setting on your UI graphic.</summary>
	[RequireComponent(typeof(RectTransform))]
	[HelpURL(LeanTouch.PlusHelpUrlPrefix + "LeanFingerDownCanvas")]
	[AddComponentMenu(LeanTouch.ComponentPathPrefix + "Finger Down Canvas")]
	public class LeanFingerDownCanvas : MonoBehaviour
	{
		[System.Serializable] public class LeanFingerEvent : UnityEvent<LeanFinger> {}
		[System.Serializable] public class Vector3Event : UnityEvent<Vector3> {}

		/// <summary>Ignore fingers with StartedOverGui?</summary>
		public bool IgnoreStartedOverGui { set { ignoreStartedOverGui = value; } get { return ignoreStartedOverGui; } } [FSA("IgnoreStartedOverGui")] [SerializeField] private bool ignoreStartedOverGui = true;

		/// <summary>If the specified object is set and isn't selected, then this component will do nothing.</summary>
		public LeanSelectable RequiredSelectable { set { requiredSelectable = value; } get { return requiredSelectable; } } [FSA("RequiredSelectable")] [SerializeField] private LeanSelectable requiredSelectable;

		/// <summary>Called on the first frame the conditions are met.</summary>
		public LeanFingerEvent OnFinger { get { if (onFinger == null) onFinger = new LeanFingerEvent(); return onFinger; } } [FormerlySerializedAs("onDown")] [FormerlySerializedAs("OnDown")] [SerializeField] private LeanFingerEvent onFinger;

		/// <summary>The method used to find world coordinates from a finger. See LeanScreenDepth documentation for more information.</summary>
		public LeanScreenDepth ScreenDepth = new LeanScreenDepth(LeanScreenDepth.ConversionType.DepthIntercept);

		/// <summary>Called on the first frame the conditions are met.
		/// Vector3 = Start point based on the ScreenDepth settings.</summary>
		public Vector3Event OnWorld { get { if (onWorld == null) onWorld = new Vector3Event(); return onWorld; } } [SerializeField] private Vector3Event onWorld;

		public bool ElementOverlapped(LeanFinger finger)
		{
			var results = LeanTouch.RaycastGui(finger.ScreenPosition, -1);

			if (results != null && results.Count > 0)
			{
				if (results[0].gameObject == gameObject)
				{
					return true;
				}
			}

			return false;
		}
		
		protected virtual void OnEnable()
		{
			LeanTouch.OnFingerDown += HandleFingerDown;
		}

		protected virtual void OnDisable()
		{
			LeanTouch.OnFingerDown -= HandleFingerDown;
		}

		private void HandleFingerDown(LeanFinger finger)
		{
			if (ignoreStartedOverGui == true && finger.IsOverGui == true)
			{
				return;
			}

			if (requiredSelectable != null && requiredSelectable.IsSelected == false)
			{
				return;
			}

			if (ElementOverlapped(finger) == true)
			{
				if (onFinger != null)
				{
					onFinger.Invoke(finger);
				}

				if (onWorld != null)
				{
					var position = ScreenDepth.Convert(finger.StartScreenPosition, gameObject);

					onWorld.Invoke(position);
				}
			}
		}
	}
}

#if UNITY_EDITOR
namespace Lean.Touch.Editor
{
	using TARGET = LeanFingerDownCanvas;

	[UnityEditor.CanEditMultipleObjects]
	[UnityEditor.CustomEditor(typeof(TARGET))]
	public class LeanFingerDownCanvas_Editor : LeanEditor
	{
		protected override void OnInspector()
		{
			TARGET tgt; TARGET[] tgts; GetTargets(out tgt, out tgts);

			Draw("ignoreStartedOverGui", "Ignore fingers with StartedOverGui?");
			Draw("requiredSelectable", "If the specified object is set and isn't selected, then this component will do nothing.");

			Separator();

			var showUnusedEvents = DrawFoldout("Show Unused Events", "Show all events?");

			if (Any(tgts, t => t.OnFinger.GetPersistentEventCount() > 0) == true || showUnusedEvents == true)
			{
				Draw("onFinger");
			}

			if (Any(tgts, t => t.OnWorld.GetPersistentEventCount() > 0) == true || showUnusedEvents == true)
			{
				Draw("ScreenDepth");
				Draw("onWorld");
			}
		}
	}
}
#endif