using System;
using System.Collections.Generic;
#if UNITY_EDITOR
using UnityEditor;
#endif
using UnityEngine;

namespace RogueUtils.Data
{
	public abstract class BaseVariableReference<TVariable, TValue> : SubBaseVariableReference where TVariable : BaseVariable<TValue>
	{
		//
		[Multiline]
		[UnityEngine.Serialization.FormerlySerializedAs("description")]
		public string m_Description = "";

		[SerializeField]
		[HideInInspector]
		protected TVariable m_Variable;

#if UNITY_EDITOR
		//
		// This is what appear in the inspector as the variable.
		// It is separate so that Inspector changes can go through the this.Value = new variable instance
		// code path.
		//
		//[ShowInInspector]
		//[OnValueChanged("BaseHandleEditorVariableChange")]
		protected TVariable m_InspectorVariable;
#endif

		/// <summary>
		/// The reason for the m_ZeroOnExitPlayMode is that it is an Unity Editor only feature and
		/// resets the Variable value so that Git does not see a bunch of changes to runtime
		/// ScriptableObject Variables
		/// </summary>
		[SerializeField]
		protected bool m_DefaultOnExitPlayMode = false;


		private event EventHandler InternalOnVariableChange;
		protected event EventHandler<BaseVariable<TValue>.OnChangeEventArgs> InternalOnReferencedValueChange;
		protected event EventHandler<BaseVariable<TValue>.OnChangeEventArgs> InternalOnValueChange;

		public event EventHandler OnVariableChange
		{
			// Not thread safe.
			// Will add tracking of subscribers
			add
			{
				InternalOnVariableChange += value;
			}

			remove
			{
				InternalOnVariableChange -= value;
			}
		}

		public event EventHandler<BaseVariable<TValue>.OnChangeEventArgs> OnReferencedValueChange
		{
			// Not thread safe.
			// Will add tracking of subscribers
			add
			{
				InternalOnReferencedValueChange += value;
			}

			remove
			{
				InternalOnReferencedValueChange -= value;
			}
		}

		public event EventHandler<BaseVariable<TValue>.OnChangeEventArgs> OnValueChange
		{
			// Not thread safe.
			// Will add tracking of subscribers
			add
			{
				InternalOnValueChange += value;
			}

			remove
			{
				InternalOnValueChange -= value;
			}
		}

		protected virtual TVariable DefaultVariable
		{
			get => default;
		}

		public virtual TVariable Variable
		{
			get
			{
				return m_Variable;
			}
			set
			{
				if (m_Variable != null)
				{
					//
					// Remove the listeners from the old variable
					//
					m_Variable.OnChange -= HandleValueChange;
				}
				m_Variable = value;

#if UNITY_EDITOR
				m_InspectorVariable = m_Variable;
#endif

				if (m_Variable != null)
				{
					m_Variable.OnChange += HandleValueChange;
				}

				TriggerVariableListeners();

				//
				// This is also a value change
				//
				if (m_Variable != null)
				{
					HandleValueChange(m_Variable, new BaseVariable<TValue>.OnChangeEventArgs(m_Variable.Value));
				}
				else
				{
					HandleValueChange(m_Variable, new BaseVariable<TValue>.OnChangeEventArgs(default));
				}
			}
		}

		public virtual TValue Value
		{
			get
			{
				return (m_Variable != null ? m_Variable.Value : default);
			}
			set
			{
				if (m_Variable != null)
				{
					m_Variable.Value = value;
				}
			}
		}

		protected virtual void HandleValueChange(object sender, BaseVariable<TValue>.OnChangeEventArgs onChangeEventArgs)
		{
			SubBaseTriggerValueListeners();
			if (m_Variable != null)
			{
				InternalOnValueChange?.Invoke(m_Variable, onChangeEventArgs);
			}
			InternalOnReferencedValueChange?.Invoke(this, onChangeEventArgs);
		}

		protected virtual void OnEnable()
		{
#if UNITY_EDITOR
			EditorApplication.playModeStateChanged += HandlePlayModeStateChange;
#endif
			//
			// Listen on the variable value changing.
			//
			if (m_Variable != null)
			{
				m_Variable.OnChange += HandleValueChange;
			}
		}

		protected virtual void OnDisable()
		{
#if UNITY_EDITOR
			EditorApplication.playModeStateChanged -= HandlePlayModeStateChange;
#endif
			//
			// Stop listening on the variable value changing.
			//
			if (m_Variable != null)
			{
				m_Variable.OnChange -= HandleValueChange;
			}

/*#if UNITY_EDITOR
			if (m_TestRuntimeVariable != null)
			{
				RogueUtils.Utils.NiceDestroy(m_TestRuntimeVariable);
				m_TestRuntimeVariable = null;
			}
#endif*/
		}

#if UNITY_EDITOR
		private void HandlePlayModeStateChange(PlayModeStateChange stateChange)
		{
			bool doDefaultVariable = false;
			switch (stateChange)
			{
				case PlayModeStateChange.EnteredEditMode:
					break;
				case PlayModeStateChange.ExitingEditMode:
					break;
				case PlayModeStateChange.EnteredPlayMode:
					break;
				case PlayModeStateChange.ExitingPlayMode:
					doDefaultVariable = m_DefaultOnExitPlayMode;
					break;
			}

			if (doDefaultVariable)
			{
				var defaultVariable = DefaultVariable;
				//Undo.RecordObject(this, $"{name}: Clearing list");
				m_Variable = defaultVariable;
				//
				// Marking this dirty so Unity sees the value is its default value
				//
				EditorUtility.SetDirty(this);
			}
		}
#endif


		public override SubBaseVariable GetVariableUntyped()
		{
			return Variable;
		}

		public override void SetVariableUntyped(SubBaseVariable variable)
		{
			if (variable is TVariable theVariable)
			{
				Variable = theVariable;
			}
		}

		public override T GetValue<T>()
		{
			var variable = Variable;
			if (variable != null)
			{
				var value = variable.Value;
				if (value is T theValue)
				{
					return theValue;
				}
			}

			return default;
		}

		public override object GetValueUntyped()
		{
			var variable = Variable;
			if (variable != null)
			{
				return variable.Value;
			}

			return default;
		}

		public override void SetValueUntyped(object value)
		{
			var variable = Variable;
			if (variable != null)
			{
				if (value is TValue theValue)
				{
					variable.Value = theValue;
				}
			}
		}


		public override void TriggerVariableListeners()
		{
			InternalOnVariableChange?.Invoke(this, EventArgs.Empty);
			base.SubBaseTriggerVariableListeners();
		}

#if UNITY_EDITOR
		[System.Diagnostics.CodeAnalysis.SuppressMessage("CodeQuality", "IDE0051:Remove unused private members", Justification = "Odin")]
		private void BaseHandleEditorVariableChange()
		{
			Variable = m_InspectorVariable;
		}

		//[FoldoutGroup("Debug", Order = 200)]
		//[BoxGroup("Debug/Runtime")]
		//[ShowInInspector]
		//[ReadOnly]
		private TVariable m_TestRuntimeVariable;

		//[BoxGroup("Debug/Runtime")]
		//[Button("Set to runtime variable instance")]
		//[System.Diagnostics.CodeAnalysis.SuppressMessage("CodeQuality", "IDE0051:Remove unused private members", Justification = "Odin")]
		private void SetToRuntimeInstance()
		{
			if (m_TestRuntimeVariable == null)
			{
				m_TestRuntimeVariable = ScriptableObject.CreateInstance<TVariable>();
			}

			Variable = m_TestRuntimeVariable;
		}
#endif
	}
}