using System;
using System.Text;
using System.Collections.Generic;
using Golems.Attributes;
#if UNITY_EDITOR
using UnityEditor;
#endif
using UnityEngine;
using UnityEngine.Serialization;

namespace RogueUtils.Data
{
    public abstract class BaseVariable<T> : SubBaseVariable, IValueMonitor<T>
#if UNITY_EDITOR
        , ISerializationCallbackReceiver
#endif
    {
        //
        // NOTE: you cannot have Editor only serialised fields in Generics, it will crash a build
        //       see https://issuetracker.unity3d.com/issues/serialization-layout-error-thrown-in-build-when-using-generic-classes-with-fields-that-only-exist-in-the-editor
        //
        [Multiline] public string m_Description = "";

        [SerializeField] protected T m_Value;

        // DW: Lets re-implement this down the line
/*#if UNITY_EDITOR
        [NonSerialized]
        [ShowInInspector]
        [OnValueChanged("BaseHandleEditorValueChange")]
        [LabelText("Value")]
        //
        // This is an inspector editable version of the value
        //
        protected T m_EditorValue;
#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<OnChangeEventArgs> InternalOnChange;

        public event EventHandler<OnChangeEventArgs> OnChange
        {
            add
            {
                InternalOnChange += value;
            }

            remove
            {
                InternalOnChange -= value;
            }
        }

        public class OnChangeEventArgs : EventArgs
        {
            public T OldValue { get; private set; }

            public T NewValue { get; private set; }
            
            public OnChangeEventArgs(T value)
            {
                OldValue = value;
                NewValue = value;
            }
            
            public OnChangeEventArgs(T oldValue, T newValue)
            {
                OldValue = oldValue;
                NewValue = newValue;
            }
        }

        protected virtual T DefaultValue
        {
            get => default;
        }

        public virtual T Value
        {
            get
            {
                return m_Value;
            }
            set
            {
                T oldValue = m_Value;
                m_Value = value;
/*#if UNITY_EDITOR
                m_EditorValue = m_Value;
#endif*/
                BaseHandleValueChange();
                InternalOnChange?.Invoke(this, new OnChangeEventArgs(oldValue, m_Value));
            }
        }
        
        [Button]
        public void ForceOnChange()
        {
            InternalOnChange?.Invoke(this, new OnChangeEventArgs(m_Value));
        }

        public override TValue GetValue<TValue>()
        {
            var value = Value;
            if (value is TValue theValue)
            {
                return theValue;
            }
            return default;
        }

        public override object GetValueUntyped()
        {
            return Value;
        }

        public override void SetValueUntyped(object value)
        {
            if (value is T theValue)
            {
                Value = theValue;
            }
        }

        public void MonitoredValueChanged(T value, T _)
        {
            Value = value;
        }

        protected virtual void OnEnable()
        {
#if UNITY_EDITOR
            EditorApplication.playModeStateChanged += HandlePlayModeStateChange;
#endif
        }

        protected virtual void OnDisable()
        {
#if UNITY_EDITOR
            EditorApplication.playModeStateChanged -= HandlePlayModeStateChange;
#endif
        }

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

            if (doDefaultValue)
            {
                var defaultValue = DefaultValue;
                //Undo.RecordObject(this, $"{name}: Clearing list");
                m_Value = defaultValue;
#if UNITY_EDITOR
//				m_EditorValue = m_Value;
#endif
                //
                // Marking this dirty so Unity sees the value is its default value
                // JJA: Doing this means the user has to manually save otherwise the Dirty flag carries over to the next time
                // Play is hit, causing it to save with the value it has after entering play mode (ie the runtime, not default value).
                // Bottom line: There is no need to set this dirty, as play mode changes aren't saved and by changing it back to default on exit we already avoid any chance of a runtime value being saved later
                //		EditorUtility.SetDirty(this);
            }

            AdditionalHandlePlayModeStateChange(stateChange);
        }

        /// <summary>
        /// Do any additional changes needed when changing PlayMode.
        /// NOTE: any override must be surrounded by #if UNITY_EDITOR as it is Editor only.
        /// </summary>
        /// <param name="stateChange"></param>
        protected virtual void AdditionalHandlePlayModeStateChange(PlayModeStateChange stateChange)
        {
        }
#endif

#if UNITY_EDITOR
        [System.Diagnostics.CodeAnalysis.SuppressMessage("CodeQuality", "IDE0051:Remove unused private members", Justification = "Odin")]
        private void BaseHandleEditorValueChange()
        {
            HandleEditorValueChange();
            //
            // Marking this dirty so Unity sees the value change
            //
            EditorUtility.SetDirty(this);
        }

        protected virtual void HandleEditorValueChange()
        {
            //Value = m_EditorValue;
        }

        // [BoxGroup("Debug/Listeners")]
        // [HideIf("@this.m_InspectorValueListeners == null || this.m_InspectorValueListeners.Count == 0")]
        // [Button("Log Listeners")]
        private void LogListListeners()
        {
            var listeners = InternalOnChange?.GetInvocationList();

            if (listeners == null)
            {
                return;
            }

            StringBuilder builder = new StringBuilder();
            foreach (var listener in listeners)
            {
                builder.AppendLine(string.Format("{0}: listener {1}", name, listener));
            }
            Debug.Log(builder.ToString());
        }
#endif

        public override string ToString()
        {
            if (m_Value == null)
            {
                return name + " (null)";
            }
            return name + " (" + m_Value.ToString() + ")";
        }

#if UNITY_EDITOR
        public void OnBeforeSerialize()
        {
        }

        public void OnAfterDeserialize()
        {
            //m_EditorValue = m_Value;
        }
#endif
    }
}