using UnityEngine;
using UnityEditor;
using UnityEditorInternal;
using System.Collections.Generic;
using YKMoon;

namespace YKMoonEditor
{
    //T: element type
    public class SubclassReorderableList<T>
    {
        private ReorderableList m_ReorderableList;
        public SerializedObject serializedObject { get; private set; }
        public SerializedProperty elements { get; private set; }
        private List<System.Type> subClassTypes;
        public SubclassReorderableList(SerializedObject serializedObject, SerializedProperty elements)
        {
            this.serializedObject = serializedObject;
            this.elements = elements;
            subClassTypes = GetSubclassTypes();
            m_ReorderableList = new ReorderableList(serializedObject, elements, true, true, true, true);

            m_ReorderableList.drawElementCallback = DrawElement;
            m_ReorderableList.elementHeightCallback = GetElementHeight;
            m_ReorderableList.drawHeaderCallback = DrawEventHeader;
            m_ReorderableList.onAddDropdownCallback = OnAddDropdown;
            //m_ReorderableList.headerHeight = 32;
        }

        private void DrawElement(Rect rect, int index, bool isActive, bool isFocused)
        {
            var element = m_ReorderableList.serializedProperty.GetArrayElementAtIndex(index);
            EditorGUI.PropertyField(rect, element);
        }

        private float GetElementHeight(int index)
        {
            var element = m_ReorderableList.serializedProperty.GetArrayElementAtIndex(index);
            return EditorGUI.GetPropertyHeight(element);
        }

        public void DoLayoutList()
        {
            m_ReorderableList.DoLayoutList();
        }

        protected virtual void DrawEventHeader(Rect headerRect)
        {
            GUIContent content = new GUIContent(string.Format("{0} ({1})", elements.name, m_ReorderableList.count), elements.tooltip);
            var style = GUI.skin.GetStyle("BoldLabel");
            style.fontSize = 16;
            EditorGUI.LabelField(headerRect, content, style);
        }
        public int arraySize {
            get {
                return m_ReorderableList.count;
            }
        }

        public int index { get => m_ReorderableList.index; set => m_ReorderableList.index = Mathf.Min(Mathf.Max(0, value), arraySize); }

        private void OnAddDropdown(Rect buttonRect, ReorderableList list)
        {
            var menu = new GenericMenu();
            foreach(var type in subClassTypes) {
                menu.AddItem(new GUIContent(type.GetDisplayName()), false, OnClickAddElement, type);
            }
            menu.ShowAsContext();
        }

        private void OnClickAddElement(object args)
        {
            System.Type subClassType = (System.Type)args;
            Undo.RecordObject(serializedObject.targetObject, "Add New Item");
            var newItem = (T)System.Activator.CreateInstance(subClassType);

            var scriptType = serializedObject.targetObject.GetType();
            var listField = scriptType.GetField(elements.name);
            List<T> list = (List<T>)listField.GetValue(serializedObject.targetObject);
            list.Add(newItem);

            this.index = list.Count - 1;

            serializedObject.ApplyModifiedProperties();
        }

        private List<System.Type> GetSubclassTypes()
        {
            List<System.Type> result = new List<System.Type>();
            var targetSuperType = typeof(T);
            foreach(var type in targetSuperType.Assembly.GetTypes()) {
                if(!type.IsAbstract && IsBaseTypeContains(type, targetSuperType)) {
                    result.Add(type);
                }
            }
            return result;
        }
        private bool IsBaseTypeContains(System.Type type, System.Type targetSuperType)
        {
            if (type.BaseType == null) {
                return false;
            }
            if (type.BaseType == targetSuperType) {
                return true;
            }
            return IsBaseTypeContains(type.BaseType, targetSuperType);
        }
    }
}