using System;
using System.Collections.Generic;
using System.Linq;
using System.Reflection;
using UnityEditor;
using UnityEngine;

namespace Funique
{
    [CustomPropertyDrawer(typeof(TypeDropdownAttribute))]
    public class TypeDropdownDrawer : PropertyDrawer
    {
        internal class TypeStorage
        {
            internal List<Type> types = new List<Type>();
        }

        internal static Dictionary<Type, TypeStorage> dict = new Dictionary<Type, TypeStorage>();
        internal static Dictionary<Type, string[]> naming_dict = new Dictionary<Type, string[]>();

        object GetValue(SerializedProperty property)
        {
            object obj = property.serializedObject.targetObject;

            FieldInfo field = null;
            foreach (var path in property.propertyPath.Split('.'))
            {
                var type = obj.GetType();
                field = type.GetField(path);
                obj = field.GetValue(obj);
            }
            return obj;
        }

        void Fill(Type type)
        {
            TypeStorage buffer = new TypeStorage();
            buffer.types.Add(null);
            dict[type] = buffer;
            Assembly[] asss = System.AppDomain.CurrentDomain.GetAssemblies();
            foreach (var i in asss)
            {
                foreach (var t in i.GetTypes())
                {
                    if (t.IsSubclassOf(type) || (t == type && !t.IsAbstract))
                    {
                        buffer.types.Add(t);
                    }
                }
            }
            naming_dict[type] = buffer.types.Select(x => x == null ? "NULL" : x.FullName).ToArray();
        }

        Type GetType(string type)
        {
            Assembly[] asss = System.AppDomain.CurrentDomain.GetAssemblies();
            Type[] r = asss.SelectMany(x => x.GetTypes()).Where(x => x.Name == type || x.FullName == type).ToArray();
            if (r.Length > 0) return r[0];
            return null;
        }

        int GetIndex(object target, Type type)
        {
            if (target == null) return 0;
            TypeStorage buffer = dict[type];
            return buffer.types.FindIndex(x => target.GetType() == x);
        }

        public override void OnGUI(Rect position, SerializedProperty property, GUIContent label)
        {
            //base.OnGUI(position, property, label);
            TypeDropdownAttribute a = (TypeDropdownAttribute)attribute;
            string typename = property.managedReferenceFieldTypename.Split(new char[] { ' ' }, StringSplitOptions.RemoveEmptyEntries)[1];
            Type type = GetType(typename);
            object obj = GetValue(property);

            if (!dict.ContainsKey(type)) Fill(type);
            int index = GetIndex(obj, type);
            string[] fs = naming_dict[type];
            int result = EditorGUI.Popup(position, label, index, fs.Select(x => new GUIContent(x)).ToArray());
            if (result != index)
            {
                if (result == 0) property.managedReferenceValue = null;
                else property.managedReferenceValue = Activator.CreateInstance(dict[type].types[result]);
                property.serializedObject.ApplyModifiedProperties();
            }
        }
    }
}