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

namespace Homebrew
{
    [CustomPropertyDrawer(typeof(TagFilterAttribute))]
    public class TagFilterPropertyDrawer : PropertyDrawer
    {
        public int currentIndex;
        public FastString fs = new FastString(128);
        public List<FieldInfo> fields = new List<FieldInfo>();

        public override void OnGUI(Rect position, SerializedProperty property, GUIContent label)
        {
            EditorGUI.BeginProperty(position, label, property);
            EditorGUI.PrefixLabel(position, GUIUtility.GetControlID(FocusType.Passive), label);

            var tagFilter = attribute as TagFilterAttribute;
            var tagType = tagFilter.Type;

            var objectFields = ReturnConst(tagType);

            var listNames = new List<string>();
            fields.Clear();

            var vv = property.intValue;

            for (var i = 0; i < objectFields.Length; i++)
            {
                var myFieldInfo = objectFields[i];
                var tagField = Attribute.GetCustomAttribute(objectFields[i], typeof(TagFieldAttribute)) as TagFieldAttribute;

                if (tagField == null) continue;
                fs.Append(tagField.categoryName).Append("/").Append(myFieldInfo.Name);
                listNames.Add(fs.ToString());
                fs.Clear();
                fields.Add(myFieldInfo);
                if (vv == (int) myFieldInfo.GetValue(this))
                    currentIndex = fields.Count - 1;
            }

            if (listNames.Count == 0)
            {
                EditorGUI.EndProperty();
                return;
            }

            currentIndex = EditorGUI.Popup(position, property.displayName, currentIndex, listNames.ToArray());


            var raw = listNames[currentIndex].Split('/');
            var name = raw[raw.Length - 1];

            var field = fields.Find(f => f.Name == name);
            property.intValue = (int) field.GetValue(this);

            EditorGUI.EndProperty();
        }


        FieldInfo[] ReturnConst(Type t)
        {
            ArrayList constants = new ArrayList();

            FieldInfo[] fieldInfos = t.GetFields(
                // Gets all public and static fields
                BindingFlags.Public | BindingFlags.Static |
                // This tells it to get the fields from all base types as well
                BindingFlags.FlattenHierarchy);

            // Go through the list and only pick out the constants
            foreach (FieldInfo fi in fieldInfos)
                // IsLiteral determines if its value is written at
                //   compile time and not changeable
                // IsInitOnly determine if the field can be set
                //   in the body of the constructor
                // for C# a field which is readonly keyword would have both true
                //   but a const field would have only IsLiteral equal to true
                if (fi.IsLiteral && !fi.IsInitOnly)
                    constants.Add(fi);

            // Return an array of FieldInfos
            return (FieldInfo[]) constants.ToArray(typeof(FieldInfo));
        }
    }
}