using System;
using System.Reflection;
using UnityEditor;
using UnityEngine;
using UnityEngine.Rendering;

namespace Misaki.ShaderGUI
{
    public class EnumFlagsUIDrawer : MaterialPropertyDrawer
    {
        private readonly Type enumType;

        public EnumFlagsUIDrawer(string enumTypeName, string assemblyName)
        {
            enumType = Type.GetType(Assembly.CreateQualifiedName(assemblyName, enumTypeName), true);
        }

        private static bool IsPropertyTypeSuitable(MaterialProperty prop)
        {
#if UNITY_6000_1_OR_NEWER
            return prop.propertyType == ShaderPropertyType.Float || prop.propertyType == ShaderPropertyType.Range || prop.propertyType == ShaderPropertyType.Int;
#else
            return prop.type == MaterialProperty.PropType.Float || prop.type == MaterialProperty.PropType.Range || prop.type == MaterialProperty.PropType.Int;
#endif
        }

        public override void OnGUI(Rect position, MaterialProperty prop, GUIContent label, MaterialEditor editor)
        {
            if (!IsPropertyTypeSuitable(prop))
            {
                var c = EditorGUIUtility.TrTempContent($"Enum flags used on a property {prop.name} with unsupported type: {prop.propertyType}");
                EditorGUI.LabelField(position, c, EditorStyles.helpBox);
                return;
            }

            MaterialEditor.BeginProperty(position, prop);

#if UNITY_6000_1_OR_NEWER
            if (prop.propertyType != ShaderPropertyType.Int)
#else
            if (prop.type != MaterialProperty.PropType.Int)
#endif
            {
                EditorGUI.BeginChangeCheck();

                var value = (int)prop.floatValue;
                EditorGUI.showMixedValue = prop.hasMixedValue;
                var enumValue = EditorGUI.EnumFlagsField(position, label, (Enum)Enum.ToObject(enumType, value));
                value = Convert.ToInt32(enumValue);
                EditorGUI.showMixedValue = false;

                if (EditorGUI.EndChangeCheck())
                {
                    prop.floatValue = value;
                }
            }
            else
            {
                EditorGUI.BeginChangeCheck();

                var value = prop.intValue;
                EditorGUI.showMixedValue = prop.hasMixedValue;
                var enumValue = EditorGUI.EnumFlagsField(position, label, (Enum)Enum.ToObject(enumType, value));
                value = Convert.ToInt32(enumValue);

                EditorGUI.showMixedValue = false;
                if (EditorGUI.EndChangeCheck())
                {
                    prop.intValue = value;
                }
            }

            MaterialEditor.EndProperty();
        }
    }
}