module-inspector/Editor/Utilities/EditorMethodUtility.cs

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

namespace Module.Inspector.Editor.Utilities
{
    internal static class EditorMethodUtility
    {
        private static Dictionary<Type, ResultPrimary[]> CACHED_TYPE_TO_PRIMARIES;
        private static Dictionary<MethodInfo, Result> CACHED_RESULTS;
        private static Dictionary<Type, Type> CACHED_ATT_TO_DRAWER;
        
        private static void InitializeCache()
        {
            if (CACHED_ATT_TO_DRAWER != null)
                return;

            CACHED_ATT_TO_DRAWER = new Dictionary<Type, Type>();

            Type baseDrawerType = typeof(AbstractMethodDrawer);
            var assembly = Assembly.GetAssembly(baseDrawerType);
            Type[] types = assembly.GetTypes();

            for (var i = 0; i < types.Length; i++)
            {
                Type type = types[i];
                    
                if (type.IsAbstract || !baseDrawerType.IsAssignableFrom(type))
                    continue;
                    
                IList<CustomAttributeData> attributes = type.GetCustomAttributesData();
                    
                for (var j = 0; j < attributes.Count; j++)
                {
                    CustomAttributeData attData = attributes[j];
                    IList<CustomAttributeTypedArgument> arguments = attData.ConstructorArguments;

                    for (var k = 0; k < arguments.Count; k++)
                    {
                        if (arguments[k].Value is Type argType)
                            CACHED_ATT_TO_DRAWER.Add(argType, type);
                    }
                }
            }
        }

        public static ResultPrimary[] QueryPrimary(Object target)
        {
            InitializeCache();
            
            if (CACHED_TYPE_TO_PRIMARIES == null)
                CACHED_TYPE_TO_PRIMARIES = new Dictionary<Type, ResultPrimary[]>();

            Type type = target.GetType();

            if (CACHED_TYPE_TO_PRIMARIES.TryGetValue(type, out ResultPrimary[] primaries))
                return primaries;

            primaries = InternalFetchPrimary(type);
            CACHED_TYPE_TO_PRIMARIES.Add(type, primaries);
            return primaries;
        }
        
        public static Result Query(MethodInfo methodInfo)
        {
            InitializeCache();
            
            if (CACHED_RESULTS == null)
                CACHED_RESULTS = new Dictionary<MethodInfo, Result>();

            if (CACHED_RESULTS.TryGetValue(methodInfo, out Result result))
                return result;

            result = InternalFetchProperties(methodInfo);
            
            if (result != null)
                CACHED_RESULTS.Add(methodInfo, result);
            
            return result;
        }

        private static ResultPrimary[] InternalFetchPrimary(Type type)
        {
            const BindingFlags FLAGS = BindingFlags.Instance | BindingFlags.Static | BindingFlags.Public | BindingFlags.NonPublic;
            
            MethodInfo[] methods = type.GetMethods(FLAGS)
                                       .Where(m => m.GetParameters().Length == 0)
                                       .ToArray();
            
            var list = new List<ResultPrimary>(methods.Length);
            
            for (var i = 0; i < methods.Length; i++)
            {
                Result result = Query(methods[i]);
                
                if (result != null)
                    list.Add(new ResultPrimary(methods[i], result));
            }

            return list.ToArray();
        }

        private static Result InternalFetchProperties(MethodInfo methodInfo)
        {
            ResultValue<DrawerMethodAttribute, DrawerMethodDrawer> drawer = null;
            ResultValue<DecoratorMethodAttribute, DecoratorMethodDrawer> decorator = null;
            var accessModifiers = new List<ResultValue<AccessModifierMethodAttribute, AccessModifierMethodDrawer>>(2);
            object[] attributes = methodInfo.GetCustomAttributes(false);

            for (var i = 0; i < attributes.Length; i++)
            {
                object att = attributes[i];

                if (att is DrawerMethodAttribute attDrawer)
                {
                    if (drawer != null)
                        continue;
                    
                    var prop = InternalCreateInstanceOf<DrawerMethodDrawer>(attDrawer);
                    
                    if (prop != null)
                        drawer = new ResultValue<DrawerMethodAttribute, DrawerMethodDrawer>(attDrawer, prop);
                }
                else if (att is AccessModifierMethodAttribute accessModifier)
                {
                    var prop = InternalCreateInstanceOf<AccessModifierMethodDrawer>(accessModifier);
                    
                    if (prop != null)
                        accessModifiers.Add(new ResultValue<AccessModifierMethodAttribute, AccessModifierMethodDrawer>(accessModifier, prop));
                }
                else if (att is DecoratorMethodAttribute attDecorator)
                {
                    if (decorator != null)
                        continue;
                    
                    var prop = InternalCreateInstanceOf<DecoratorMethodDrawer>(attDecorator);
                    
                    if (prop != null)
                        decorator = new ResultValue<DecoratorMethodAttribute, DecoratorMethodDrawer>(attDecorator, prop);
                }
            }

            if (drawer == null && decorator == null && accessModifiers.Count == 0)
                return null;
            
            return new Result(drawer, decorator, accessModifiers);
        }

        private static T InternalCreateInstanceOf<T>(AbstractMethodAttribute att) where T : AbstractMethodDrawer
        {
            if (CACHED_ATT_TO_DRAWER.TryGetValue(att.GetType(), out Type drawerType))
                return Activator.CreateInstance(drawerType) as T;

            return null;
        }
        
        /// <summary>
        /// Class: Result from method query
        /// </summary>
        public sealed class Result
        {
            public readonly ResultValue<DrawerMethodAttribute, DrawerMethodDrawer> draw;
            public readonly ResultValue<DecoratorMethodAttribute, DecoratorMethodDrawer> decorator;
            public readonly List<ResultValue<AccessModifierMethodAttribute, AccessModifierMethodDrawer>> accessModifiers;

            public Result(ResultValue<DrawerMethodAttribute, DrawerMethodDrawer> draw,
                          ResultValue<DecoratorMethodAttribute, DecoratorMethodDrawer> decorator,
                          List<ResultValue<AccessModifierMethodAttribute, AccessModifierMethodDrawer>> accessModifiers)
            {
                this.draw = draw;
                this.decorator = decorator;
                this.accessModifiers = accessModifiers;
            }
            
            public T GetAccessModifier<T>() where T : AccessModifierMethodAttribute
            {
                for (var i = 0; i < accessModifiers.Count; i++)
                {
                    if (accessModifiers[i].attribute is T att)
                        return att;
                }

                return null;
            }
        }
        
        /// <summary>
        /// Class: Contains attribute and drawer values
        /// </summary>
        /// <typeparam name="T0"></typeparam>
        /// <typeparam name="T1"></typeparam>
        public sealed class ResultValue<T0, T1> where T0 : AbstractMethodAttribute
                                                where T1 : AbstractMethodDrawer
        {
            public readonly T0 attribute;
            public readonly T1 drawer;

            public ResultValue(T0 attribute, T1 drawer)
            {
                this.attribute = attribute;
                this.drawer = drawer;
            }
        }

        /// <summary>
        /// Class: Contains primary method info and drawer for a specific method
        /// </summary>
        public sealed class ResultPrimary
        {
            public readonly MethodInfo methodInfo;
            public readonly AbstractMethodDrawer drawer;

            public ResultPrimary(MethodInfo methodInfo, AbstractMethodDrawer drawer)
            {
                this.methodInfo = methodInfo;
                this.drawer = drawer;
            }
            
            public ResultPrimary(MethodInfo methodInfo, Result result)
            {
                this.methodInfo = methodInfo;

                if (result.draw != null)
                    drawer = result.draw.drawer;
                else if (result.decorator != null)
                    drawer = result.decorator.drawer;
                else if (result.accessModifiers != null && result.accessModifiers.Count > 0)
                    drawer = result.accessModifiers[0].drawer;
            }
        }
    }
}