AutoDelegationAttribute.cs

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using System;
using System.Collections.Generic;
using System.Linq;
using System.Reflection;
using Loot.Api.Core;
using Loot.Api.Delegators;

namespace Loot.Api.Attributes
{
    [AttributeUsage(AttributeTargets.Method)]
    public sealed class AutoDelegation : Attribute
    {
        private readonly IEnumerable<string> _delegationTypes;

        public IEnumerable<string> DelegationTypes => new List<string>(_delegationTypes);

        public AutoDelegation(params string[] types)
        {
            _delegationTypes = new List<string>(GetTargetNames(types));
        }

        public AutoDelegation(params DelegationTarget[] targets)
        {
            _delegationTypes = new List<string>(
                GetTargetNames(targets
                    .Select(target => Enum.GetName(typeof(DelegationTarget), target))));
        }

        private IEnumerable<string> GetTargetNames(IEnumerable<string> names)
            => names.Select(GetFilteredName);

        private string GetFilteredName(string name)
        {
            if (name.StartsWith("On")) name = name.Substring(2);
            if (!name.EndsWith("Event")) name = $"{name}Event";
            return name;
        }

        public void Attach(ModifierDelegatorPlayer delegatorPlayer, MethodInfo method, ModifierEffect effect)
        {
            foreach (string type in _delegationTypes)
            {
                EventInfo evt = delegatorPlayer.GetType().GetEvent(type, BindingFlags.Instance | BindingFlags.Public);
                if (evt != null)
                {
                    try
                    {
                        Delegate handler = Delegate.CreateDelegate(evt.EventHandlerType, effect, method);
                        evt.AddEventHandler(delegatorPlayer, handler);
                    }
                    catch (Exception e)
                    {
                        Loot.Logger.Error("An error just occurred. Please share this error log with the mod author.", e);
                    }
                }
            }
        }

        public void Detach(ModifierDelegatorPlayer delegatorPlayer, MethodInfo method, ModifierEffect effect)
        {
            foreach (string type in _delegationTypes)
            {
                EventInfo evt = delegatorPlayer.GetType().GetEvent(type, BindingFlags.Instance | BindingFlags.Public);
                if (evt != null)
                {
                    try
                    {
                        Delegate handler = Delegate.CreateDelegate(evt.EventHandlerType, effect, method);
                        evt.RemoveEventHandler(delegatorPlayer, handler);
                    }
                    catch (Exception e)
                    {
                        Loot.Logger.Error("An error just occurred. Please share this error log with the mod author.", e);
                    }
                }
            }
        }

        // TODO I forgot why I added this
        //public bool IsMethodCompatibleWithDelegate<T>(MethodInfo method) where T : class
        //{
        //  Type delegateType = typeof(T);
        //  MethodInfo delegateSignature = delegateType.GetMethod("Invoke");

        //  bool parametersEqual = delegateSignature
        //      .GetParameters()
        //      .Select(x => x.ParameterType)
        //      .SequenceEqual(method.GetParameters()
        //          .Select(x => x.ParameterType));

        //  return delegateSignature.ReturnType == method.ReturnType &&
        //         parametersEqual;
        //}
    }
}