esiur-dotnet/Esiur/Resource/Template/EventTemplate.cs

using Esiur.Core;
using Esiur.Data;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Reflection;
using System.Runtime.CompilerServices;
using System.Text;
using System.Threading.Tasks;

namespace Esiur.Resource.Template;
public class EventTemplate : MemberTemplate
{
    public string Annotation
    {
        get;
        set;
    }

    public bool Listenable { get; set; }

    public EventInfo EventInfo { get; set; }

    public RepresentationType ArgumentType { get; set; }

    public override byte[] Compose()
    {
        var name = base.Compose();

        var hdr = Inherited ? (byte)0x80 : (byte)0;

        if (Listenable)
            hdr |= 0x8;

        if (Annotation != null)
        {
            var exp = DC.ToBytes(Annotation);
            hdr |= 0x50;
            return new BinaryList()
                    .AddUInt8(hdr)
                    .AddUInt8((byte)name.Length)
                    .AddUInt8Array(name)
                    .AddUInt8Array(ArgumentType.Compose())
                    .AddInt32(exp.Length)
                    .AddUInt8Array(exp)
                    .ToArray();
        }
        else
            hdr |= 0x40;
        return new BinaryList()
                .AddUInt8(hdr)
                .AddUInt8((byte)name.Length)
                .AddUInt8Array(name)
                .AddUInt8Array(ArgumentType.Compose())
                .ToArray();
    }

    public EventTemplate(TypeTemplate template, byte index, string name, bool inherited, RepresentationType argumentType, string annotation = null, bool listenable = false)
       : base(template, index, name, inherited)
    {
        this.Annotation = annotation;
        this.Listenable = listenable;
        this.ArgumentType = argumentType;
    }

    public static EventTemplate MakeEventTemplate(Type type, EventInfo ei, byte index = 0, string customName = null, TypeTemplate typeTemplate = null)
    {

        if (!ei.EventHandlerType.IsGenericType)
            throw new Exception($"Unsupported event handler type in event `{type.Name}.{ei.Name}`");

        if (ei.EventHandlerType.GetGenericTypeDefinition() != typeof(ResourceEventHandler<>)
            && ei.EventHandlerType.GetGenericTypeDefinition() != typeof(CustomResourceEventHandler<>))
            throw new Exception($"Unsupported event handler type in event `{type.Name}.{ei.Name}`");


        var argType = ei.EventHandlerType.GenericTypeArguments[0];
        var evtType = RepresentationType.FromType(argType);

        if (evtType == null)
            throw new Exception($"Unsupported type `{argType}` in event `{type.Name}.{ei.Name}`");

        var annotationAttr = ei.GetCustomAttribute<AnnotationAttribute>(true);
        var listenableAttr = ei.GetCustomAttribute<ListenableAttribute>(true);

        evtType.Nullable =  new NullabilityInfoContext().Create(ei).ReadState is NullabilityState.Nullable;

        //var nullableAttr = ei.GetCustomAttribute<NullableAttribute>(true);
        //var nullableContextAttr = ei.GetCustomAttribute<NullableContextAttribute>(true);

        //var flags = nullableAttr?.Flags?.ToList() ?? new List<byte>();

        //// skip the eventHandler class
        //if (flags.Count > 1)
        //    flags = flags.Skip(1).ToList();

        //if (nullableContextAttr?.Flag == 2)
        //{
        //    if (flags.Count == 1)
        //        evtType.SetNotNull(flags.FirstOrDefault());
        //    else
        //        evtType.SetNotNull(flags);
        //}
        //else
        //{
        //    if (flags.Count == 1)
        //        evtType.SetNull(flags.FirstOrDefault());
        //    else
        //        evtType.SetNull(flags);
        //}

        var et = new EventTemplate(typeTemplate, index, customName ?? ei.Name, ei.DeclaringType != type, evtType);
        et.EventInfo = ei;

        if (annotationAttr != null)
            et.Annotation = annotationAttr.Annotation;

        if (listenableAttr != null)
            et.Listenable = true;

        return et;
    }

}