#nullable enable

using System;
using System.Collections.Generic;
using System.Linq;
using Cysharp.Threading.Tasks;
using ShrinkEventBus;

namespace ShrinkNetwork.Integration
{
    public readonly struct ShrinkNetworkEventRegistration
    {
        public ShrinkNetworkEventRegistration(Type eventType, int opcode, string? route,
            Func<IShrinkEvent, UniTask> dispatch,
            Func<ShrinkNetworkContext, IShrinkEvent, UniTask<object?>>? requestDispatch)
        {
            EventType = eventType ?? throw new ArgumentNullException(nameof(eventType));
            Opcode = opcode;
            Route = route;
            Dispatch = dispatch ?? throw new ArgumentNullException(nameof(dispatch));
            RequestDispatch = requestDispatch;
        }

        public Type EventType { get; }
        public int Opcode { get; }
        public string? Route { get; }
        public Func<IShrinkEvent, UniTask> Dispatch { get; }
        public Func<ShrinkNetworkContext, IShrinkEvent, UniTask<object?>>? RequestDispatch { get; }
    }

    public static class ShrinkNetworkEventRegistry
    {
        private static readonly object Gate = new();
        private static readonly Dictionary<Type, ShrinkNetworkEventRegistration> Registrations = new();

        public static void Register<TEvent>(int opcode, string? route)
            where TEvent : IShrinkEvent, IShrinkNetworkMessage
        {
            var registration = new ShrinkNetworkEventRegistration(
                typeof(TEvent), opcode, route,
                static eventData => ShrinkNetworkEventBusBridge.DispatchGeneratedAsync((TEvent)eventData),
                typeof(IShrinkNetworkRequest).IsAssignableFrom(typeof(TEvent))
                    ? static (context, eventData) =>
                        ShrinkNetworkEventBusBridge.DispatchGeneratedRequestAsync(context, (TEvent)eventData)
                    : null);
            lock (Gate)
                Registrations[typeof(TEvent)] = registration;
        }

        internal static IReadOnlyList<ShrinkNetworkEventRegistration> Snapshot()
        {
            lock (Gate)
                return Registrations.Values.ToArray();
        }
    }
}