#nullable enable

using System;
using System.Collections.Generic;

namespace ShrinkNetwork
{
    public sealed class ShrinkNetworkMessageRegistry
    {
        private readonly Dictionary<int, ShrinkNetworkMessageMeta> _opcodeToMeta = new();
        private readonly Dictionary<Type, ShrinkNetworkMessageMeta> _typeToMeta = new();

        public void Register<TMessage>(int opcode, string? route = null) where TMessage : IShrinkNetworkMessage
            => Register(typeof(TMessage), opcode, route);

        public void Register(Type messageType, int opcode, string? route = null)
        {
            if (messageType == null)
                throw new ArgumentNullException(nameof(messageType));
            if (!typeof(IShrinkNetworkMessage).IsAssignableFrom(messageType))
                throw new ArgumentException($"Type {messageType.FullName} is not a network message.", nameof(messageType));
            if (_opcodeToMeta.ContainsKey(opcode))
                throw new InvalidOperationException($"Opcode {opcode} is already registered.");
            if (_typeToMeta.ContainsKey(messageType))
                throw new InvalidOperationException($"Message type {messageType.FullName} is already registered.");

            var meta = new ShrinkNetworkMessageMeta(opcode, messageType, route);
            _opcodeToMeta.Add(opcode, meta);
            _typeToMeta.Add(messageType, meta);
        }

        public bool TryGetMeta(int opcode, out ShrinkNetworkMessageMeta? meta) => _opcodeToMeta.TryGetValue(opcode, out meta);

        public bool TryGetMeta(Type type, out ShrinkNetworkMessageMeta? meta) => _typeToMeta.TryGetValue(type, out meta);

        public ShrinkNetworkMessageMeta GetMeta<TMessage>() where TMessage : IShrinkNetworkMessage => GetMeta(typeof(TMessage));

        public ShrinkNetworkMessageMeta GetMeta(Type type)
        {
            if (_typeToMeta.TryGetValue(type, out var meta))
                return meta;

            throw new KeyNotFoundException($"Message type {type.FullName} is not registered.");
        }
    }

    public sealed class ShrinkNetworkMessageMeta
    {
        public int Opcode { get; }
        public Type MessageType { get; }
        public string? Route { get; }

        public ShrinkNetworkMessageMeta(int opcode, Type messageType, string? route)
        {
            Opcode = opcode;
            MessageType = messageType;
            Route = route;
        }
    }
}