using ProjectM.Simulation;
using Unity.Collections;
using Unity.Entities;
using Unity.NetCode;
using Unity.Networking.Transport;
using UnityEngine;

namespace ProjectM.Client
{
    /// <summary>
    /// Client/thin-client half of the M4 LAN join flow. When the per-world <see cref="ConnectionConfig"/>
    /// requests <see cref="ConnectionMode.Join"/>, creates a <see cref="NetworkStreamRequestConnect"/>
    /// entity for the parsed endpoint and clears the request. Runs in both full and thin client worlds so
    /// the editor auto-host can connect thin clients too. Not Burst-compiled: <c>NetworkEndpoint.TryParse</c>
    /// takes a managed string and this is a cold path.
    /// </summary>
    [WorldSystemFilter(WorldSystemFilterFlags.ClientSimulation | WorldSystemFilterFlags.ThinClientSimulation)]
    public partial struct ClientConnectionControlSystem : ISystem
    {
        public void OnCreate(ref SystemState state)
        {
            state.RequireForUpdate<ConnectionConfig>();
        }

        public void OnUpdate(ref SystemState state)
        {
            var cfgRef = SystemAPI.GetSingletonRW<ConnectionConfig>();
            if (!cfgRef.ValueRO.Requested || cfgRef.ValueRO.Mode != ConnectionMode.Join)
                return;

            // Clear first so a malformed address does not retry-spam every frame.
            cfgRef.ValueRW.Requested = false;

            var address = cfgRef.ValueRO.Address;
            var port = cfgRef.ValueRO.Port;
            if (!NetworkEndpoint.TryParse(address.ToString(), port, out var endpoint, NetworkFamily.Ipv4))
            {
                Debug.LogError($"[ClientConnectionControlSystem] Invalid join address '{address}'.");
                return;
            }

            var ecb = new EntityCommandBuffer(Allocator.Temp);
            var req = ecb.CreateEntity();
            ecb.AddComponent(req, new NetworkStreamRequestConnect { Endpoint = endpoint });
            ecb.Playback(state.EntityManager);
            ecb.Dispose();
        }
    }
}