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

namespace ProjectM.Server
{
    /// <summary>
    /// Server-world half of the M4 LAN host flow. When the per-world <see cref="ConnectionConfig"/>
    /// requests <see cref="ConnectionMode.Host"/>, creates a <see cref="NetworkStreamRequestListen"/>
    /// entity (netcode binds the server driver and starts listening) and clears the request. Replaces the
    /// old <c>AutoConnectPort</c> auto-listen. Not Burst-compiled: a cold path that fires only on an
    /// explicit host request.
    /// </summary>
    [WorldSystemFilter(WorldSystemFilterFlags.ServerSimulation)]
    public partial struct ServerConnectionControlSystem : 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.Host)
                return;

            cfgRef.ValueRW.Requested = false;

            var endpoint = cfgRef.ValueRO.Address.ToString() == "127.0.0.1"
                ? NetworkEndpoint.LoopbackIpv4.WithPort(cfgRef.ValueRO.Port)   // single-player: bind loopback only (no firewall prompt)
                : NetworkEndpoint.AnyIpv4.WithPort(cfgRef.ValueRO.Port);        // host: accept LAN peers

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