using System;
using System.Linq;
using System.Net;
using System.Net.WebSockets;
using System.Threading;
using System.Threading.Tasks;
using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.Hosting;
using Microsoft.AspNetCore.Hosting.Server;
using Microsoft.AspNetCore.Hosting.Server.Features;
using Microsoft.AspNetCore.Http;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Hosting;
using Microsoft.Extensions.Logging;
using XWorld.Framework.Protocol;
using XWorld.Server.Host;
using XWorld.Server.Auth;

namespace XWorld.Server.Gateway
{
    // 建 Kestrel + /ws 端点，把 socket 接入 ServerLoop。Start 返回实际监听地址（端口由系统分配）。
    public sealed class GameServerHost
    {
        private WebApplication _app;
        private ServerLoop _loop;
        private CancellationTokenSource _cts;
        private Task _loopTask;
        private DevDiscoveryResponder _discovery;
        private AccountStore _accounts;

        public string WsBaseUrl { get; private set; } // 例如 ws://127.0.0.1:54321
        public int DevDiscoveryPort => _discovery?.Port ?? 0;

        public async Task StartAsync(string gamesRoot, int tickIntervalMs, long reconnectWindowTicks = 100,
            long matchTimeoutTicks = 150, float? logicalDt = null, string publicKeyPem = null, int listenPort = 0,
            bool bindAllInterfaces = false,
            string devDiscoveryToken = null, string advertiseGatewayUrl = null, string advertiseResourceBaseUrl = null,
            int devDiscoveryPort = DevDiscovery.Port,
            byte[] authSecret = null, string authDbPath = null)
        {
            _loop = new ServerLoop(gamesRoot, new ConsoleLogger("[loop]"), reconnectWindowTicks, matchTimeoutTicks, publicKeyPem);
            _cts = new CancellationTokenSource();
            float dt = logicalDt ?? tickIntervalMs / 1000f;

            var builder = WebApplication.CreateBuilder();
            builder.Logging.ClearProviders();
            builder.WebHost.ConfigureKestrel(o =>
                o.Listen(bindAllInterfaces ? IPAddress.Any : IPAddress.Loopback, listenPort)); // 0 = 临时端口

            TokenService tokens = null;
            if (authSecret != null)
            {
                tokens = new TokenService(authSecret);
                _accounts = new AccountStore(string.IsNullOrEmpty(authDbPath)
                    ? "Data Source=accounts.db" : authDbPath);
            }

            var app = builder.Build();
            app.UseWebSockets();
            if (tokens != null)
                AuthEndpoints.Map(app, _accounts, tokens, TimeSpan.FromDays(7));
            app.Use(async (ctx, next) =>
            {
                if (ctx.Request.Path == "/ws" && ctx.WebSockets.IsWebSocketRequest)
                {
                    int pid;
                    if (tokens != null)
                    {
                        string token = ctx.Request.Query["token"];
                        if (!tokens.Verify(token, out pid))
                        {
                            ctx.Response.StatusCode = 401;
                            return;
                        }
                    }
                    else if (!int.TryParse(ctx.Request.Query["pid"], out pid))
                    {
                        ctx.Response.StatusCode = 400;
                        return;
                    }
                    using var ws = await ctx.WebSockets.AcceptWebSocketAsync();
                    var conn = new Connection(pid, ws, _loop);
                    _loop.Submit(new ConnectCommand { PlayerId = pid, Connection = conn });
                    try { await conn.RunAsync(ctx.RequestAborted); }
                    catch (OperationCanceledException) { } // 关停/中止：正常收束
                    finally
                    {
                        if (ws.State == WebSocketState.Open)
                        {
                            try { await ws.CloseAsync(WebSocketCloseStatus.NormalClosure, "server stopping", CancellationToken.None); }
                            catch { /* 关闭握手尽力而为 */ }
                        }
                        _loop.Submit(new DisconnectCommand { PlayerId = pid, Connection = conn });
                    }
                }
                else
                {
                    await next();
                }
            });

            await app.StartAsync();
            _app = app;

            var addresses = app.Services.GetRequiredService<IServer>()
                .Features.Get<IServerAddressesFeature>().Addresses;
            string http = addresses.FirstOrDefault()
                ?? throw new InvalidOperationException("Kestrel 已启动但未注册任何监听地址");
            WsBaseUrl = http.Replace("http://", "ws://");

            if (!string.IsNullOrEmpty(devDiscoveryToken))
            {
                string adGw = advertiseGatewayUrl;
                if (string.IsNullOrEmpty(adGw))
                {
                    // 绑所有网卡时 WsBaseUrl 形如 ws://0.0.0.0:port，对内网其它设备无意义 ——
                    // 用本机真实 LAN IP 广而告之（仿 C++ XBroadcastServer.GetLocalIPAddress）。
                    if (bindAllInterfaces)
                        adGw = $"ws://{LanIp.Resolve()}:{new Uri(WsBaseUrl).Port}/ws";
                    else
                        adGw = WsBaseUrl + "/ws";
                }
                _discovery = new DevDiscoveryResponder(
                    Environment.MachineName, adGw, advertiseResourceBaseUrl ?? "", devDiscoveryToken, devDiscoveryPort);
                _discovery.Start();
            }

            _loopTask = _loop.RunAsync(tickIntervalMs, dt, _cts.Token);
        }

        public async Task StopAsync()
        {
            if (_discovery != null)
            {
                await _discovery.StopAsync();
                _discovery = null;
            }
            _cts.Cancel();
            try { await _loopTask; } catch { /* 忽略取消 */ }
            await _app.StopAsync();
            await _app.DisposeAsync();
            _accounts?.Dispose();
            _accounts = null;
        }
    }
}