using System;
using System.Net;
using System.Text;
using System.Threading;
using System.Threading.Tasks;
using Newtonsoft.Json;

namespace IvfTl.ControlHost
{
    /// <summary>
    /// control 进程内的本地 HTTP 小服务,只监听 127.0.0.1:port。
    /// 阶段1:/ping、/status。阶段2 扩展 /serial/pause|resume、/shutdown。
    /// </summary>
    public class ControlHttpServer
    {
        private readonly int _port;
        private readonly Func<StatusDto> _statusProvider;
        private readonly Action<string> _log;
        private HttpListener _listener;
        private CancellationTokenSource _cts;

        public ControlHttpServer(int port, Func<StatusDto> statusProvider, Action<string> log)
        {
            _port = port;
            _statusProvider = statusProvider;
            _log = log ?? (_ => { });
        }

        public void Start()
        {
            _listener = new HttpListener();
            _listener.Prefixes.Add($"http://127.0.0.1:{_port}/");
            _listener.Start();
            _cts = new CancellationTokenSource();
            _log($"ControlHttpServer 监听 http://127.0.0.1:{_port}/");
            Task.Run(() => Loop(_cts.Token));
        }

        private async Task Loop(CancellationToken token)
        {
            while (!token.IsCancellationRequested)
            {
                HttpListenerContext ctx;
                try { ctx = await _listener.GetContextAsync(); }
                catch (Exception ex) { if (!token.IsCancellationRequested) _log("HttpListener 异常:" + ex.Message); break; }
                try { Handle(ctx); }
                catch (Exception ex) { _log("处理请求异常:" + ex.Message); }
            }
        }

        private void Handle(HttpListenerContext ctx)
        {
            string path = ctx.Request.Url.AbsolutePath.TrimEnd('/').ToLowerInvariant();
            string body;
            int code = 200;
            switch (path)
            {
                case "/ping":
                case "/status":
                    body = JsonConvert.SerializeObject(_statusProvider());
                    break;
                default:
                    code = 404; body = "{\"ok\":false,\"error\":\"not found\"}";
                    break;
            }
            byte[] buf = Encoding.UTF8.GetBytes(body);
            ctx.Response.StatusCode = code;
            ctx.Response.ContentType = "application/json";
            ctx.Response.ContentLength64 = buf.Length;
            ctx.Response.OutputStream.Write(buf, 0, buf.Length);
            ctx.Response.OutputStream.Close();
        }

        public void Stop()
        {
            try { _cts?.Cancel(); _listener?.Stop(); _listener?.Close(); }
            catch (Exception ex) { _log("ControlHttpServer 停止异常:" + ex.Message); }
        }
    }
}