using System;
using System.Net;
using System.Text;
using System.Threading.Tasks;
using Newtonsoft.Json;
using log4net;
using CncCollector.Core;
using System.IO;

namespace CncCollector.Api
{
    /// <summary>
    /// Lightweight HTTP API server，用于控制 CollectEngine 的状态与配置刷新。
    /// </summary>
    public class CollectorApiServer
    {
        private readonly CollectorEngine _engine;
        private readonly string _apiKey;
        private readonly int _port;
        private readonly HttpListener _listener = new HttpListener();
        private readonly ILog _log = LogManager.GetLogger(typeof(CollectorApiServer));
        private Task _listenTask;
        private bool _running;

        public CollectorApiServer(CollectorEngine engine, string apiKey, int port = 0)
        {
            _engine = engine;
            _apiKey = apiKey;
            _port = port > 0 ? port : 8080;
        }

        public void Start()
        {
            var prefix = $"http://+:{_port}/api/collector/";
            _listener.Prefixes.Add(prefix);
            _listener.Start();
            _running = true;
            _log.Info("CollectorApiServer started on " + prefix);
            _listenTask = Task.Run(() => ListenLoop());
        }

        public void Stop()
        {
            _running = false;
            _listener.Stop();
        }

        private async Task ListenLoop()
        {
            while (_running)
            {
                try
                {
                    var ctx = await _listener.GetContextAsync();
                    _ = Task.Run(() => ProcessRequest(ctx));
                }
                catch (HttpListenerException)
                {
                    // 监听关闭
                    break;
                }
                catch (Exception ex)
                {
                    _log.Error("CollectorApiServer 处理请求异常", ex);
                }
            }
        }

        private void ProcessRequest(HttpListenerContext ctx)
        {
            var req = ctx.Request;
            var res = ctx.Response;
            // 简单的 API-Key 认证
            if (!ValidateApiKey(req))
            {
                res.StatusCode = 401;
                WriteJson(res, new { code = 1, message = "Unauthorized" });
                return;
            }

            string path = req.Url.AbsolutePath.ToLower();
            switch (req.HttpMethod)
            {
                case "GET":
                    if (path.EndsWith("/status"))
                        WriteJson(res, new { code = 0, message = "success", data = new { status = _engine.Status } });
                    else
                        WriteJson(res, new { code = 0, message = "unknown endpoint" });
                    break;
                case "POST":
                    if (path.EndsWith("/start"))
                    {
                        _engine.Start();
                        WriteJson(res, new { code = 0, message = "started" });
                    }
                    else if (path.EndsWith("/stop"))
                    {
                        _engine.Stop();
                        WriteJson(res, new { code = 0, message = "stopped" });
                    }
                    else if (path.EndsWith("/refresh"))
                    {
                        _engine.Refresh();
                        WriteJson(res, new { code = 0, message = "refreshed" });
                    }
                    else
                    {
                        WriteJson(res, new { code = 0, message = "unknown endpoint" });
                    }
                    break;
                default:
                    res.StatusCode = 405;
                    WriteJson(res, new { code = 1, message = "method not allowed" });
                    break;
            }
        }

        private bool ValidateApiKey(HttpListenerRequest req)
        {
            var header = req.Headers["X-Api-Key"];
            return !string.IsNullOrEmpty(_apiKey) && string.Equals(_apiKey, header);
        }

        private void WriteJson(HttpListenerResponse res, object data)
        {
            var json = JsonConvert.SerializeObject(data);
            var buffer = Encoding.UTF8.GetBytes(json);
            res.ContentType = "application/json";
            res.ContentLength64 = buffer.Length;
            res.OutputStream.Write(buffer, 0, buffer.Length);
        }
    }
}