using System;
using System.IO;
using System.Net;
using System.Text;
using System.Threading;
using System.Threading.Tasks;
using Newtonsoft.Json;
using Newtonsoft.Json.Linq;
using IvfTl.ControlHost.Debug;

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:/status 补全(rich) + /serial/pause|resume(借串口) + /shutdown(受护栏停止)。
    /// </summary>
    public class ControlHttpServer
    {
        private readonly int _port;
        private readonly Func<StatusDto> _pingProvider;        // /ping 轻量存活
        private readonly Func<object> _statusProvider;         // /status 完整快照(阶段2 §6 三块)
        private readonly Func<string, bool> _shutdownHandler;  // /shutdown(token 校验后安全停机)
        private readonly Func<int, bool> _serialPauseHandler;  // /serial/pause(借串口:control 让路该舱)
        private readonly Func<int, bool> _serialResumeHandler; // /serial/resume(归还:恢复采集)
        private readonly Action<string> _log;
        private readonly DebugSessionManager _debug;
        private HttpListener _listener;
        private CancellationTokenSource _cts;

        public ControlHttpServer(
            int port,
            Func<StatusDto> pingProvider,
            Func<object> statusProvider,
            Func<string, bool> shutdownHandler,
            Func<int, bool> serialPauseHandler,
            Func<int, bool> serialResumeHandler,
            Action<string> log,
            DebugSessionManager debug = null)
        {
            _port = port;
            _pingProvider = pingProvider;
            _statusProvider = statusProvider;
            _shutdownHandler = shutdownHandler;
            _serialPauseHandler = serialPauseHandler;
            _serialResumeHandler = serialResumeHandler;
            _log = log ?? (_ => { });
            _debug = debug;
        }

        public void Start()
        {
            _listener = new HttpListener();
            // 仅本机回环,拒绝外部访问(防外部调停机/借串口)。
            _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 method = ctx.Request.HttpMethod.ToUpperInvariant();
            string body;
            int code = 200;
            switch (path)
            {
                case "/ping":
                    body = JsonConvert.SerializeObject(_pingProvider());
                    break;
                case "/status":
                    body = JsonConvert.SerializeObject(_statusProvider());
                    break;
                case "/shutdown":
                    if (method != "POST") { code = 405; body = Err("method not allowed"); break; }
                    {
                        string token = ReadField(ctx, "token");
                        bool ok = _shutdownHandler != null && _shutdownHandler(token ?? "");
                        code = ok ? 200 : 403;
                        body = "{\"ok\":" + (ok ? "true" : "false") + (ok ? "" : ",\"error\":\"token invalid\"") + "}";
                    }
                    break;
                case "/serial/pause":
                case "/serial/resume":
                    if (method != "POST") { code = 405; body = Err("method not allowed"); break; }
                    {
                        int houseSn = ReadIntField(ctx, "houseSn");
                        bool isPause = path == "/serial/pause";
                        var handler = isPause ? _serialPauseHandler : _serialResumeHandler;
                        bool ok = handler != null && houseSn > 0 && handler(houseSn);
                        code = ok ? 200 : 400;
                        body = "{\"ok\":" + (ok ? "true" : "false") + ",\"houseSn\":" + houseSn + (ok ? "" : ",\"error\":\"bad houseSn or handler\"") + "}";
                    }
                    break;
                case "/debug/acquire":
                    if (method != "POST") { code = 405; body = Err("method not allowed"); break; }
                    {
                        int houseSn = ReadIntField(ctx, "houseSn");
                        var r = _debug != null ? _debug.Acquire(houseSn) : DebugCommandResult.Fail("NO_HANDLE", "debug 未装配");
                        code = r.Ok ? 200 : 409; body = JsonConvert.SerializeObject(r);
                    }
                    break;
                case "/debug/heartbeat":
                    if (method != "POST") { code = 405; body = Err("method not allowed"); break; }
                    {
                        var r = _debug != null ? _debug.Heartbeat(ReadField(ctx, "sessionId")) : DebugCommandResult.Fail("SESSION_EXPIRED", "debug 未装配");
                        code = r.Ok ? 200 : 410; body = JsonConvert.SerializeObject(r);
                    }
                    break;
                case "/debug/release":
                    if (method != "POST") { code = 405; body = Err("method not allowed"); break; }
                    {
                        var r = _debug != null ? _debug.Release(ReadField(ctx, "sessionId")) : DebugCommandResult.Okay();
                        code = 200; body = JsonConvert.SerializeObject(r);
                    }
                    break;
                case "/debug/command":
                    if (method != "POST") { code = 405; body = Err("method not allowed"); break; }
                    {
                        var jo = ReadBody(ctx);
                        string sid = jo?["sessionId"]?.ToString();
                        string op = jo?["op"]?.ToString();
                        var argsObj = jo?["args"] as Newtonsoft.Json.Linq.JObject;
                        var r = _debug != null ? _debug.Execute(sid, op, argsObj) : DebugCommandResult.Fail("SESSION_EXPIRED", "debug 未装配");
                        code = r.Ok ? 200 : (r.Code == "SESSION_EXPIRED" ? 410 : (r.Code == "OUT_OF_RANGE" ? 400 : 200));
                        body = JsonConvert.SerializeObject(r);
                    }
                    break;
                case "/debug/preview/stream":
                    if (method != "GET") { code = 405; body = Err("method not allowed"); break; }
                    {
                        string sid = ctx.Request.QueryString["sessionId"];
                        if (_debug == null || sid == null || !_debug.TryGet(sid, out var session))
                        {
                            code = 404; body = Err("session not found");
                            break;  // 走统一收尾返回 404
                        }
                        // 校验通过:分流起后台推流线程,不走统一收尾(那会 Close 流终止推流)。
                        StartPreviewStream(ctx, session);
                        return;
                    }
                default:
                    code = 404; body = Err("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();
        }

        private static string Err(string msg) => "{\"ok\":false,\"error\":\"" + msg + "\"}";

        /// <summary>读 POST JSON body 的某字符串字段(失败返回 null)。</summary>
        private string ReadField(HttpListenerContext ctx, string field)
        {
            try
            {
                using (var sr = new StreamReader(ctx.Request.InputStream, ctx.Request.ContentEncoding ?? Encoding.UTF8))
                {
                    string raw = sr.ReadToEnd();
                    if (string.IsNullOrEmpty(raw)) return null;
                    var jo = JObject.Parse(raw);
                    return jo[field]?.ToString();
                }
            }
            catch (Exception ex) { _log("解析请求体异常:" + ex.Message); return null; }
        }

        private int ReadIntField(HttpListenerContext ctx, string field)
        {
            string s = ReadField(ctx, field);
            return int.TryParse(s, out int v) ? v : -1;
        }

        /// <summary>把 POST body 整体解析为 JObject(失败返回 null)。/debug/command 多字段用。</summary>
        private Newtonsoft.Json.Linq.JObject ReadBody(HttpListenerContext ctx)
        {
            try
            {
                using (var sr = new StreamReader(ctx.Request.InputStream, ctx.Request.ContentEncoding ?? Encoding.UTF8))
                {
                    string raw = sr.ReadToEnd();
                    return string.IsNullOrEmpty(raw) ? null : Newtonsoft.Json.Linq.JObject.Parse(raw);
                }
            }
            catch (Exception ex) { _log("解析 body 异常:" + ex.Message); return null; }
        }

        /// <summary>
        /// 推流分支:起专用后台线程,抓帧→JPEG→multipart 持续写。
        /// HttpListener 工作线程立即返回(本方法起线程后即返回),不被推流阻塞。
        /// 任何退出路径都标记 session.StreamBroken,会话靠心跳 TTL 看门狗最终回收(spec §7)。
        /// </summary>
        private void StartPreviewStream(HttpListenerContext ctx, IvfTl.ControlHost.Debug.DebugSession session)
        {
            var resp = ctx.Response;
            resp.StatusCode = 200;
            resp.ContentType = IvfTl.ControlHost.Debug.MjpegStreamWriter.ContentType;
            resp.SendChunked = true;  // 流式,长度未知
            resp.Headers.Add("Cache-Control", "no-cache");

            var t = new Thread(() =>
            {
                int errCount = 0;
                var cam = session.Lease?.Camera;
                try
                {
                    if (cam == null) { _log($"[debug] 推流舱{session.HouseSn} 无相机句柄,放弃"); return; }
                    cam.SetOpMode(1);  // 实时模式(0=单帧/1=实时,见 ICamera 注释)
                    var outStream = resp.OutputStream;
                    while (true)
                    {
                        // 会话已被回收(release/超时)→ 停推流
                        if (!_debug.TryGet(session.SessionId, out _)) { _log($"[debug] 推流舱{session.HouseSn} 会话已失效,停"); break; }
                        try
                        {
                            byte[] bgr = cam.GrabStable();   // 走全进程相机锁,与采集/对焦串行
                            if (bgr == null) { Thread.Sleep(100); continue; }
                            byte[] jpeg = IvfTl.ControlHost.Debug.MjpegStreamWriter.EncodeJpeg(bgr, cam.Width, cam.Height);
                            if (jpeg == null) { Thread.Sleep(100); continue; }
                            byte[] frame = IvfTl.ControlHost.Debug.MjpegStreamWriter.FrameBytes(jpeg);
                            outStream.Write(frame, 0, frame.Length);
                            outStream.Flush();
                            errCount = 0;
                            Thread.Sleep(66);  // ~15fps(spec §4.2)
                        }
                        catch (IOException) { _log($"[debug] 推流舱{session.HouseSn} 客户端断开"); break; }     // operate 关预览/崩溃:正常退出
                        catch (HttpListenerException) { _log($"[debug] 推流舱{session.HouseSn} 连接断开"); break; }
                        catch (Exception ex)
                        {
                            errCount++;
                            _log($"[debug] 推流舱{session.HouseSn} 抓帧/编码异常({errCount}/5): {ex.Message}");
                            if (errCount >= 5) { _log($"[debug] 推流舱{session.HouseSn} 连续错误过多,停"); break; }
                            Thread.Sleep(500);
                        }
                    }
                }
                catch (Exception ex) { _log($"[debug] 推流舱{session.HouseSn} 线程异常: {ex.Message}"); }
                finally
                {
                    session.StreamBroken = true;   // 可回收快信号;会话最终由心跳 TTL 看门狗收(不在此 Dispose,避免与命令分发/超时回收争 lease)
                    try { resp.OutputStream.Close(); } catch { }
                    try { resp.Close(); } catch { }
                    _log($"[debug] 推流舱{session.HouseSn} 线程结束");
                }
            });
            t.IsBackground = true;
            t.Name = $"MjpegStream-h{session.HouseSn}";
            t.Start();
        }

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