using System;
using System.Collections.Generic;
using System.Net;
using System.Text;
using System.Threading;
using UnityEngine;

namespace KindRetargeting.Remote
{
    /// <summary>
    /// HTTP 서버 - 웹 리모컨 UI 페이지를 제공합니다.
    /// Resources 폴더에서 CSS, HTML 템플릿, JavaScript를 로드합니다.
    /// </summary>
    public class RetargetingHTTPServer
    {
        private HttpListener listener;
        private Thread listenerThread;
        private bool isRunning = false;

        private int httpPort;
        private int wsPort;

        private string cachedCSS = "";
        private string cachedTemplate = "";
        private string cachedJS = "";

        private List<string> boundAddresses = new List<string>();

        public bool IsRunning => isRunning;
        public IReadOnlyList<string> BoundAddresses => boundAddresses;

        public RetargetingHTTPServer(int httpPort, int wsPort)
        {
            this.httpPort = httpPort;
            this.wsPort = wsPort;
        }

        public void Start()
        {
            if (isRunning) return;

            LoadResources();

            try
            {
                listener = new HttpListener();
                boundAddresses.Clear();

                // 로컬 접속 지원
                listener.Prefixes.Add($"http://localhost:{httpPort}/");
                boundAddresses.Add($"http://localhost:{httpPort}");

                listener.Prefixes.Add($"http://127.0.0.1:{httpPort}/");
                boundAddresses.Add($"http://127.0.0.1:{httpPort}");

                // 외부 접속도 시도
                try
                {
                    listener.Prefixes.Add($"http://+:{httpPort}/");
                    string localIP = GetLocalIPAddress();
                    if (!string.IsNullOrEmpty(localIP))
                    {
                        boundAddresses.Add($"http://{localIP}:{httpPort}");
                    }
                }
                catch (Exception)
                {
                    Debug.LogWarning("[RetargetingHTTP] 외부 접속 바인딩 실패. localhost만 사용 가능합니다.");
                }

                listener.Start();
                isRunning = true;

                listenerThread = new Thread(HandleRequests);
                listenerThread.IsBackground = true;
                listenerThread.Start();

                Debug.Log("[RetargetingHTTP] HTTP 서버 시작됨");
                foreach (var addr in boundAddresses)
                {
                    Debug.Log($"[RetargetingHTTP] 접속: {addr}");
                }
            }
            catch (Exception ex)
            {
                Debug.LogError($"[RetargetingHTTP] 서버 시작 실패: {ex.Message}");
            }
        }

        public void Stop()
        {
            if (!isRunning) return;

            isRunning = false;

            try
            {
                listener?.Stop();
                listener?.Close();
            }
            catch (Exception) { }

            Debug.Log("[RetargetingHTTP] HTTP 서버 중지됨");
        }

        private void LoadResources()
        {
            TextAsset cssAsset = Resources.Load<TextAsset>("KindRetargeting/retargeting_style");
            TextAsset templateAsset = Resources.Load<TextAsset>("KindRetargeting/retargeting_template");
            TextAsset jsAsset = Resources.Load<TextAsset>("KindRetargeting/retargeting_script");

            cachedCSS = cssAsset != null ? cssAsset.text : GetFallbackCSS();
            cachedTemplate = templateAsset != null ? templateAsset.text : GetFallbackTemplate();
            cachedJS = jsAsset != null ? jsAsset.text : GetFallbackJS();

            if (cssAsset == null || templateAsset == null || jsAsset == null)
            {
                Debug.LogWarning("[RetargetingHTTP] 일부 리소스를 로드할 수 없습니다. Fallback 사용 중.");
            }
        }

        private void HandleRequests()
        {
            while (isRunning)
            {
                try
                {
                    HttpListenerContext context = listener.GetContext();
                    ProcessRequest(context);
                }
                catch (HttpListenerException)
                {
                    // 서버 종료 시 발생
                }
                catch (Exception ex)
                {
                    if (isRunning)
                    {
                        Debug.LogError($"[RetargetingHTTP] 요청 처리 오류: {ex.Message}");
                    }
                }
            }
        }

        private void ProcessRequest(HttpListenerContext context)
        {
            try
            {
                string path = context.Request.Url.AbsolutePath;

                string responseContent;
                string contentType;

                if (path == "/" || path == "/index.html")
                {
                    responseContent = GenerateHTML();
                    contentType = "text/html; charset=utf-8";
                }
                else if (path == "/style.css")
                {
                    responseContent = cachedCSS;
                    contentType = "text/css; charset=utf-8";
                }
                else if (path == "/script.js")
                {
                    responseContent = cachedJS.Replace("{{WS_PORT}}", wsPort.ToString());
                    contentType = "application/javascript; charset=utf-8";
                }
                else
                {
                    context.Response.StatusCode = 404;
                    responseContent = "Not Found";
                    contentType = "text/plain";
                }

                byte[] buffer = Encoding.UTF8.GetBytes(responseContent);
                context.Response.ContentType = contentType;
                context.Response.ContentLength64 = buffer.Length;
                context.Response.AddHeader("Cache-Control", "no-cache");
                context.Response.OutputStream.Write(buffer, 0, buffer.Length);
                context.Response.Close();
            }
            catch (Exception ex)
            {
                Debug.LogError($"[RetargetingHTTP] 응답 처리 오류: {ex.Message}");
            }
        }

        private string GenerateHTML()
        {
            string html = cachedTemplate;
            html = html.Replace("{{CSS}}", cachedCSS);
            html = html.Replace("{{JS}}", cachedJS.Replace("{{WS_PORT}}", wsPort.ToString()));
            return html;
        }

        private string GetLocalIPAddress()
        {
            try
            {
                var host = Dns.GetHostEntry(Dns.GetHostName());
                foreach (var ip in host.AddressList)
                {
                    if (ip.AddressFamily == System.Net.Sockets.AddressFamily.InterNetwork)
                    {
                        return ip.ToString();
                    }
                }
            }
            catch (Exception) { }
            return "";
        }

        private string GetFallbackCSS()
        {
            return @"
body { font-family: sans-serif; background: #1a1a2e; color: #fff; padding: 20px; }
.error { color: #ff6b6b; padding: 20px; text-align: center; }
";
        }

        private string GetFallbackTemplate()
        {
            return @"
<!DOCTYPE html>
<html>
<head>
    <meta charset=""UTF-8"">
    <title>리타게팅 리모컨</title>
    <style>{{CSS}}</style>
</head>
<body>
    <div class=""error"">
        리소스 파일을 찾을 수 없습니다.<br>
        Assets/Resources/KindRetargeting/ 폴더에 파일이 있는지 확인해주세요.
    </div>
</body>
</html>";
        }

        private string GetFallbackJS()
        {
            return "console.error('JavaScript resource not found');";
        }
    }
}