using System;
using System.IO;
using System.Net;
using System.Text;
using System.Threading.Tasks;
using System.Web.Script.Serialization;

namespace Card_Dispenser_Service
{
    // Wrapper to hand both the parsed values and the network connection back to DoWork
    internal class IncomingRequestContext
    {
        public CardTaskResponse TaskData { get; set; }
        public HttpListenerContext HttpContext { get; set; }
    }

    internal class API
    {
        private static HttpListener _httpListener;
        public static readonly JavaScriptSerializer _serializer = new JavaScriptSerializer();

        public static void StartListener(int port)
        {
            try
            {
                _httpListener = new HttpListener();
                _httpListener.Prefixes.Add($"http://*:{port}/");
                _httpListener.Start();
                Utils.LogToFile($"HTTP Server started listening on port {port}...");
            }
            catch (Exception ex)
            {
                Utils.LogToFile($"Failed to start HTTP Listener: {ex.Message}");
                throw;
            }
        }

        public static void StopListener()
        {
            try
            {
                if (_httpListener != null && _httpListener.IsListening)
                {
                    _httpListener.Stop();
                    _httpListener.Close();
                    Utils.LogToFile("HTTP Server stopped.");
                }
            }
            catch (Exception ex)
            {
                Utils.LogToFile($"Error stopping HTTP Listener: {ex.Message}");
            }
        }

        /// <summary>
        /// Asynchronously waits for a request, reads the payload, and holds the connection open.
        /// </summary>
        public static async Task<IncomingRequestContext> WaitForRequestAsync()
        {
            if (_httpListener == null || !_httpListener.IsListening)
            {
                Utils.LogToFile("Cannot wait for request; HTTP listener is not running.");
                return null;
            }

            try
            {
                HttpListenerContext context = await _httpListener.GetContextAsync();
                HttpListenerRequest request = context.Request;
                CardTaskResponse taskData = null;

                if (request.HasEntityBody)
                {
                    using (Stream body = request.InputStream)
                    using (StreamReader reader = new StreamReader(body, request.ContentEncoding))
                    {
                        string jsonString = await reader.ReadToEndAsync();
                        taskData = _serializer.Deserialize<CardTaskResponse>(jsonString);
                    }
                }

                return new IncomingRequestContext
                {
                    TaskData = taskData,
                    HttpContext = context
                };
            }
            catch (Exception ex)
            {
                Utils.LogToFile($"Error processing incoming HTTP request: {ex.Message}");
                return null;
            }
        }

        /// <summary>
        /// Sends the calculated hardware response text back to the waiting client.
        /// </summary>
        public static async Task SendResponseAsync(HttpListenerContext context, string jsonResponseString, HttpStatusCode statusCode = HttpStatusCode.OK)
        {
            try
            {
                if (context == null) return;

                HttpListenerResponse response = context.Response;
                byte[] buffer = Encoding.UTF8.GetBytes(jsonResponseString);

                response.ContentLength64 = buffer.Length;
                response.ContentType = "application/json";
                response.StatusCode = (int)statusCode;

                using (Stream output = response.OutputStream)
                {
                    await output.WriteAsync(buffer, 0, buffer.Length);
                }
            }
            catch (Exception ex)
            {
                Utils.LogToFile($"Error sending dynamic response to client: {ex.Message}");
            }
        }
    }

    internal class CardTaskResponse
    {
        public string Command { get; set; }
        public int Sector { get; set; }
        public int Block { get; set; }
        public string Data { get; set; }
        public string Serial { get; set; }
        public int BaudRate { get; set; }
    }
}