using System;
using ln.snmp.types;
using System.Net;
using System.Collections.Generic;
using System.Linq;
using ln.snmp.endpoint;
using System.Reflection;
using System.Threading;
using ln.logging;

namespace ln.snmp.endpoint
{
    public abstract class SnmpEndpoint : SnmpInterface, IDisposable
    {
        public SNMPEngine SNMPEngine { get; }
        public IPEndPoint RemoteEndpoint { get; set; }

        public int Retries { get; set; } = 3;

        public SnmpEndpoint(SNMPEngine snmpEngine, IPEndPoint remoteEndpoint)
        {
            SNMPEngine = snmpEngine;
            RemoteEndpoint = remoteEndpoint;

            SNMPEngine.RegisterEndpoint(this);
        }

        public void Close()
        {
            Dispose();
        }

        public virtual void Send(SnmpMessage message)
        {
            //message.MessageID = SNMPEngine.NextMessageID;
            //if (requestMessage.snmpPDU != null)
            //{
            //    requestMessage.snmpPDU.RequestID.LongValue = SNMPEngine.NextMessageID;
            //}

            message = Encrypt(message);
            message = ApplyAuthentication(message);
            SNMPEngine.SendMessage(RemoteEndpoint, message);
        }

        public virtual void DispatchReceived(SnmpMessage message)
        {
            lock (queuedRequests)
            {
                if (queuedRequests.ContainsKey(message.MessageID))
                {
                    SnmpMessage queuedMessage = queuedRequests[message.MessageID];
                    lock (queuedMessage)
                    {
                        queuedRequests[message.MessageID] = message;
                        Monitor.PulseAll(queuedMessage);
                    }
                }
                else
                {
                    long dt = DateTimeOffset.Now.ToUnixTimeSeconds() - message.MessageID;
                    Logging.Log(LogLevel.WARNING, "SNMPEndpoint: Received unqueued message id: {0} (0x{0:x8}) possibly D-T: {1}", message.MessageID,dt);
                }
            }
        }

        public virtual void Received(SnmpMessage message)
        {
            message = CheckAuthentication(message);
            message = Decrypt(message);

            DispatchReceived(message);
        }

        public virtual SnmpMessage Encrypt(SnmpMessage message) => message;
        public virtual SnmpMessage ApplyAuthentication(SnmpMessage message) => message;

        public virtual SnmpMessage CheckAuthentication(SnmpMessage message) => message;
        public virtual SnmpMessage Decrypt(SnmpMessage message) => message;

        /**
         * Requests
         **/
        private Dictionary<int, SnmpMessage> queuedRequests = new Dictionary<int, SnmpMessage>();

        public SnmpMessage EnqueueRequest(SnmpMessage requestMessage)
        {
            lock (queuedRequests)
            {
                queuedRequests.Add(requestMessage.MessageID, requestMessage);

                Monitor.Exit(queuedRequests);

                lock (requestMessage)
                {
                    Send(requestMessage);
                    Monitor.Wait(requestMessage, SNMPEngine.Timeout);
                }

                Monitor.Enter(queuedRequests);

                SnmpMessage responseMessage = queuedRequests[requestMessage.MessageID];
                if (responseMessage == requestMessage)
                    throw new TimeoutException();

                return responseMessage;
            }
        }


        public override void Dispose()
        {
            SNMPEngine.UnregisterEndpoint(this);
            base.Dispose();
        }
    }
}