using System;
using System.Collections;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using uPLibrary.Networking.M2Mqtt.Messages;
using uPLibrary.Networking.M2Mqtt.Session;

namespace uPLibrary.Networking.M2Mqtt.Managers
{
    /// <summary>
    /// Manager for client session
    /// </summary>
    public class MqttSessionManager
    {
        // subscription info for each client
        private Dictionary<string, MqttBrokerSession> sessions;

        /// <summary>
        /// Constructor
        /// </summary>
        public MqttSessionManager()
        {
            this.sessions = new Dictionary<string, MqttBrokerSession>();
        }

        /// <summary>
        /// Save session for a client (all related subscriptions)
        /// </summary>
        /// <param name="clientId">Client Id to save subscriptions</param>
        /// <param name="clientSession">Client session with inflight messages</param>
        /// <param name="subscriptions">Subscriptions to save</param>
        public void SaveSession(string clientId, MqttClientSession clientSession, List<MqttSubscription> subscriptions)
        {
            MqttBrokerSession session = null;

            // session doesn't exist
            if (!this.sessions.ContainsKey(clientId))
            {
                // create new session
                session = new MqttBrokerSession();
                session.ClientId = clientId;

                // add to sessions list
                this.sessions.Add(clientId, session);
            }
            else
            {
                // get existing session
                session = this.sessions[clientId];
            }

            // null reference to disconnected client
            session.Client = null;

            // update subscriptions
            session.Subscriptions = new List<MqttSubscription>();
            foreach (MqttSubscription subscription in subscriptions)
            {
                session.Subscriptions.Add(new MqttSubscription(subscription.ClientId, subscription.Topic, subscription.QosLevel, null));
            }

            // update inflight messages
            session.InflightMessages = new Hashtable();
            foreach (MqttMsgContext msgContext in clientSession.InflightMessages.Values)
            {
                session.InflightMessages.Add(msgContext.Key, msgContext);
            }
        }

        /// <summary>
        /// Get session for a client
        /// </summary>
        /// <param name="clientId">Client Id to get subscriptions</param>
        /// <returns>Subscriptions for the client</returns>
        public MqttBrokerSession GetSession(string clientId)
        {
            if (!this.sessions.ContainsKey(clientId))
                return null;
            else
                return this.sessions[clientId];
        }

        /// <summary>
        /// 
        /// </summary>
        /// <returns></returns>
        public List<MqttBrokerSession> GetSessions()
        {
            // TODO : verificare altro modo
            return new List<MqttBrokerSession>(this.sessions.Values);
        }

        /// <summary>
        /// Clear session for a client (all related subscriptions)
        /// </summary>
        /// <param name="clientId">Client Id to clear session</param>
        public void ClearSession(string clientId)
        {
            if (this.sessions.ContainsKey(clientId))
            {
                // clear and remove client session
                this.sessions[clientId].Clear();
                this.sessions.Remove(clientId);
            }
        }
    }
}