using System;
using System.Threading;

namespace Maki.Gateway
{
    /// <summary>
    /// Handles Heartbeat (pings) in the background for a Shard
    /// </summary>
    class GatewayHeartbeatManager
    {
        /// <summary>
        /// Subject shard
        /// </summary>
        private readonly GatewayShard Shard;

        /// <summary>
        /// Interval timer for repeating the request
        /// </summary>
        private Timer Timer = null;

        /// <summary>
        /// Constructor
        /// </summary>
        /// <param name="shard">Parent GatewayShard instance</param>
        public GatewayHeartbeatManager(GatewayShard shard)
        {
            Shard = shard;
        }

        /// <summary>
        /// Starts sending heartbeats
        /// </summary>
        public void Start()
        {
            if (Timer != null)
                Stop();

            Timer = new Timer(Handler, null, TimeSpan.Zero, Shard.HeartbeatInterval);
        }

        /// <summary>
        /// Heartbeat sender
        /// </summary>
        /// <param name="state"></param>
        private void Handler(object state)
        {
            Shard.Send(GatewayOPCode.Heartbeat, Shard.LastSequence);
        }

        /// <summary>
        /// Stops sending heartbeats
        /// </summary>
        public void Stop()
        {
            if (Timer == null)
                return;

            Timer.Dispose();
            Timer = null;
        }
    }
}