using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using VRage.Game;
using VRageMath;

namespace ShipyardMod.ItemClasses
{
    public class PacketManager
    {
        public Vector3D Origin;
        public Vector3D Target;
        private double _multiplier;
        private List<PacketItem> _packets = new List<PacketItem>();
        private double _travelDist;
        private bool _init;
        private Vector4 _color;

        private class PacketItem
        {
            public PacketItem( Vector3D position )
            {
                Position = position;
                Ticks = 0;
            }
            public Vector3D Position;
            public int Ticks;
        }

        public PacketManager( Vector3D origin, Vector3D target )
        {
            this.Origin = origin;
            this.Target = target;
        }

        private void Init()
        {
            _travelDist = Vector3D.Distance(Origin, Target);
            _packets.Add(new PacketItem(Origin));
            //packets move at 5m/s
            _multiplier = 1 / ((_travelDist / 20) * 60);
            //_multiplier = 0.001;
            _color = Color.Orange.ToVector4();
        }

        public void DrawPackets()
        {
            UpdatePackets();

            foreach ( var packet in _packets )
            {
                //Vector3D end = packet.Position + (0.5 * ( Target - packet.Position ));
                //Vector3D end = Vector3D.Lerp( packet.Position, Target, 1 / _travelDist);
                Vector3D end = 1.2 * Vector3D.Normalize( Target - packet.Position ) + packet.Position;
                MySimpleObjectDraw.DrawLine( packet.Position, end, "ShotgunParticle", ref _color, 0.6f );
            }
        }

        private void UpdatePackets()
        {
            if ( !_init )
            {
                _init = true;
                Init();
            }

            List<PacketItem> toRemove = new List<PacketItem>();
            foreach ( var packet in _packets )
            {
                packet.Ticks++;
                packet.Position = Vector3D.Lerp( Origin, Target, (_multiplier * packet.Ticks) );

                //delete the packet once it gets to the destination
                if ( (_multiplier * packet.Ticks) > 1 )
                    toRemove.Add( packet );
            }

            foreach ( var removePacket in toRemove )
                _packets.Remove( removePacket );

            //if the last packet to go out is more than 10m from origin, add a new one
            var lastPacket = _packets.Last();
            if ( Vector3D.DistanceSquared( lastPacket.Position, Origin ) > 100 )
                _packets.Add( new PacketItem( Origin ) );

        }
    }
}