//using System;
//using System.Collections.Generic;
//using System.Linq;
//using System.Windows;
//using AIStudio.Wpf.DiagramDesigner.Geometrys;

//namespace AIStudio.Wpf.DiagramDesigner.Layout
//{
//    internal class Engine
//    {
//        internal void ApplyRandomShift(DiagramViewModel network)
//        {
//            Random random = new Random();
//            foreach (var node in network.Items.OfType<DesignerItemViewModelBase>())
//            {
//                node.Position = node.Position + new VectorBase(random.NextDouble(), random.NextDouble());
//            }
//        }

//		internal void Update(int deltaTMillis, IState state, Configuration config)
//		{
//			// Calculate forces
//			int nodeCount = config.Network.Items.Count;
//			IList<(DesignerItemViewModelBase, VectorBase)> nodeForces = new List<(DesignerItemViewModelBase, VectorBase)>(nodeCount);

//			foreach (var node in config.Network.Items.OfType<DesignerItemViewModelBase>())
//			{
//				if (!config.IsFixedNode(node))
//				{
//                    nodeForces.Add((node, CalculateNodeForce(node, state, config)));
//                }
//			}

//			// Apply forces
//			foreach (var (node, force) in nodeForces)
//			{
//                VectorBase speed = state.GetNodeSpeed(node);
//                VectorBase pos = state.GetNodePosition(node);
//                double deltaT = deltaTMillis / 1000.0;
//                state.SetNodePosition(node, pos + ((speed * deltaT) + (force * deltaT * deltaT / 2)));
//                state.SetNodeSpeed(node, speed + ((force / config.NodeMass(node)) * deltaT));
//            }
//		}

//		private VectorBase CalculateNodeForce(DesignerItemViewModelBase node, IState state, Configuration config)
//		{
//            VectorBase force = new VectorBase();

//			// Calculate total force on node from endpoints
//            if (node.InputConnectors.Count > 0 || node.OutputConnectors.Count > 0)
//            {
//                force += node.InputConnectors.Concat(node.OutputConnectors)
//                    .Select(e => CalculateEndpointForce(e, state, config))
//                    .Aggregate((v1, v2) => v1 + v2);
//			}

//			// Apply node repulsion force so nodes don't overlap
//			var nodeCenter = state.GetNodePosition(node) + (new VectorBase(node.Size.Width, node.Size.Height) / 2.0);
//			foreach (var otherNode in config.Network.Items.OfType<DesignerItemViewModelBase>())
//			{
//				if (node == otherNode)
//				{
//					continue;
//				}

//				var otherNodeCenter = state.GetNodePosition(otherNode) + (new VectorBase(otherNode.Size.Width, otherNode.Size.Height) / 2.0);
//				var thisToOther = otherNodeCenter - nodeCenter;
//				var dist = thisToOther.Length;
//				thisToOther.Normalize();

//                var repulsionX = thisToOther.X * (-1 * ((node.Size.Width + otherNode.Size.Width) / 2) / dist);
//				var repulsionY = thisToOther.Y * (-1 * ((node.Size.Height + otherNode.Size.Height) / 2) / dist);
//                force += new VectorBase(repulsionX, repulsionY) * config.NodeRepulsionForce;
//            }

//			// Apply friction to make the movement converge to a stable state.
//			float gravity = 9.8f;
//			float normalForce = gravity * config.NodeMass(node);
//            float kineticFriction = normalForce * config.FrictionCoefficient(node);
//            VectorBase frictionVector = new VectorBase();
//			var nodeSpeed = state.GetNodeSpeed(node);
//			if (nodeSpeed.Length > 0)
//			{
//				frictionVector = new VectorBase(nodeSpeed.X, nodeSpeed.Y);
//				frictionVector.Normalize();
//				frictionVector *= -1.0 * kineticFriction;
//			}
//			force += frictionVector;

//			return force;
//		}

//		private VectorBase CalculateEndpointForce(ConnectorInfoBase endpoint, IState state, Configuration config)
//		{
//			var pos = state.GetEndpointPosition(endpoint);

//			VectorBase force = new VectorBase();

//			foreach (var conn in endpoint.Connections.Items)
//			{
//				var otherSide = conn.Input == endpoint ? (ConnectorInfoBase)conn.Output : conn.Input;
//				var otherSidePos = state.GetEndpointPosition(otherSide);
//				var dist = (otherSidePos - pos).Length;
//				var angle = Math.Acos((otherSidePos.X - pos.X) / dist);
//				if (otherSidePos.Y < pos.Y)
//				{
//					angle *= -1.0;
//				}

//				// Put a spring between connected endpoints.
//				var hookForce = (dist - config.EquilibriumDistance(conn)) * config.SpringConstant(conn);
//				force += new VectorBase(Math.Cos(angle), Math.Sin(angle)) * hookForce;

//				// Try to 'straighten' out the graph horizontally.
//				var isLeftSide = endpoint.Orientation ==  ConnectorOrientation.Left;
//				var rowForce = (isLeftSide ? 1 : -1) * config.RowForce(conn);
//				force.X += rowForce;
//			}

//			return force;
//		}
//	}
//}