using NodeDev.Core.Connections;

using NodeDev.Core.Types;

using System.Linq.Expressions;

using System.Runtime.InteropServices;

namespace NodeDev.Core.Nodes.Flow;

public class ReturnNode : FlowNode

{

public override string TitleColor => "red";

public override bool BreaksDeadEnd => true;

public ReturnNode(Graph graph, string? id = null) : base(graph, id)

{

Name = "Return";

Inputs.Add(new("Exec", this, TypeFactory.ExecType));

Refresh();

}

private bool HasReturnValue => Graph.SelfMethod.ReturnType != TypeFactory.Void;

public override bool IsFlowNode => throw new NotImplementedException();

public override string GetExecOutputPathId(string pathId, Connection execOutput) => throw new NotImplementedException();

public override bool DoesOutputPathAllowDeadEnd(Connection execOutput) => true; // Return by definition bypasses any dead-end restrictions

public override bool DoesOutputPathAllowMerge(Connection execOutput) => throw new NotImplementedException();

internal override Expression BuildExpression(Dictionary<Connection, Graph.NodePathChunks>? subChunks, BuildExpressionInfo info)

{

// Assign any out parameters before returning

var inputs = CollectionsMarshal.AsSpan(Inputs)[1..^(HasReturnValue ? 1 : 0)];

var assigns = new List<Expression>(inputs.Length);

foreach (var input in inputs)

{

var valueExpression = info.LocalVariables[input];

var assign = Expression.Assign(info.MethodParametersExpression[input.Name], valueExpression);

assigns.Add(assign);

}

if (HasReturnValue)

return Expression.Return(info.ReturnLabel, info.LocalVariables[Inputs[^1]]);

else

return Expression.Return(info.ReturnLabel);

}

internal void Refresh()

{

var removedConnections = Inputs.Skip(1).ToList(); // everything except exec

var newConnections = Graph.SelfMethod.Parameters.Where(x => x.IsOut).Select(x => new Connection(x.Name, this, x.ParameterType)).ToList();

if (HasReturnValue)

newConnections.Add(new Connection("Return", this, Graph.SelfMethod.ReturnType));

Inputs.RemoveRange(1, Inputs.Count - 1);

Inputs.AddRange(newConnections);

Graph.Manager.MergeRemovedConnectionsWithNewConnections(newConnections, removedConnections);

}

}