using System;
using System.Collections.Generic;
using System.Linq;
using System.Reactive.Linq;
using System.Text;
using System.Threading.Tasks;
using DynamicData;
using DynamicData.Aggregation;
using NodeNetwork.Views;
using ReactiveUI;

namespace NodeNetwork.ViewModels
{
    /// <summary>
    /// Represents a connection between a node input and a node output
    /// </summary>
    public class ConnectionViewModel : ReactiveObject
    {
        static ConnectionViewModel()
        {
            NNViewRegistrar.AddRegistration(() => new ConnectionView(), typeof(IViewFor<ConnectionViewModel>));
        }

        #region Logger
        private static readonly log4net.ILog log = log4net.LogManager.GetLogger(System.Reflection.MethodBase.GetCurrentMethod().DeclaringType);
        #endregion

        /// <summary>
        /// The network that contains this connection
        /// </summary>
        public NetworkViewModel Parent { get; }

        /// <summary>
        /// The viewmodel of the node input that is on one end of the connection.
        /// </summary>
        public NodeInputViewModel Input { get; }

        /// <summary>
        /// The viewmodel of the node output that is on one end of the connection.
        /// </summary>
        public NodeOutputViewModel Output { get; }
        
        #region CanBeRemovedByUser
        /// <summary>
        /// If false, the user cannot delete this connection. True by default.
        /// </summary>
        public bool CanBeRemovedByUser
        {
            get => _canBeRemovedByUser;
            set => this.RaiseAndSetIfChanged(ref _canBeRemovedByUser, value);
        }
        private bool _canBeRemovedByUser;
        #endregion

        #region IsHighlighted
        /// <summary>
        /// If true, the connection is highlighted.
        /// </summary>
        public bool IsHighlighted
        {
            get => _isHighlighted;
            set => this.RaiseAndSetIfChanged(ref _isHighlighted, value);
        }
        private bool _isHighlighted;
        #endregion

        #region IsInErrorState
        /// <summary>
        /// If true, the connection is displayed as being in an erroneous state.
        /// </summary>
        public bool IsInErrorState
        {
            get => _isInErrorState;
            set => this.RaiseAndSetIfChanged(ref _isInErrorState, value);
        }
        private bool _isInErrorState;
        #endregion

        #region IsMarkedForDelete
        /// <summary>
        /// If true, the connection is displayed as being marked for deletion.
        /// </summary>
        public bool IsMarkedForDelete => _isMarkedForDelete.Value;
        private ObservableAsPropertyHelper<bool> _isMarkedForDelete;
        #endregion

        public ConnectionViewModel(NetworkViewModel parent, NodeInputViewModel input, NodeOutputViewModel output)
        {
            Parent = parent;
            Input = input;
            Output = output;
			
			this.WhenAnyValue(v => v.Parent.CutLine.IntersectingConnections)
	            .Where(l => l != null)
	            .Select(list => list.Connect().Filter(c => c == this).Count().Select(c => c > 0))
	            .Switch()
	            .ToProperty(this, vm => vm.IsMarkedForDelete, out _isMarkedForDelete);
        }
    }
}