using GongSolutions.Wpf.DragDrop;
using NationalInstruments.TestStand.Interop.API;
using Plugin.SeqEditor.Entity;
using System.Collections.ObjectModel;
using System.Windows;
using System.Windows.Controls;

namespace Plugin.SeqEditor.ViewModel
{
    public class TreeListViewHandler : DefaultDropHandler
    {
        private SeqEditorViewModel model;
        public TreeListViewHandler(SeqEditorViewModel model)
        {
            this.model = model;
        }

        public bool CanConvert(IDropInfo dropInfo)
        {
            if (!(dropInfo.TargetItem is StepUI target))
            {
                return false;
            }

            if (!(dropInfo.Data is StepUI source))
            {
                return false;
            }

            if (source == target)
            {
                return false;
            }

            if (target.sequence != source.sequence)
            {
                return false;
            }
            return true;
        }

        public override void DragOver(IDropInfo dropInfo)
        {
            if (CanConvert(dropInfo))
            {
                dropInfo.Effects = DragDropEffects.Move;

                if (dropInfo.InsertPosition.HasFlag(RelativeInsertPosition.TargetItemCenter))
                {
                    dropInfo.DropTargetAdorner = null;
                }
                else
                {
                    dropInfo.DropTargetAdorner = DropTargetAdorners.Insert;
                }

                //if (dropInfo.DropTargetAdorner == DropTargetAdorners.Highlight) { 

                //}
                //dropInfo.DropTargetAdorner = DropTargetAdorners.Insert;
                dropInfo.DropTargetHintState = DropHintState.Active;
                dropInfo.DropTargetHintAdorner = DropTargetAdorners.Hint;
            }
            else
            {
                dropInfo.Effects = DragDropEffects.None;
                dropInfo.DropTargetHintAdorner = DropTargetAdorners.Hint;
                dropInfo.DropTargetHintState = DropHintState.Error;
            }
        }

        public override void Drop(IDropInfo dropInfo)
        {
            if (!CanConvert(dropInfo))
            {
                return;
            }
            //var sourceItem = (TreeItemData)dropInfo.Data;
            //var targetItem = (TreeItemData)dropInfo.TargetItem;

            var source = dropInfo.Data as StepUI;
            var target = dropInfo.TargetItem as StepUI;

            int sourceIndex = source.IndexInSequence;
            int targetIndex = target.IndexInSequence;


            if (sourceIndex == targetIndex)
            {
                return;
            }

            bool insertBefore = dropInfo.InsertPosition.HasFlag(RelativeInsertPosition.BeforeTargetItem);

            if (!insertBefore && (sourceIndex == targetIndex + 1)) {
                return;
            }

            ObservableCollection<StepUI> datasource = model.sequenceCache[source.sequence];
            int uiSourceIndex = datasource.IndexOf(source);
            int uiTargetIndex = datasource.IndexOf(target);

            StepGroups group = target.StepGroup;

            if (sourceIndex < targetIndex)
            {
                source.sequence.DeleteStep(sourceIndex, source.StepGroup);
                target.sequence.InsertStep(source.step, targetIndex, group);
                datasource.Move(uiSourceIndex, uiTargetIndex);
            }
            else if (sourceIndex > targetIndex)
            {
                source.sequence.DeleteStep(sourceIndex, source.StepGroup);
                target.sequence.InsertStep(source.step, targetIndex, group);
                datasource.Move(uiSourceIndex, uiTargetIndex);
            }
        }
    }
}