using GongSolutions.Wpf.DragDrop;
using HMI.UI;
using NationalInstruments.TestStand.Interop.API;
using Plugin.SeqEditor.Entity;
using System.Windows;

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

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

            if (!(targetItem.Data is StepUI target))
            {
                return false;
            }

            if (!(dropInfo.Data is TreeItemData sourceItem))
            {
                return false;
            }

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

            if (targetItem.ParentItem != sourceItem.ParentItem)
            {
                return false;
            }

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

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

            return true;
        }

        public override void DragOver(IDropInfo dropInfo)
        {
            if (CanConvert(dropInfo))
            {
                dropInfo.Effects = DragDropEffects.Move;
                dropInfo.DropTargetHintState = DropHintState.Active;
            }
            else
            {
                dropInfo.DropTargetHintState = DropHintState.None;
            }
        }

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

            var source = sourceItem.Data as StepUI;
            var target = targetItem.Data as StepUI;
            int sourceIndex = source.IndexInSequence;
            int targetIndex = target.IndexInSequence;

            TreeItemDataCollection collection = model.TreeCollection;

            List<TreeItemData> datasource;

            if (sourceItem.ParentItem == null)
            {
                datasource = collection.RootItems;
            }
            else
            {
                datasource = sourceItem.ParentItem.Items;
            }

            //ObservableCollection<TreeItemData> datasource =
            //   (ObservableCollection<TreeItemData>)dropInfo.TargetCollection.TryGetList();

            int uiSourceIndex = collection.IndexOf(sourceItem);
            int uiTargetIndex = collection.IndexOf(targetItem);

            if (uiSourceIndex == uiTargetIndex + 1)
            {
                return;
            }

            StepGroups group = target.StepGroup;
            if (sourceIndex == targetIndex) {
                return;
            }

            if (sourceIndex < targetIndex)
            {
                source.sequence.DeleteStep(sourceIndex, source.StepGroup);
                target.sequence.InsertStep(source.step, targetIndex, group);

                collection.Move(uiSourceIndex, uiTargetIndex);

                //datasource.RemoveAt(uiSourceIndex);
                //datasource.Insert(uiTargetIndex, sourceItem);
            }
            else if (sourceIndex > targetIndex)
            {
                source.sequence.DeleteStep(sourceIndex, source.StepGroup);
                target.sequence.InsertStep(source.step, targetIndex + 1, group);

                collection.Move(uiSourceIndex, uiTargetIndex);
            }
            model.CurrentSeqUI.IsChanged = true;
            //var task = Task.Run(() =>
            //{
            //    collection.ResetItems();
            //    model.TreeItemData = sourceItem;
            //});
            //task.Wait();
        }
    }
}