using System;
using System.Linq;
using System.Collections.Generic;
using N2.Collections;
using N2.Engine;
using N2.Persistence;
using N2.Web;

namespace N2.Edit
{
    [Service(typeof(ITreeSorter))]
    public class TreeSorter : ITreeSorter
    {
        IPersister persister;
        IEditManager editManager;
        IWebContext webContext;

        public TreeSorter(IPersister persister, IEditManager editManager, IWebContext webContext)
        {
            this.persister = persister;
            this.editManager = editManager;
            this.webContext = webContext;
        }

        #region ITreeSorter Members

        public void MoveUp(ContentItem item)
        {
            if (item.Parent != null)
            {
                ItemFilter filter = editManager.GetEditorFilter(webContext.User);
                IList<ContentItem> siblings = item.Parent.Children;
                IList<ContentItem> filtered = new ItemList(siblings, filter);

                int index = filtered.IndexOf(item);
                if (index > 0)
                {
                    MoveTo(item, NodePosition.Before, filtered[index - 1]);
                }
            }
        }

        public void MoveDown(ContentItem item)
        {
            if (item.Parent != null)
            {
                ItemFilter filter = editManager.GetEditorFilter(webContext.User);
                IList<ContentItem> siblings = item.Parent.Children;
                IList<ContentItem> filtered = new ItemList(siblings, filter);
                int index = filtered.IndexOf(item);
                if (index + 1 < filtered.Count)
                {
                    MoveTo(item, NodePosition.After, filtered[index + 1]);
                }
            }
        }

        public void MoveTo(ContentItem item, ContentItem parent)
        {
            if (item.Parent == parent)
            {
                // move it last
                item.AddTo(null);
                item.AddTo(parent);
            }
            else if (item.Parent == null || !parent.Children.Contains(item))
                item.AddTo(parent);

            using (var tx = persister.Repository.BeginTransaction())
            {
                foreach (ContentItem updatedItem in Utility.UpdateSortOrder(parent.Children))
                {
                    persister.Repository.SaveOrUpdate(updatedItem);
                }
                tx.Commit();
            }
        }

        public void MoveTo(ContentItem item, ContentItem parent, int index)
        {
            if (item.Parent != parent || !parent.Children.Contains(item))
                item.AddTo(parent);
            else if (parent.Children.Contains(item) && parent.Children.Last() != item)
            {
                item.AddTo(null);
                item.AddTo(parent);
            }

            IList<ContentItem> siblings = parent.Children;
            Utility.MoveToIndex(siblings, item, index);
            using (var tx = persister.Repository.BeginTransaction())
            {

				persister.Repository.SaveOrUpdate(item);

				foreach (ContentItem updatedItem in Utility.UpdateSortOrder(siblings))
                {
                    persister.Repository.SaveOrUpdate(updatedItem);
                }
                tx.Commit();
            }
        }

        public void MoveTo(ContentItem item, int index)
        {
            IList<ContentItem> siblings = item.Parent.Children;
            Utility.MoveToIndex(siblings, item, index);
            using (var tx = persister.Repository.BeginTransaction())
            {
                foreach (ContentItem updatedItem in Utility.UpdateSortOrder(siblings))
                {
                    persister.Repository.SaveOrUpdate(updatedItem);
                }
                tx.Commit();
            }
        }

        public void MoveTo(ContentItem item, NodePosition position, ContentItem relativeTo)
        {
            if (relativeTo == null) throw new ArgumentNullException("item");
            if (relativeTo == null) throw new ArgumentNullException("relativeTo");
            if (relativeTo.Parent == null) throw new ArgumentException("The supplied item '" + relativeTo + "' has no parent to add to.", "relativeTo");
            
            if (item.Parent == null 
                || item.Parent != relativeTo.Parent
                || !item.Parent.Children.Contains(item))
                item.AddTo(relativeTo.Parent);

            IList<ContentItem> siblings = item.Parent.Children;
            
            int itemIndex = siblings.IndexOf(item);
            int relativeToIndex = siblings.IndexOf(relativeTo);
            
            if(itemIndex < 0)
            {
                if(position == NodePosition.Before)
                    siblings.Insert(relativeToIndex, item);
                else
                    siblings.Insert(relativeToIndex + 1, item);
            }
            else if(itemIndex < relativeToIndex && position == NodePosition.Before)
                MoveTo(item, relativeToIndex - 1);
            else if (itemIndex > relativeToIndex && position == NodePosition.After)
                MoveTo(item, relativeToIndex + 1);
            else
                MoveTo(item, relativeToIndex);
        }
        #endregion
    }
}