/*
The MIT License

Copyright (c) 2009-2010. Carlos Guzmán Álvarez. http://chronoswpf.codeplex.com/

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in
all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
THE SOFTWARE.
*/

using System;
using System.Collections.Generic;
using System.Linq;
using Chronos.Presentation.Windows.Controls;

namespace Chronos.Presentation.Windows
{
    internal sealed class SelectionService
    {
        #region · Fields ·

        private Desktop             canvas;
        private List<ISelectable>   currentSelection;

        #endregion

        #region · Internal Properties ·

        internal List<ISelectable> CurrentSelection
        {
            get
            {
                if (currentSelection == null)
                {
                    currentSelection = new List<ISelectable>();
                }

                return currentSelection;
            }
        }

        #endregion

        #region · Constructors ·

        public SelectionService(Desktop canvas)
        {
            this.canvas = canvas;
        }

        #endregion

        #region · Internal Methods ·

        internal void SelectItem(ISelectable item)
        {
            this.ClearSelection();
            this.AddToSelection(item);
        }

        internal void AddToSelection(ISelectable item)
        {
            if (item is IGroupable)
            {
                List<IGroupable> groupItems = this.GetGroupMembers(item as IGroupable);

                foreach (ISelectable groupItem in groupItems)
                {
                    groupItem.IsSelected = true;
                    this.CurrentSelection.Add(groupItem);
                }
            }
            else
            {
                item.IsSelected = true;
                this.CurrentSelection.Add(item);
            }
        }

        internal void RemoveFromSelection(ISelectable item)
        {
            if (item is IGroupable)
            {
                List<IGroupable> groupItems = GetGroupMembers(item as IGroupable);

                foreach (ISelectable groupItem in groupItems)
                {
                    groupItem.IsSelected = false;
                    this.CurrentSelection.Remove(groupItem);
                }
            }
            else
            {
                item.IsSelected = false;
                this.CurrentSelection.Remove(item);
            }
        }

        internal void ClearSelection()
        {
            this.CurrentSelection.ForEach(item => item.IsSelected = false);
            this.CurrentSelection.Clear();
        }

        internal void SelectAll()
        {
            this.ClearSelection();
            this.CurrentSelection.AddRange(canvas.Children.OfType<ISelectable>());
            this.CurrentSelection.ForEach(item => item.IsSelected = true);
        }

        internal List<IGroupable> GetGroupMembers(IGroupable item)
        {
            IEnumerable<IGroupable> list        = canvas.Children.OfType<IGroupable>();
            IGroupable              rootItem    = this.GetRoot(list, item);

            return GetGroupMembers(list, rootItem);
        }

        internal IGroupable GetGroupRoot(IGroupable item)
        {
            IEnumerable<IGroupable> list = this.canvas.Children.OfType<IGroupable>();

            return this.GetRoot(list, item);
        }

        #endregion

        #region · Private Methods ·

        private IGroupable GetRoot(IEnumerable<IGroupable> list, IGroupable node)
        {
            if (node == null || node.ParentId == Guid.Empty)
            {
                return node;
            }
            else
            {
                foreach (IGroupable item in list)
                {
                    if (item.Id == node.ParentId)
                    {
                        return this.GetRoot(list, item);
                    }
                }

                return null;
            }
        }

        private List<IGroupable> GetGroupMembers(IEnumerable<IGroupable> list, IGroupable parent)
        {
            List<IGroupable> groupMembers = new List<IGroupable>();
            groupMembers.Add(parent);

            var children = list.Where(node => node.ParentId == parent.Id);

            foreach (IGroupable child in children)
            {
                groupMembers.AddRange(this.GetGroupMembers(list, child));
            }

            return groupMembers;
        }

        #endregion
    }
}