using System;
using System.Collections.Generic;
using System.Collections.ObjectModel;
using System.Windows;
using System.Windows.Media;
using Caliburn.MemoryManagement;
using Caliburn.Metadata;
using Caliburn.Services;

namespace Caliburn
{
    public class PresenterManager : IPresenterManager
    {
        protected readonly Dictionary<Type, PresenterInfo> _presenterMetadata =
            new Dictionary<Type, PresenterInfo>();

        protected readonly WeakDictionary<DependencyObject, object> _presenters =
            new WeakDictionary<DependencyObject, object>();

        #region IPresenterManager Members

        public virtual void AddBinding(object presenter, DependencyObject target)
        {
            _presenters[target] = presenter;

            FrameworkElement element = target as FrameworkElement;
            if(element != null)
                element.DataContext = presenter;
        }

        public virtual void RemoveBinding(DependencyObject target)
        {
            _presenters.Remove(target);
        }

        public virtual PresenterBinding GetBinding(DependencyObject target)
        {
            if(target != null)
            {
                object presenter;

                if(_presenters.TryGetValue(target, out presenter))
                    return new PresenterBinding(target, presenter);
                else
                {
                    try
                    {
                        DependencyObject parent = LogicalTreeHelper.GetParent(target);

                        if (parent == null)
                            parent = VisualTreeHelper.GetParent(target);

                        return GetBinding(parent);
                    }
                    catch
                    {
                        return PresenterBinding.NotFound;
                    }
                }
            }
            else return PresenterBinding.NotFound;
        }

        public virtual PresenterInfo GetInfo(Type presenterType)
        {
            PresenterInfo info;

            if (!_presenterMetadata.TryGetValue(presenterType, out info))
            {
                info = PresenterInfo.Create(presenterType);
                _presenterMetadata[presenterType] = info;
            }

            return info;
        }

        public virtual IList<DependencyObject> GetBoundViews(object presenter)
        {
            List<DependencyObject> views = new List<DependencyObject>();

            _presenters.RemoveCollectedEntries();

            foreach(KeyValuePair<DependencyObject, object> binding in _presenters)
            {
                if(binding.Value == presenter)
                    views.Add(binding.Key);
            }

            return new ReadOnlyCollection<DependencyObject>(views);
        }

        #endregion
    }
}