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

namespace Developpez.Dotnet.Windows.Behaviors
{
    /// <summary>
    /// Fournit des propriétés attachées pour ajouter des fonctionnalités aux menus
    /// </summary>
    public static class MenuBehavior
    {
        /// <summary>
        /// Obtient la valeur de la propriété attachée OptionGroupName
        /// </summary>
        /// <param name="obj">L'objet pour lequel on veut obtenir la valeur</param>
        /// <returns>Le nom du groupe d'options auquel appartient cet élément</returns>
        [AttachedPropertyBrowsableForType(typeof(MenuItem))]
        public static string GetOptionGroupName(MenuItem obj)
        {
            return (string)obj.GetValue(OptionGroupNameProperty);
        }

        /// <summary>
        /// Définit la valeur de la propriété attachée OptionGroupName
        /// </summary>
        /// <param name="obj">L'objet pour lequel on veut définir la valeur</param>
        /// <param name="value">Le nom du groupe d'options auquel appartient cet élément</param>
        public static void SetOptionGroupName(MenuItem obj, string value)
        {
            obj.SetValue(OptionGroupNameProperty, value);
        }

        /// <summary>
        /// Identifiant de la propriété OptionGroupName
        /// </summary>
        public static readonly DependencyProperty OptionGroupNameProperty =
            DependencyProperty.RegisterAttached(
              "OptionGroupName",
              typeof(string),
              typeof(MenuBehavior),
              new UIPropertyMetadata(
                null,
                OptionGroupNameChanged));

        private static void OptionGroupNameChanged(DependencyObject o, DependencyPropertyChangedEventArgs e)
        {
            var menuItem = o as MenuItem;
            if (menuItem == null)
                return;

            var oldValue = (string)e.OldValue;
            var newValue = (string)e.NewValue;

            if (!string.IsNullOrEmpty(oldValue))
            {
                RemoveFromOptionGroup(menuItem);
            }
            if (!string.IsNullOrEmpty(newValue))
            {
                AddToOptionGroup(menuItem);
            }
        }

        private static Dictionary<string, HashSet<MenuItem>> GetOptionGroups(DependencyObject obj)
        {
            return (Dictionary<string, HashSet<MenuItem>>)obj.GetValue(OptionGroupsPropertyKey.DependencyProperty);
        }

        private static void SetOptionGroups(DependencyObject obj, Dictionary<string, HashSet<MenuItem>> value)
        {
            obj.SetValue(OptionGroupsPropertyKey, value);
        }

        private static readonly DependencyPropertyKey OptionGroupsPropertyKey =
            DependencyProperty.RegisterAttachedReadOnly("OptionGroups", typeof(Dictionary<string, HashSet<MenuItem>>), typeof(MenuBehavior), new UIPropertyMetadata(null));

        private static HashSet<MenuItem> GetOptionGroup(MenuItem menuItem, bool create)
        {
            string groupName = GetOptionGroupName(menuItem);
            if (groupName == null)
                return null;

            if (menuItem.Parent == null)
                return null;

            var optionGroups = GetOptionGroups(menuItem.Parent);
            if (optionGroups == null)
            {
                if (create)
                {
                    optionGroups = new Dictionary<string, HashSet<MenuItem>>();
                    SetOptionGroups(menuItem.Parent, optionGroups);
                }
                else
                {
                    return null;
                }
            }

            HashSet<MenuItem> group;
            if (!optionGroups.TryGetValue(groupName, out group) && create)
            {
                group = new HashSet<MenuItem>();
                optionGroups[groupName] = group;
            }
            return group;
        }

        private static void AddToOptionGroup(MenuItem menuItem)
        {
            var group = GetOptionGroup(menuItem, true);
            if (group == null)
                return;

            if (group.Add(menuItem))
            {
                menuItem.Checked += menuItem_Checked;
                menuItem.Unchecked += menuItem_Unchecked;
            }
        }

        private static void RemoveFromOptionGroup(MenuItem menuItem)
        {
            var group = GetOptionGroup(menuItem, false);
            if (group == null)
                return;

            if (group.Remove(menuItem))
            {
                menuItem.Checked -= menuItem_Checked;
                menuItem.Unchecked -= menuItem_Unchecked;
            }
        }

        private static void menuItem_Checked(object sender, RoutedEventArgs e)
        {
            MenuItem menuItem = sender as MenuItem;
            if (menuItem == null)
                return;

            string groupName = GetOptionGroupName(menuItem);
            if (groupName == null)
                return;

            // More than 1 checked option is allowed
            if (groupName.EndsWith("*") || groupName.EndsWith("+"))
                return;

            var group = GetOptionGroup(menuItem, false);
            if (group == null)
                return;

            foreach (var item in group)
            {
                if (item != menuItem)
                    item.IsChecked = false;
            }
        }

        private static void menuItem_Unchecked(object sender, RoutedEventArgs e)
        {
            MenuItem menuItem = sender as MenuItem;
            if (menuItem == null)
                return;

            string groupName = GetOptionGroupName(menuItem);
            if (groupName == null)
                return;

            // 0 checked option is allowed
            if (groupName.EndsWith("*") || groupName.EndsWith("?"))
                return;

            var group = GetOptionGroup(menuItem, false);
            if (group == null)
                return;

            if (!group.Any(item => item.IsChecked))
                menuItem.IsChecked = true;
        }
    }

}