///////////////////////////////////////////////////////////////////////////
//  Copyright (C) Wizardry and Steamworks 2016 - License: GNU GPLv3      //
//  Please see: http://www.gnu.org/licenses/gpl.html for legal details,  //
//  rights of fair usage, the disclaimer and warranty conditions.        //
///////////////////////////////////////////////////////////////////////////
/// From https://gist.github.com/kzu/cfe3cb6e4fe3efea6d24

using System;
using System.Collections;
using System.Collections.Generic;
using System.Collections.Specialized;
using System.ComponentModel;
using System.Diagnostics;
using System.Dynamic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace wasSharp.Collections.Specialized
{
    /// <summary>
    /// Provides a dictionary for use with data binding.
    /// </summary>
    /// <typeparam name="TKey">Specifies the type of the keys in this collection.</typeparam>
    /// <typeparam name="TValue">Specifies the type of the values in this collection.</typeparam>
    [DebuggerDisplay("Count={Count}")]
    public class ObservableDictionary<TKey, TValue> :
        ICollection<KeyValuePair<TKey, TValue>>, IDictionary<TKey, TValue>,
        INotifyCollectionChanged, INotifyPropertyChanged
    {
        readonly IDictionary<TKey, TValue> dictionary;

        /// <summary>Event raised when the collection changes.</summary>
        public event NotifyCollectionChangedEventHandler CollectionChanged = (sender, args) => { };

        /// <summary>Event raised when a property on the collection changes.</summary>
        public event PropertyChangedEventHandler PropertyChanged = (sender, args) => { };

        /// <summary>
        /// Initializes an instance of the class.
        /// </summary>
        public ObservableDictionary()
            : this(new Dictionary<TKey, TValue>())
        {
        }

        /// <summary>
        /// Initializes an instance of the class using another dictionary as 
        /// the key/value store.
        /// </summary>
        public ObservableDictionary(IDictionary<TKey, TValue> dictionary)
        {
            this.dictionary = dictionary;
        }

        void AddWithNotification(KeyValuePair<TKey, TValue> item)
        {
            AddWithNotification(item.Key, item.Value);
        }

        void AddWithNotification(TKey key, TValue value)
        {
            dictionary.Add(key, value);

            CollectionChanged(this, new NotifyCollectionChangedEventArgs(NotifyCollectionChangedAction.Add,
                new KeyValuePair<TKey, TValue>(key, value)));
            PropertyChanged(this, new PropertyChangedEventArgs("Count"));
            PropertyChanged(this, new PropertyChangedEventArgs("Keys"));
            PropertyChanged(this, new PropertyChangedEventArgs("Values"));
        }

        bool RemoveWithNotification(TKey key)
        {
            TValue value;
            if (dictionary.TryGetValue(key, out value) && dictionary.Remove(key))
            {
                CollectionChanged(this, new NotifyCollectionChangedEventArgs(NotifyCollectionChangedAction.Remove,
                    new KeyValuePair<TKey, TValue>(key, value)));
                PropertyChanged(this, new PropertyChangedEventArgs("Count"));
                PropertyChanged(this, new PropertyChangedEventArgs("Keys"));
                PropertyChanged(this, new PropertyChangedEventArgs("Values"));

                return true;
            }

            return false;
        }

        public void Clear()
        {
            dictionary.Clear();

            CollectionChanged(this, new NotifyCollectionChangedEventArgs(NotifyCollectionChangedAction.Reset));
            PropertyChanged(this, new PropertyChangedEventArgs("Count"));
            PropertyChanged(this, new PropertyChangedEventArgs("Keys"));
            PropertyChanged(this, new PropertyChangedEventArgs("Values"));
        }

        void UpdateWithNotification(TKey key, TValue value)
        {
            TValue existing;
            if (dictionary.TryGetValue(key, out existing))
            {
                dictionary[key] = value;

                CollectionChanged(this, new NotifyCollectionChangedEventArgs(NotifyCollectionChangedAction.Replace,
                    new KeyValuePair<TKey, TValue>(key, value),
                    new KeyValuePair<TKey, TValue>(key, existing)));
                PropertyChanged(this, new PropertyChangedEventArgs("Values"));
            }
            else
            {
                AddWithNotification(key, value);
            }
        }

        /// <summary>
        /// Allows derived classes to raise custom property changed events.
        /// </summary>
        protected void RaisePropertyChanged(PropertyChangedEventArgs args)
        {
            PropertyChanged(this, args);
        }

        #region IDictionary<TKey,TValue> Members

        /// <summary>
        /// Adds an element with the provided key and value to the <see cref="T:System.Collections.Generic.IDictionary`2" />.
        /// </summary>
        /// <param name="key">The object to use as the key of the element to add.</param>
        /// <param name="value">The object to use as the value of the element to add.</param>
        public void Add(TKey key, TValue value)
        {
            AddWithNotification(key, value);
        }

        /// <summary>
        /// Determines whether the <see cref="T:System.Collections.Generic.IDictionary`2" /> contains an element with the specified key.
        /// </summary>
        /// <param name="key">The key to locate in the <see cref="T:System.Collections.Generic.IDictionary`2" />.</param>
        /// <returns>
        /// true if the <see cref="T:System.Collections.Generic.IDictionary`2" /> contains an element with the key; otherwise, false.
        /// </returns>
        public bool ContainsKey(TKey key)
        {
            return dictionary.ContainsKey(key);
        }

        /// <summary>
        /// Gets an <see cref="T:System.Collections.Generic.ICollection`1" /> containing the keys of the <see cref="T:System.Collections.Generic.IDictionary`2" />.
        /// </summary>
        /// <returns>An <see cref="T:System.Collections.Generic.ICollection`1" /> containing the keys of the object that implements <see cref="T:System.Collections.Generic.IDictionary`2" />.</returns>
        public ICollection<TKey> Keys
        {
            get { return dictionary.Keys; }
        }

        /// <summary>
        /// Removes the element with the specified key from the <see cref="T:System.Collections.Generic.IDictionary`2" />.
        /// </summary>
        /// <param name="key">The key of the element to remove.</param>
        /// <returns>
        /// true if the element is successfully removed; otherwise, false.  This method also returns false if <paramref name="key" /> was not found in the original <see cref="T:System.Collections.Generic.IDictionary`2" />.
        /// </returns>
        public bool Remove(TKey key)
        {
            return RemoveWithNotification(key);
        }

        /// <summary>
        /// Gets the value associated with the specified key.
        /// </summary>
        /// <param name="key">The key whose value to get.</param>
        /// <param name="value">When this method returns, the value associated with the specified key, if the key is found; otherwise, the default value for the type of the <paramref name="value" /> parameter. This parameter is passed uninitialized.</param>
        /// <returns>
        /// true if the object that implements <see cref="T:System.Collections.Generic.IDictionary`2" /> contains an element with the specified key; otherwise, false.
        /// </returns>
        public bool TryGetValue(TKey key, out TValue value)
        {
            return dictionary.TryGetValue(key, out value);
        }

        /// <summary>
        /// Gets an <see cref="T:System.Collections.Generic.ICollection`1" /> containing the values in the <see cref="T:System.Collections.Generic.IDictionary`2" />.
        /// </summary>
        /// <returns>An <see cref="T:System.Collections.Generic.ICollection`1" /> containing the values in the object that implements <see cref="T:System.Collections.Generic.IDictionary`2" />.</returns>
        public ICollection<TValue> Values
        {
            get { return dictionary.Values; }
        }

        /// <summary>
        /// Gets or sets the element with the specified key.
        /// </summary>
        /// <param name="key">The key.</param>
        /// <returns></returns>
        public TValue this[TKey key]
        {
            get { return dictionary[key]; }
            set { UpdateWithNotification(key, value); }
        }

        #endregion

        #region ICollection<KeyValuePair<TKey,TValue>> Members

        void ICollection<KeyValuePair<TKey, TValue>>.Add(KeyValuePair<TKey, TValue> item)
        {
            AddWithNotification(item);
        }

        void ICollection<KeyValuePair<TKey, TValue>>.Clear()
        {
            dictionary.Clear();

            CollectionChanged(this, new NotifyCollectionChangedEventArgs(NotifyCollectionChangedAction.Reset));
            PropertyChanged(this, new PropertyChangedEventArgs("Count"));
            PropertyChanged(this, new PropertyChangedEventArgs("Keys"));
            PropertyChanged(this, new PropertyChangedEventArgs("Values"));
        }

        bool ICollection<KeyValuePair<TKey, TValue>>.Contains(KeyValuePair<TKey, TValue> item) =>
            dictionary.Contains(item);

        void ICollection<KeyValuePair<TKey, TValue>>.CopyTo(KeyValuePair<TKey, TValue>[] array, int arrayIndex)
        {
            dictionary.CopyTo(array, arrayIndex);
        }

        int ICollection<KeyValuePair<TKey, TValue>>.Count =>
           dictionary.Count();

        bool ICollection<KeyValuePair<TKey, TValue>>.IsReadOnly =>
            dictionary.IsReadOnly;

        bool ICollection<KeyValuePair<TKey, TValue>>.Remove(KeyValuePair<TKey, TValue> item) =>
            RemoveWithNotification(item.Key);

        #endregion

        #region IEnumerable<KeyValuePair<TKey,TValue>> Members

        IEnumerator<KeyValuePair<TKey, TValue>> IEnumerable<KeyValuePair<TKey, TValue>>.GetEnumerator() =>
            dictionary.GetEnumerator();

        IEnumerator IEnumerable.GetEnumerator() =>
            dictionary.GetEnumerator();

        #endregion

        #region Extensions
        public IEnumerator<KeyValuePair<TKey, TValue>> GetEnumerator()
        {
            return dictionary.GetEnumerator();
        }
        #endregion
    }
}