using System;
using System.Collections.Generic;
using System.Collections.ObjectModel;
using System.Collections.Specialized;
using System.Runtime.Serialization;
using Umbraco.Extensions;

namespace Umbraco.Cms.Core.Models
{
    /// <summary>
    /// Represents a collection of <see cref="PropertyGroup"/> objects
    /// </summary>
    [Serializable]
    [DataContract]
    // TODO: Change this to ObservableDictionary so we can reduce the INotifyCollectionChanged implementation details
    public class PropertyGroupCollection : KeyedCollection<string, PropertyGroup>, INotifyCollectionChanged, IDeepCloneable
    {
        /// <summary>
        /// Initializes a new instance of the <see cref="PropertyGroupCollection" /> class.
        /// </summary>
        public PropertyGroupCollection()
        { }

        /// <summary>
        /// Initializes a new instance of the <see cref="PropertyGroupCollection" /> class.
        /// </summary>
        /// <param name="groups">The groups.</param>
        public PropertyGroupCollection(IEnumerable<PropertyGroup> groups) => Reset(groups);

        /// <summary>
        /// Resets the collection to only contain the <see cref="PropertyGroup"/> instances referenced in the <paramref name="groups"/> parameter.
        /// </summary>
        /// <param name="groups">The property groups.</param>
        /// <remarks></remarks>
        internal void Reset(IEnumerable<PropertyGroup> groups)
        {
            // Collection events will be raised in each of these calls
            Clear();

            // Collection events will be raised in each of these calls
            foreach (var group in groups)
                Add(group);
        }

        protected override void SetItem(int index, PropertyGroup item)
        {
            var oldItem = index >= 0 ? this[index] : item;

            base.SetItem(index, item);

            oldItem.Collection = null;
            item.Collection = this;

            OnCollectionChanged(new NotifyCollectionChangedEventArgs(NotifyCollectionChangedAction.Replace, item, oldItem));
        }

        protected override void RemoveItem(int index)
        {
            var removed = this[index];

            base.RemoveItem(index);

            removed.Collection = null;

            OnCollectionChanged(new NotifyCollectionChangedEventArgs(NotifyCollectionChangedAction.Remove, removed));
        }

        protected override void InsertItem(int index, PropertyGroup item)
        {
            base.InsertItem(index, item);

            item.Collection = this;

            OnCollectionChanged(new NotifyCollectionChangedEventArgs(NotifyCollectionChangedAction.Add, item));
        }

        protected override void ClearItems()
        {
            foreach (var item in this)
            {
                item.Collection = null;
            }

            base.ClearItems();
            OnCollectionChanged(new NotifyCollectionChangedEventArgs(NotifyCollectionChangedAction.Reset));
        }

        public new void Add(PropertyGroup item)
        {
            // Ensure alias is set
            if (string.IsNullOrEmpty(item.Alias))
            {
                throw new InvalidOperationException("Set an alias before adding the property group.");
            }

            // Note this is done to ensure existing groups can be renamed
            if (item.HasIdentity && item.Id > 0)
            {
                var index = IndexOfKey(item.Id);
                if (index != -1)
                {
                    var keyExists = Contains(item.Alias);
                    if (keyExists)
                        throw new ArgumentException($"Naming conflict: changing the alias of property group '{item.Name}' would result in duplicates.");

                    // Collection events will be raised in SetItem
                    SetItem(index, item);
                    return;
                }
            }
            else
            {
                var index = IndexOfKey(item.Alias);
                if (index != -1)
                {
                    // Collection events will be raised in SetItem
                    SetItem(index, item);
                    return;
                }
            }

            // Collection events will be raised in InsertItem
            base.Add(item);
        }

        internal void ChangeKey(PropertyGroup item, string newKey) => ChangeItemKey(item, newKey);

        public bool Contains(int id) => this.IndexOfKey(id) != -1;

        public int IndexOfKey(string key) => this.FindIndex(x => x.Alias == key);

        public int IndexOfKey(int id) => this.FindIndex(x => x.Id == id);

        protected override string GetKeyForItem(PropertyGroup item) => item.Alias;

        public event NotifyCollectionChangedEventHandler? CollectionChanged;

        /// <summary>
        /// Clears all <see cref="CollectionChanged"/> event handlers
        /// </summary>
        public void ClearCollectionChangedEvents() => CollectionChanged = null;

        protected virtual void OnCollectionChanged(NotifyCollectionChangedEventArgs args) => CollectionChanged?.Invoke(this, args);

        public object DeepClone()
        {
            var clone = new PropertyGroupCollection();
            foreach (var group in this)
            {
                clone.Add((PropertyGroup)group.DeepClone());
            }

            return clone;
        }
    }
}