#nullable disable
using System;
using System.Collections.Generic;
using System.Collections.ObjectModel;
using System.Collections.Specialized;
using System.ComponentModel;
using System.Linq;
 
namespace Microsoft.Maui.Controls
{
	/// <include file="../../docs/Microsoft.Maui.Controls/FormattedString.xml" path="Type[@FullName='Microsoft.Maui.Controls.FormattedString']/Docs/*" />
	[ContentProperty("Spans")]
	[TypeConverter(typeof(FormattedStringConverter))]
	public class FormattedString : Element
	{
		readonly SpanCollection _spans = new SpanCollection();
		internal event NotifyCollectionChangedEventHandler SpansCollectionChanged;
 
		/// <include file="../../docs/Microsoft.Maui.Controls/FormattedString.xml" path="//Member[@MemberName='.ctor']/Docs/*" />
		public FormattedString() => _spans.CollectionChanged += OnCollectionChanged;
 
		protected override void OnBindingContextChanged()
		{
			base.OnBindingContextChanged();
			for (int i = 0; i < Spans.Count; i++)
				SetInheritedBindingContext(Spans[i], BindingContext);
		}
 
		/// <include file="../../docs/Microsoft.Maui.Controls/FormattedString.xml" path="//Member[@MemberName='Spans']/Docs/*" />
		public IList<Span> Spans => _spans;
 
		public static explicit operator string(FormattedString formatted) => formatted.ToString();
 
		public static implicit operator FormattedString(string text) => new FormattedString { Spans = { new Span { Text = text } } };
 
		/// <include file="../../docs/Microsoft.Maui.Controls/FormattedString.xml" path="//Member[@MemberName='ToString']/Docs/*" />
		public override string ToString() => string.Concat(Spans.Select(span => span.Text));
 
		void OnCollectionChanged(object sender, NotifyCollectionChangedEventArgs e)
		{
			if (e.OldItems != null)
			{
				foreach (object item in e.OldItems)
				{
					var bo = item as Span;
					if (bo != null)
					{
						bo.Parent?.RemoveLogicalChild(bo);
						bo.PropertyChanging -= OnItemPropertyChanging;
						bo.PropertyChanged -= OnItemPropertyChanged;
					}
 
				}
			}
 
			if (e.NewItems != null)
			{
				foreach (object item in e.NewItems)
				{
					var bo = item as Span;
					if (bo != null)
					{
						this.AddLogicalChild(bo);
						bo.PropertyChanging += OnItemPropertyChanging;
						bo.PropertyChanged += OnItemPropertyChanged;
					}
 
				}
			}
 
			OnPropertyChanged(nameof(Spans));
			SpansCollectionChanged?.Invoke(sender, e);
		}
 
		void OnItemPropertyChanged(object sender, PropertyChangedEventArgs e) => OnPropertyChanged(nameof(Spans));
 
		void OnItemPropertyChanging(object sender, PropertyChangingEventArgs e) => OnPropertyChanging(nameof(Spans));
 
		class SpanCollection : ObservableCollection<Span>
		{
			protected override void InsertItem(int index, Span item) => base.InsertItem(index, item ?? throw new ArgumentNullException(nameof(item)));
			protected override void SetItem(int index, Span item) => base.SetItem(index, item ?? throw new ArgumentNullException(nameof(item)));
 
			protected override void ClearItems()
			{
				var removed = new List<Span>(this);
				base.ClearItems();
				base.OnCollectionChanged(new NotifyCollectionChangedEventArgs(NotifyCollectionChangedAction.Remove, removed));
			}
		}
 
		private sealed class FormattedStringConverter : TypeConverter
		{
			public override bool CanConvertFrom(ITypeDescriptorContext context, Type sourceType)
				=> sourceType == typeof(string);
 
			public override bool CanConvertTo(ITypeDescriptorContext context, Type destinationType)
				=> destinationType == typeof(string);
 
			public override object ConvertFrom(ITypeDescriptorContext context, System.Globalization.CultureInfo culture, object value)
			{
				if (value is string strValue)
				{
					return (FormattedString)strValue;
				}
 
				throw new NotSupportedException();
			}
 
			public override object ConvertTo(ITypeDescriptorContext context, System.Globalization.CultureInfo culture, object value, Type destinationType)
			{
				if (value is FormattedString formattedStr)
				{
					return (string)formattedStr;
				}
 
				throw new NotSupportedException();
			}
		}
	}
}