using ElmSharp;
using System.Collections.Generic;
using EColor = ElmSharp.Color;

namespace Xamarin.Forms.Platform.Tizen
{
	public abstract class CellRenderer : IRegisterable
	{
		const string _heightProperty = "Height";
		protected static readonly EColor s_defaultTextColor = EColor.Black;
		protected static readonly EColor s_defaultBackgroundColor = EColor.White;
		readonly Dictionary<Cell, Dictionary<string, EvasObject>> _realizedNativeViews = new Dictionary<Cell, Dictionary<string, EvasObject>>();

		protected CellRenderer(string style)
		{
			Class = new GenItemClass(style)
			{
				GetTextHandler = GetText,
				GetContentHandler = GetContent,
				DeleteHandler = ItemDeleted,
			};
		}

		public GenItemClass Class
		{
			get;
			private set;
		}

		protected virtual bool OnCellPropertyChanged(Cell cell, string property, Dictionary<string, EvasObject> realizedView)
		{
			if (property == _heightProperty)
			{
				return true;
			}
			return false;
		}

		protected virtual Span OnGetText(Cell cell, string part)
		{
			return null;
		}
		protected virtual EvasObject OnGetContent(Cell cell, string part)
		{
			return null;
		}
		protected virtual void OnDeleted(Cell cell)
		{
		}

		protected virtual void OnUnrealizedCell(Cell cell)
		{
		}

		protected int FindCellContentHeight(Cell cell)
		{
			ViewCell viewCell = cell as ViewCell;
			if (viewCell != null)
			{
				var parentWidth = (cell.Parent as VisualElement).Width;
				var view = viewCell.View;
				return (int)view.Measure(parentWidth, double.PositiveInfinity).Request.Height;
			}
			else
				return -1;
		}

		static Native.Span ToNative(Span span)
		{
			var nativeSpan = new Native.Span();
			nativeSpan.Text = span.Text;
			nativeSpan.ForegroundColor = span.ForegroundColor.IsDefault ? s_defaultTextColor : span.ForegroundColor.ToNative();
			nativeSpan.FontAttributes = span.FontAttributes;
			nativeSpan.BackgroundColor = span.BackgroundColor.IsDefault ? s_defaultBackgroundColor : span.BackgroundColor.ToNative();
			nativeSpan.FontSize = span.FontSize;
			nativeSpan.FontFamily = span.FontFamily;
			return nativeSpan;
		}

		internal void SendCellPropertyChanged(Cell cell, GenListItem item, string property)
		{
			Dictionary<string, EvasObject> realizedView = null;
			_realizedNativeViews.TryGetValue(cell, out realizedView);

			// just to prevent null reference exception in OnCellPropertyChanged
			realizedView = realizedView ?? new Dictionary<string, EvasObject>();

			if (property == Cell.IsEnabledProperty.PropertyName)
			{
				item.IsEnabled = cell.IsEnabled;
			}
			// if true was returned, item was updated
			// if it's possible to update the cell property without Update(), return false
			else if (OnCellPropertyChanged(cell, property, realizedView))
			{
				item.Update();
			}
		}

		internal void SendUnrealizedCell(Cell cell)
		{
			_realizedNativeViews.Remove(cell);
			OnUnrealizedCell(cell);
		}

		string GetText(object data, string part)
		{
			var span = OnGetText((data as Native.ListView.ItemContext).Cell, part);
			return span != null ? ToNative(span).GetDecoratedText() : null;
		}

		EvasObject GetContent(object data, string part)
		{
			var cell = (data as Native.ListView.ItemContext).Cell;
			EvasObject nativeView = OnGetContent(cell, part);
			if (part != null && nativeView != null)
			{
				Dictionary<string, EvasObject> realizedView = null;
				_realizedNativeViews.TryGetValue(cell, out realizedView);
				if (realizedView == null)
				{
					realizedView = new Dictionary<string, EvasObject>();
					_realizedNativeViews[cell] = realizedView;
				}
				realizedView[part] = nativeView;

				nativeView.Deleted += (sender, e) =>
				{
					realizedView.Remove(part);
				};
			}
			return nativeView;
		}

		void ItemDeleted(object data)
		{
			var cell = (data as Native.ListView.ItemContext).Cell;
			_realizedNativeViews.Remove(cell);
			OnDeleted(cell);
		}
	}
}