using System;
using ElmSharp;
using EBox = ElmSharp.Box;

namespace Xamarin.Forms.Platform.Tizen.Native
{
	/// <summary>
	/// The native widget which provides Xamarin.MasterDetailPage features.
	/// </summary>
	public class MasterDetailPage : EBox
	{
		/// <summary>
		/// The portion of the screen that the MasterPage takes in Split mode.
		/// </summary>
		static readonly double s_splitRatio = 0.35;

		/// <summary>
		/// The portion of the screen that the MasterPage takes in Popover mode.
		/// </summary>
		static readonly double s_popoverRatio = 0.8;

		/// <summary>
		/// The default master behavior (a.k.a mode).
		/// </summary>
		static readonly MasterBehavior s_defaultMasterBehavior = (Device.Idiom == TargetIdiom.Phone) ? MasterBehavior.Popover : MasterBehavior.SplitOnLandscape;

		/// <summary>
		/// The MasterPage native container.
		/// </summary>
		readonly Canvas _masterCanvas;

		/// <summary>
		/// The DetailPage native container.
		/// </summary>
		readonly Canvas _detailCanvas;

		/// <summary>
		/// The container for <c>_masterCanvas</c> and <c>_detailCanvas</c> used in split mode.
		/// </summary>
		readonly Panes _splitPane;

		/// <summary>
		/// The container for <c>_masterCanvas</c> used in popover mode.
		/// </summary>
		readonly Panel _drawer;

		/// <summary>
		/// The <see cref="MasterBehavior"/> property value.
		/// </summary>
		MasterBehavior _masterBehavior = s_defaultMasterBehavior;

		/// <summary>
		/// The actual MasterDetailPage mode - either split or popover. It depends on <c>_masterBehavior</c> and screen orientation.
		/// </summary>
		MasterBehavior _internalMasterBehavior = MasterBehavior.Popover;

		/// <summary>
		/// The <see cref="Master"/> property value.
		/// </summary>
		EvasObject _master;

		/// <summary>
		/// The <see cref="Detail"/> property value.
		/// </summary>
		EvasObject _detail;

		/// <summary>
		/// The main widget - either <see cref="_splitPlane"/> or <see cref="_detailPage"/>, depending on the mode.
		/// </summary>
		EvasObject _mainWidget;

		/// <summary>
		/// The <see cref="IsGestureEnabled"/> property value.
		/// </summary>
		bool _isGestureEnabled;

		/// <summary>
		/// Initializes a new instance of the <see cref="Xamarin.Forms.Platform.Tizen.Native.MasterDetailPage"/> class.
		/// </summary>
		/// <param name="parent">Parent evas object.</param>
		public MasterDetailPage(EvasObject parent) : base(parent)
		{
			// we control the layout ourselves
			Resized += (sender, e) =>
			{
				var g = Geometry;

				// main widget should fill the area of the MasterDetailPage
				if (_mainWidget != null)
				{
					_mainWidget.Geometry = g;
				}

				g.Width = (int)((s_popoverRatio * (double)g.Width));
				_drawer.Geometry = g;
			};

			// create the controls which will hold the master and detail pages
			_masterCanvas = new Canvas(this);
			_masterCanvas.SetAlignment(-1.0, -1.0);  // fill
			_masterCanvas.SetWeight(1.0, 1.0);  // expand
			_masterCanvas.LayoutUpdated += (sender, e) =>
			{
				UpdatePageGeometry(_master);
			};

			_detailCanvas = new Canvas(this);
			_detailCanvas.SetAlignment(-1.0, -1.0);  // fill
			_detailCanvas.SetWeight(1.0, 1.0);  // expand
			_detailCanvas.LayoutUpdated += (sender, e) =>
			{
				UpdatePageGeometry(_detail);
			};

			_splitPane = new Panes(this)
			{
				IsFixed = true,
				IsHorizontal = false,
				Proportion = s_splitRatio,
			};

			_drawer = new Panel(Forms.Context.MainWindow)
			{
				Direction = PanelDirection.Left,
			};
			_drawer.SetScrollable(_isGestureEnabled);
			_drawer.SetScrollableArea(1.0);
			_drawer.Toggled += (object sender, EventArgs e) =>
			{
				IsPresentedChanged?.Invoke(this, EventArgs.Empty);
			};

			ConfigureLayout();

			// in case of the screen rotation we may need to update the choice between split
			// and popover behaviors and reconfigure the layout
			Forms.Context.MainWindow.RotationChanged += (sender, e) =>
			{
				UpdateMasterBehavior();
			};
		}

		/// <summary>
		/// Occurs when the MasterPage is shown or hidden.
		/// </summary>
		public event EventHandler IsPresentedChanged;

		/// <summary>
		/// Gets or sets the MasterDetailPage behavior.
		/// </summary>
		/// <value>The behavior of the <c>MasterDetailPage</c> requested by the user.</value>
		public MasterBehavior MasterBehavior
		{
			get
			{
				return _masterBehavior;
			}

			set
			{
				if (_masterBehavior != value)
				{
					_masterBehavior = value;

					UpdateMasterBehavior();
				}
			}
		}

		/// <summary>
		/// Gets or sets the content of the MasterPage.
		/// </summary>
		/// <value>The MasterPage.</value>
		public EvasObject Master
		{
			get
			{
				return _master;
			}

			set
			{
				if (_master != value)
				{
					_master = value;
					UpdatePageGeometry(_master);
					_masterCanvas.Children.Clear();
					_masterCanvas.Children.Add(_master);
				}
			}
		}

		/// <summary>
		/// Gets or sets the content of the DetailPage.
		/// </summary>
		/// <value>The DetailPage.</value>
		public EvasObject Detail
		{
			get
			{
				return _detail;
			}

			set
			{
				if (_detail != value)
				{
					_detail = value;
					UpdatePageGeometry(_detail);
					_detailCanvas.Children.Clear();
					_detailCanvas.Children.Add(_detail);
				}
			}
		}

		/// <summary>
		/// Gets or sets a value indicating whether the MasterPage is shown.
		/// </summary>
		/// <value><c>true</c> if the MasterPage is presented.</value>
		public bool IsPresented
		{
			get
			{
				return _drawer.IsOpen;
			}

			set
			{
				if (_drawer.IsOpen != value)
				{
					_drawer.IsOpen = value;
				}
			}
		}

		/// <summary>
		/// Gets or sets a value indicating whether a MasterDetailPage allows showing MasterPage with swipe gesture.
		/// </summary>
		/// <value><c>true</c> if the MasterPage can be revealed with a gesture.</value>
		public bool IsGestureEnabled
		{
			get
			{
				return _isGestureEnabled;
			}

			set
			{
				if (_isGestureEnabled != value)
				{
					_isGestureEnabled = value;
					_drawer.SetScrollable(_isGestureEnabled);
				}
			}
		}

		/// <summary>
		/// Provides destruction for native element and contained elements.
		/// </summary>
		protected override void OnUnrealize()
		{
			_drawer.Unrealize();

			base.OnUnrealize();
		}

		/// <summary>
		/// Updates the geometry of the selected page.
		/// </summary>
		/// <param name="page">Master or Detail page to be updated.</param>
		void UpdatePageGeometry(EvasObject page)
		{
			if (page != null)
			{
				if (_master == page)
				{
					// update the geometry of the master page
					page.Geometry = _masterCanvas.Geometry;
				}
				else if (_detail == page)
				{
					// update the geometry of the detail page
					page.Geometry = _detailCanvas.Geometry;
				}
			}
		}

		/// <summary>
		/// Updates <see cref="_internalMasterBehavior"/> according to <see cref="MasterDetailBehavior"/> set by the user and current screen orientation.
		/// </summary>
		void UpdateMasterBehavior()
		{
			var behavior = (_masterBehavior == MasterBehavior.Default) ? s_defaultMasterBehavior : _masterBehavior;

			// Screen orientation affects those 2 behaviors
			if (behavior == MasterBehavior.SplitOnLandscape ||
				behavior == MasterBehavior.SplitOnPortrait)
			{
				var rotation = Forms.Context.MainWindow.Rotation;

				if (((rotation == 90 || rotation == 270) && behavior == MasterBehavior.SplitOnLandscape) ||
					((rotation == 0 || rotation == 90) && behavior == MasterBehavior.SplitOnPortrait))
				{
					behavior = MasterBehavior.Split;
				}
				else
				{
					behavior = MasterBehavior.Popover;
				}
			}

			if (behavior != _internalMasterBehavior)
			{
				_internalMasterBehavior = behavior;

				ConfigureLayout();
			}
		}

		/// <summary>
		/// Composes the structure of all the necessary widgets.
		/// </summary>
		void ConfigureLayout()
		{
			_drawer.SetContent(null, true);
			_drawer.Hide();

			_splitPane.SetPartContent("left", null, true);
			_splitPane.SetPartContent("right", null, true);
			_splitPane.Hide();

			UnPackAll();

			// the structure for split mode and for popover mode looks differently
			if (_internalMasterBehavior == MasterBehavior.Split)
			{
				_splitPane.SetPartContent("left", _masterCanvas, true);
				_splitPane.SetPartContent("right", _detailCanvas, true);
				PackEnd(_splitPane);

				_splitPane.Show();

				_mainWidget = _splitPane;

				IsPresented = true;
			}
			else
			{
				_drawer.SetContent(_masterCanvas, true);
				PackEnd(_detailCanvas);
				_drawer.Show();

				_mainWidget = _detailCanvas;
				_drawer.IsOpen = IsPresented;
			}

			_masterCanvas.Show();
			_detailCanvas.Show();
		}
	}
}