using System;
using System.Collections;
using AppKit;
using Foundation;
using Xamarin.PropertyEditing.ViewModels;

namespace Xamarin.PropertyEditing.Mac
{
	internal abstract class BasePathEditorControl<T> : PropertyEditorControl<PropertyViewModel<T>>
	{
		private const string PathRevealName = "pe-path-reveal";
		private const string PathBrowseName = "pe-path-browse";

		protected readonly TextFieldSmallButtonContainer currentTextField;

		protected readonly NSOpenPanel panel;
		protected readonly SmallButton browsePathButton;
		protected readonly SmallButton revealPathButton;

		public override NSView FirstKeyView => this.currentTextField;
		public override NSView LastKeyView => this.revealPathButton.Enabled ? this.revealPathButton : this.browsePathButton;

		private readonly NSObject[] objects;
		public override NSObject[] AccessibilityChildren { get => this.objects; }

		private readonly TextNextResponderDelegate textNextResponderDelegate;

		class BasePathEditordDelegate : TextNextResponderDelegate
		{
			WeakReference<BasePathEditorControl<T>> weakView;

			public BasePathEditordDelegate (BasePathEditorControl<T> basePathEditorControl)
			{
				weakView = new WeakReference<BasePathEditorControl<T>>(basePathEditorControl);
			}

			public override void Changed (NSNotification notification)
			{
				if (this.weakView.TryGetTarget(out BasePathEditorControl<T> t)) {
					t.StoreCurrentValue ();
				}
			}
		}

		protected BasePathEditorControl (IHostResourceProvider hostResource)
			: base (hostResource)
		{
			this.currentTextField = new TextFieldSmallButtonContainer ();

			this.textNextResponderDelegate = new BasePathEditordDelegate (this)
			{
				ResponderProxy = new ProxyRowResponder(this, ProxyRowType.SingleView)
			};
			this.currentTextField.Delegate = this.textNextResponderDelegate;
			AddSubview (this.currentTextField);

			#region Reveal handler

			this.revealPathButton = new SmallButton {
				Font = NSFont.FromFontName (DefaultFontName, DefaultFontSize),
				Image = HostResources.GetNamedImage (PathRevealName),
				StringValue = string.Empty
			};

			this.currentTextField.AddButton (this.revealPathButton);

			this.panel = NSOpenPanel.OpenPanel;

			// update the value on keypress
			this.revealPathButton.Activated += OnRevealPathButtonActivated;

			#endregion

			#region Browse Path

			this.browsePathButton = new SmallButton {
				Font = NSFont.FromFontName (DefaultFontName, DefaultFontSize),
				Image = HostResources.GetNamedImage (PathBrowseName),
				StringValue = string.Empty
			};
			this.browsePathButton.Activated += BrowsePathButton_Activated;
			this.currentTextField.AddButton (this.browsePathButton);

			this.objects = new NSObject[3];
			this.objects[0] = this.currentTextField;
			this.objects[1] = this.browsePathButton;
			this.objects[2] = this.revealPathButton;
			AccessibilityElement = true;
			AccessibilityRole = NSAccessibilityRoles.GroupRole;

			this.currentTextField.AccessibilityRole = NSAccessibilityRoles.TextFieldRole;
			this.revealPathButton.AccessibilityRole = NSAccessibilityRoles.ButtonRole;
			this.browsePathButton.AccessibilityRole = NSAccessibilityRoles.ButtonRole;

			#endregion

			AddConstraints (new[] {
				NSLayoutConstraint.Create (this.currentTextField, NSLayoutAttribute.Left, NSLayoutRelation.Equal, this, NSLayoutAttribute.Left, 1, 0f),
				NSLayoutConstraint.Create (this.currentTextField, NSLayoutAttribute.CenterY, NSLayoutRelation.Equal, this, NSLayoutAttribute.CenterY, 1, 0f),
				NSLayoutConstraint.Create (this.currentTextField, NSLayoutAttribute.Width, NSLayoutRelation.Equal, this, NSLayoutAttribute.Width, 1, 0f),
				NSLayoutConstraint.Create (this.currentTextField, NSLayoutAttribute.Height, NSLayoutRelation.Equal, this, NSLayoutAttribute.Height, 1, -6f),
			});
		}

		private void CurrentTextField_Changed (object sender, EventArgs e)
		{
			StoreCurrentValue ();
		}

		private void BrowsePathButton_Activated (object sender, EventArgs e)
		{
			Window.MakeFirstResponder (this.currentTextField);

			this.panel.AllowsMultipleSelection = false;
			this.panel.CanCreateDirectories = true;
			this.panel.ShowsHiddenFiles = false;
			this.panel.ShowsResizeIndicator = true;
			this.panel.TreatsFilePackagesAsDirectories = true;
			this.panel.BeginSheet (Window, HandleAction);
		}

		protected abstract void OnRevealPathButtonActivated (object sender, EventArgs e);
		protected abstract void StoreCurrentValue ();

		private void HandleAction (nint result)
		{
			if (result == 1) {
				NSUrl url = this.panel.Url;
				if (url.IsFileUrl) {
					this.currentTextField.StringValue = url.Path;
					StoreCurrentValue ();
				}
			}
		}

		protected override void SetEnabled ()
		{
			this.currentTextField.Enabled =
			this.browsePathButton.Enabled =
			this.revealPathButton.Enabled = ViewModel.Property.CanWrite;
		}

		protected override void Dispose (bool disposing)
		{
			this.currentTextField.Changed -= CurrentTextField_Changed;
			this.browsePathButton.Activated -= BrowsePathButton_Activated;
			this.revealPathButton.Activated -= OnRevealPathButtonActivated;
			base.Dispose (disposing);
		}

		protected override void AppearanceChanged ()
		{
			base.AppearanceChanged ();

			this.revealPathButton.Image = HostResources.GetNamedImage (PathRevealName);
			this.browsePathButton.Image = HostResources.GetNamedImage (PathBrowseName);
		}
	}
}