namespace Eto.Forms;

/// <summary>
/// Direction of the stepper when it has been clicked
/// </summary>
public enum StepperDirection
{
	/// <summary>
	/// The Up direction, which usually increases the value
	/// </summary>
	Up,
	/// <summary>
	/// The Down direction, which usually decreases the value
	/// </summary>
	Down
}

/// <summary>
/// Valid stepper directions for the (typically) up/down buttons
/// </summary>
/// <remarks>
/// Note that some platforms do not actually disable the up or down buttons, but just won't trigger the <see cref="Stepper.Step"/>
/// event when it is not valid.
/// </remarks>
[Flags]
public enum StepperValidDirections
{
	/// <summary>
	/// Neither the up or down buttons are valid
	/// </summary>
	None = 0,
	/// <summary>
	/// Specifies that the up/increase button is a valid direction for the stepper
	/// </summary>
	Up = 1,
	/// <summary>
	/// Specifies that the down/decrease button is a valid direction for the stepper
	/// </summary>
	Down = 2,
	/// <summary>
	/// Combines both the <see cref="Up"/> and <see cref="Down"/> flags.
	/// </summary>
	Both = Up | Down
}

/// <summary>
/// Arguments for the <see cref="Stepper"/> and <see cref="TextStepper"/> to give you the direction of the step.
/// </summary>
public class StepperEventArgs : EventArgs
{
	/// <summary>
	/// Gets the step direction, either up/increase, or down/decrease.
	/// </summary>
	/// <value>The step direction.</value>
	public StepperDirection Direction { get; }

	/// <summary>
	/// Initializes a new instance of the <see cref="T:Eto.Forms.StepperEventArgs"/> class.
	/// </summary>
	/// <param name="direction">Direction of the step that the user clicked.</param>
	public StepperEventArgs(StepperDirection direction)
	{
		Direction = direction;
	}
}

/// <summary>
/// Control that allows you to "step" through values, usually presented by two buttons arranged vertically with up and down arrows.
/// </summary>
[Handler(typeof(IHandler))]
public class Stepper : Control
{
	new IHandler Handler { get { return (IHandler)base.Handler; } }

	/// <summary>
	/// Identifier for the <see cref="Step"/> event.
	/// </summary>
	public const string StepEvent = "Stepper.Step";

	/// <summary>
	/// Event to handle when the user clicks on one of the step buttons, either up or down.
	/// </summary>
	public event EventHandler<StepperEventArgs> Step
	{
		add { Properties.AddHandlerEvent(StepEvent, value); }
		remove { Properties.RemoveEvent(StepEvent, value); }
	}

	/// <summary>
	/// Triggers the <see cref="Step"/> event.
	/// </summary>
	/// <param name="e">Event arguments</param>
	protected void OnStep(StepperEventArgs e)
	{
		Properties.TriggerEvent(StepEvent, this, e);
	}

	/// <summary>
	/// Gets or sets the valid directions the stepper will allow the user to click.
	/// </summary>
	/// <remarks>
	/// On some platforms, the up and/or down buttons will not appear disabled, but will not trigger any events when they are 
	/// not set as a valid direction.
	/// </remarks>
	/// <value>The valid directions for the stepper.</value>
	[DefaultValue(StepperValidDirections.Both)] 
	public StepperValidDirections ValidDirection
	{
		get { return Handler.ValidDirection; }
		set { Handler.ValidDirection = value; }
	}

	ICallback callback = new Callback();

	/// <summary>
	/// Gets the callback.
	/// </summary>
	/// <returns>The callback.</returns>
	protected override object GetCallback() => callback;

	/// <summary>
	/// Callback interface for the Stepper
	/// </summary>
	public new interface ICallback : Control.ICallback
	{
		/// <summary>
		/// Triggers the <see cref="Step"/> event.
		/// </summary>
		/// <param name="widget">Widget instance to trigger the event</param>
		/// <param name="e">Event arguments</param>
		void OnStep(Stepper widget, StepperEventArgs e);
	}

	/// <summary>
	/// Callback implementation for the Stepper
	/// </summary>
	protected new class Callback : Control.Callback, ICallback
	{
		/// <summary>
		/// Triggers the <see cref="Step"/> event.
		/// </summary>
		/// <param name="widget">Widget instance to trigger the event</param>
		/// <param name="e">Event arguments</param>
		public void OnStep(Stepper widget, StepperEventArgs e)
		{
			using (widget.Platform.Context)
				widget.OnStep(e);
		}
	}

	/// <summary>
	/// Handler interface for the Stepper
	/// </summary>
	public new interface IHandler : Control.IHandler
	{
		/// <summary>
		/// Gets or sets the valid directions the stepper will allow the user to click.
		/// </summary>
		/// <remarks>
		/// On some platforms, the up and/or down buttons will not appear disabled, but will not trigger any events when they are 
		/// not set as a valid direction.
		/// </remarks>
		/// <value>The valid directions for the stepper.</value>
		StepperValidDirections ValidDirection { get; set; }
	}
}