// -----------------------------------------------------------------------
// <copyright file="IInputElement.cs" company="Steven Kirk">
// Copyright 2014 MIT Licence. See licence.md for more information.
// </copyright>
// -----------------------------------------------------------------------

namespace Perspex.Input
{
    using System;
    using Perspex.Interactivity;

    /// <summary>
    /// Defines input-related functionality for a control.
    /// </summary>
    public interface IInputElement : IInteractive, IVisual
    {
        /// <summary>
        /// Occurs when the control receives focus.
        /// </summary>
        event EventHandler<RoutedEventArgs> GotFocus;

        /// <summary>
        /// Occurs when the control loses focus.
        /// </summary>
        event EventHandler<RoutedEventArgs> LostFocus;

        /// <summary>
        /// Occurs when a key is pressed while the control has focus.
        /// </summary>
        event EventHandler<KeyEventArgs> KeyDown;

        /// <summary>
        /// Occurs when a key is released while the control has focus.
        /// </summary>
        event EventHandler<KeyEventArgs> KeyUp;

        /// <summary>
        /// Occurs when the pointer enters the control.
        /// </summary>
        event EventHandler<PointerEventArgs> PointerEnter;

        /// <summary>
        /// Occurs when the pointer leaves the control.
        /// </summary>
        event EventHandler<PointerEventArgs> PointerLeave;

        /// <summary>
        /// Occurs when the pointer is pressed over the control.
        /// </summary>
        event EventHandler<PointerPressEventArgs> PointerPressed;

        /// <summary>
        /// Occurs when the pointer moves over the control.
        /// </summary>
        event EventHandler<PointerEventArgs> PointerMoved;

        /// <summary>
        /// Occurs when the pointer is released over the control.
        /// </summary>
        event EventHandler<PointerEventArgs> PointerReleased;

        /// <summary>
        /// Occurs when the mouse wheen is scrolled over the control.
        /// </summary>
        event EventHandler<PointerWheelEventArgs> PointerWheelChanged;

        /// <summary>
        /// Gets or sets a value indicating whether the control can receive keyboard focus.
        /// </summary>
        bool Focusable { get; }

        /// <summary>
        /// Gets or sets a value indicating whether the control is enabled for user interaction.
        /// </summary>
        bool IsEnabled { get; }

        /// <summary>
        /// Gets a value indicating whether the control is effectively enabled for user interaction.
        /// </summary>
        /// <remarks>
        /// The <see cref="IsEnabled"/> property is used to toggle the enabled state for individual
        /// controls. The <see cref="IsEnabledCore"/> property takes into account the
        /// <see cref="IsEnabled"/> value of this control and its parent controls.
        /// </remarks>
        bool IsEnabledCore { get; }

        /// <summary>
        /// Gets or sets a value indicating whether the control is focused.
        /// </summary>
        bool IsFocused { get; }

        /// <summary>
        /// Gets or sets a value indicating whether the control is considered for hit testing.
        /// </summary>
        bool IsHitTestVisible { get; }

        /// <summary>
        /// Gets or sets a value indicating whether the pointer is currently over the control.
        /// </summary>
        bool IsPointerOver { get; }

        /// <summary>
        /// Focuses the control.
        /// </summary>
        void Focus();

        /// <summary>
        /// Returns the input element that can be found within the current control at the specified
        /// position.
        /// </summary>
        /// <param name="p">The position, in control coordinates.</param>
        /// <returns>The <see cref="IInputElement"/> at the specified position.</returns>
        IInputElement InputHitTest(Point p);
    }
}