#region CPL License
/*
Nuclex Framework
Copyright (C) 2002-2010 Nuclex Development Labs

This library is free software; you can redistribute it and/or
modify it under the terms of the IBM Common Public License as
published by the IBM Corporation; either version 1.0 of the
License, or (at your option) any later version.

This library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
IBM Common Public License for more details.

You should have received a copy of the IBM Common Public
License along with this library
*/
#endregion

using System;
using System.Collections.Generic;

using Nuclex.Input;
using Nuclex.UserInterface.Input;

namespace Nuclex.UserInterface.Controls.Desktop {

  /// <summary>Base class for a slider that can be moved using the mouse</summary>
  /// <remarks>
  ///   Implements the common functionality for a slider moving either the direction
  ///   of the X or the Y axis (but not both). Derive any scroll bar-like controls
  ///   from this class to simplify their implementation.
  /// </remarks>
  public abstract class SliderControl : Control {

    /// <summary>Triggered when the slider has been moved</summary>
    public event EventHandler Moved;

    /// <summary>Initializes a new slider control</summary>
    public SliderControl() {
      this.ThumbPosition = 0.0f;
      this.ThumbSize = 1.0f;
    }

    /// <summary>whether the mouse is currently hovering over the thumb</summary>
    public bool MouseOverThumb {
      get { return this.mouseOverThumb; }
    }

    /// <summary>Whether the pressable control is in the depressed state</summary>
    public virtual bool ThumbDepressed {
      get {
        return
          this.pressedDown &&
          this.mouseOverThumb;
      }
    }

    /// <summary>Called when a mouse button has been pressed down</summary>
    /// <param name="button">Index of the button that has been pressed</param>
    protected override void OnMousePressed(MouseButtons button) {
      if(button == MouseButtons.Left) {
        RectangleF thumbRegion = GetThumbRegion();
        if(thumbRegion.Contains(this.pickupX, this.pickupY)) {
          this.pressedDown = true;
          
          this.pickupX -= thumbRegion.X;
          this.pickupY -= thumbRegion.Y;
        }
      }
    }

    /// <summary>Called when a mouse button has been released again</summary>
    /// <param name="button">Index of the button that has been released</param>
    protected override void OnMouseReleased(MouseButtons button) {
      if(button == MouseButtons.Left) {
        this.pressedDown = false;
      }
    }

    /// <summary>Called when the mouse position is updated</summary>
    /// <param name="x">X coordinate of the mouse cursor on the control</param>
    /// <param name="y">Y coordinate of the mouse cursor on the control</param>
    protected override void OnMouseMoved(float x, float y) {
      if(this.pressedDown) {
        
        //RectangleF bounds = GetAbsoluteBounds();
        MoveThumb(x - this.pickupX, y - this.pickupY);
        
      } else {
        this.pickupX = x;
        this.pickupY = y;
      }

      this.mouseOverThumb = GetThumbRegion().Contains(x, y);
    }

    /// <summary>
    ///   Called when the mouse has left the control and is no longer hovering over it
    /// </summary>
    protected override void OnMouseLeft() {
      this.mouseOverThumb = false;
    }

    /// <summary>Fires the slider's Moved event</summary>
    protected virtual void OnMoved() {
      if(Moved != null) {
        Moved(this, EventArgs.Empty);
      }
    }

    /// <summary>Moves the thumb to the specified location</summary>
    /// <returns>Location the thumb will be moved to</returns>
    protected abstract void MoveThumb(float x, float y);

    /// <summary>Obtains the region covered by the slider's thumb</summary>
    /// <returns>The region covered by the slider's thumb</returns>
    protected abstract RectangleF GetThumbRegion();

    /// <summary>Can be set by renderers to allow the control to locate its thumb</summary>
    public IThumbLocator ThumbLocator;
    /// <summary>Fraction of the slider filled by the thumb (0.0 .. 1.0)</summary>
    public float ThumbSize;
    /// <summary>Position of the thumb within the slider (0.0 .. 1.0)</summary>
    public float ThumbPosition;

    /// <summary>Whether the mouse cursor is hovering over the thumb</summary>
    private bool mouseOverThumb;
    /// <summary>Whether the slider's thumb is currently in the depressed state</summary>
    private bool pressedDown;
    /// <summary>X coordinate at which the thumb was picked up</summary>
    private float pickupX;
    /// <summary>Y coordinate at which the thumb was picked up</summary>
    private float pickupY;


  }

} // namespace Nuclex.UserInterface.Controls.Desktop