#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 Microsoft.Xna.Framework;

namespace Nuclex.UserInterface.Visuals.Flat.Renderers {

  /// <summary>Renders text input controls in a traditional flat style</summary>
  public class FlatInputControlRenderer :
    IFlatControlRenderer<Controls.Desktop.InputControl>,
    Controls.Desktop.IOpeningLocator {

    /// <summary>Style from the skin this renderer uses</summary>
    private const string Style = "input.normal";

    /// <summary>
    ///   Renders the specified control using the provided graphics interface
    /// </summary>
    /// <param name="control">Control that will be rendered</param>
    /// <param name="graphics">
    ///   Graphics interface that will be used to draw the control
    /// </param>
    public void Render(
      Controls.Desktop.InputControl control, IFlatGuiGraphics graphics
    ) {
      RectangleF controlBounds = control.GetAbsoluteBounds();

      // Draw the control's frame and background
      graphics.DrawElement(Style, controlBounds);

      using(graphics.SetClipRegion(controlBounds)) {
        string text = control.Text ?? string.Empty;

        // Amount by which the text will be moved within the input box in
        // order to keep the caret in view even when the text is wider than
        // the input box.
        float left = 0;

        // Only scroll the text within the input box when it has the input
        // focus and the caret is being shown.
        if(control.HasFocus) {

          // Find out where the cursor is from the left end of the text
          RectangleF stringSize = graphics.MeasureString(
            Style, controlBounds, text.Substring(0, control.CaretPosition)
          );

          // TODO: Renderer should query the size of the control's frame
          //   Otherwise text will be visible over the frame, which might look bad
          //   if a skin uses a frame wider than 2 pixels or in a different color
          //   than the text.
          while(stringSize.Width + left > controlBounds.Width) {
            left -= controlBounds.Width / 10.0f;
          }
          
        }

        // Draw the text into the input box
        controlBounds.X += left;
        graphics.DrawString(Style, controlBounds, control.Text);

        // If the input box is in focus, also draw the caret so the user knows
        // where characters will be inserted into the text.
        if(control.HasFocus) {
          if(control.MillisecondsSinceLastCaretMovement % 500 < 250) {
            graphics.DrawCaret(
              "input.normal", controlBounds, control.Text, control.CaretPosition
            );
          }
        }
      }

      // Let the control know that we can provide it with additional informations
      // about how its text is being rendered
      control.OpeningLocator = this;
      this.graphics = graphics;
    }

    /// <summary>
    ///   Calculates which opening between two letters is closest to a position
    /// </summary>
    /// <param name="bounds">
    ///   Boundaries of the control, should be in absolute coordinates
    /// </param>
    /// <param name="text">Text in which the opening will be looked for</param>
    /// <param name="position">
    ///   Position to which the closest opening will be found,
    ///   should be in absolute coordinates
    /// </param>
    /// <returns>The index of the opening closest to the provided position</returns>
    public int GetClosestOpening(
      RectangleF bounds, string text, Vector2 position
    ) {
      return this.graphics.GetClosestOpening("input.normal", bounds, text, position);
    }

    // TODO: Find a better solution than remembering the graphics interface here
    //   Otherwise the renderer could try to renderer when no frame is being drawn.
    //   Also, the renderer makes the assumption that all drawing happens through
    //   one graphics interface only.

    /// <summary>Graphics interface we used for the last draw call</summary>
    private IFlatGuiGraphics graphics;

  }

} // namespace Nuclex.UserInterface.Visuals.Flat.Renderers