/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*-
 *
 * The contents of this file are subject to the Netscape Public License
 * Version 1.0 (the "NPL"); you may not use this file except in
 * compliance with the NPL.  You may obtain a copy of the NPL at
 * http://www.mozilla.org/NPL/
 *
 * Software distributed under the NPL is distributed on an "AS IS" basis,
 * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the NPL
 * for the specific language governing rights and limitations under the
 * NPL.
 *
 * The Initial Developer of this code under the NPL is Netscape
 * Communications Corporation.  Portions created by Netscape are
 * Copyright (C) 1998 Netscape Communications Corporation.  All Rights
 * Reserved.
 */
#include "nsCOMPtr.h"
#include "nsHTMLParts.h"
#include "nsIHTMLContent.h"
#include "nsLeafFrame.h"
#include "nsIRenderingContext.h"
#include "nsIStyleContext.h"
#include "nsColor.h"
#include "nsIPresContext.h"
#include "nsIStyleContext.h"
#include "nsHTMLIIDs.h"
#include "nsHTMLAtoms.h"
#include "nsIFontMetrics.h"
#include "nsIHTMLAttributes.h"
#include "nsStyleConsts.h"
#include "nsCSSRendering.h"
#include "nsIDOMHTMLHRElement.h"
#include "nsIDeviceContext.h"
#include "nsStyleUtil.h"

static NS_DEFINE_IID(kIDOMHTMLHRElementIID, NS_IDOMHTMLHRELEMENT_IID);

// default hr thickness in pixels
#define DEFAULT_THICKNESS 3

class HRuleFrame : public nsFrame {
public:
  HRuleFrame();

  NS_IMETHOD Reflow(nsIPresContext& aPresContext,
                    nsHTMLReflowMetrics& aDesiredSize,
                    const nsHTMLReflowState& aReflowState,
                    nsReflowStatus& aStatus);
  NS_IMETHOD Paint(nsIPresContext& aPresContext,
                   nsIRenderingContext& aRenderingContext,
                   const nsRect& aDirtyRect,
                   nsFramePaintLayer aWhichLayer);

protected:
  PRBool GetNoShade();

  nsMargin mBorderPadding;
  nscoord mThickness;
};

nsresult
NS_NewHRFrame(nsIFrame** aNewFrame)
{
  NS_PRECONDITION(aNewFrame, "null OUT ptr");
  if (nsnull == aNewFrame) {
    return NS_ERROR_NULL_POINTER;
  }
  HRuleFrame* it = new HRuleFrame;
  if (nsnull == it) {
    return NS_ERROR_OUT_OF_MEMORY;
  }
  *aNewFrame = it;
  return NS_OK;
}

HRuleFrame::HRuleFrame()
{
}

NS_METHOD
HRuleFrame::Paint(nsIPresContext&      aPresContext,
                  nsIRenderingContext& aRenderingContext,
                  const nsRect&        aDirtyRect,
                  nsFramePaintLayer    aWhichLayer)
{
  if (NS_FRAME_PAINT_LAYER_FOREGROUND != aWhichLayer) {
    return NS_OK;
  }

  const nsStyleDisplay* disp =
    (const nsStyleDisplay*)mStyleContext->GetStyleData(eStyleStruct_Display);
  if (!disp->mVisible) {
    return NS_OK;
  }

  float p2t;
  aPresContext.GetScaledPixelsToTwips(&p2t);
  nscoord thickness = mThickness;

  // Get style data
  nscoord x0 = mBorderPadding.left;
  nscoord y0 = mBorderPadding.top;
  nscoord width = mRect.width -
    (mBorderPadding.left + mBorderPadding.right);
  nscoord height = mRect.height -
    (mBorderPadding.top + mBorderPadding.bottom);

  // Center hrule vertically within the available space
  y0 += (height - thickness) / 2;
  height = thickness;

  // To shade or not to shade, that is the question. Begin by collecting the
  // three decision criteria: rendering to the printer or the display, is the
  // "Beveled Lines" checkbox set in the page setup dialog, and does the tag
  // have the NOSHADE attribute set.
	PRBool noShadeAttribute = GetNoShade();

  // Now that we have the data to make the shading criteria, we next
  // collect the decision criteria for rending in solid black:
  // printing (which we already have) and the "Black Lines" setting in
  // the page setup dialog

  const nsStyleColor* color;
  // Draw a "shadowed" box around the rule area
  if (!noShadeAttribute) {
    nsRect rect(x0, y0, width, height);

    const nsStyleSpacing* spacing = 
      (nsStyleSpacing*)mStyleContext->GetStyleData(eStyleStruct_Spacing);
    color = (nsStyleColor*)mStyleContext->GetStyleData(eStyleStruct_Color);
    
    nsCSSRendering::PaintBackground(aPresContext, aRenderingContext,
                                    this,aDirtyRect, rect, *color, 
                                    *spacing, 0, 0);
    nsCSSRendering::PaintBorder(aPresContext, aRenderingContext,
                                this,aDirtyRect, rect, *spacing,
                                mStyleContext, 0);
  } else {
    nscolor colors[2]; 
    // Get the background color that applies to this HR 
    color = nsStyleUtil::FindNonTransparentBackground(mStyleContext); 
    NS_Get3DColors(colors, color->mBackgroundColor); 

    // When a rule is not shaded, then we use a uniform color and
    // draw half-circles on the end points.
    aRenderingContext.SetColor (colors[0]);
    nscoord diameter = height;
    if ((diameter > width) || (diameter < NSIntPixelsToTwips(3, p2t))) {
      // The half-circles on the ends of the rule aren't going to
      // look right so don't bother drawing them.
      aRenderingContext.FillRect(x0, y0, width, height);
    } else {
      aRenderingContext.FillArc(x0, y0, diameter, diameter, 90.0f, 270.0f);
      aRenderingContext.FillArc(x0 + width - diameter, y0,
                                diameter, diameter, 270.0f, 180.0f);
      aRenderingContext.FillRect(x0 + diameter/2, y0,
                                 width - diameter, height);
     }
  }
  return nsFrame::Paint(aPresContext, aRenderingContext, aDirtyRect, aWhichLayer);
}

NS_IMETHODIMP
HRuleFrame::Reflow(nsIPresContext&          aPresContext,
                   nsHTMLReflowMetrics&     aDesiredSize,
                   const nsHTMLReflowState& aReflowState,
                   nsReflowStatus&          aStatus)
{
  NS_PRECONDITION(mState & NS_FRAME_IN_REFLOW, "frame is not in reflow");

  // Compute the width
  float p2t;
  aPresContext.GetScaledPixelsToTwips(&p2t);
  if (NS_UNCONSTRAINEDSIZE != aReflowState.mComputedWidth) {
    aDesiredSize.width = aReflowState.mComputedWidth;
  }
  else {
    if (NS_UNCONSTRAINEDSIZE == aReflowState.availableWidth) {
      aDesiredSize.width = nscoord(p2t);
    }
    else {
      aDesiredSize.width = aReflowState.availableWidth;
    }
  }
  aDesiredSize.width += aReflowState.mComputedBorderPadding.left +
    aReflowState.mComputedBorderPadding.right;

  // Get the thickness of the rule. Note that this specifies the
  // height of the rule, not the height of the frame.
  nscoord thickness;
  if (NS_UNCONSTRAINEDSIZE != aReflowState.mComputedHeight) {
    thickness = aReflowState.mComputedHeight;
  }
  else {
    thickness = NSIntPixelsToTwips(DEFAULT_THICKNESS, p2t);
  }
  mThickness = thickness;

  // Compute height of "line" that hrule will layout within. Use the
  // font-size to do this.
  nscoord minLineHeight = thickness + NSIntPixelsToTwips(2, p2t);
  const nsStyleFont* font;
  GetStyleData(eStyleStruct_Font, (const nsStyleStruct*&) font);
  const nsFont& f = font->mFont;
  nsCOMPtr<nsIFontMetrics> fm;
  aPresContext.GetMetricsFor(f, getter_AddRefs(fm));
  nscoord fontHeight;
  fm->GetHeight(fontHeight);

  aDesiredSize.height =
    (minLineHeight < fontHeight ? fontHeight : minLineHeight) +
    aReflowState.mComputedBorderPadding.top +
    aReflowState.mComputedBorderPadding.bottom;
  aDesiredSize.ascent = aDesiredSize.height;
  aDesiredSize.descent = 0;

  // HR's do not impact the max-element-size, unless a width is
  // specified otherwise tables behave badly. This makes sense -- they
  // are springy.
  if (nsnull != aDesiredSize.maxElementSize) {
    nscoord onePixel = NSIntPixelsToTwips(1, p2t);
    if (NS_UNCONSTRAINEDSIZE != aReflowState.mComputedWidth) {
      if (eStyleUnit_Percent ==
          aReflowState.mStylePosition->mWidth.GetUnit()) {
        // When the HR is using a percentage width, make sure it
        // remains springy.
        aDesiredSize.maxElementSize->width = onePixel;
      }
      else {
        aDesiredSize.maxElementSize->width = aReflowState.mComputedWidth;
      }
    }
    else {
      aDesiredSize.maxElementSize->width = onePixel;
    }
    aDesiredSize.maxElementSize->height = aDesiredSize.height;
  }

  aStatus = NS_FRAME_COMPLETE;
  return NS_OK;
}

PRBool
HRuleFrame::GetNoShade()
{
  PRBool result = PR_FALSE;
  nsIDOMHTMLHRElement* hr = nsnull;
  mContent->QueryInterface(kIDOMHTMLHRElementIID, (void**) &hr);
  if (nsnull != hr) {
    hr->GetNoShade(&result);
    NS_RELEASE(hr);
  }
  return result;
}