/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

#include "nsCOMPtr.h"
#include "nsPIListBoxObject.h"
#include "nsBoxObject.h"
#include "nsIFrame.h"
#include "nsBindingManager.h"
#include "nsIDOMElement.h"
#include "nsIDOMNodeList.h"
#include "nsGkAtoms.h"
#include "nsIScrollableFrame.h"
#include "nsListBoxBodyFrame.h"
#include "ChildIterator.h"

class nsListBoxObject : public nsPIListBoxObject, public nsBoxObject
{
public:
  NS_DECL_ISUPPORTS_INHERITED
  NS_DECL_NSILISTBOXOBJECT

  // nsPIListBoxObject
  virtual nsListBoxBodyFrame* GetListBoxBody(bool aFlush) MOZ_OVERRIDE;

  nsListBoxObject();

  // nsPIBoxObject
  virtual void Clear() MOZ_OVERRIDE;
  virtual void ClearCachedValues() MOZ_OVERRIDE;
  
protected:
  nsListBoxBodyFrame *mListBoxBody;
};

NS_IMPL_ISUPPORTS_INHERITED(nsListBoxObject, nsBoxObject, nsIListBoxObject,
                            nsPIListBoxObject)

nsListBoxObject::nsListBoxObject()
  : mListBoxBody(nullptr)
{
}

//////////////////////////////////////////////////////////////////////////
//// nsIListBoxObject

NS_IMETHODIMP
nsListBoxObject::GetRowCount(int32_t *aResult)
{
  nsListBoxBodyFrame* body = GetListBoxBody(true);
  if (body)
    return body->GetRowCount(aResult);
  return NS_OK;
}

NS_IMETHODIMP
nsListBoxObject::GetNumberOfVisibleRows(int32_t *aResult)
{
  nsListBoxBodyFrame* body = GetListBoxBody(true);
  if (body)
    return body->GetNumberOfVisibleRows(aResult);
  return NS_OK;
}

NS_IMETHODIMP
nsListBoxObject::GetIndexOfFirstVisibleRow(int32_t *aResult)
{
  nsListBoxBodyFrame* body = GetListBoxBody(true);
  if (body)
    return body->GetIndexOfFirstVisibleRow(aResult);
  return NS_OK;
}

NS_IMETHODIMP nsListBoxObject::EnsureIndexIsVisible(int32_t aRowIndex)
{
  nsListBoxBodyFrame* body = GetListBoxBody(true);
  if (body)
    return body->EnsureIndexIsVisible(aRowIndex);
  return NS_OK;
}

NS_IMETHODIMP
nsListBoxObject::ScrollToIndex(int32_t aRowIndex)
{
  nsListBoxBodyFrame* body = GetListBoxBody(true);
  if (body)
    return body->ScrollToIndex(aRowIndex);
  return NS_OK;
}

NS_IMETHODIMP
nsListBoxObject::ScrollByLines(int32_t aNumLines)
{
  nsListBoxBodyFrame* body = GetListBoxBody(true);
  if (body)
    return body->ScrollByLines(aNumLines);
  return NS_OK;
}

NS_IMETHODIMP
nsListBoxObject::GetItemAtIndex(int32_t index, nsIDOMElement **_retval)
{
  nsListBoxBodyFrame* body = GetListBoxBody(true);
  if (body)
    return body->GetItemAtIndex(index, _retval);
  return NS_OK;
}

NS_IMETHODIMP
nsListBoxObject::GetIndexOfItem(nsIDOMElement* aElement, int32_t *aResult)
{
  *aResult = 0;

  nsListBoxBodyFrame* body = GetListBoxBody(true);
  if (body)
    return body->GetIndexOfItem(aElement, aResult);
  return NS_OK;
}

//////////////////////

static nsIContent*
FindBodyContent(nsIContent* aParent)
{
  if (aParent->Tag() == nsGkAtoms::listboxbody) {
    return aParent;
  }

  mozilla::dom::FlattenedChildIterator iter(aParent);
  for (nsIContent* child = iter.GetNextChild(); child; child = iter.GetNextChild()) {
    nsIContent* result = FindBodyContent(child);
    if (result) {
      return result;
    }
  }

  return nullptr;
}

nsListBoxBodyFrame*
nsListBoxObject::GetListBoxBody(bool aFlush)
{
  if (mListBoxBody) {
    return mListBoxBody;
  }

  nsIPresShell* shell = GetPresShell(false);
  if (!shell) {
    return nullptr;
  }

  nsIFrame* frame = aFlush ? 
                      GetFrame(false) /* does Flush_Frames */ :
                      mContent->GetPrimaryFrame();
  if (!frame)
    return nullptr;

  // Iterate over our content model children looking for the body.
  nsCOMPtr<nsIContent> content = FindBodyContent(frame->GetContent());

  if (!content)
    return nullptr;

  // this frame will be a nsGFXScrollFrame
  frame = content->GetPrimaryFrame();
  if (!frame)
     return nullptr;
  nsIScrollableFrame* scrollFrame = do_QueryFrame(frame);
  if (!scrollFrame)
    return nullptr;

  // this frame will be the one we want
  nsIFrame* yeahBaby = scrollFrame->GetScrolledFrame();
  if (!yeahBaby)
     return nullptr;

  // It's a frame. Refcounts are irrelevant.
  nsListBoxBodyFrame* listBoxBody = do_QueryFrame(yeahBaby);
  NS_ENSURE_TRUE(listBoxBody &&
                 listBoxBody->SetBoxObject(this),
                 nullptr);
  mListBoxBody = listBoxBody;
  return mListBoxBody;
}

void
nsListBoxObject::Clear()
{
  ClearCachedValues();

  nsBoxObject::Clear();
}

void
nsListBoxObject::ClearCachedValues()
{
  mListBoxBody = nullptr;
}

// Creation Routine ///////////////////////////////////////////////////////////////////////

nsresult
NS_NewListBoxObject(nsIBoxObject** aResult)
{
  *aResult = new nsListBoxObject;
  if (!*aResult)
    return NS_ERROR_OUT_OF_MEMORY;
  NS_ADDREF(*aResult);
  return NS_OK;
}