/* -*- 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 "JoinNodeTransaction.h"

#include "mozilla/EditorBase.h"  // for EditorBase
#include "nsAString.h"
#include "nsDebug.h"              // for NS_ASSERTION, etc.
#include "nsError.h"              // for NS_ERROR_NULL_POINTER, etc.
#include "nsIContent.h"           // for nsIContent
#include "nsIDOMCharacterData.h"  // for nsIDOMCharacterData
#include "nsIEditor.h"            // for EditorBase::IsModifiableNode
#include "nsISupportsImpl.h"      // for QueryInterface, etc.

namespace mozilla {

using namespace dom;

// static
already_AddRefed<JoinNodeTransaction> JoinNodeTransaction::MaybeCreate(
    EditorBase& aEditorBase, nsINode& aLeftNode, nsINode& aRightNode) {
  RefPtr<JoinNodeTransaction> transaction =
      new JoinNodeTransaction(aEditorBase, aLeftNode, aRightNode);
  if (NS_WARN_IF(!transaction->CanDoIt())) {
    return nullptr;
  }
  return transaction.forget();
}

JoinNodeTransaction::JoinNodeTransaction(EditorBase& aEditorBase,
                                         nsINode& aLeftNode,
                                         nsINode& aRightNode)
    : mEditorBase(&aEditorBase),
      mLeftNode(&aLeftNode),
      mRightNode(&aRightNode),
      mOffset(0) {}

NS_IMPL_CYCLE_COLLECTION_INHERITED(JoinNodeTransaction, EditTransactionBase,
                                   mEditorBase, mLeftNode, mRightNode, mParent)

NS_INTERFACE_MAP_BEGIN_CYCLE_COLLECTION(JoinNodeTransaction)
NS_INTERFACE_MAP_END_INHERITING(EditTransactionBase)

bool JoinNodeTransaction::CanDoIt() const {
  if (NS_WARN_IF(!mLeftNode) || NS_WARN_IF(!mRightNode) ||
      NS_WARN_IF(!mEditorBase) || !mLeftNode->GetParentNode()) {
    return false;
  }
  return mEditorBase->IsModifiableNode(mLeftNode->GetParentNode());
}

// After DoTransaction() and RedoTransaction(), the left node is removed from
// the content tree and right node remains.
NS_IMETHODIMP
JoinNodeTransaction::DoTransaction() {
  if (NS_WARN_IF(!mEditorBase) || NS_WARN_IF(!mLeftNode) ||
      NS_WARN_IF(!mRightNode)) {
    return NS_ERROR_NOT_INITIALIZED;
  }

  // Get the parent node
  nsCOMPtr<nsINode> leftParent = mLeftNode->GetParentNode();
  NS_ENSURE_TRUE(leftParent, NS_ERROR_NULL_POINTER);

  // Verify that mLeftNode and mRightNode have the same parent
  if (leftParent != mRightNode->GetParentNode()) {
    NS_ASSERTION(false, "Nodes do not have same parent");
    return NS_ERROR_INVALID_ARG;
  }

  // Set this instance's mParent.  Other methods will see a non-null mParent
  // and know all is well
  mParent = leftParent;
  mOffset = mLeftNode->Length();

  return mEditorBase->JoinNodesImpl(mRightNode, mLeftNode, mParent);
}

// XXX: What if instead of split, we just deleted the unneeded children of
//     mRight and re-inserted mLeft?
NS_IMETHODIMP
JoinNodeTransaction::UndoTransaction() {
  if (NS_WARN_IF(!mParent) || NS_WARN_IF(!mLeftNode) ||
      NS_WARN_IF(!mRightNode)) {
    return NS_ERROR_NOT_INITIALIZED;
  }

  // First, massage the existing node so it is in its post-split state
  ErrorResult rv;
  if (mRightNode->GetAsText()) {
    rv = mRightNode->GetAsText()->DeleteData(0, mOffset);
  } else {
    nsCOMPtr<nsIContent> child = mRightNode->GetFirstChild();
    for (uint32_t i = 0; i < mOffset; i++) {
      if (rv.Failed()) {
        return rv.StealNSResult();
      }
      if (!child) {
        return NS_ERROR_NULL_POINTER;
      }
      nsCOMPtr<nsIContent> nextSibling = child->GetNextSibling();
      mLeftNode->AppendChild(*child, rv);
      child = nextSibling;
    }
  }
  // Second, re-insert the left node into the tree
  nsCOMPtr<nsINode> refNode = mRightNode;
  mParent->InsertBefore(*mLeftNode, refNode, rv);
  return rv.StealNSResult();
}

}  // namespace mozilla