/**********************************************************************
 * LeechCraft - modular cross-platform feature rich internet client.
 * Copyright (C) 2006-2014  Georg Rudoy
 *
 * Boost Software License - Version 1.0 - August 17th, 2003
 *
 * Permission is hereby granted, free of charge, to any person or organization
 * obtaining a copy of the software and accompanying documentation covered by
 * this license (the "Software") to use, reproduce, display, distribute,
 * execute, and transmit the Software, and to prepare derivative works of the
 * Software, and to permit third-parties to whom the Software is furnished to
 * do so, all subject to the following:
 *
 * The copyright notices in the Software and this entire statement, including
 * the above license grant, this restriction and the following disclaimer,
 * must be included in all copies of the Software, in whole or in part, and
 * all derivative works of the Software, unless such copies or derivative
 * works are solely in the form of machine-executable object code generated by
 * a source language processor.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE, TITLE AND NON-INFRINGEMENT. IN NO EVENT
 * SHALL THE COPYRIGHT HOLDERS OR ANYONE DISTRIBUTING THE SOFTWARE BE LIABLE
 * FOR ANY DAMAGES OR OTHER LIABILITY, WHETHER IN CONTRACT, TORT OR OTHERWISE,
 * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
 * DEALINGS IN THE SOFTWARE.
 **********************************************************************/

#pragma once

#include <boost/iterator.hpp>
#include <boost/iterator/function_input_iterator.hpp>
#include <boost/range.hpp>
#include <QDomElement>
#include <QString>

namespace LeechCraft
{
namespace Util
{
	namespace detail
	{
		class DomSiblingsIterator : public boost::iterator_facade<
				DomSiblingsIterator,
				QDomElement,
				boost::single_pass_traversal_tag,
				const QDomElement&
			>
		{
			QDomElement Elem_;
			const QString TagName_;
		public:
			DomSiblingsIterator () = default;

			DomSiblingsIterator (const QDomElement& firstChild, const QString& tagName)
			: Elem_ { firstChild }
			, TagName_ { tagName }
			{
			}

			void increment ()
			{
				Elem_ = Elem_.nextSiblingElement (TagName_);
			}

			const QDomElement& dereference () const
			{
				return Elem_;
			}

			bool equal (const DomSiblingsIterator& other) const
			{
				return Elem_ == other.Elem_;
			}
		};
	}

	/** @brief Creates a range iterating over direct children named \em tag.
	 *
	 * The returned range is suitable for range-based for loops, in particular. For instance, the
	 * following is correct:
	 * \code{.cpp}
	 	QDomDocument doc;
	 	doc.setContent (R"(
	 				<root>
	 					<child num="1">first text</child>
	 					<child num="2">second text</child>
	 					<child num="3">third text</child>
	 				</root>
	 			)");

	 	for (const auto& elem : MakeDomSiblingsRange (doc.firstChildElement ("root"), "child"))
	 		qDebug () << elem.text () << elem.attribute ("num");
	   \endcode
	 *
	 * Modifying the underlying DOM tree will result in the same effects as modifying it during the
	 * canonical Qt-way of repeatedly calling <code>QDomElement::nextSiblingElement()</code> until
	 * the element becomes null.
	 *
	 * @param parent The parent element whose children should be iterated over.
	 * @param tag The tag name of the child nodes (or an empty string for .
	 * @return The range object representing the collection of the child nodes.
	 */
	auto MakeDomChildrenRange (const QDomElement& parent, const QString& tag)
	{
		auto child = parent.firstChildElement (tag);
		return boost::make_iterator_range<detail::DomSiblingsIterator> ({ child, tag }, {});
	}
}
}
