#pragma once

#ifndef TCG_MESH_BGL_H
#define TCG_MESH_BGL_H

// TCG includes
#include "mesh.h"

// Boost includes
#include <boost/graph/graph_traits.hpp>

/*
  \file     tcg_mesh_bgl.h

  \brief    This file contains TCG adapters to Boost's Graph Library (BGL).
*/

//************************************************************************************
//    boost::graph_traits to tcg::Mesh concept type
//************************************************************************************

namespace boost
{

template <typename V, typename E, typename F>
struct graph_traits<typename tcg::Mesh<V, E, F>> {
	// Preliminar typedefs
	typedef typename tcg::Mesh<V, E, F> mesh_type;
	typedef typename mesh_type::vertex_type vertex_type;
	typedef typename mesh_type::edge_type edge_type;

	typedef typename vertex_type::edges_const_iterator edge_const_iterator;

	// V/E descriptors
	typedef int vertex_descriptor;

	struct edge_descriptor // NOTE: Can't use std::pair due to std conflicts
	{
		int m_e, m_src;

		edge_descriptor() : m_e(-1), m_src(-1) {}
		edge_descriptor(int e, int src) : m_e(e), m_src(src) {}

		bool operator==(const edge_descriptor &e_d) { return m_e == e_d.m_e; } // Undirected
		bool operator!=(const edge_descriptor &e_d) { return !operator==(e_d); }
	};

	// Iterators
	struct out_edge_iterator : public edge_const_iterator {
		int m_src;

		out_edge_iterator() : edge_const_iterator(), m_src(-1) {}
		out_edge_iterator(const edge_const_iterator &it, int src)
			: edge_const_iterator(it), m_src(src) {}

		edge_descriptor operator*() const
		{
			return edge_descriptor(edge_const_iterator::operator*(), m_src);
		}
	};

	typedef typename tcg::list<vertex_type>::const_iterator vertex_iterator;
	typedef typename tcg::list<edge_type>::const_iterator edge_iterator;

	// Categories
	typedef undirected_tag directed_category;
	typedef allow_parallel_edge_tag edge_parallel_category;

	typedef struct our_category : public bidirectional_graph_tag, public vertex_list_graph_tag, public edge_list_graph_tag {
	} traversal_category;

	// Sizes
	typedef int vertices_size_type;
	typedef int edges_size_type;
	typedef int degree_size_type;

	// Functions
	static inline vertex_descriptor null_vertex() { return -1; }
};

template <typename V, typename E, typename F>
struct graph_traits<typename tcg::TriMesh<V, E, F>>
	: public graph_traits<typename tcg::Mesh<V, E, F>> {
};

} // namespace boost

//************************************************************************************
//    tcg::bgl  helpers to edge data
//************************************************************************************

namespace tcg
{
namespace bgl
{

template <typename Mesh>
inline int source(const typename boost::graph_traits<Mesh>::edge_descriptor &edge_descr, const Mesh &mesh)
{
	return edge_descr.m_src;
}

//---------------------------------------------------------------------------------------

template <typename Mesh>
inline int target(const typename boost::graph_traits<Mesh>::edge_descriptor &edge_descr, const Mesh &mesh)
{
	const typename Mesh::edge_type &ed = mesh.edge(edge_descr.m_e);
	return (ed.vertex(0) == edge_descr.m_src) ? ed.vertex(1) : ed.vertex(0);
}

//---------------------------------------------------------------------------------------

template <typename Mesh>
inline std::pair<typename boost::graph_traits<Mesh>::out_edge_iterator,
				 typename boost::graph_traits<Mesh>::out_edge_iterator>
out_edges(int v, const Mesh &mesh)
{
	typedef typename boost::graph_traits<Mesh>::out_edge_iterator out_edge_iterator;

	return make_pair(
		out_edge_iterator(mesh.vertex(v).edgesBegin(), v),
		out_edge_iterator(mesh.vertex(v).edgesEnd(), v));
}

//---------------------------------------------------------------------------------------

template <typename Mesh>
inline int out_degree(int v, const Mesh &mesh)
{
	return mesh.vertex(v).edgesCount();
}
}
} // namespace tcg::bgl

#endif // TCG_MESH_BGL_H