/*
 * KiRouter - a push-and-(sometimes-)shove PCB router
 *
 * Copyright (C) 2013  CERN
 * Author: Tomasz Wlostowski <tomasz.wlostowski@cern.ch>
 * 
 * This program is free software: you can redistribute it and/or modify it
 * under the terms of the GNU General Public License as published by the
 * Free Software Foundation, either version 3 of the License, or (at your
 * option) any later version.
 * 
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * General Public License for more details.
 * 
 * You should have received a copy of the GNU General Public License along
 * with this program.  If not, see <http://www.gnu.or/licenses/>.
 */

#ifndef __PNS_JOINT_H
#define __PNS_JOINT_H

#include <vector>
#include <boost/functional/hash.hpp>

#include <math/vector2d.h>

#include "pns_item.h"
#include "pns_segment.h"

/**
 * Class PNS_JOINT
 * 
 * Represents a 2D point on a given set of layers and belonging to a certain net,
 * that links together a number of board items.
 * A hash table of joints is used by the router to follow connectivity between the items.
 **/

class PNS_JOINT : public PNS_ITEM
{
public:
	typedef std::vector<PNS_ITEM *> LinkedItems;

	///> joints are hashed by their position, layers and net. Linked items are, obviously, not hashed
	struct HashTag {
		VECTOR2I pos;
		int net;
	};
	
	PNS_JOINT():
		PNS_ITEM(JOINT) {}

	PNS_JOINT(const VECTOR2I& aPos, const PNS_LAYERSET& aLayers, int aNet = -1):
		PNS_ITEM(JOINT)
	{
		m_tag.pos = aPos;
		m_tag.net = aNet;
		m_layers = aLayers;
	}

	PNS_JOINT(const PNS_JOINT& b): 
		PNS_ITEM(JOINT)
	{
		m_layers = b.m_layers;
		m_tag.pos = b.m_tag.pos;
		m_tag.net = b.m_tag.net;
		m_linkedItems = b.m_linkedItems;
		m_layers = b.m_layers;
	}

	PNS_ITEM *Clone() const
	{
		assert(false);
		return NULL;
	}

	///> returns true if the joint is a trivial line corner, connecting two segments of the same net, on the same layer.
	bool IsLineCorner() const
	{
		if(m_linkedItems.size() != 2)
			return false;

		if( m_linkedItems[0]->GetKind() != SEGMENT || m_linkedItems[1]->GetKind() != SEGMENT )
			return false;

		PNS_SEGMENT *seg1 = static_cast<PNS_SEGMENT *> (m_linkedItems[0]);
		PNS_SEGMENT *seg2 = static_cast<PNS_SEGMENT *> (m_linkedItems[1]);

		// joints between segments of different widths are not trivial.
		return (seg1->GetWidth() == seg2->GetWidth());
	}

	///> Links the joint to a given board item (when it's added to the PNS_NODE)
	void Link ( PNS_ITEM *aItem )
	{
		LinkedItems::iterator f = std::find(m_linkedItems.begin(), m_linkedItems.end(), aItem);
		if(f != m_linkedItems.end())
			return;
		m_linkedItems.push_back(aItem);
	}

	///> Unlinks a given board item from the joint (upon its removal from a PNS_NODE)
	///> Returns true if the joint became dangling after unlinking.
	bool Unlink ( PNS_ITEM *aItem )
	{
		LinkedItems::iterator f = std::find(m_linkedItems.begin(), m_linkedItems.end(), aItem);
		if(f != m_linkedItems.end())
			m_linkedItems.erase(f);
		return (m_linkedItems.size() == 0);
	}

	///> For trivial joints, returns the segment adjacent to (aCurrent). For non-trival ones, returns 
	///> NULL, indicating the end of line.
	PNS_SEGMENT* NextSegment( PNS_SEGMENT* aCurrent) const
	{
		if(!IsLineCorner())
			return NULL;
		
		return static_cast<PNS_SEGMENT *> (m_linkedItems [ m_linkedItems[0] == aCurrent ? 1 : 0 ] );
	}

	/// trivial accessors	
	const HashTag& GetTag() const 	{ return m_tag; }
	const VECTOR2I& GetPos() const 	{ return m_tag.pos; }
	int GetNet() const 				{ return m_tag.net; }
	LinkedItems & GetLinkList() 	{ return m_linkedItems; };

	///> Returns the number of linked items of types listed in aMask.
	int LinkCount( int aMask = -1 ) const
	{
		int n = 0;
		for(LinkedItems::const_iterator i = m_linkedItems.begin(); i!= m_linkedItems.end(); ++i)
			if( (*i)->GetKind() & aMask )
				n++;
		return n;
	}

	void Dump() const;
	
	bool operator==(const PNS_JOINT& rhs)  const
	{
		return m_tag.pos == rhs.m_tag.pos && m_tag.net == rhs.m_tag.net;
	}

	void Merge( const PNS_JOINT& aJoint )
	{
		if(!Overlaps(aJoint))
			return;
		
		m_layers.Merge (aJoint.m_layers);

		// fixme: duplicate links (?)
		for(LinkedItems::const_iterator i =aJoint.m_linkedItems.begin(); i!=aJoint.m_linkedItems.end();++i)
			m_linkedItems.push_back(*i);
	}

	bool Overlaps(const PNS_JOINT& rhs) const
	{
		return m_tag.pos == rhs.m_tag.pos && m_tag.net == rhs.m_tag.net && m_layers.Overlaps(rhs.m_layers);
	}

private:

	///> hash tag for unordered_multimap
	HashTag m_tag;

	///> list of items linked to this joint
	LinkedItems m_linkedItems;
};


// hash function & comparison operator for boost::unordered_map<>
inline bool operator==(PNS_JOINT::HashTag const& p1, PNS_JOINT::HashTag const& p2)
{
    return p1.pos == p2.pos && p1.net == p2.net;
}

inline std::size_t hash_value(PNS_JOINT::HashTag const& p) 
{
    std::size_t seed = 0;
    boost::hash_combine(seed, p.pos.x);
    boost::hash_combine(seed, p.pos.y);
    boost::hash_combine(seed, p.net);
    return seed;
}

#endif // __PNS_JOINT_H