// Copyright (C) 2012-2013 ChaosForge / Kornel Kisielewicz
// http://chaosforge.org/
//
// This file is part of NV Libraries.
// For conditions of distribution and use, see copyright notice in nv.hh

#include "nv/gl/texture_atlas.hh"

#include "nv/logging.hh"
#include <iostream>

using namespace nv;

texture_atlas::texture_atlas( glm::ivec2 size, size_t depth )
	: image( size, depth ), m_used( 0 )
{
	m_nodes.push_back( glm::ivec3( 1, 1, m_size.x - 2 ) );
	fill( 0 );
}

region texture_atlas::get_region( glm::ivec2 size )
{
	region r ( glm::ivec2(0,0), size );

	int best_height = INT_MAX;
	int best_index  = -1;
	int best_width  = INT_MAX;
	std::cout << "The size is: " << m_nodes.size() << std::endl;
	for( size_t i=0; i < m_nodes.size(); ++i )
	{
		int y = fit( i, size );
		if( y >= 0 )
		{
			glm::ivec3 node = m_nodes[ i ];
			if ( ( (y + size.y) < best_height ) ||
				( ((y + size.y) == best_height) && (node.z < best_width)) )
			{
				best_height = y + size.y;
				best_index = i;
				best_width = node.z;
				r.pos.x = node.x;
				r.pos.y = y;
			}
		}
	}
   
	if ( best_index == -1 )
	{
		return region( glm::ivec2( -1, -1 ), glm::ivec2( 0, 0 ) );
	}

	m_nodes.insert( m_nodes.begin() + best_index, glm::ivec3( r.pos.x, r.pos.y + size.y, size.x ) );

	for( size_t i = best_index+1; i < m_nodes.size(); ++i )
	{
		glm::ivec3 node = m_nodes[ i ];
		glm::ivec3 prev = m_nodes[ i-1 ];

		if (node.x < (prev.x + prev.z) )
		{
			int shrink = prev.x + prev.z - node.x;
			m_nodes[ i ].x += shrink;
			m_nodes[ i ].z -= shrink;

			if (m_nodes[ i ].z <= 0)
			{
				m_nodes.erase( m_nodes.begin() + i );
				--i;
			}
			else
			{
				break;
			}
		}
		else
		{
			break;
		}
	}
	merge();
	m_used += size.x * size.y;
	return r;
}

int texture_atlas::fit( size_t index, glm::ivec2 size )
{
	glm::ivec3 node = m_nodes[ index ];

	if ( (  node.x + size.x ) > ( m_size.x - 1 ) ) 
	{
		return -1;
	}

	int y     = node.y;
	int wleft = size.x;

	while( wleft > 0 )
	{
		node = m_nodes[ index ];
		if( node.y > y )
		{
			y = node.y;
		}
		if( (y + size.y) > (m_size.y-1) )
		{
			return -1;
		}
		wleft -= node.z;
		++index;
	}
	return y;
}

void texture_atlas::merge()
{
	for( size_t i=0; i < m_nodes.size()-1; ++i )
    {
		if( m_nodes[ i ].y == m_nodes[ i+1 ].y )
		{
			m_nodes[ i ].z += m_nodes[ i+1 ].z;
            m_nodes.erase( m_nodes.begin()+i+1 );
			--i;
		}
    }
}

void texture_atlas::clear()
{
	m_nodes.clear();
	m_used = 0;
	m_nodes.push_back( glm::ivec3( 1, 1, m_size.x - 2 ) );
	fill( 0 );
}