/*
Minetest-c55
Copyright (C) 2010 celeron55, Perttu Ahola <celeron55@gmail.com>

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 2 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, write to the Free Software Foundation, Inc.,
51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/

/*
(c) 2010 Perttu Ahola <celeron55@gmail.com>
*/

#include "heightmap.h"

// For MAP_BLOCKSIZE
#include "mapblock.h"

/*
	ValueGenerator
*/

ValueGenerator* ValueGenerator::deSerialize(std::string line)
{
	std::istringstream ss(line);
	//ss.imbue(std::locale("C"));
	
	std::string name;
	std::getline(ss, name, ' ');

	if(name == "constant")
	{
		f32 value;
		ss>>value;
		
		return new ConstantGenerator(value);
	}
	else if(name == "linear")
	{
		f32 height;
		v2f slope;

		ss>>height;
		ss>>slope.X;
		ss>>slope.Y;

		return new LinearGenerator(height, slope);
	}
	else if(name == "power")
	{
		f32 height;
		v2f slope;
		f32 power;

		ss>>height;
		ss>>slope.X;
		ss>>slope.Y;
		ss>>power;

		return new PowerGenerator(height, slope, power);
	}
	else
	{
		throw SerializationError
		("Invalid heightmap generator (deSerialize)");
	}
}

/*
	FixedHeightmap
*/

f32 FixedHeightmap::avgNeighbours(v2s16 p, s16 d)
{
	v2s16 dirs[4] = {
		v2s16(1,0),
		v2s16(0,1),
		v2s16(-1,0),
		v2s16(0,-1)
	};
	f32 sum = 0.0;
	f32 count = 0.0;
	for(u16 i=0; i<4; i++){
		v2s16 p2 = p + dirs[i] * d;
		f32 n = getGroundHeightParent(p2);
		if(n < GROUNDHEIGHT_VALID_MINVALUE)
			continue;
		sum += n;
		count += 1.0;
	}
	assert(count > 0.001);
	return sum / count;
}

f32 FixedHeightmap::avgDiagNeighbours(v2s16 p, s16 d)
{
	v2s16 dirs[4] = {
		v2s16(1,1),
		v2s16(-1,-1),
		v2s16(-1,1),
		v2s16(1,-1)
	};
	f32 sum = 0.0;
	f32 count = 0.0;
	for(u16 i=0; i<4; i++){
		v2s16 p2 = p + dirs[i] * d;
		f32 n = getGroundHeightParent(p2);
		if(n < GROUNDHEIGHT_VALID_MINVALUE)
			continue;
		sum += n;
		count += 1.0;
	}
	assert(count > 0.001);
	return sum / count;
}

/*
	Adds a point to transform into a diamond pattern
	center = Center of the diamond phase (center of a square)
	a = Side length of the existing square (2, 4, 8, ...)

	Adds the center points of the next squares to next_squares as
	dummy "true" values.
*/
void FixedHeightmap::makeDiamond(
		v2s16 center,
		s16 a,
		f32 randmax,
		core::map<v2s16, bool> &next_squares)
{
	/*dstream<<"makeDiamond(): center="
			<<"("<<center.X<<","<<center.Y<<")"
			<<", a="<<a<<", randmax="<<randmax
			<<", next_squares.size()="<<next_squares.size()
			<<std::endl;*/

	f32 n = avgDiagNeighbours(center, a/2);
	// Add (-1.0...1.0) * randmax
	n += ((float)myrand() / (float)(MYRAND_MAX/2) - 1.0)*randmax;
	bool worked = setGroundHeightParent(center, n);
	
	if(a >= 2 && worked)
	{
		next_squares[center + a/2*v2s16(-1,0)] = true;
		next_squares[center + a/2*v2s16(1,0)] = true;
		next_squares[center + a/2*v2s16(0,-1)] = true;
		next_squares[center + a/2*v2s16(0,1)] = true;
	}
}

/*
	Adds a point to transform into a square pattern
	center = The point that is added. The center of a diamond.
	a = Diameter of the existing diamond. (2, 4, 8, 16, ...)

	Adds center points of the next diamonds to next_diamonds.
*/
void FixedHeightmap::makeSquare(
		v2s16 center,
		s16 a,
		f32 randmax,
		core::map<v2s16, bool> &next_diamonds)
{
	/*dstream<<"makeSquare(): center="
			<<"("<<center.X<<","<<center.Y<<")"
			<<", a="<<a<<", randmax="<<randmax
			<<", next_diamonds.size()="<<next_diamonds.size()
			<<std::endl;*/

	f32 n = avgNeighbours(center, a/2);
	// Add (-1.0...1.0) * randmax
	n += ((float)myrand() / (float)(MYRAND_MAX/2) - 1.0)*randmax;
	bool worked = setGroundHeightParent(center, n);
	
	if(a >= 4 && worked)
	{
		next_diamonds[center + a/4*v2s16(1,1)] = true;
		next_diamonds[center + a/4*v2s16(-1,1)] = true;
		next_diamonds[center + a/4*v2s16(-1,-1)] = true;
		next_diamonds[center + a/4*v2s16(1,-1)] = true;
	}
}