// Build a cloud layer based on metar
//
// Written by Harald JOHNSEN, started April 2005.
//
// Copyright (C) 2005  Harald JOHNSEN - hjohnsen@evc.net
//
// 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.
//
//

#ifdef HAVE_CONFIG_H
#  include "config.h"
#endif

#include <Main/fg_props.hxx>

#include <simgear/constants.h>
#include <simgear/sound/soundmgr_openal.hxx>
#include <simgear/scene/sky/sky.hxx>
#include <simgear/environment/visual_enviro.hxx>
#include <simgear/scene/sky/cloudfield.hxx>
#include <simgear/scene/sky/newcloud.hxx>
#include <simgear/math/sg_random.h>
#include <simgear/props/props_io.hxx>

#include <Main/globals.hxx>
#include <Airports/simple.hxx>
#include <Main/util.hxx>

#include "fgclouds.hxx"

extern SGSky *thesky;


FGClouds::FGClouds() :
    snd_lightning(0),
    clouds_3d_enabled(false)
{
	update_event = 0;
}

FGClouds::~FGClouds() {
}

int FGClouds::get_update_event(void) const {
	return update_event;
}

void FGClouds::set_update_event(int count) {
	update_event = count;
	buildCloudLayers();
}

void FGClouds::init(void) {
	if( snd_lightning == NULL ) {
		snd_lightning = new SGSoundSample(globals->get_fg_root().c_str(), "Sounds/thunder.wav");
		snd_lightning->set_max_dist(7000.0f);
		snd_lightning->set_reference_dist(3000.0f);
		SGSoundMgr *smgr = (SGSoundMgr *)globals->get_subsystem("soundmgr");
		SGSampleGroup *sgr = smgr->find("weather", true);
		sgr->add( snd_lightning, "thunder" );
		sgEnviro.set_sampleGroup( sgr );
	}
}

void FGClouds::buildCloud(SGPropertyNode *cloud_def_root, SGPropertyNode *box_def_root, const string& name, sgVec3 pos, SGCloudField *layer) {
	SGPropertyNode *box_def=NULL;
	SGPropertyNode *cld_def=NULL;

	SGPath texture_root = globals->get_fg_root();
	texture_root.append("Textures");
	texture_root.append("Sky");

	box_def = box_def_root->getChild(name.c_str());
  
	string base_name = name.substr(0,2);
	if( !box_def ) {
		if( name[2] == '-' ) {
			box_def = box_def_root->getChild(base_name.c_str());
		}
		if( !box_def )
			return;
	}
        
	for(int i = 0; i < box_def->nChildren() ; i++) {
		SGPropertyNode *abox = box_def->getChild(i);
		if( strcmp(abox->getName(), "box") == 0) {
			double x = abox->getDoubleValue("x") + pos[0];
			double y = abox->getDoubleValue("y") + pos[1];
			double z = abox->getDoubleValue("z") + pos[2];
			SGVec3f newpos = SGVec3f(x, z, y);
                        
			string type = abox->getStringValue("type", "cu-small");
                               
			cld_def = cloud_def_root->getChild(type.c_str());
			if ( !cld_def ) return;
                        
			double min_width = cld_def->getDoubleValue("min-cloud-width-m", 500.0);
			double max_width = cld_def->getDoubleValue("max-cloud-width-m", 1000.0);
			double min_height = cld_def->getDoubleValue("min-cloud-height-m", min_width);
			double max_height = cld_def->getDoubleValue("max-cloud-height-m", max_width);
			double min_sprite_width = cld_def->getDoubleValue("min-sprite-width-m", 200.0);
			double max_sprite_width = cld_def->getDoubleValue("max-sprite-width-m", min_sprite_width);
			double min_sprite_height = cld_def->getDoubleValue("min-sprite-height-m", min_sprite_width);
			double max_sprite_height = cld_def->getDoubleValue("max-sprite-height-m", max_sprite_width);
			int num_sprites = cld_def->getIntValue("num-sprites", 20);
			int num_textures_x = cld_def->getIntValue("num-textures-x", 1);
			int num_textures_y = cld_def->getIntValue("num-textures-y", 1);
			double bottom_shade = cld_def->getDoubleValue("bottom-shade", 1.0);
			string texture = cld_def->getStringValue("texture", "cl_cumulus.rgb");

			SGNewCloud *cld = 
				new SGNewCloud(type,
					texture_root, 
					texture, 
					min_width, 
					max_width, 
					min_height,
					max_height,
					min_sprite_width,
					max_sprite_width,
					min_sprite_height,
					max_sprite_height,
					bottom_shade,
					num_sprites,
					num_textures_x,
					num_textures_y);
			layer->addCloud(newpos, cld);
		}
	}
}

void FGClouds::buildLayer(int iLayer, const string& name, double alt, double coverage) {
	struct {
		string name;
		double count;
	} tCloudVariety[20];
	int CloudVarietyCount = 0;
	double totalCount = 0.0;
        
	SGPropertyNode *cloud_def_root = fgGetNode("/environment/cloudlayers/clouds", false);
	SGPropertyNode *box_def_root   = fgGetNode("/environment/cloudlayers/boxes", false);
	SGPropertyNode *layer_def_root = fgGetNode("/environment/cloudlayers/layers", false);
        SGCloudField *layer = thesky->get_cloud_layer(iLayer)->get_layer3D();
	layer->clear();
        
	// If we don't have the required properties, then render the cloud in 2D
	if ((! clouds_3d_enabled) || coverage == 0.0 ||
		layer_def_root == NULL || cloud_def_root == NULL || box_def_root == NULL) {
			thesky->get_cloud_layer(iLayer)->set_enable3dClouds(false);
			return;
	}
        
	// If we can't find a definition for this cloud type, then render the cloud in 2D
	SGPropertyNode *layer_def=NULL;
	layer_def = layer_def_root->getChild(name.c_str());
	if( !layer_def ) {
		if( name[2] == '-' ) {
			string base_name = name.substr(0,2);
			layer_def = layer_def_root->getChild(base_name.c_str());
		}
		if( !layer_def ) {
			thesky->get_cloud_layer(iLayer)->set_enable3dClouds(false);
			return;
		}
	}
        
	// At this point, we know we've got some 3D clouds to generate.
	thesky->get_cloud_layer(iLayer)->set_enable3dClouds(true);

	double grid_x_size = layer_def->getDoubleValue("grid-x-size", 1000.0);
	double grid_y_size = layer_def->getDoubleValue("grid-y-size", 1000.0);
	double grid_x_rand = layer_def->getDoubleValue("grid-x-rand", grid_x_size);
	double grid_y_rand = layer_def->getDoubleValue("grid-y-rand", grid_y_size);
	double grid_z_rand = layer_def->getDoubleValue("grid-z-rand");

	for(int i = 0; i < layer_def->nChildren() ; i++) {
		SGPropertyNode *acloud = layer_def->getChild(i);
		if( strcmp(acloud->getName(), "cloud") == 0) {
			string cloud_name = acloud->getStringValue("name");
			tCloudVariety[CloudVarietyCount].name = cloud_name;
			double count = acloud->getDoubleValue("count", 1.0);
			tCloudVariety[CloudVarietyCount].count = count;
			int variety = 0;
			cloud_name = cloud_name + "-%d";
			char variety_name[50];
			do {
				variety++;
				snprintf(variety_name, sizeof(variety_name) - 1, cloud_name.c_str(), variety);
			} while( box_def_root->getChild(variety_name, 0, false) );

			totalCount += count;
			if( CloudVarietyCount < 20 )
				CloudVarietyCount++;
		}
	}
	totalCount = 1.0 / totalCount;
        
	for(double px = 0.0; px < SGCloudField::fieldSize; px += grid_x_size) {
		for(double py = 0.0; py < SGCloudField::fieldSize; py += grid_y_size) {
			double x = px + grid_x_rand * (sg_random() - 0.5) - (SGCloudField::fieldSize / 2.0);
			double y = py + grid_y_rand * (sg_random() - 0.5) - (SGCloudField::fieldSize / 2.0);
			double z = grid_z_rand * (sg_random() - 0.5);
                        
			if (sg_random() < coverage) {
				double choice = sg_random();
    
				for(int i = 0; i < CloudVarietyCount ; i ++) {
					choice -= tCloudVariety[i].count * totalCount;
					if( choice <= 0.0 ) {
						sgVec3 pos={x,z,y};

						buildCloud(cloud_def_root, 
							box_def_root, 
							tCloudVariety[i].name, 
							pos, 
							layer);
						break;
					}
				}
			}
		}
	}

	// Now we've built any clouds, enable them and set the density (coverage)
	//layer->setCoverage(coverage);
	//layer->applyCoverage();
	thesky->get_cloud_layer(iLayer)->set_enable3dClouds(clouds_3d_enabled);
}

void FGClouds::buildCloudLayers(void) {
	SGPropertyNode *metar_root = fgGetNode("/environment", true);

	//double wind_speed_kt	 = metar_root->getDoubleValue("wind-speed-kt");
	double temperature_degc  = metar_root->getDoubleValue("temperature-sea-level-degc");
	double dewpoint_degc	 = metar_root->getDoubleValue("dewpoint-sea-level-degc");
	double pressure_mb		= metar_root->getDoubleValue("pressure-sea-level-inhg") * SG_INHG_TO_PA / 100.0;

	double dewp = pow(10.0, 7.5 * dewpoint_degc / (237.7 + dewpoint_degc));
	double temp = pow(10.0, 7.5 * temperature_degc / (237.7 + temperature_degc));
	double rel_humidity = dewp * 100 / temp;

	// formule d'Epsy, base d'un cumulus
	double cumulus_base = 122.0 * (temperature_degc - dewpoint_degc);
	double stratus_base = 100.0 * (100.0 - rel_humidity) * SG_FEET_TO_METER;

	for(int iLayer = 0 ; iLayer < thesky->get_cloud_layer_count(); iLayer++) {
		SGPropertyNode *cloud_root = fgGetNode("/environment/clouds/layer", iLayer, true);

		double alt_ft = cloud_root->getDoubleValue("elevation-ft");
		double alt_m = alt_ft * SG_FEET_TO_METER;
                string coverage = cloud_root->getStringValue("coverage");
                
		double coverage_norm = 0.0;
		if( coverage == "few" )
			coverage_norm = 2.0/8.0;	// <1-2
		else if( coverage == "scattered" )
			coverage_norm = 4.0/8.0;	// 3-4
		else if( coverage == "broken" )
			coverage_norm = 6.0/8.0;	// 5-7
		else if( coverage == "overcast" )
			coverage_norm = 8.0/8.0;	// 8

		string layer_type = "nn";
		if( coverage == "cirrus" ) {
			layer_type = "ci";
		} else if( alt_ft > 16500 ) {
//			layer_type = "ci|cs|cc";
			layer_type = "ci";
		} else if( alt_ft > 6500 ) {
//			layer_type = "as|ac|ns";
			layer_type = "ac";
			if( pressure_mb < 1005.0 && coverage_norm >= 0.5 )
				layer_type = "ns";
		} else {
//			layer_type = "st|cu|cb|sc";
			if( cumulus_base * 0.80 < alt_m && cumulus_base * 1.20 > alt_m ) {
				// +/- 20% from cumulus probable base
				layer_type = "cu";
			} else if( stratus_base * 0.80 < alt_m && stratus_base * 1.40 > alt_m ) {
				// +/- 20% from stratus probable base
				layer_type = "st";
			} else {
				// above formulae is far from perfect
				if ( alt_ft < 2000 )
					layer_type = "st";
				else if( alt_ft < 4500 )
					layer_type = "cu";
				else
					layer_type = "sc";
			}
		}
                
		buildLayer(iLayer, layer_type, alt_m, coverage_norm);
	}
}

void FGClouds::set_3dClouds(bool enable)
{
  if (enable != clouds_3d_enabled) {
    clouds_3d_enabled = enable;
    buildCloudLayers();
  }
}

bool FGClouds::get_3dClouds() const {
  return clouds_3d_enabled;
}